COST C16
Improving the Quality of Existing Urban Building Envelopes
FACADES AND ROOFS
Research in Architectural Engineering Series Volume 5 ISSN 1873-6033 Previously published in this series: Volume 4. R. di Giulio, Z. Bozinovski and L.G.W. Verhoef (Eds.) COST C16 Improving the Quality of Existing Urban Building Envelopes – Structures Volume 3. E. Melgaard, G. Hadjimichael, M. Almeida and L.G.W. Verhoef (Eds.) COST C16 Improving the Quality of Existing Urban Building Envelopes – Needs Volume 2. M.T. Andeweg, S. Brunoro and L.G.W. Verhoef (Eds.) COST C16 Improving the Quality of Existing Urban Building Envelopes – State of the Art Volume 1. M. Crisinel, M. Eekhout, M. Haldimann and R. Visser (Eds.) EU COST C13 Glass and Interactive Building Envelopes – Final Report
COST C16
Improving the Quality of Existing Urban Building Envelopes
FACADES AND ROOFS
edited by: Luís Bragança Christian Wetzel Vincent Buhagiar Leo G.W. Verhoef
IOS Press
© 2007 IOS Press and the Authors. All rights reserved ISBN 978-1-58603-737-6 Published by IOS Press under the imprint Delft University Press Publisher IOS Press BV Nieuwe Hemweg 6b 1013 BG Amsterdam The Netherlands tel: +31-20-688 3355 fax: +31-20-687 0019 e-mail:
[email protected] www.iospress.nl www.dupress.nl LEGAL NOTICE The publisher is not responsible for the use which might be made of the following information PRINTED IN THE NETHERLANDS
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Table of Contents Preface L.G.W. Verhoef
vii
Introduction V. Buhagiar
1
Summary V. Buhagiar
3
Country Contribution Papers Technical Improvement of Housing Envelopes in Cyprus P. Lapithis, Ch. Efstathiades, G. Hadjimichael
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Technical Improvement of Housing Envelopes in Denmark T. Dahl, E. Melgaard, J. Engelmark
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Technical Improvement of Housing Envelopes in France D. Groleau, F. Allard, G. Guarracino, B. Peuportier,
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Technical Improvement of Housing Envelopes in Germany Ch. Wetzel, F.U. Vogdt
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Technical Improvement of Housing Envelopes in Hungary A. Zöld, T. Csoknyai
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Technical Improvement of Housing Envelopes in Italy S. Brunoro
69
Technical Improvement of Housing Envelopes in the F.Y.R. of Macedonia S. Trpevski
83
Technical Improvement of Housing Envelopes in Malta V. Buhagiar
95
Technical Improvement of Housing Envelopes in Poland Z. Plewako, A. Kozáowski, A. Rybka
103
Technical Improvement of Housing Envelopes in Portugal L. Bragança, M. Almeida, R. Mateus
115
Technical Improvement of Housing Envelopes in Slovenia M. Sijanec Zavrl, J. Selih, R. Zarnic
127
Technical Improvement of Housing Envelopes in The Netherlands Ch. M. Ravesloot
139
vi
Comparison of Design Criteria Comparison of Design Criteria Ch. Wetzel
153
Annex COST C16 Management Committee
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COST C16 Working Group Members
171
vii
Preface
In front of you lies one of the four books produced within the scope of Action C16 “Improving the quality of existing urban building envelopes” which started as a COST UCE programme. The acronym ‘COST’ stands for European COoperation in the field of Scientific and Technical research, and falls under the Urban Civil Engineering Technical Committee (UCE). The main characteristic of COST is a ‘bottom-up approach’. The idea and subject of a COST Action comes from the European scientists themselves. Participation is open to all COST countries but only those countries that wish to participate in an Action do so. As a precursor to advanced multidisciplinary research, COST has a very important role in building the European Research area (ERA), anticipating and complementing the activities of the Framework Programmes, acting as a bridge between the scientific communities of emerging countries, increasing the mobility of researchers across Europe and fostering the establishment of large Framework Programme projects in many key scientific domains. It covers both basic and applied or technological research and also addresses issues of a pre-normative nature or of societal importance. The organisation of COST reflects its inter-governmental nature. Key decisions are taken at Ministerial conferences and also delegated to the Committee of Senior Officials (CSO), which is charged with the oversight and strategic development of COST. The COST Action C16 “Improving the quality of existing urban building envelopes” is directed to multi-storey residential blocks from the period after World War II, especially those built during the period when the need for housing in Europe was at its greatest. That is why the COST Action C16 focussed on the period 1950 to 1980. We found it necessary to propose this Action after the completion of Action C5 “Urban heritage/building maintenance”. According to studies carried out by Action COST C-5, the estimated value of the European Urban Heritage amounts to about 40 trillion Euro (1998 prices) for the housing stock alone. The same research indicated the differences between the countries of the EU as well as what they have in common. The age profile of the building stock of a country like the Netherlands differs from that of the UK. Of interest too, are the costs of maintenance, renovation and refurbishment of the building stock. For the EU as a whole, this amount is about 1 trillion Euros per year (1998 prices). At the same time the three ‘Building Decay Surveys’ issued by the Federal Government of Germany that were based on systematic, scientific building research projects, indicated that 80% of all building decay is found in urban building envelopes (roof, walls, foundation). There are elements in the building stock that are common to the countries in Europe. These include: Most of the buildings were completed after 1950. For a country like the Netherlands this means 75% of the existing buildings. The maintenance costs are mainly incurred in urban building envelopes, The renovation of buildings and reconstruction to provide an improved or different range of use will influence the building envelope, The quality of the building envelope very often fails to meet current demands and will certainly not meet future demands.
viii An important conclusion deriving from the points mentioned above is that however important maintenance may be, it does not lead to the desired improvement in the quality of urban building envelopes. Improvement of the quality of urban building envelopes must be the real task. Such improvement requires the development of new and suitable strategies for local authorities, housing corporations and owners and also architects and civil engineers. Until now integrated engineering aspects have been disregarded in this process. In many European countries new technologies have been developed, but these have either not yet been translated into practice, or have been only locally used to achieve a higher quality in urban buildings. This results in a limited impact on urban environments. Therefore it is essential to bring all kinds of local solutions together, to learn from these and to find a more general approach that can be used for building systems. Often problems and their solutions are approached in isolation. The wish to improve the quality of an individual building envelope usually leads to a local, project-based solution. Solving the specific problems of this renovation-project becomes the sole target. To reach maximum value for money, it is essential to integrate all the factors influencing urban building envelopes and look at them in a broader scope. As a result of changes in the composition of the population, society continuously changes with respect to various factors including age-structure, family composition and the availability of energy. Changes lead to situations that are reflected in the commissioning of buildings, which is gradually shifting from new construction to the reuse and renovation of existing buildings that often requires the modification of their facades. Even when buildings may still be functionally satisfactory, there may be external factors, such as the dullness of the image that they summon up or their poor technical quality, that require that attention should be paid to the shell of the building. There are many reasons why buildings may no longer be adequate. Failure to satisfy current demands may be expressed in lack of occupancy and further deterioration of the neighbourhood. This establishes a vicious circle, which can and must be broken. All too quickly discussions turn to demolition and new development, without prior investigation of the reasons for the situation. From an economic point of view, renovation and the reuse of buildings, which takes into consideration the technical and spatial functions and also the urban and architectural aspects, often appears to provide a better solution. The aim of the COST Action C16 is to improve techniques and methods used to adapt the envelopes of buildings constructed during the second half of the 20th century in the COST countries. These ‘non-traditional buildings' were constructed from in situ poured concrete systems, large scale prefabricated systems and/or small concrete/mixed elements although in some countries brick or stone was still used. The demand for housing in the post-war period necessitated the rapid production of large numbers of dwellings. Qualitative aspects were less important. Furthermore dwellings of the types constructed at that time no longer fulfil contemporary or anticipated future demands for housing, with the possible exception only of those built during the last 5 years. At this stage, it must be noted that two other ongoing Actions in the field of Urban Civil Engineering, also address issues related to buildings: COST Action C12 on “Improving buildings’ structural quality by new technologies”; and COST Action C13 on “Glass and interactive building envelopes”. The Technical Committee on Urban Civil Engineering considers that in addition to the tasks directly connected to the main objective of their Action, participants in the COST Action on “Improving the quality of existing urban building envelopes” should establish and maintain close contacts with the two above mentioned Actions. This will foster co-operation with these Actions and avoid potential overlaps. About one year after the start of COST Action C16, it was put on a hold for more than 8 months, to permit the ‘renaissance’ of the COST programmes, while in the meantime COST C12 had almost ended and it was considered that the C13 Action had only a slight connection
ix with the targets of COST C16. The CSO therefore agreed with the request of the Management Committee that the end of this Action should also be postponed by 8 months so that it would still last for the planned duration of four years. SCIENTIFIC PROGRAMME To date problems relating “Urban Building Envelopes” and their solutions are approached in isolation. The original design planners, architects and engineers work together to realise a building according the current state of knowledge, but this co-operation longer exists during the lifecycle of the building. For far too long prolongation of the occupation by the use of maintenance was sole aim. If improvement did become an option only a few aspects were considered. At present the current state of knowledge is usually local, being concentrated in some of the housing co-operations, architectural and engineering companies. However much has been done to spread this information in order to initiate discussion about when and how existing buildings with their envelopes can be improved to fit them for the future. The COST mechanism will foster international concentration on the integrated problems related to non-traditional dwellings. It will create a direction for improvement of urban building envelopes and also illustrate the state of the art in the various countries concerned.. What has already been learned in one country can now easily be shared or can be translated to fit the needs of other countries. His will make the implementation of new practices much easier. The World Wide Web will be used to bring all the information on the major non-traditional housing systems in Europe together as well as the various techniques for the improvement of urban building envelopes. We are happy to announce that for the first time since the establishment COST, it has become possible not only to publish books but to place the information on the World Wide Web. See www.costc16.org. High schools and universities interested in the subject of the renovation of existing buildings can now have east access to this knowledge. This study was based on the following scientific programme: Description and analysis of the types of system related to the factors influencing urban building envelopes; Analysis and comparison of the legislation and technical regulations relating to renovation in European countries; Analysis of how urban building envelopes have been changed to date in relation to relevant factors; A survey of existing engineering techniques that can be used, modified or developed to reach this goal; A synthesis of possible global approaches leading to guidelines on how to reach maximum value for money in relation to the desired quality and working conditions in the urban environment and also how this approach can be reached for other types of buildings. THE SCHEME OF THE APPROACH OF ACTION C16 The original idea given in the technical annex of the Action was to start with a preliminary approach lasting six months. After that, three working groups would be set up on the themes of: the current envelopes, the needs and the techniques. A period of three years was allocated for this. The last six months of this period would have been used to integrate the result of the working groups and to prepare the final international symposium. As stated above, one year after the start of the Action C16, together with other Actions, was placed on hold, because of the reorganisation of the COST organisation to create an umbrella organisation. At the beginning of 2004, on the basis of the contract between the European Science Foundation and the European Commission for the Support of COST, this reorganisation started with the establishment of the fully operative COST office in Brussels.
x This delay caused to loss of some momentum. A second problem that had to be solved was that the members of C16 came from a variety disciplines and included structural engineers, architects and physicians. Although an interdisciplinary approach is one of the targets of a COST Action, this did give rise to problems in the working group on techniques. For example bearing structures demand a different specialisation from that required for secondary elements, such as facades and roofs. The management committee was wise in its decision to split the Techniques Working Group into a working group on structures and a working group on facades and roofs. THE METHODOLOGY The methodology used for the work of the four working groups of the Action C16 “Improving the quality of existing urban building envelopes” differs. The first book entitled ‘The state of the art’ is divided into two parts. The first part comprises a survey on the housing stock for each country. It contains data related to the building period, main typology and technologies. In the second part the topics covered describe the quality of the housing stock. The ‘state of the art’ depends on the time at which a survey takes place. That is why we consider it an advantage to also publish the two keynote lectures in this first book. These describe approaches to the modification of the multi storey family stock that is currently under investigation. In the second book, ‘The needs’, the method used to obtain precise information was to develop a table that includes the needs, solutions and priorities for each country. It is evident that these needs and priorities will differ greatly from country to country, as illustrated for example by comparing Sweden to Malta. To determine these aspects, criteria such as land use, architectural aspects and building physics are used, as well as aspects relating to finance and management. In the third book, ‘Structures’, a framework for possible solutions has been set up. It contains 20 case studies in which changes in bearing structures to fit for future purposes was the goal. Examples include descriptions of how to build extra floors onto existing buildings for both financial reasons and also to make the installation of elevators more profitable.. Another example illustrates the need for greater flexibility, and shows how a part of the bearing structure can be changed to provide this. In the fourth book, ‘Facades and roofs’, which is based on the results of the working groups’ The state of the art’ and ‘Needs’, two documents have been developed, ‘Technical Improvement of housing Envelopes’ and ‘Country Criteria in the form of a matrix’. Relations between the most frequently used refurbishing solutions and their impact on sustainability have been worked out in depth. Sustainability is described in a set of performances such as, technical, economic, functional/social and environmental. Case studies illustrate these theories. Together these books provide much information and can help countries and people to learn from each other. It is my wish that that you will all profit from their content. Leo G.W. Verhoef (Chairman COST Action C16) April 2007
Introduction V. Buhagiar Faculty of Architecture and Civil Engineering, University of Malta, Malta.
The main goal of the Working Group 3B (WG3B) of the COST Action C16 was to study the different technical possibilities to retrofit the functional requirements of the multi-storey housing building envelopes of European buildings built after the II World War. This work is based on the State-of-the-Art documents and on the needs of such buildings that were identified by Working Group 2. For the output of the WG3B was possible to gather the contribution of 14 different European countries: Cyprus, Denmark, France, Germany, Greece, Hungary, Italy, Macedonia, Malta, The Netherlands, Poland, Portugal, Slovenia and Sweden. The output of the scientific work that was carried out by each participant country on the context of this working group is set through two types of documents, organized in two Chapters: Technical Improvement of Housing Envelopes and Country; Comparison of Design Criteria. In order to facilitate the comparison between countries and the interpretation of data, a format for each type of document was created to guide the authors. The contributions from all EU member states represented in this workgroup, numbering eleven countries, are now complied. Each paper describes the different aspects of an exterior refurbishment in the respective country, under a standard list of headings, namely the technical, functional, social performance, economical performance and the environmental performance of the building after a façade or roof retrofit. It is worth highlighting that this COST C16 action was not based on a research-funded initiative and hence no pure research was carried out. However members to all workgroups were experienced hands-on practitioners, bringing in their own ‘baggage’ of knowledge through private research and a wealth of experience in the respective fields of architecture, engineering or building physics, thus enriching the workgroups through dissemination of knowledge. It was for this reason that a screening process is typically carried out for the selection of national delegates, through the respective country’s COST Office and scientific officers. The papers are the fruit of all this. Although some papers may be describing practical standard methods for technical improvements in the building envelope, these are by no means to be considered as prescriptive for a quick-fix solution, as every case needs to be studied separately on its own merit. Further details on each paper may be obtained through direct contact with the author, whose details may be retrieved from the cost web site, under the respective workgroup or Institution. The aim of Chapter “Technical Improvement of Housing Envelopes” is to present the main problems in multi-storey building envelopes of each country and to present the main technical solutions that are being adopted to overcome those problems. The format consists in four parts: In the first part the most relevant problems in the envelopes and the most used retrofitting solutions are identified;
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Introduction
The second part resumes the technical specifications of the most used refurbishing solution; In the third part the document presents the impact of the most used refurbishing solution on the sustainability topics. The sustainability topics are divided in technical performance, economic performance, functional/social performance and environmental performance; At the end, each document presents a case study about a real example related to the adoption of the refurbishing solution that was presented.
The impact of the most commonly used refurbishment actions was studied under the point of view of the several aspects of the envelope performance as follows: Technical performance - stability, capacity, earthquake resistance, fire protection, noise insulation, weather protection, moisture protection, conductivity, heat flow, radiation, convection and durability (service life); Functional and social performance - flexibility, comfort (thermal, acoustical, visual), health (air quality, VOCs, mould & fungus growth), safety, barrier free, etc.; Economical performance - building costs and running costs (heat losses, cooling, cleaning, inspection, maintenance, etc.); Environmental performance - use of resources (non renewable, renewable), energy consumption for heating/cooling (non renewable, renewable), environmental impacts (global warming potential, acidification potential, nitrification potential, eutrophication potential, ozone depleting potential, photochemical ozone creation) and waste. In spite of the differences found between countries, the analysis of the documents shows that one of the most used solutions to refurbish the multi-storey housing European buildings is to coat the existing façades with an external thermal insulation composite system (ETICS). Comparing the different documents it is possible to identify and compare the technical differences and the impact on the sustainable topics of the different solutions. The aim of Chapter “Comparison of Design Criteria” is to compare the design criteria used in each participating country. For that purpose a Country Criteria Matrix was established on the basis of a survey carried out in each country. The Country Criteria Matrix is a table that summarizes the actual thermal requirements and some proprieties of the current building envelopes (façades and roofs). The comparison of the design criteria is organized in four parts: The first part starts with a survey on the climate and on the thermal requirements of each country’s legislation; The second part reports about the current solutions found in the façades of the buildings and the most used solutions used to refurbish it; The third part deals with the same issues as the second part but for roofs; The comparison ends with a survey about the adoption of the new European Energy Performance of Buildings Directive in the participating countries. From the analysis of the results interesting salient features were highlighted and it is also possible to verify that not all aspects could be applied to every country and some aspects were interpreted differently. Another relevant aspect is that there are huge differences between the current technical solutions observed in the participant countries, mainly between those that were and were not involved on the II World War and between Mediterranean and Northern countries. Finally, and as concluding remarks, WG3B was an excellent forum of exchanges between experts in separate disciplines which complement each other in the integration of technologies for the improvement of envelopes in view of higher living quality in urban environment. The results achieved can have direct positive impact on the environment through the savings on material and energy consumption and the possibilities for dismantling and recycling. Expertise on each of WG3B topics exists in all European countries, but until now no integrated knowledge was available. In this context the COST scheme was the ideal platform to gather a multidisciplinary team to integrate new technologies in the field of the renovation of urban buildings envelopes and to disseminate understanding and knowledge.
Summary V. Buhagiar Faculty of Architecture and Civil Engineering, University of Malta, Malta.
In post-war Europe, the main thrust behind residential building projects was for every country to provide social low-rent housing in most job-depressed cities. This was every government’s moral obligation. This building activity brought with it the fast track, low-cost pre-fabricated concrete structures and loose masonry or composite steel construction, all oblivious to upcoming social needs, rapid advances in construction technology and the importance of energy efficiency in buildings. Since the 1950s and 1960s such problems had not yet emerged. However with the onset of the energy crisis in the 1970s a greater energy consciousness emerged, not for environmental motives but moreover for diminishing the added financial burden for social low to middle income earners. Between 1980 and 2000 a wave of refurbishment projects went through Europe, especially with the enlargement of the European Union, which saw an increase from 15 to 27 member states (2007), thus increasing the importance of energy conservation in a more sustainable unified approach, through quasi-streamlined solutions and legislation. This prompted the need for a concerted awareness of common problems, through a state of the art assessment, prompting needs and the ensuing structural and environmental solutions towards this goal. This C16 COST action purports to achieve just that. Through its four workgroups, these four books are the product of its work package output, over four years. Although not a research based action, COST C16 pulls together a whole baggage of experience and individual research initiatives of each member put together in these four volumes. The fourth workgroup, namely 3B, sums up the possible technical solutions for an energy conscious, cost-sensitive refurbishment of the urban building envelope. Today this encompasses both private and social housing, on both a minor and major scale. Solutions vary from innovative technological solutions, or the now established ETICS (exterior thermal insulation composite systems) to simple projections and attic insulation. Solutions vary from country to country across the enlarged European Union. It is perhaps in the spirit of this union that these solutions needed to be brought together in this book, one of four in the series, summing up the end product of four years’ hard work of the C16 COST action. This fourth and last book is perhaps the first ever collated set of technical solutions in one volume. An overview summary of each chapter, country by country is now given. COUNTRY CONTRIBUTION PAPERS Cyprus This contribution highlights the main problems associated with the building envelopes in Cyprus and current standards applicable for existing buildings. Since most buildings in Cyprus are constructed with little or no insulation, this results in a greater summer and winter discomfort, attracting the associated energy demands for cooling and heating respectively. A description of the most commonly used refurbishment options for standard envelopes are tabulated and discussed, followed by multi-faceted recommendations for the technical, functional, social, eco-
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Summary
nomical and environmental aspects of existing building stock. Finally application methods are described through two different case studies, one on an existing energy efficient refurbishment and another highlighting the potential for energy efficiency through passive solar architectural design. Denmark The increasing demand for energy conservation, decay of building materials, alternative methods of façade construction, leaking roofs and water penetrating vertical cladding have all prodded the need for major refurbishment jobs to post-war housing stock in Denmark, as highlighted in this contribution. The Danish way of renovating is however multifaceted. There is not a single or a general method or technology. The original external walls can be divided in three different types of construction: traditional masonry cavity walls, the industrialised concrete sandwich wall and the lightweight wooden façade system with plates or boards of wood, fibrecement or any other materials used as cladding. The general problems are most significant for the non-traditional built external walls, and they are most commonly renovated by adding an external secondary lightweight construction with extra insulation and new cladding, which might be with or without ventilation behind. The paper gives a general description of the performance of such systems illustrated through two case studies demonstrating renovation of sandwich and lightweight constructions respectively. France The country’s paper highlights the fact that the improvement of housing envelopes can play
an important role to change the image of such a building with its users and external environment. Internally, these same blocks are also changed with such a refurbishment exercise. With all this in perspective, since 1980 in France, rehabilitation of façades has been one of the predominant measures applied to externally modify the image of the building without disturbing tenants’ lifestyle. Aesthetics apart, from a technical aspect, the main technique used consists of applying an external modern skin to the existing façade, including thermal insulation. This naturally offers numerous technical and functional advantages over existing cladding or load bearing wall systems. Such changes however do not come without side-effects: an increase in indoor temperatures was noted, as well as a change in habitat and use of spaces by tenants. Although occupants are first sceptical about such retrofitting, the paper highlights the importance of involving all stakeholders from day one, namely building consultants, municipalities and residents, highlighting that the effects of such changes will only be felt over a period of time. The true success of a retrofitting operation is strongly dependant on the quality level of implementation and degree of acceptance of each project. Germany The paper outlines the motive behind energy efficient refurbishment of façades in Germany: this was sparked off by the first ever legislation for energy efficient construction in 1985. This specified stringent heating insulation requirements for new buildings (circa 88 % of today’s stock) while the remaining12% of existing stock were considered as having ‘sufficient’ insulation levels. However if a refurbishment job is undertaken, and if more than 25% of the existing cladding of the building façade has to be removed, then the whole new façade had to reach a U-value lower than 0.4 W/m²K. This brought about the need for ETICS (External Thermal Insulation Composite Systems), where out of this necessity a thick layer of around 12-15cm insulation was needed to reach this U-value. The paper deals with a novel way of recycling and re-use of such insulation materials for a different type of ETICS.
Summary
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Hungary Considering that heating energy consumption stands at 150-220 kWh/m2year, the thermal performance of post-war social housing stock is unacceptable by today’s standards. This is attributed to the post-war need for rapid speed of construction, use of prefabrication elements and poor detailing culminating in today’s energy wastage. Moreover in early post-war days (194050s) energy costs were only 1% of today’s figures. The principal problems found in early social housing in Hungary are associated with poor thermal performance: thermal bridges, bad whether proofing and lack of air-tightness combined with related fabric damages. This resulted in high operational costs and a low standard of living. Uncontrollable heating systems increased energy wastage. Although several implemented initiatives were not so successful in the last decade due to false pretexts on payback periods, today successful demonstration projects prove the energy saving potential from such retrofits. This is demonstrated through a quality case study. Italy The main problems associated with Italian building envelopes are the lack of thermal and acoustic insulation and the poor quality of the windows (single-glazed windows and window frames with low air-tightness). The lack of performance and the consequent inability to make use of the climatic resources cause a high level of heat loss in winter and overheating in summer. The use of a ventilated façade in the refurbishment and upgrading of existing buildings is recommended in a wide variety of scenarios. The procedure must be carefully designed and planned in order to evaluate which will be the most appropriate and successful solution. Examples of ETICS and novel construction materials – through detailed case studies – demonstrate that a specific design, relating in particular to the individual situation can be beneficial to both the technical and architectural quality of the building with reasonable costs and positive environmental effects. F.Y.R. of Macedonia Buildings consume a large slice of the energy consumption of Macedonia, as elsewhere. The paper highlights the potential for energy savings in the residential and tertiary sectors. Given the low turn-over rate of buildings (lifetime of 50 to more than 100 years) it is clear that the largest impact for improving energy performance in the short and medium term is in the existing building stock. Major renovations of existing buildings (above a certain size) are regarded as an opportunity to take cost effective measures to enhance energy performance by meeting minimum energy performance standards tailored to the local climate. Over the past 20-25 years, in many cases standards have been reinforced two to four times, including some very recent revisions. Towards this aim, for façade refurbishment, the most appropriate technical solution is selected called “Externally Insulated Façade System”- EIFS (similar to ETICS). An important case study in Skopje manifests its application. Malta The principal problem of residential building envelopes in post-war Malta is that there was never a deliberate effort to use insulation in cavity walls, be it for thermal or acoustic performance. However there was always a concern for moisture isolation by the use of cavity walls against rain penetrating the external porous limestone skin and using a damproof course to isolate the lower damp foundations from the rest of the building. In all fairness there is no real extensively designed façade refurbishment in Malta, which is purposely designed for energy efficiency, particularly in the housing sector. As from 2007, with the introduction of the new building regulations (part F), the enforceable legislation has made it mandatory for walls and flat roofs to reach a certain U-value, albeit even if still considered lenient. In government housing projects there have never been any new energy conscious design or refurbishments to social housing blocks, except for one new project in Birkirkara, a first of its kind for Malta, executed in 2005 by the author.
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Summary
Poland The idea of External Thermal Insulating Dry System (ETIDS) consists of adding insulation sheets to an existing façade, covered by an external cladding panel, supported with a structural frame, and fixing it to original wall structure. Although the system was developed as an original idea, it was based on commonly available materials. It was especially dedicated to improve the thermal insulation of pre-cast external walls in large panel building technologies – the most popular technology of multi dwelling building in Poland. This paper presents one of the first popular technologies widely used in Poland for upgrading the thermal resistance of façades in multi-family housing buildings, made with the use of a non-traditional technology. As a reaction to more strict control over energy consumption, it became popular in the 1980s due to its material and technological simplicity resulting in relatively low construction costs. Description of this system contains basic data of system elements, installing technology, details and performance with pointed out impact of the refurbishment action with ETIDS system on sustainability topics. Specification of ETIDS is complemented with examples of typical applications. Portugal The paper highlights the main problems in multi-storey post-war building envelopes, namely the low thermal insulation and low airborne sound insulation. Today the most used refurbishing solutions for vertical envelopes are: the External Thermal Insulation Composite Systems (ETICS), the Ventilated Façades and the replacement of existing windows by double glazed and low air permeability ones. In this paper, the potential of the ventilated façade as a refurbishing solution, mainly for buildings built after the 70’s, is assessed. Façades built in this period do not fulfil actual users’ comfort standards and construction codes. It was therefore necessary to find the most appropriate technical solutions to refurbish such façades. This paper evaluates the impacts of this technical solution in standard envelopes, analysing the data available, and compares it with data from other technical solutions, weighting the different dimensions according to local constrains and the objectives of the project. The paper also highlights the possibility to evaluate the sustainability of the ventilated façade as a solution to improve conventional façades. Slovenia: The social housing stock built between 1946-1970 had no thermal insulation, possibly with double glazed box windows, but since the 1970s early thermal insulation materials were introduced. Nowadays, these buildings offer significant energy saving potential and often need repair because of inadequate maintenance. Since Slovenia is an earthquake prone zone interventions in envelopes in many cases comprise also additional strengthening of the structure. Recently (2002), national legislation imposed some obligatory measures on envelope refurbishment, which are however supported by subsidies for energy efficiency. Although there are different technical solutions for envelope insulation improvement, the most frequently applied is the external thermal insulation system where a thin layer of plaster is used, accompanied with multi-chamber PVC windows with low-e double glazing. The durability of a thin layer plaster ETICS may not be as high as in case of ventilated insulation system, but this limitation can be compensated with far lower investment costs. To overcome the general financial barriers for renovation of building envelopes for major renovation, State subsidies are made available, if specific energy efficiency targets are met. A well-detailed recent case study reflects today’s correct contemporary approach toward such a refurbishment. The Netherlands This final contribution identifies typical problems in post-war building stock as being the lack of thermal comfort, loss of functionality of the floor plan and social deterioration of the neighbourhood. Changes of the dwellings in such housing complexes include energy saving measures, alteration of the floor plan functionality in more differentiated housing types and upgrade of socio-economic services in the immediate neighbourhood of high rise housing complexes. Technical improvements are not that difficult to make, considering that the standard in comfort, energy saving and functionality of the floor plan for newly built houses has been proven as being technically and economically feasible. The paper highlights the social dimension, namely the problem of shifting occupants, with their low-income budget and many differ-
Summary
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entiated expectations. In this paper the existing standard in functionality of dwellings in relation to comfort and energy saving was addressed. In contrast with established post-war low-rise housing stock, high-rise residential towers are also assessed for their socio-economic problems concerning the organisation of large scale renovation. Two exemplary case studies in the Amsterdam South-East Quarter and in the Delft Quarter of the Poptahof were elaborated to illustrate the practical meaning of improvement of comfort and energy saving in high rise building stock in The Netherlands. DESIGN CRITERIA & COUNTRY CRITERIA MATRIX Following the country contribution papers, design criteria are highlighted as one way how to read a set of parameters summarised in tabulated form, better known as the country parameters matrix. The salient features are pointed out in a brief summary at the end of the matrix, summing up chapter 3. Concluding remarks follow suite. CONCLUSION As typical in most of post-war depressed Europe, fast-track provision of social (low-cost) housing was the key to attracting settlement of families in job-depressed areas, superseding all other priorities. Each country had its own particular social needs, based on traditional state of the art building technology of the day. Today such needs prompted the challenge to take stock of what is recyclable en-mass and refurbish it in the light of its structural integrity and energy efficiency by today’s standards, to the tune of sustainability, for an improved quality of life for future generations.
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Technical Improvement of Housing Envelopes in Cyprus P. Lapithis Design Department, Intercollege, Nicosia, Cyprus
Ch. Efstathiades Lemesos, Cyprus
G. Hadjimichael Town Planning Department, Nicosia, Cyprus
ABSTRACT: The main problems in the building envelopes in Cyprus and the actual standards for existing buildings are being identified. The legislative, natural (climatic boundary conditions) and other influencing factors that lead to the standard solution are being described. Also descriptions of the most commonly used refurbishment actions standard envelopes are being discussed with recommendations on how to solve these problems. The impact of the most commonly used refurbishment actions are being described loooking at the technical, functional, social, economical and environmental on the existing buildings. Finally application methods are being described through two different case studies
1 INTRODUCTION 1.1 Standard envelopes in Cyprus Cyprus gained its independence in 1960 and was proclaimed a Republic. At the period 1960-73 Cyprus went through a fast and almost uninterrupted growth. Despite the breakdown, in the years 1974-75, due to the Turkish invasion and the occupation of 38% of its territory by military forces, the economy recovered soon after and a substantial growth has been achieved. In the years 1975-1993 Cyprus once again witnessed additional economic growth, accompanied by an expansion of social services. Today the people of Cyprus, who live in the Government controlled part of the country, enjoy a high level of education, low unemployment and a good standard of health care. 69% of the population is living in urban areas, which cover 9.6% of the island. The population in 2001, in the area controlled by the Cyprus Government, was 689.565. The total number of units was 286.000 in 2000. Almost 85.000 of these units were built in the period from 1960-1980. Out of the total number of units, nearly 60.000 are apartment blocks and 125, 000 are detached or semidetached houses. The average dwelling area is 189 m2 and the average construction cost is 568 Euros per m2 for the year 2000. The average number of persons per dwelling was 3.23 for 1992 and 3.06 for 2001. In addition to that the number of square meters per person was 49.5 for 1992 and 61 for 2001. Within the context of the housing policy for the refugees, the government of Cyprus has introduced various schemes and programs like the “Low Cost Government Housing Scheme” that provides houses free of charge to low-income families (5.6% of the total number of households were benefited from this scheme). In addition to that the government provides the “Self-help Housing Program on Government Land” (4.1% of the total number of households), the “Selfhelp Housing Program on Private Land” and the “Purchase of a House/Apartment Scheme”. COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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Technical Improvement of Housing Envelopes in Cyprus
In the private sector, development and construction companies offer in the free market various types of housing units, mainly apartment or terrace houses. This type of development satisfies nearly 30% of the total demand. A substantial number of families however, choose to build their own detached or semi-detached house, on an individual plot of land, which has an average surface of 520 m2 (68.2% of the total number of households have their own private housing units). Three categories of construction financing have been developed. In the first, a contractor undertakes the construction of the building. In the second, the owner of the property decides to play the role of the contractor-entrepreneur and undertakes the responsibility of constructing and financing the project. He/she usually sells or rents most of the apartments keeping one or two for him/her. In the third (the gradual method of construction), the owner of the property builds one housing unit for the present needs of his/her family, allowing for the possibility of constructing additional apartments in the future to cover the needs of the growing family or merely for investment reasons. The results of this practice are the following: Lack of planned connection between housing areas and other areas of the city (educational, commercial, etc). Mixed housing areas with industrial or other areas, dangerous for public health. Very limited green and open spaces within the housing areas. Bad relation between street width and building height. Different housing types even in the same street (large apartment blocks adjacent to low houses). Unplanned and often unhealthy interaction between the built and natural environment. Contemporary life and the building industry in Cyprus are greatly affected by the proliferation of apartment blocks in the large urban centres. The apartment house became the symbol of the final stage of urbanisation. And since urbanisation is for certain reason a preferable way of living for the contemporary Cypriot; the apartment model is extensively adopted even in medium size settlements in the countryside. 1.2 Requirements in Cyprus, that enforce a reaction to refurbish envelopes The Law (The Minister of the Interior is the Planning Authority), considering the kind of development, specifies the appropriate drawings and any other documents, certificates etc., which they have to be submitted with the application form to the Director of Town Planning and Housing Department and later on to the Municipal Council. Three main issues can be mentioned here. There is not any legal obligation to submit designs or calculations for thermal, acoustic, light and fire performance of a conventional building within the application form. Although civil engineering calculations have to be submitted at the building permit application process, these drawings are roughly checked and the responsibility for any structural failure remains on the civil engineer’s side. According to a recent regulation of 2000 all new constructions, renovations and generally any structure, have to be inspected by authorized engineers. Therefore inspections are compulsory for freelance practitioners, though are not compulsory for Responsible Authorities. For this very reason the enforcement of the Planning and Building laws, is not so effective. All building modifications require a “building permit” and moreover, the modifications that are regarded as “substantial” require an additional “planning permit” in advance. The specific provision is very vague and therefore depends on the discretion of the respective Town Planning Authorities, to judge whether a modification is substantial or not. The painting of a building for example does not require any permit, simply because is not regarded as a substantial modification. There are no specific data concerning maintenance, renovations, and modifications etc. of building envelopes. Indicative data however suggest that the average Cyprus family does not pay a lot of attention on these matters, that people extent as long as possible the various works needed and that they proceed to the necessary works, only when the performance of their building is intolerable, or dangerous looking always for the absolute minimum expense.
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No specific legislation was ever passed before 80’s concerning incentives for organized housing complexes. The only regulatory tools were the commonly used town planning restriction which concern plot ratio, plot coverage, maximum height, and maximum number of stories, a general aesthetic framework and some indirect density standards, concerning the minimum surface in relation to the size of housing units. This is actually the very reason that multi-story family buildings were very few till 80’s. Some sort of incentives for organized housing complexes up to three stories, were introduced in the revised statutory local plans in 2003. There are no specific regulations concerning architectural and functional aspects. The authority that is responsible for issuing the Planning Permit, decides whether a certain development rests within the environment of the surrounding area. There are however indirect density standards, concerning the minimum size of housing units. Practice however is much different especially as far as the aesthetic control is concerned. Problems also arise when dealing with the incorporation of small but vital structures, like solar panels, antennas etc. There are specific rules and regulations for new buildings and public uses according to which accessibility to people with special needs, including access ramps and larger toilets in the ground floors, must be provided. 2 SPECIFICATION OF THE TECHNICAL SOLUTION In general the typical housing construction system in Cyprus is based on the conventional construction system, quite common in this part of the Mediterranean Sea. The system comprises the use of reinforced concrete for the load bearing part of the building, which is completed by masonry walls. Prefabrication systems have rarely been used in the past, mainly by the Government in the construction of some low cost refugee estates in the late 70´s. So reinforced concrete, from foundations to the roof applies for the vast majority of the housing constructions. Preliminary regulations concerning the calculation of seismic loads were issued in the late 80´s and that detailed construction regulations were adopted in the beginning of the 90´s. Thus all the buildings built before, may sometime in the future, face possible seismic failure. There is a variety of foundations types according to the type and size of the structure. The most popular are the separate footings with connecting beams and the slab-foundation. The outer skin of a structure, is usually created by the reinforced concrete parts (for the load bearing structure) and a single layer of bricks, (200mm), both coated with three layers of plaster (20-25 mm) and a finishing layer of paint or sprits. The roofs are usually flat concrete slabs, which are covered with light concrete or screed of 50-100 mm for rain-drainage and on top with an asphalt layer of 2-5 mm for humidity insulation. The final touch is given by the use of reflective paints. The last 10-15 years some buildings appeared to form a different top finish with a complete or partial pitched roof. This is used not so much for insulation reasons, but rather for sales promotion reasons since it gives a touch of more domestic or more humane housing buildings. As far as windows are concerned, the vast majority of them are single glazed (4-5 mm) with aluminium frames whereas a small proportion of multi-story family houses, especially after 1980, used double glassed windows. 3 THE IMPACT OF THE MOST COMMONLY USED REFURBISHMENT ACTION ON SUSTAINABILITY TOPICS 3.1 Technical performance 3.1.1 Structural integrity Cyprus has already adopted five compulsory standards concerning the quality of cement, sand, gravel, concrete and brick. The enforcement of these standards lies on three Government bodies, which are, the Mines and Quarries Department, the Public Works Department and the Competition and Consumers Protection Service. It is worth mentioning that by the 1st of May 2004, Cy-
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prus became a full member-state in European Union, and therefore all the relative European standards (Euro-codes, etc.) have to be established in the respective case-law. 3.1.2 Fire protection The bearing structure and any stair of a prefabricated building should provide at least 1/2 an hour fire resistance. The “Cyprus Organization for the Promotion of Quality” chaired by the Ministry of Commerce Industry and Tourism plans to establish quality standards and enforce them as compulsory. 3.1.3 Noise Insulation The “Cyprus Organization for the Promotion of Quality” has already specified some recommended Noise insulation (for 500Hz in dB) Walls (45), Roof (45), slab between floors (50). 3.1.4 Weather and moisture protection The most habitual problem that Cyprus faces is the total absence of damp proofing and thermal insulation of the majority of the housing units. This has direct and severe implications on the energy consumption and the discomfort many people experience. In this case certain parts of the building envelopes, like the roofs and external openings, have to attract more of our attention than others. Besides that one could mention of course some other smaller problems like the moisture problems (due to substandard plumbing installations and poor ventilation) and the poor acoustic insulation (due to light building envelopes). Damp regularly appears in several elements of the buildings, causing surface stains, appearance of humidified and watered surface, color weathering and peeling, detachments, material decay, ruptures and cracks, oxidation of unveiled steel bars and mold formation. 3.1.5 Conductivity (U-value), Heat flow (g-value), radiation, convection The “Cyprus Organization for the Promotion of Quality” has already specified some recommended thermal insulation values for conventional buildings, which however are not compulsory. Thermal Insulation (U value in W/m2°K): Walls (1.7), Roof (2.0), Slab between floors (2.0). 3.1.6
Durability (service life)
No information available. 3.2 Functional / social performance 3.2.1 Flexibility In an attempt to evaluate some of the current housing habits in Cyprus, two questionnaires were compiled (Lapithis, 2002). From the outcome of both questionnaires, it transpired that most dwellings in Cyprus are constructed with little or no insulation and this is the most likely cause for the high percentage of summer and winter discomfort as well as noise complaints. Most other complaints stated (e.g. poor natural lighting) are the result of unsuccessful bioclimatically orientated design. All this suggests the need for better, more bioclimatically appropriate constructions, with adequate insulation and proper orientation with respect to the sun. A high percentage (69%) of the survey participants experience bothersome noises from the outside, probably as a result of poorly insulated wall surfaces and single glazing which not only allow heat enter and exit freely, but also allow noise to penetrate with little difficulty. A high percentage of the participants frequently felt cold in the winter (80%) and an even greater number feel warm in the summer (87%). There were complains about bothersome cold surfaces (70%). Another problem area, which can be minimized by proper passive design, is the need for artificial lighting (64%).
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Participants experience drafts from windows and doors (86%). An element of ventilation that can be exploited in a passive system, if it is designed properly. There is a need for a more widespread use of double-glazing windows in order to minimize moisture condensation on windows (65%), and for a better thermal and noise control. An interesting fact deduced from the survey is that the overwhelming majority of Cypriots feel safe in and around their house (91%), which makes it easier for a passive solar designer to arrange for ventilation systems requiring frequent openings especially for night time ventilation. Another advantage the passive solar designer will have in Cyprus is the fact that the Cypriots seem to appreciate the use of shutters (87%), which have been used in traditional architecture. Of the 13% of participants who did not find shutters an acceptable means of controlling indoor temperatures, most attributed it to the fact the shutters do not work properly. This implies the need for shutters to be placed in front of windows more appropriately planned. The majority of dwellings have no insulation (66%). Of the houses that do have some insulation (34%), it mostly is in the form of double-glazed windows and reflective silver coatings (a waterproofing material, which is misunderstood to act as a thermal insulator) rather than in structural constructions, which implies that most insulation in the surveyed houses was more or less treated as an afterthought. 3.2.2 Comfort (thermal, acoustical, visual) The existing legal framework does not incorporate any objective criteria and indices concerning the technical characteristics (like the thermal conductivity (K), the thermal transmittance coefficient (U), the sound reduction index (SRI) etc), the performance of the building materials and the whole structure of conventional buildings. Therefore in most of the cases the free market, especially the local one, does not provide the necessary technical specifications of the relevant advertised products. So only practice can show the real fire resistance, thermal, acoustic and light performance of any housing unit. The aspects relating to external mass are of particular significance for Cyprus due to the large diurnal fluctuations (15 to 25 ºC), and the potential possessed by mass for large solar contribution in winter and cooling in summer. This implies that heat admitted during the day in winter could be stored for use during the evening hours and in the summer could be decapitated in the cool night. Thermal performance of traditional, contemporary and solar houses have been researched in relation to climate and in terms of the various aspects necessary for understanding such performances (Lapithis, 2004). These aspects include architectural design, constructional materials and methods, occupancy patterns and planning. Different architectural and constructional elements and techniques that were used in traditional houses have been studied in relation to their use in passive design today and serve as fine examples of energy-saving architecture. Cypriot traditional houses have proved to be superiorly energy-efficient (243 kWh/m²) when compared to contemporary houses (368 kWh/m²) resulting to the most energy efficient being a passive solar house (121 kWh/m²) due to the thermal performance of all cases based on their architectural design. Cyprus is within the temperate Mediterranean zone. The thermal comfort zone limits (Lapithis, 2002) are 19.5°C – 29°C as the proposed temperature and 20-75% as the proposed relative humidity. The best thermal comfort is achieved in the months of April, May, October and November. These months need no extra heating or cooling. To achieve thermal comfort conditions, ventilation is required in the summer months (June, July, August and September). In the months of December, January, February and March passive solar gains are used to achieve thermal comfort. It must be noted that steps should be taken to avoid over heating in the summer.
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Technical Improvement of Housing Envelopes in Cyprus
Despite the fact that there are some fine examples of contemporary buildings based on correct design principles and a better understanding of the local climatic conditions, the great majority of contemporary buildings are erected without consideration of the climatic conditions and their influence on comfort and the well being of the occupants. This is mainly because due to lack of knowledge about the thermal performance of contemporary constructional materials and methods and to the shortage of building regulations which govern this aspect of the art of building. In most cases, good thermal conditions are achieved by using (energy consuming external and mechanical methods) air-conditioning systems or split units. 3.2.3
Health (air quality, TVOC etc., mould & fungus growth)
No information available. (See also 3.2.1) 3.2.4
Safety, security
No information available. (See also 3.2.1) 3.2.5
Barrier free, accessibility in use
No information available. (See also 3.2.1) 3.2.6 Aesthetical perception Social and aesthetical aspects are usually forgotten because they are not directly related to primary human needs but rather to comfort and quality needs of the people. Designers and contractors prefer the straight-forward solutions, that satisfy the main humans needs. On the other hand, most of the buyers and tenants prefer simpler and cheaper housing units, than buildings or complexes that accommodate “social spaces”. This is because social places will have an increase on the cost of the buildings or the rents. 3.3 Economical performance 3.3.1 Building costs Unfortunately traditional construction methods, techniques , materials etc have been ignored for the sake of fast development and fast profits ( by the building industry) due to the absence of the necessary statutory framework that would guarantee the building quality, but also due to poor awareness of consumers' rights. Due to the age of the buildings many problems are observed. The main problem is their maintenance. The maintenance and the administrative matters of the apartment buildings is entrusted by the residents. In cases where maintenance costs are higher, the agreement of all the residents is required in practice, which often encounters difficulties even in simple administrative matters and often proves to be ineffective in the case of serious repairs or maintenance work on the building. Therefore a lot can be done in this area. The first refers to the statutory establishment of the necessary standards, (concerning not only thermal standards but also acoustic standards as well as standards concerning the dangerous building materials). Today only prefabricated buildings have to meet certain thermal, fire and stability requirements. The second issue concerns the need for licensing the necessary construction details of the buildings. Finally, a last but not least issue, concerns the enforcement of the various permits provisions by the competent authorities. 3.3.2
Running costs (heat losses, cooling, cleaning, inspection, maintenance, etc.)
No information available.
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3.3.3 Increased rent potential vs.vacancies through building action There are many questions on the social aspects that the economical performance of the buildings is affected. Few of these questions need to be answered wit a thorough research: Owned property vs. rented. Cost of building construction vs. renting (years of payoff of rent or build or buy). Developers vs. clients vs. renting. Prices depending from the location (town or suburbs). Cost of maintenance- façade, services. Every how many years is maintenance needed. Lack of investment in building maintenance/conservation vs. high degradation level of facades. Different owners of a building resulting with serious problems in putting money together. Old building rental policy plays a role in insufficient execution of maintenance work by the owner. 3.4 Environmental performance 3.4.1 Use of resources (non renewable, renewable) With the exception of solar energy, Cyprus has no other energy resources of its own and has to rely heavily on fossil fuel imports. Energy consumption (non renewable, renewable) - production / assembly - heating / cooling The energy consumption is predominantly oil based. The contribution of solar energy to meet the primary energy needs of the country is estimated to be 5.9%. (Synergy Program, 1995) Thus, more than 94% of the total primary energy is supplied by imports. The cost of imported energy represents 63% of the domestic exports. Due to the developmental nature of the economy of Cyprus energy consumption is increasing at an average annual rate, for the last ten years, at about 6.9%. The total annual energy consumption (electricity included by the domestic sector) in Cyprus comprises of 15.1% with electricity at 34%. Based on consumption by households, a rate of growth of 4.6% is indicated yearly. Breakdown of residential energy consumption in terms of final energy used shows its large share of electricity consumption. In terms of end-use of energy in households, water heating holds the highest place being half of the total consumption, and more than half of the electricity. The present construction trends indicating distinct preference to private, detached houses over apartment flats (60% prefer private detached houses), coupled with higher standard of living (70% of houses are built with central heating) imply a larger energy saving potential in this particular type of dwelling (Ministry of Commerce and Industry, 1994).
3.4.2
3.4.3
Environmental impacts, (GWP global warming potential, AP acidification potential, NP nitrification potential, EP eutrophication potential, ODP ozone depleting potential, POCP photochemical ozone creation)
No information available. 3.4.4 Waste and recycling and re-use potential Not applicable in Cyprus.
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Technical Improvement of Housing Envelopes in Cyprus
4 CASE STUDY 4.1 Case study 1: Low Energy Building The construction was decided to be a concrete frame and floors and roof (constructed as the typical Cypriot contemporary buildings) (Lapithis, 2002). Typical concrete foundations are used for the anti earthquake calculations. The design demonstrates that with an understanding of the principles of environmental physics, appropriate use of available technology and judicious use of materials and resources, it is possible to achieve comfortable living conditions and low energy use. Hourly temperature and relative humidity readings were taken all year round. The indoor temperature remained steady at around 22oC. Overall, the 24-hour indoor measurements indicate a variation of 0-2ºC temperature swing. Taking into account that the external temperature swing is 10-15ºC, this shows that a constant temperature is preserved throughout the day. The building rewarded the inhabitants with a low winter and summer utility bill, considering that no air conditioning system is required. There is an energy saving of 85% comparing the contemporary building with the low energy building. In the construction of the low energy building 13 methods of wall construction and 3 methods of roof construction were taken under consideration. Upon further examination of all viable options for an efficient passive solar building, the chosen type of wall construction is type 6 and for the roof construction is type 1 (Figure 1 and Figure 2). For a passive solar building the walls need thermal mass in order to retain heat. With that in mind, type 11 and 13 listed below are immediately rejected in the case of the low energy building. Types 11 and 13 can be used for passive buildings as long as the walls will not be used as thermal mass. Since the U-value of the wall is an important factor, types 1, 3, 5, 7 and 9 are rejected since they have an unacceptable U-value. Type 10 and 12 have an acceptable U-value, but the high manufacturing cost does not make them cost efficient. The types 2, 4, 6, 7 and 8 are viable options. Type 6, 7 and 8 seems to be the best of at of the 25cm thickness of the concrete frame of the building (beams and columns). A better architectural design is achieved by avoiding the 5cm gap between the external walls and the columns and beams. With these comparisons in mind, the chosen type of wall construction for the low energy building is type 6, since it effectively insulates the whole structure and avoids thermal bridges where the columns and beams occur. Taking into account the advantages and disadvantages of the passive solar system it is concluded that the best systems which can be used for the low energy buildings are Direct Gain, Thermal Insulation and Thermal Storage (Interior Mass). The simplest heat storage approach is to construct the building of massive structural materials insulated on the exterior, to couple the mass of the indoor space. Double-glazed with low emmisivity film and argon-filledare the best windows to use. Shading can be easily controlled for the non-heating season taking into account solar control by use of orientation and shading devices. Natural Ventilation is applied by the use of cross ventilation, stack effect, night ventilation and ceiling fans.
Technical Improvement of Housing Envelopes in Cyprus
Figure 1. Wall construction consideration methods
Figure 2. Wall and Roof construction consideration methods
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Technical Improvement of Housing Envelopes in Cyprus
4.2 Case study 2: Government refugee estate ´´Archbishop Makarios III´ The Government refugee estate ´´Archbishop Makarios III´ is situated in Limassol town, just 3.5 Km from the central area. It comprises two phases (Figure 3 and 4). The first one was build in 1979-80 and the second in 1984-86. It has a total number of 378 housing units, out of which 138 are apartments in three-floor family houses built during the first phase. Buildings followed a simple “cubic form” for functional, economical and practical reasons. No efforts for differentiations were made during the primary construction phase, although some effort were being made during the on going renovation phase. All the multi-story buildings of the estate followed the typical flat slabs concrete structure, filled with plastered bricks as described above. The reconstruction of the buildings was based on typical and conventional techniques and materials. The construction safety was the main issue of this case study. The vast majority of the renovations are related to the construction safety and the stability against earthquake actions. A lot of unnecessary loads, like surrounding walls on top of the buildings or balconies, were removed. The walls were plastered and painted while the roof was damp proofed. No thermal insulation was used either on the walls or on the roof. No specific studies were carried out concerning the building physics. There is no doubt that the general living conditions have been improved a lot. However newly installed air–conditioning units can be seen on some renovated buildings. This indicates that expensive renovations cannot do miracles in a problematic old housing estate and that air split units were reinstalled, after the completion of the renovation works. The average construction cost of the estate (according to 1979 values) was 130 Euro/m2 and the renovation cost (according to 2003 values) is estimated to reach 170 Euro/m2. There is no doubt that direct comparisons may be misleading and that feasibility studies carried out so far, had already taken into account the inflation rate, the cost of living and the final product.
Figure 3. A typical three storey building in refugee estate and typical interventions by the residents to gain some space.
Figure 4. A typical three storey building in refugee estate and typical interventions by the residents to gain some space.
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5 CONCLUSIONS Most building in Cyprus are constructed with little or no insulation, thus causing a high percentage of summer and winter discomfort. The low energy building is designed in accordance to comfort zone calculations so as to ensure the maximum comfort of its occupants. The wall and roof construction plays a significant role in the insulation of the building. The application of the science and art of passive solar architecture to reduce the demand for thermal energy in a building represents a growing area. Retrofitting existing buildings and novel designs of new buildings to this end are a major technical challenge to the near future for Cyprus. At this time, it can be argued that passive design is experiencing a maturity of design applications in which solar energy is utilised in heating, cooling and daylighting buildings. The message here to advance this important beginning, it is that passive design is a sophisticated process to reach simple solutions. Therefore the innovations to look for in the years ahead will be first the development of design methods to enable building professionals to identify balanced and practical solar designs, and second the development of variations of passive solar techniques suited to local climate and resource conditions. This could result to a clearer vision by everyone involved of how passive design is the most cost-effective strategy available in creating an environmentally sound habitat in the climate of Cyprus or any climate of the world. Because of Lefkosia climate, passive solar architecture works to its full capacity, meaning that a passive solar building has 100% energy saving potential. 6 REFERENCES Government of Cyprus. 1972. Town and Country Planning Law (Law 90/72). Lefkosia: Government of Cyprus Government of Cyprus. 1996. Streets and Building Law (Cap. 96). Lefkosia: Government of Cyprus Government of Cyprus. Immovable Property Law (Tenure, Registration and Evaluation – Chapter 224). Government of Cyprus. 1985. Municipalities Law (Law 111/85). Lefkosia: Government of Cyprus. Government of Cyprus. 1984. Ministry of Commerce and Industry and the Department of Statistics and Research. Lefkosia: Government of Cyprus. Lapithis, P. 2003. Solar Architecture in Cyprus. ISES 2003 Conference Proceedings. Gothenburg: ISES Lapithis, P. 2004. “Importance of Passive solar Design in Cyprus”. Proceedings ISES Conference, Orlando, USA. 6-10 August 2005. Lapithis, P. 2004. “Traditional vs. Contemporary vs. Solar Buildings”. Proceedings ISES Conference, Freiburg, Germany. 19-22 July 2004. Lapithis, P. 2002. “Solar Architecture in Cyprus”, PhD Thesis, University of Wales, UK, 2002 Ministry of Commerce. 1998. CYS 98, Cyprus Organization for Standards and Control of Quality. Lefkosia Statistical Service. 2001. Population Census. Lefkosia: Government of Cyprus Synergy Program. 1995. “Preparation of an Action Plan for Improving the Efficiency of the Energy Sector in Cyprus”, Energia, 1995, pp 5-11
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Technical Improvement of Housing Envelopes in Denmark T. Dahl The Royal Danish Academy of Fine Arts, School of Architecture
E. Melgaard The Royal Danish Academy of Fine Arts, School of Architecture
J. Engelmark BYG.DTU, Dept. of Civil Engineering, DTU, Technical University of Denmark
ABSTRACT: The most important reason for renovating Danish housing estates from the post war period has been adaptation to increasing demands on energy conservation, but decay of materials and constructions in the façade, leaking roofs and penetrating water have also necessitated reconstruction and modernisation of façades in the housing stock from that period. The Danish way of renovating is however multifaceted. There is not a single or a general method or technology. The original external walls can be divided in three different constructions: traditional masonry cavity walls, the industrialised concrete sandwich wall and finally the lightweight wooden façade system with plates or boards of wood, fibercement or other materials as cladding. The general problems are most significant for the non traditional built external walls, and they are most commonly renovated by adding an external secondary lightweight construction with extra insulation and new cladding, which might be with or without ventilation behind. The article gives a general description of the performance of the construction and 2 cases representing renovation of sandwich and lightweight constructions respectively. 1 DESCRIPTION OF STANDARD ENVELOPES FOR HOUSING IN DENMARK The typical lay out of apartment blocks in Danish multi-storey buildings has not changed radically over the last hundred years: The basic unit being preferably 2 apartments pr. storey – till the 1930’s served by 2 staircases made of wood, and after by only one made of concrete. The decade 1965-75 gave the biggest rise in new build dwellings ever seen in Denmark. The annual output were in average 45.000 new build dwellings with a peak production of 55.000 (1973) and the lowest 40.000 (1966). This was a result partly of the growth in material welfare and partly because the war situation gave a significant rise in population, which at this time had the resulting effect in needs of dwellings. 1.1 Description of the main technologies Building in Denmark for housing, is in general described as being “traditional” up to the middle of the 20th century, and hereby meaning: the predominant use of the two structural elements/materials: wood- and brickwork, and also including that the majority of the work was concentrated to the actual building site.
The big change came in the 1960’s. Almost all multi storey buildings were then made from concrete, factory made load bearing and bracing elements, vertical as well as horizontal, just as-sembled by crane at the site and usually on foundations/basement cast in situ. Two ways of construction were dominant. One was a system with load bearing transverse walls and non-bearing light weight facade elements. The other was a system COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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Technical Improvement of Housing Envelopes in Denmark
with load-bearing facades of sandwich type and spine wall. The first system is far the most common. Other systems based on the use of columns, beams, frames etc. are very unusual.
Figure 1. (left). Facade and lay-out of apartment in buildings with load bearing facades and spine wall, as a minor part of the building stock from the 1970’s and on were build (right) Typical facade and layout of apartments in buildings with transverse load bearing walls, as they were build from the start of the 1960’s and to present days. The system can have a light weight wooden facade construction, but the facade might as well be concrete sandwich elements.
Figure 2. Development of the traditional Danish external brick wall during the 20th century from the massive load bearing masonry wall through the cavity wall to the clay tile-covered sandwich concrete wall.
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Figure 3. Left: Vertical section, Load-bearing concrete sandwich element and slab, (gable). Right: vertical section, lightweight non load-bearing façade element - edge of floor-unit. Both elements have insulations with a thickness of 50 to 70 mm, which is approximately one third of the demand in 2006.
1.2 Requirements in Denmark that enforce a reaction to refurbish envelopes Due to the overheated building situation in the 60'ies many untested building techniques were used and new building materials were applied, first and foremost concrete, steel and lightweight claddings like fibre reinforced cement plates (Eternit). The majority of the technical problems are related to the envelope of the buildings. These problems were mainly caused by lack of durability and insufficient performance against moisture, rain, low temperatures and wind. Concrete surfaces were to a great extend replacing bricks and were considered as durable as the masonry. This would appear not to be true. So the motivation for refurbishment was partly the bad physical condition. But also the changing building legislation played a role. Building in Denmark was from the beginning of the 1960's regulated by a common building code. This building code was different from the former ones by expressing demands in terms of performance of building parts and materials instead of descriptions of the constructions. Anyhow the new demands were based on the minimum performances of the earlier prescribed constructions, so to a start the new building code did not give reasons to a complete delete of the traditional way of building, but made it easier to introduce new materials, constructions and methods. The code was revised in 1966, 1972, 1977, 1982 and in 1995. A new revision has been released in 2006. The most significant change through the years has been regulations for the energy consumption of new buildings. The demands in the code have – until 1995 – concentrated on specifying U-values in every part of the envelope. But from 1995 it has been possible to calculate and estimate energy consumption within certain limits for heat loss and later on limits for the total energy consumption. Until the latest building code there has been a distinction between heavy and lightweight external walls and between high rise (more than 2 storeys) and small buildings (up to 2 storeys) From 2006 there is only a distinction between housing and commercial buildings. Commercial buildings have larger limits, but must at the same time include the consumption from electric powered light and computers etc.
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Figure 4. U-values in external walls, roofs and windows/doors in Danish Building codes from 1966 to 2006
2 SPECIFICATION OF THE TECHNICAL SOLUTION The most often used refurbishment action in Denmark is adding extra insulation to the outside of the external wall, mostly combined with new claddings in steel, wood, ceramic tiles or bricks.
Figure 5: Typical technical solutions for adding extra insulation on lightweight and concrete sandwich external walls.
3 THE IMPACT OF THE MOST COMMONLY USED REFURBISHMENT ACTION ON SUSTAINABILITY TOPICS PERFORMANCE 3.1 Technical performance 3.1.1 Stability, capacity, (earthquake) No serious problems and no greater changes in building codes and regulations have normally caused upgrading and need of improvements in the structural systems. 3.1.2 Fire protection External walls in buildings in more than 1 storey should, according to the building code, be covered with claddings in the so called Class 1 claddings, which means inorganic materials like stone, bricks plaster of lime, gypsum boards or fire-protected plywood and boards.
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3.1.3 Noise insulation. Demands on the acoustic performance of the façade is normally formulated as demands on an acceptable indoor level of noise, which means that the construction must provide an indoor level not exceeding 30 dB. According to the building code of 1961 horizontal airborne-sound insulation in between apartments should be at least 50 dB and vertical at least 52 dB, also including impact-sound insulation. These values would be obtained with e.g. a massive brick-build wall with a thickness of 23 cm – a normal thickness of a wall also fulfilling demands to fire safety. Respectively a floor construction of concrete with a mass of 2400 kg/m3 – either as 12 cm massive concrete cast in situ or as 18 cm of hollow prefabricated concrete slabs, in both cases topped with a raised wooden floor on battens supported on soft material. The building code of 1977 sharpened the demands to 52 dB horizontal and 53 dB vertical. In this code the demands to impact-sound insulation were redefined as demands to the impactsound level in the apartments. The demand was set as a maximum of 63 dB – in practice to be obtained with the same kind of constructions as the ones giving an airborne-sound insulation vertical of the required 53 dB. Now days the demands to airborne-sound insulation are still the same, but the demand to impact-sound level insulation is a maximum of 58 dB. The main acoustic problem in multi-storey-housing estates, which is the transfer of noise from one apartment to another, is seldom taken care of in connection with general refurbishment actions. 3.1.4 weather protection. The Danish climate can be characterized as wet, cold and windy. Mean relative humidity is between 70 and 90 depending on distance to the sea. At this level of humidity most materials are substance to decay, especially those materials preferred as external construction or cladding material in the sixties and seventies. High humidity in combination with frequent change between frost and thaw is harmful to most concrete and cement based surfaces 3.1.5 moisture protection With a climate like the Danish and with a temperature in winter popping up and down around zero degree, the construction of envelopes has always had to be in accordance with this situation. So problems with moisture mostly occur as a result of either bad work in the actual case or by using new and not yet proved constructions – of cause also the combination of the two. An example of this was a wide spread use of flat roofs in the 1960’s and –70’s; now a days in general solved by replacing the old with new ones. The buildings from the period where brick-build external walls were used, have not offered bigger problems than known for centuries and coped with accordingly. The 1950’s with all the experiments in alternative constructions and methods of building gave lessons in how to cope with other kinds of envelopes, but no definite solutions. From the 1960’s and forwards there has been a focus on the construction of envelopes securing that internal produced moisture should not give reasons for accumulation in the construction, and that external water was appropriate rejected. 3.1.6 conductivity, heat flow, radiation, convection st Thermal insulation: As late as 1 of April 2006 the chapter in the code of 1995 on thermal insulation was renamed “energy consumption”, and by this a new attitude was fulfilled. Hereafter the demands are based only on a calculation on the total energy use for heating, cooling, ventilation and hot domestic water in a building and based on the supply for this from none renewal resources; but taking in account alternative supply of energy e.g. from the sun directly. As an alternative to the traditional way of handling thermal insulation, this had all ready been introduced as a possibility in the code of 1995 as originally issued. This so-called energy-frame for domestic buildings is in the revised chapter in the 1995 code defined as: (70 + 2.200/A) kWh per m2 a year, where A is the heated area of the building. Accompanying this overall demand the dimensioning transmission loss for buildings must not exceed 6 W respectively 8 W per m2 of the envelope exclusive windows and doors for buildings up to 3 storeys high respectively higher. Also demands to a minimum U-value of the different building parts are still in force, as described below. But as the overall demands are supposed to
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effectively reduce energy consumption in buildings, the demands to the single building part is rather relaxed compared to the earlier. According to the building code of 1961 external walls should satisfy U-values ranging from a minimum of 0,6 to 1.3 W/m2C determined by the choice of construction. The lowest value being the demand to a light-weight construction (defined as types with a weight less than 100 kg/m2). The highest value was the demand to a heavy one (e.g. a massive brick-built wall with a thickness of 48 cm). Other values in between these were fixed to likewise heavy constructions of different materials/thickness. According to the building code of 1995, as it was issued originally, the same demands were 0,2 respectively 0,3 W/m2C. The lowest value as defined above and the highest to walls with a weight of 100 kg /m2 or more. The latest revision describes a minimum U-value of 0,4 W/m2C. Windows and glazed walls should according to the code of 1961 be “2 panes of glass with a minimum distance of 12 mm” – equivalent to a U-value of 2,9 W/m2C. The original issued code of 1995 prescribed 1,8 W/m2C. The latest revision describes 2,3 W/m2C, which after 1st of January 2008 should be 2,0 W/m2C. The building code of 1961 demanded a minimum U-value of 0.5 W/m2C for floors over basements, solid ground floors and roofs. The same demands in the code of 1995, as it was issued originally, were 0,2 W/m2C. The latest revision describes 0,3 W/m2C for floors over basements and solid ground floors, and for roofs 0,25 W/m2C. The housing stock build before the appearance of the common code of 1961 has originally less U-values than stated here. Far the majority of the buildings were built with massive facades of brickwork or alike heavy materials. Windows were at the most of the type with 2 panes in coupled frames, but often just single paned. Floors and roofs were merely insulated at all. Anyhow all of these buildings have undergone some kind of updating in thermal insulation over the years, partly in combination with (regular) maintenance and/or partly as a result of the oil crisis. This is also in general the situation for the oldest part of the buildings being build according to the code of 1961. 3.1.7 durability (service life) When the new outer lightweight cladding consists of wood, metal-sheets or fiber-cement plates, the durability is somewhat reduced compared to the original concrete surface. At the same time it often demands a regular maintenance process. 3.1.8 functional / social performance - flexibility, - no comments - comfort (thermal, acoustical, visual) – no comments - health (air quality, TVOC etc., mould & fungus growth) – no comments - safety, - no comments - barrier free, - no comments 3.1.9 Economical performance - Building costs. The average cost for repairing damages and upgrading the façade for multi storey housing built in the 60'ies and the early 70'ies is 25 – 30.000 Euros pr flat, but there are quite a few cases showing costs 3-5 times that amount. - Running costs. A typical rent paid for a 100 m2 flat in social housing around Copenhagen amounts to 1.000 Euros including heat consumption, cooling, cleaning, inspection, maintenance, etc. 3.1.10 Environmental performance - use of resources (non renewable, renewable) – no comments - energy consumption (non renewable, renewable) - production / assembly - heating / cooling – no comments - environmental impacts, (GWP global warming potential, AP acidification potential, NP nitrification potential, EP eutrophication potential, ODP ozone depleting potential, POCP photochemical ozone creation) – no comments - waste – no comments
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4 CASE STUDIES The following two case studies are typical examples from the period, where the Danish housing stock increased significantly and where the industrial prefab production was the predominantly used building technology. CASE STUDY 1 – COURT-YARD HOUSES, ALBERTSLUND 'Albertslund Syd' was built in 1963-67 by the non-profit housing associations Vridsløselille Andelsboligforening and Herstedernes Kommunes Boligselskab. The structural principle was point foundations, which support pre-cast reinforced concrete foundation beams. The roof is covered with wooden stress-skin elements, supported by the façades and the partition walls. The outside walls of the court-yard-houses are 19 cm thick precast concrete sandwich walls, and the walls towards the garden are storey-high lightweight wooden elements.
Figure 6: Perspective drawing illustrating the assembly of the court-yard house (3 stages – 3 houses)
The courtyard house is brought into this article because of the amount of houses built by this building-system. During the period from 1963 to 1973 there were erected 11 housing estates with a total of 3211 houses, which in a Danish context is approximately 10 % of one years total amount of new houses in that period. The estates are spread around Copenhagen within a radius of 30 miles from the city centre. Before the first estate was 20 years old, it suffered from a number of construction failures and insufficient performances like leaking roofs, dry-rot in the lightweight façade elements, in doors and windows and in the roofs, mould on concrete walls, and week and wavy floors. At the same time the building code prescribed the insulation to be about twice as thick as the original one in both concrete and lightweight walls. It was decided to carry through a comprehensive renovation to restore and update the construction to contemporary building standard.
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Figure 7. Court-yard houses before and after renovation. The original concrete wall was cast in white concrete with a roughly brushed surface.
Figure 8. Section in concrete sandwich wall before and after renovation. After renovation the wall was supplemented with 10 cm extra insulation in a double – horizontal and vertical - wooden structure bolted to the concrete surface and with a cladding of fibre reinforced cement plates between horizontal wooden boards. The extra insulation lowered the U-value from approximately 0,50 to 0,24. The roof was raised and supplied with an extra 10 cm of insulation. The former ventilation space in the old roof was closed.
CASE STUDY 2 – HEDEPARKEN, BALLERUP This second case study is a high rise 3-4 storeys in blocks containing 40 – 60 flats. The development plan was built from 1966 by the non-profit housing association Arbejdernes Andels Boligforening
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Figure 9. Aerial photo of the estate Hedeparken, Ballerup. Only the 7 buildings in the front are refurbished in the way described.
The structural principle is load-bearing cross walls of pre-cast elements, with floor elements of pre-cast hollow-core reinforced concrete elements. The exterior walls are made by wooden elements covered on the outside with grey asbestos cement sheets.
Figure 10. External walls before and after refurbishment. The concrete parapets and the horizontal lines are replaced by vertical parts with balconies and parts with lightweight parapets with tile-cladding
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Figure 11. Vertical section showing insulation, new window and new ceramic tile cladding.
Figure 12. Fotos Ceramic tiles fastened on vertical metal rails
5 REFERENCES Bertelsen, S. 1997 Bellahøj, Ballerup, Brøndby Strand - 25 år der industrialiserede byggeriet. Hørsholm: Statens Byggeforskningsinstitut (SBI) Danish Ministry of Housing, 1997. 22 Overfrakker (22 Overcoats) New Claddings - a collection of examples Engelmark, J. and Melgaard, E. 2004. COST-16, Improving the quality of existing urban building envelopes. State of the art - Denmark Fællestegnestuen for Albertslund Syd, 1964. Albertslund Syd, Teknisk projekt til gårdhuse og rækkehuse. Copenhagen: Byggeindustrien Landsbyggefonden, 2001. Fysisk opretning og forbedring af almene boligafdelinger. Copenhagen: Landsbyggefonden Nissen, H. 1972. Industrialized Building and Modular Design. London: Cement and Concrete Association SBI-rapport 75, 1971. TÆT LAV - en boligform, Eksempelsamling, Hørsholm: Statens Byggeforskningsinstitut (SBI)
Technical Improvement of Housing Envelopes in France Dominique Groleau CERMA, UMR CNRS 1563, Ecole Nationale Supérieure d'Architecture de Nantes, France
Francis Allard LEPTAB, Université de La Rochelle, France
Gérard Guarracino DGCB, Ecole Nationale des Travaux Publics de l’Etat, Vaulx en Velin, France
Bruno Peuportier, CEP, Ecole des Mines de Paris, France
ABSTRACT: The improvement of housing envelopes can play an important role to change the image of the building, to modify the use inside the dwelling, to transform the immediate surroundings of the buildings, to improve the technical and functional performance of the building and to enhance the life environment of inhabitants. In this perspective, and since 1980 in France, rehabilitation of façades has been one of the predominant measures applied to modify, from outside, the image of the building without perturbing the life of inhabitants. From a technical point of view, the main technique used that consists in applying to the existing façade an external skin including thermal insulation offers numerous technical and functional advantages. 1 INTRODUCTION 1.1 Standard envelopes in France In France, in 2002, the number of dwellings/apartments was about 25.000.000 in main homes, whose 77% were built before 1981 and 65% before 1974. The stock of buildings of more than 25 years old shows the importance of the rehabilitation and the neccesity to mantain in a continuous way buildings and the urban environment. But, until today and since the end of the sixties, rehabilitation has been a permanent architectural preocupation, in opposition with the previous massive destructions of whole districts after 1950 carried out against unhealthiness of cities. From 1970, rehabilitation has concerned mainly the "grands ensembles", detached multi-storey buildings designed as the urban expression of the modernity, with their lot of social problems. Over time, the notion of urban heritage has been modified and the fields of intervention have changed to concern not only the 60's urbanisation, but downton and suburbs, private and public housing. Today, with the rapid transformation of society, technology but also way of life, rehabilitation interests every type of building trying to improve housing, regarding as much its technical and functional components as its social and economical dimensions, interesting the architectural level as much as the urban dimension. It is not a question of isolated actions over time but of a continuous preocupation that has to manage the architectural heritage of the near or far past, and at the same time the living environment of inhabitants. Thus, it can be observed that, in France, between 50 and 55% of the construction activity results of maintenance, improvement and rehabilitation. However, out of the private sector, the part of the building heritage that concerns the social housing built from 1955 to 1980 is always one of the main domain of rehabilitation actions, due to the social, economical and urban problems occuring in these areas but also as regard to the importance of the stock they represent and its relative homogeneity (in constructive terms with their reinforced concrete frame, multi-storey buildings, and with the same social characteristics). Some of them have already been renovated in the 1980's and 1990's (1.3 Millions since 1975). Social housing organisms manage more than 3.6 Millions of apartments and rehabilitate more COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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than 120000 dwellings per year, and it is estmated that 100000 dwellings have to be rehabilitated per year during the next 10 years. But, since 1980, results of rehabilitation in this sector are considered as limited. In spite of the relative public investments (PALULOS for the public housing, ANAH for the private), the inadequacy of means mainly used up by technical needs (thermal isolation, security...), the lack of concertation with inhabitants and implications of elected representative, and the absence of qualitative improvment in term of attractivity, explain this situation. From now, the rehabilitation solutions propose simultaneously the renovation of the building stock (quality of the dwelling, technical standards), the urban re-development and the social measures that reinforce the insertion of these districts into the city. 1.2 Requirements in France, that enforce a reaction to refurbish envelopes Actual standards and recent regulations (thermal, acoustical, health...) imply new ways to design buildings, but there is no obligatory retroactive effect on the stock of ancient buildings. However, several objectives and actions edicted at the national level encourage and make necessary the improvement of buildings. They are also supported by public and private organisms and associations, that intervene at industrial or informational levels to propose help, prescriptions or solutions for sustainable and environmental devolpments. Particularly, the French objective proposed in the Climate Plan to reduce the energetic consumption in order to divide by 4 the CO2 emissions in France from now to 2050, but also the RT2005 thermal and NRA2000 acoustic regulations lead to action plans, national programs and projects. They impose reinforced standards for the design of new buildings, but higlight also the necessity to find solutions for a massive and energetically performant rehabilitation of existing buildings. In its context, intervention on the envelop of buildings is an interesting mean to answer to theses objectives. The social and urban problems encountered in numerous underprivileged suburban zones, constitute another preocupation field that favours urban rehabilitation operations. But, rehabilitation carried out at an urban level implies to reconsider the way to operate on the buildings. So, normalization of buildings (settings of standards) is a decision that has to be weighted by its impact on the global expected improvement of the dwelling and the district. Thus, the intervention choices on a building requires at first to make a precise diagnosis of the building (state, use, maintenance, environment), then to measure the architectural, technical, human, social and economical impact of the proposed solutions. 2 SPECIFICATION OF THE TECHNICAL SOLUTION Interventions on the 1950-1975 social housing have met three successive periods (Joffroy,1999): the first focusing on technical problems (disorders repairing, thermal insulation...), the second on functional questions (entrance halls, interior of the dwelling…), and then the third with interventions associating the question of the dwelling, the district and the city (social exclusion, private/public spaces, conviviality and proximity...). The interventions on envelopes must take place in this global context that aim to change and improve all aspects of environment and life. Thus, the improvement of façade can play an important role in its expected transformation being a mean to change the image of the building, to modify the use inside the dwelling, to transform the immediate surroundings of the buildings, to improve the technical and functional performance of the building and to enhance the life environment of inhabitants. In this perspective, and since 1980, rehabilitation of façades has been the predominant measure used to modify, from outside, the image of the building without perturbing the life of inhabitants. From a technical point of view, external thermal insulation offers numerous technical advantages with a better energetic performance, the removal of thermal bridges and a possibility of architectural and aesthetic effects. It implies to pay attention to the implementation of that system in order to reduce damages such as the lack of ventilation or the weakness of the structure. Not very used in new building, it is at the present time less commonly used in rehabilitation, mainly due to the impact on the global budget of rehabilitation and the real efficiency of the system. However, many progresses on products, system and implementation were carried
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out and a large set of solutions are proposed for designing performant exernal skins on existing façades. In rehabilitation, external skins are able to integrate the overal constraints, including easy maintenance, protection against pollutions, savety... They become a feasible technical solution, that enables at the same time to change windows and to modify the architectural aspect of the façade (balconies, wall/window ratio, material, color). Six types of external skins applied to the vertical walls constituting the building envelope, are able to include external insulation to reduce efficiently energy consumption; they are (reVetir, 2004, Buttenwieser,1997): thin or thick cement rendering upon insulation; this technology is largely dedicated to the rehabilitation in France, light coat made of insulating granular elements, that gives a suplementary insulation, weather boarding applied to the existing wall with thermal insulation, insulated wall panels; they associate a covering and an insulating material (often polystyrene); they represents 10% of insulation technics and are used essentially in the social housing. the "vêtage" is a traditional principle that consists to fix up manufactured elements directly on the wall support, without framing, with thermal insulation, attached covering of thin stones with thermal insulation.
Figure 1. Several types of external skin: cement rendering, weather boarding, insulated wall panel, "vetage" according to Buttenwieser, I.,CSTB 1997
Each of these system can be applied on every type of buildings whose external vertical walls are made with concrete blocks, walled concrete or prefabricated concrete. A classification based on performance criteria is proposed that takes into account: repairs facility, maintainability, wind pressure resistance, tightness, impact resistance, fire-resistance rating, thermal resistance. Based on site characteristics, environmental situation or climatic conditions and costs, performances can be explicitly identified and a system selected that will be more in adequacy with the imposed constrainsts. 3 THE IMPACT OF THE MOST COMMONLY USED REFURBISHMENT ACTION ON SUSTAINABILITY TOPICS The most commonly used refurbishment applied to buildings in social housing is the application of an external skin on the existing façades. It corresponds to the apparition of the external insulation in France from 1974, in order to reduce the energy consumption and to insulate non insulated buildings; so its real use is focused in the refurbishment market and mainly in the frame of rehabilitation of block of flats. Several technologies can be applied depending on the state of the façade, its structure or its architectural shape and the possible investment. But each of them shares common characteristics and properties that gives a real efficiency to this type of solution. So, detailed and specific properties of each possible technology, presented in the previous paragraph, will not be described in detail in terms of performance, but mentioned only when a very different behavior can be observed for a particular solution.
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3.1 Technical performance 3.1.1 Stability, capacity, resistance Generally, the external skin is tied to the structure, either directly, without frame, upon the existing wall of the façade, either indirectly through an intermediate frame or light structure fixed up to the wall. So, the stability is primarily maintained by the wall and the structure of the building. Generally, the type of structure used commonly during the sixties and seventies with the formed concrete or tunnel formworks techniques offers a very stable structure. Only the way to fix the second skin and elements that forms the external skin has to be adjusted to maintain the stability of the second skin itself. However, the most outer layer of the skin has to be impact resistant. Five classes of impact are considered in technical guides concerning the level of impact exposure (expressed according to French norms in Kg/J) , depending of the position of the skin in the façade, at the floor level or in a non accessible or protected location. Generally the cement rendering has a better resistance to impacts than insulated wall panels. 3.1.2 Fire protection Various experiments carried out on whole system including skin and insulation have enabled to impose levels and minimal requirements to be applied. These requirements help then to choose an appropriate technique among the available technical solutions. Generally applied to non attached buildings, accessibility to fight fire is then well insured. 3.1.3 Noise insulation Generally the social housing built during the period 1959-1970 are now included in the dense urbanization, often submitted to the nearby important traffic noise. Then, the tight external skin enables to reduce considerably the air tightness, thus air and sound infiltration. The effect of the added external thermal insulation plays also an important role in the acoustic absorption property of the whole façade. The sound attenuation obtained by the use of a mineral wool can reach 5 dB(A); equivalent performance can be obtained with elastified polystyrene, but not extruded or expanded polystyrene. In any case however, the solution cannot be wholly performing without improving, at the same time, the acoustical level of windows. 3.1.4 Weather protection The external skin is quite a natural way to protect inner rooms against the weather attacks. It acts as a second skin that plays a global role of protection against water, against non controlled air ventilation, against pollution lead by wind and rain, again heat penetration and so on. However, moreover of the simple wind resistance of this second skin that has to be controlled, two elements have to be considered: the air and the water tightness. 3.1.5 Moisture protection Four water tightness classes are proposed to distinguish external insulation systems: the first does not inhibit the water to reach the wall support; the second inhibits the penetration up to the support; the third has some disposal to catch the water behind the external skin; the last comprises a water tightness skin with a possible way to retrieve water. A weighted factor is applied according to the exposure level to the wind and enables to define the obtained type of wall. However, an important attention has to be paid about the ventilation system in order to not create internal disorders in the building due to a too important air tightness. 3.1.6 Conductivity, heat flow, radiation, convection The main effect of the insulated second skin is to reduce considerably the thermal losses and energy consumption. The use of low conductivity mineral wool and polystyrene in a layer to 6 to 8 cm gives a global thermal resistance of the wall about 1.5 to 2.5 m2.K/W that corresponds to the required performance of the thermal regulation. It is also an efficient way to suppress the existing thermal bridges between floor slab and walls. Another improvement related to the weather protection effect is to mitigate the uncontrolled air penetration, so lowering the thermal losses due to convective exchange. The solar effect is also reduced and does not reach the wall of the structure. So thermal shocks that can affect the façade are avoided and the inertia of the wall can play its positive role during summertime.
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3.1.7 Durability Being a protection system against outdoor aggressions, the external skin play an important role in the durability of the building (structure, concrete, iron corrosion). But the second skin has to be maintained itself over time. Being generally a light structure, very accessible by outer, the maintenance can be easy. However, the cement rendering upon insulation is a technical solution that can demand more maintenance due to fissuration and cleaning than others solutions built upon a light structure. Many weather boarding elements are self-cleaning, therefore resistant to pollution and mosses. Inversely, boarding elements can be less resistant to impacts and when, broken or pulled out, have to be replaced very quickly to maintain safe the global protection of the external skin. 3.2 Functional / social performance 3.2.1 Flexibility The external insulation skin enables easily to change the façade, mainly to modify the windows distribution or to reduce the glasses ratio of façades. It is also a performing way to correct defaults or light disorders of façades and to change the architectural aspect of the building. 3.2.2 Thermal, acoustical, visual comfort The second skin can improve considerably the comfort inside the buildings. In summer, the internal inertia of the protected concrete wall mitigates the elevation of indoor air temperature; and, the protection of the walls against sun exposure inhibits the elevation of wall surface temperature. In winter, with the external insulation layer, the walls are maintained to a sufficient temperature and are not perceived as cold surfaces by inhabitants. The acoustical performance of this technical solution contributes to lower the level of outdoor noise but can inversely, due to the decrease of the ambient noise level, bring to light internal noise from neighbouring apartments. The visual effect of the external skin is mainly perceived from outside by people walking in the site; the second skin, by modifying architectural aspect of the building, can therefore participate to create a new image of the building and of its environment. One of the main benefit of this technical solution is that it improves the global indoor conditions by clothing the existing façade, therefore masking imperfections, defaults and defacements of the existing façade and creating a new attractive one. 3.2.3 Health The external insulated skin maintains a good protection against outdoor constraints (heat and cold, noise, rain, wind and air infiltration) and therefore participates greatly to the global comfort and health of inhabitants. Another social benefit (but also economic) comes from the fact that this kind of technical solution enables to keep people staying in their apartment without creating an unbearable situation during construction. Generally, this technical solution implies, by performance coherence, that windows are also changed to answer to the actual technical standards. The new windows can be then in some cases located in the outer wall surface, so adding an available space in the width of the window frame to manage new fittings and modifying the visual relationship between indoor and outdoor. 3.3 Economical performance 3.3.1 Building costs, As mentioned just previously, keeping people in their dwellings during work does not involve a cost overrun due to the non occupancy of apartments. The costs of the external insulation skin are dependent of the type of the used technique. In 1999, costs could vary from 40 Euros by m2 for the cement rendering up to 80 and 90 Euros for the system including a weather boarding. They depend also of the type of building and the desired level of rehabilitation.
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3.3.2 Running costs Important gains can be obtained from this type of technical solution. The reinforcement of the width of the thermal insulation and the control of air infiltration contribute for a large amount to reduce, in dwellings, the energy cost during the heating period. It is generally admitted that the percentage of thermal gains can reach up to 30% but the real economy will result of the specific characteristics of the used solution ( insulation thickness) and of the previous situation. In term of cleaning, many coatings are nowadays self-cleaning, reducing therefore the necessary periodic cleaning of the external skin. However, maintenance can be increased in case of board constituted of small elements (as slates, ceramic tiles) more exposed to wind and less shockresistant that have to be replaced from time to time. 3.4 Environnemental performance 3.4.1 Energy consumption With this kind of technical solution, the energy consumption is considerably reduced with the insulation layer. The maximum insulation thickness seems to be 8 to 10cm. In summer, the protected internal inertia prevents again excessive indoor heat, so reducing the need for fresh air conditioner. 3.4.2 Use of resources and environmental impacts They depend greatly of the type of material used and of the thickness of the insulation layer. Moreover, the field of technical solutions to achieve the external skin is very open; a large choice of systems and material enables to choose performing solutions that have a reduced impact on environment. However, the selected solution has to be assessed in terms of sustainability. 4 CASE STUDY Façade renovation of a dwelling block, La Noue, Montreuil, France Situation: Montreuil, Seine Saint Denis (93) FRANCE Participants: Contracting Authority : OPHLM Montreuil Architect : Ligne 7 Architecture (Paris) Energetician : Armines (Paris), MVE (Montreuil) Local authority : Mission environment, town of Montreuil Type of rehabilitation : façade of a four storey building built in 1969 Renovation date : 2001-2002 4.1 Context of the renovation operation The municipality of Montreuil, near Paris, has launched a green neighbourhood pilot project to renovate, with the municipal social housing office, 500 apartments. In one building, a more efficient energy renovation program was performed in the frame of the European REGEN LINK demonstration project. This program integrates the successive steps of the renovation process, design, construction, commissioning, monitoring, reporting and dissemination; so it enables to have a complete report of this operation including simulation, measurements and a tenants survey (Peuportier,2002,2004). 4.2 Objectives The general objective is to demonstrate that, in existing building and in the social housing sector, it is possible to achieve high environmental and energy performance. More specifically, for the renovated apartments block, the aim is to reduce the heating load by 60% and, by a large amount, the CO2 emissions.
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4.3 Description before renovation The four storey building of 52 social dwellings represents a floor area de 4500 m2. It is heated by a district heating using mainly coal fuel. Built in 1969, the building has no thermal insulation and uses a large area percentage of single glazed windows in façades. The load bearing structure is composed with reinforced concrete shells and concrete floor. The heating load before renovation was estimated to 170 kWh/m2/year. 4.4 Main design and technical measures proposed for rehabilitation The proposed rehabilitation measures are largely based on bioclimatic potentialities of the building that faces to the south and therefore can benefit solar gains, but also on internal layout with living rooms located in the south façade and bedrooms to the north. The main measures and techniques involved in this project were: To install external insulation with reinforcement of the insulation thickness, To use advanced glazing (with low emissivity and argon layer) instead of standard double glazing, To adjust glazing properties (in surface, in solar transmission) according to the south or north orientation, To design some glazed balconies, as solar collectors, in order to preheat ventilation air and reduce thermal bridges, To enable crossing ventilation in summer thanks to the double orientation and to benefit of the strong inertia of walls and floors. To propose additional measures in order to save domestic water or to reduce ventilation heat losses using a moisture control system. 4.5 Technical performances 4.5.1 Thermal performance The insulation standard corresponds to an external insulation layer of 6cm width. In the project, a 10cm thickness was adopted to contribute to reduce more drastically the heat losses. The external insulation inhibits the thermal bridges (specially at the slab level) except to the balconies. It is why it was proposed to glaze several balconies and to use them as solar collectors (preheating of the fresh air). The type of glazing is low emissivity, with a U value of 1.7 (1.1 in some apartments where argon has been used). Hard coating low emissivity has been used in glazed balconies, with a solar factor of 0.72 enabling a higher solar transmission : the U-value is a little higher, i.e. 1.9 W/(m2.K) but the global energy balance is improved compared to soft coating. The glazing area has been reduced by 50% in the north façade in order to reduce heat losses, and by 20% in the south facade (increasing the heating load by 2% but improving the economic balance of the project). 4.5.2 Ventilation, humidity A moisture control system was installed in order to control the air flow according to indoor humidity, leading to a reduction of the flow rate when the apartments are not occupied. The external insulation is protected by a weather boarding that insures water tightness of the façade. 4.5.3 Noise protection The external insulation and the advanced glazing with its two layers contributes largely to the protection of apartments from the outside sound. 4.5.4 Recycling, Durability The weather boarding, made with recycled material (cellulose), is a high pressure laminate with an exceptional resistance to impact and moisture.
38
Technical Improvement of Housing Envelopes in France
4.6 Functional and social performances 4.6.1 Thermal comfort The improved insulation of the building and the night thermal mass help to protect apartment from overheating in summer period. In winter, the reduced heat losses helps to maintain easily a comfortable indoor ambiance, but generally with higher indoor air temperatures after renovation. The glazed balcony is technically interesting but is difficult to manage when tenants are absents; the absence of ventilation and high temperature can damage plants. 4.6.2 Humidity Measures shows that internal humidity stays between 30 and 50% when heating is on. Before renovation, similar values were measured. 4.6.3 Daylighting and visual comfort Illuminance measurements during diffuse sky days shows that the obtained levels are satisfactory, with 200 lux in living rooms. The daylight factor has not significantly changed by the reduction of glazed area, but some people complain that they cannot so easily look outside. 4.6.4 Acoustical comfort The external insulation and particularly the advanced glazing have considerably contributed to increase the acoustical insulation of the dwellings from outdoor airborne-sound. However, tenants inform that noise is transmitted from others dwellings; maybe the reduction of the external noise level (background noise) is responsible of the emergence of internal noises. 4.6.5 Air quality Air flow and air quality are more controlled after renovation. Air flows are adjusted to hygienic and sanitary constraints but some people feel like not having enough fresh air. 4.6.6 Inhabitant behaviour As it can be see in the tenants survey, the building before renovation was not a performing building but it was not systematically perceived by inhabitants as being uncomfortable. Building transformations affects directly tenants that often compare the new situation with previous one. Generally satisfied with the renovation, tenants however formulate some comments and critics. For example, some people feel cold due to a lower temperature of radiators whereas the indoor air temperature is 23°C, or perceive negatively the reduction of glazed area that limits their outside view, or still complaint the lack of fresh air. Technical performances are thus sometimes not totally efficient due to the behaviour of tenants that open windows to get new air or leave open doors between living room and glazed balconies. Discrepancy between calculations and measurements is partly explain by the various types of occupancy and it needs time and cooperation in order that people adjust their behaviour with the new situation. 4.7 Economical performances The building renovation cost was 3500 Euros per dwelling corresponding to about 41 Euros/m2 of floor. The supplementary investment cost compared to a standard renovation was 185000 Euros. The annual energy saving is about 12000 Euros, so the pay back time is about 16 years. More precisely, the pay back time is estimated to 2 years for low emissivity windows, but up to 20 years for increasing the insulation thickness. Some measures are not particularly economical like glazed loggia but their impact must not be limited to the only thermal dimension; the loggia contributes also largely to the attractiveness of the living room. Apartments owned by OPHLM of Montreuil will be rented during the next 30 years, so life span of external insulation, windows, glazed balconies and district heating loop is expected to be also 30 years. At the same time due to renovation, rents for the tenants have been increased.
Technical Improvement of Housing Envelopes in France
39
4.8 Environmental performances 4.8.1 Energy consumption Energy consumption measurements carried out in the building after renovation shows that energy heating consumption reduction was reduced by 32%; it was expected by calculation a reduction of 60%. Two main causes explain this difference. The first one is due to the increase of indoor air temperature greater than 3°C after renovation that creates a 22% supplementary thermal load. The second one results from improvement of certain parts of the building; thus, the heating of ground floor produces an additional energy consumption, estimated to 25%. Consequently, after correction, the reduction of heating energy consumption can be estimated to 50% that corresponds to an energy consumption of 70 kWh/m2/year. 4.8.2 Water consumption In order to reduce the water consumption, a low flow-rate sanitary equipment was installed. In the shower system, a Venturi effect increases the speed of water flow producing an equivalent comfort level but with a smaller water flow. This efficient water system has enabled to reduce water consumption up to 30%. 4.9 Environmental impact A life cycle assessment was performed. It shows that an important gain was obtained to reduce up to 50% the CO2 emission. In the first year, renovation has enabled to avoid the emission of 76 tons of CO2 and further corrections proposed can still improve the situation. Several others indicators were assessed, like acidification, eutrophication, human toxicity or waste; comparatively to the previous situation, the renovation performs better scores for all the targets. 4.10 Field of application This renovated building is very representative of a large amount of buildings built in the sixties before the introduction of a thermal regulation in France. Thus, the type of techniques and measures proposed in this renovation can be easily apply, specially external insulation and performing glazed windows. Data collected in the survey can also serve to better manage the rehabilitation procedure by favouring people participation to the global renovation process. 5 CONCLUSIONS This kind of renovation operation shows the necessity to follow with the help of experiments and surveys the behaviour of the building after renovation in order to measure the real impact and performances of design and technical solutions proposed in the renovation. Side effects, maybe more important in renovated existing buildings than in new buildings, can then be observed as the increase of indoor air temperature or a modified use of spaces by inhabitants. In the previously analysed operation, some adjustments were proposed, for example, to lower the heating loop temperature and to better observe the performance of glazed balconies. It is important also to convince building advisor, municipalities and inhabitants that solutions are efficient over time and without risk for people. It can be seen for example that technical performance improvement in existing buildings can modify considerably the way of life of inhabitants, at least the way to perceive the new things relatively to the previous situation. More generally, results shows that rehabilitation concerns all actors (community, owners, architects, contractors, technical experts, manufacturer and inhabitants…) and that the true success of a renovation operation is strongly dependant of the level of implication and acceptance of each one in the project.
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Technical Improvement of Housing Envelopes in France
Figure 1. The building before renovation
Figure 2. The building after renovation
Figure 3. Layout of the district
Figure 4. The glazed balconies
6 REFERENCES Buttenwieser, I. Panorama des techniques du bâtiment 1947-1997.Plan construction et architecture. CSTB. 1997 Classement reVETIR des systèmes d'isolation thermique des façades par l'extérieur. Selection 2004 des produits pour l'habitat et les équipements collectifs. Groupe Moniteur. 2004, pp. 32-33. issued from Cahier du CSTB 2929, livraison 375, décembre 1996 EDIF, Energies durables en Ile de France, brochure Agence Nationale de l'Environnement et des Nouvelles Energies Ile de France, janvier 2004 Enveloppe du bâti: l'innovation n'est plus prioritaire. Dossier spécial HLM, n°245 septembre 2004, les Cahiers Techniques du Bâtiment, pp75-78 Joffroy, P., La réhabilitation des bâtiments, conserver, améliorer, restructurer les logements et les équipements. 1999. Collection Techniques de conception, Le Moniteur, Paris, France. Logement social, les nouveaux axes de réhabilitation. Dossier, n° 227 septembre 2002, les Cahiers Techniques du Bâtiment. Peuportier, B.,Deliverable D5 : final technical report including monitoring results and analysis. REGEN LINK, site 4 La Noue, OPHLM de Montreuil et ARMINES, 2004 Peuportier, B., Assessment and design of a renovation project using life cycle analysis and GB tool. Sustainable building conference, Oslo, 2002. Réhabilitation des grands ensembles. Architecture d'Aujourd'hui. N°194, 1977
Technical Improvement of Housing Envelopes in Germany Christian Wetzel CalCon Holding GmbH, Munich, Germany
Frank-Ulrich Vogdt Institut für Erhaltung und Modernisierung von Bauwerken e.V. (IEMB), Berlin, Germany
ABSTRACT: The improvement of housing envelopes can play an important role to change the image of the building, to modify the use inside the dwelling, to transform the immediate surroundings of the buildings, to improve the technical and functional performance of the building and to enhance the life environment of inhabitants. In this perspective, and since 1980, rehabilitation of façades has been one of the predominant measures applied to modify, from outside, the image of the building without perturbing the life of inhabitants. From a technical point of view, the main technique used that consists in applying to the existing façade an external skin including thermal insulation offers numerous technical and functional advantages. 1 INTRODUCTION 1.1 Standard envelopes in Germany The German climatic boundary conditions do not vary a lot. Regarding heat degree days (based on 12°C) the values vary between 4623 [Kd] in Hof in the Eastern Bavarian hillside region close to the Czech border and Freiburg in the upper Rhine-valley with 3178 [Kd]. The solar radiation varies from 53 [kWh/m²] (December value for Harzgerode in northern Germany to 608 [kWh/m²] (July value for Garmisch in southern Bavaria). According to these climatic boundary conditions heating and warm water production are contribution to the energy consumption of the building stock. Cooling energy is only necessary in modern office buildings with large window areas. The heating period in Germany usually starts October 1st and ends April 30. In 1985 the first regulation for energy saving in construction passed the German parliament. From that time on every new building had to fulfill certain heat insulation requirements. This means for buildings younger than 1985, that acceptable heat insulation is already existing. Nevertheless these buildings contain only around 12,5% of the whole dwellings in Germany, meaning that around 87,5% of the German building stock were built without legal obstruction to fulfill a certain heating energy demand. The energy directives issued since 1985 also contain requirements for existing buildings, e.g. for facades: if more than 25% of the existing cladding of one side of the building façade have to be removed caused by a refurbishment action, the whole side of the façade had to reach an U-value lower than 0,4 [W(/m²K]. In most cases this reduced U-value only can be reached by implementing an additional insulation layer on the façade. But, as the energy directive for existing buildings was not coupled with a fine or penalty most building owners in Germany did not obey to the directive. Beside the legal obligation the development of new building materials as well as the customers/users requirements for proper indoor environment quality with according reduced "cold" radiation from inside of exterior walls caused also in the years before 1985 improvements of the thermal insulation of the building envelopes.
COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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Technical Improvement of Housing Envelopes in Germany
1.2 Requirements in Germany, that enforce a reaction to refurbish envelopes The below listed values are an excerpt and not complete list from the current energy directive in Germany. If more than 20% of one façade orientation of a building are being "changed", the following U-values have to be fulfilled: First implementation of a wall, complete replacement of a wall, implementation of an additional interior layer on the exterior wall or new fillings for timber constructions:
U < 0,45 (W/m²K)
Implementation of an additional layer on the exterior side of the wall, implementation of insulation layers and, if the cladding of an existing wall with more than U > 0,9 [W/m²K] is being replaced
U < 0,35 (W/m²K)
Windows on façade and roof (with exception +0,1 for special glazing, e.g. additional sound insulation etc)
U < 1,70 (W/m²K)
Non openable fixed glas-elements (also with exception +0,1 for special glazing)
U < 1,50 (W/m²K)
Flat roof (heated area to outside air)
U < 0,25 (W/m²K)
Sloped roof (heated area to outside air)
U < 0,30 (W/m²K)
Ceilings and walls to unheated areas
U < 0,40 (W/m²K)
Walls to ground
U < 0,50 (W/m²K)
2 SPECIFICATION OF THE TECHNICAL SOLUTION Extenal thermal insulation composite systems (ETICS) are used in the first place to improve the thermal protection of external wall constructions and are becoming increasingly more important.
50 45 sales [mio. m²]
40 35 30 25 20 15 10 5 97
95
93
91
89
87
85
83
81
79
77
to 76
0
Fig. 1: Number of thermal insulation composite system areas [m²] laid annually in Germany.
The first ETICS were developed in the 1950s. In these polystyrene rigid foam plastics battens were bonded onto the supporting base using plastic dispersion adhesive and then covered with the reinforced rendering (Fig. 2). From the mid 70s ETICS mineral fibre boards were used that are bonded to a supporting base and dowelled (Fig. 2). In the 80s systems mineral fibre lamellas were also used. In the 90s varied systems were developed using other types of insulating mate-
Technical Improvement of Housing Envelopes in Germany
43
rial made from wood fibres or mineral foam plates (foam concrete), however no adequate long term experience is available for these yet. a) Oberputz bewehrter Unterputz Polystyrol
Verankerung Schiene (siehe Detail) Oberputz
Kleber teilflächig
bewehrter Unterputz
KS-Mauerwerk
Wärmedämmung Klebepunkt Dübel
b)
KS-Mauerwerk Oberputz bewehrter Leichtputz
Detail
Bohrung Ø 8.2 / 10.2
Fig. 2: (a) Bonded polystyrene system (PS-ETICS), (b) Bonded and dowelled mineral fibre system (MFETICS), (c) System with rail mounting (from [1])
Along with the purely bonded or bonded and dowelled systems, systems with rail mounting (Fig. 2) were offered for modernisation, these could be used where the base surface is unfavourable. The development of possible cladding variants has become very diverse in the last few years. Along with the rendering systems – such as pure synthetic resin plaster or modified plastic mineral plaster – brick strip or natural stone claddings are offered. 3 THE IMPACT OF THE MOST COMMONLY USED REFURBISHMENT ACTION ON SUSTAINABILITY TOPICS 3.1 Technical performances 3.1.1 Struktural integrity Proof of stability of ETICS is shown within the framework of the technical approval procedure. When the requirements for the building inspection approval are adhered to in respect of - proportion of adhesive surface, - number of dowels dependent on the base surface and wind load zones, as well as - the material properties of the individual components (e.g. transverse tensile strength). then the stability of the thermal insulation composite system is guaranteed. In the case of systems that are bonded only, then the unevenness of the base surface must be a maximum of 1cm/m. In the case of bonded and dowelled systems it is 2 cm/m and in the case of systems with rail fastening 3 cm/m. The maximum thermal insulation material thicknesses are limited dependent on the respective system (e.g. PS-ETICS d 400 mm) In the case of normal base surfaces, such as brick, concrete or lightweight concrete walls, proof of stability for the wall itself is not necessary, as the additional loads from the ETICS are limited as a rule to 35 kg/m². In the case of light constructions such as e.g. walls of wooden post-and-beam construction, proof of stability may be necessary.
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Technical Improvement of Housing Envelopes in Germany
Special dowels for anchoring in thin layers of concrete are offered for dowelled systems for three layer elements with thin facing shells (dd 6 cm). ETICS do not increase the stability of the existing supporting structure. 3.1.2 Fire protection ETICS may only be used in Germany in building heights up to tower block height (Hd 21 m) as flameproof systems (that also means using PS-ETICS). In the building expansion joint area use of a strip made from non-flammable insulation material (e.g. mineral fibre boards sheets or mineral fibre lamellas) may be necessary in accordance with building regulations. Where the heat insulation thickness of the polystyrene rigid foam plastic is over 10 cm, use of non-flammable heat insulation is required in the lintel area of wall openings. Where buildings exceed tower block height (>21 m), the use of non-flammable systems is necessary. 3.1.3 Noise Isolation ETICS can cause the existing sound insulation against external noise to improve as well as deteriorate. An example of this is shown in Table 1 for an existing single shell construction using an existing sound insulation of Rw, = 54 dB. Table 1: Improvement and deterioration of the sound insulation of an existing external wall by fitting ETICS (+ = improvement - = deterioration).
bonded PS-ETICS bonded PS-ETICS with more elastic PS
rendering g d 10 kg/m² - 2 dB 0 dB
rendering g > 10 kg/m² -1 dB +1 dB
bonded and dowelled PS-ETICS
-1 dB
-2 dB
bonded MF-lamella-ETICS bonded and d = 50 mm dowelled MFd = 100 mm ETICS PS-ETICS with rail mounting
-5 dB
-5 dB
-4 dB -2 dB
+4 dB +2 dB
+2 dB
+2 dB
3.1.4 Weather Protection and moisture protection The weather protection of an existing external wall construction can be improved considerably by fitting ETICS. The weather protection of the ETICS itself is in particular determined by the rendering system. ETICS with water-repellent renderings can also be used in areas with the highest degree of stress from driving rain. Renderings are water-repellent when the capillary water absorption w and the diffusion of vapour equivalent air space thickness sd is limited. As can be seen from Fig. 4, most rendering systems show water-repellent properties. In the case of existing monolithic external walls made of brick or concrete the diffusion of vapour requirements for moisture are guaranteed. In the case of light constructions such as e.g. external walls of wooden post-and-beam construction, proof of vapour diffusion may be necessary.
Technical Improvement of Housing Envelopes in Germany
45
Fig. 4: Evaluation of 170 different ETICS in respect of the water-repellent properties of the rendering systems.
The material combinations of insulating material and rendering system must be adhered to in technical approvals. This means for example that the use of a relatively vapour diffusion tight artificial resin rendering system on mineral fibre insulation that is open to diffusion is not permitted. Some people are afraid, that the fitting of ETICS reduces the possibility for the wall to "breathe" and therefore the interior moisture problems are increased. This argument has been tested several times and was proven wrong. Only a fraction of the moisture occurring due to the use of the rooms is transported outside by way of vapour diffusion and that is independent from whether there is a ETICS or not. The more effective way to the power of ten is the removal of moisture by means of ventilation. 3.1.5 Conductivity (U-value), Heat flow (g-value), radiation, convection Improvement of the thermal protection is dependent on - the heat transfer coefficient U of the existing construction and - in particular the thermal insulation thickness d and the thermal conductivity O of the insulating material. Fig. 3 shows an example of the improvement of the U-value of an existing construction (Uexisting = 1.5 W/(K.m²)) dependent on the thickness of the thermal insulation material and the thermal conductivity of the material.
Fig. 3: U-value of a wall after fitting a ETICS.
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Technical Improvement of Housing Envelopes in Germany
3.1.6 Durability (service life) ETICS have proven themselves in the long term. Cautious estimate on the life expectancy of thermal insulation composite systems is given in [2] as 25 to 45 years, on average 30 years. ETICS have considerable influence on the increase of the remaining durability of the existing construction. After fitting ETICS the existing construction behind it dries out in the long term (Fig. 5).
Fig. 5: Long term drying out of the concrete facing layer of a three layer external wall element after fitting a polystyrene-ETICS (from [3]).
The equilibrium moisture content in the concrete then falls under a critical value of 80%. Below this moisture content corrosion of the reinforcement can be excluded. Fitting a ETICS therefore stops the corrosion process. 3.2 Functional/social performance 3.2.1 Flexibility ETICS can not contribute to an increase in flexibility in the inside of the building or in the external area. 3.2.2 Comfort (thermal, acoustical, visual) ETICS improve the thermal comfort. Fitting additional thermal insulation measures increases the temperature of the inside surface of the external wall (Fig. 6).
Fig. 6: March of temperature through the external wall without and with ETICS
This reduces the heat loss due to radiation from the human body to the colder external wall. The “operative” – that is the sensed – temperature increases at the same room air temperature. People find this more comfortable. The acoustic comfort can be influenced in a negative manner by ETICS. When the sound insulation dimension is improved against external noise (Section 2.1.4) it is possible that noise
Technical Improvement of Housing Envelopes in Germany
47
from the neighbouring apartment is perceived as disturbing, as the basic noise level falls due to the external noise. The possibility of improving the visual comfort by fitting ETICS is limited to the external area. Only by selecting the cladding, rendering, clinker strips or natural stone can the aesthetic appearance be altered. There is however no considerable change to the aesthetics or the design of the whole building. 3.2.3 Health (air quality, TVOC etc.,mould & fungus growth) As described in the section above, fitting ETICS increases the internal surface temperature of the external wall. At the same time the danger of mould fungus formation drops. 3.2.4 Other functional or social properties Other properties, such as social benefit, security, breaking down of barriers etc. cannot be quoted in connection with the fitting of ETICS. 3.3 Economic Performances 3.3.1 Building Costs The set up costs for ETICS are on the one hand dependent on the type of the system (Table 2) and on the other hand on the arrangement of the façade. Table 2: Set up costs for thermal insulation composite systems in Germany costs [€/m²] from
to
avarage
PS-ETICS (d = 10 cm) with synthetic resin-based rendering
63
75
70
PS-ETICS (d = 10 cm) with mineral rendering
68
80
75
MF ETICS (d = 10 cm) with mineral rendering
78
98
90
3.3.2 Running Costs (heat losses, cooling, cleaning, inspection, maintenance, etc.) Fitting additional thermal insulation measures reduces the transmission heat losses through the external wall. The reduction in operating costs connected with this must be compared with the investment costs. An example of this: In the case of brick-external wall construction the rendering needs to be renewed. A feasibility study should be carried out to see if additional thermal insulation measures are useful. The costs for renewing the rendering and fitting a thermal insulation system as per table 3 are put in comparison here. The amount of difference results in the “energy related” extra costs of 22 € per m² component area.
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Technical Improvement of Housing Envelopes in Germany
Table 3: Building Costs ETICS [€/m²]
renewed rendering [€/m²]
Gantry, cleaning Renewed rendering / coating ETICS (d = 12 cm) Edge protection profile, movement joint profile Starter profile, window sill, rainwater downpipe, roof parapet
10 44 2
10 34 3
10
-
Others, fee of architect
13
10
total 79 “energy reduction related” extra costs: 79 – 57 = 22 €/m²
57
Based on an interest rate of 5.75%, a price increase of 5.4% and taking the service life of the thermal insulation composite system as 30 years, as well as the assumption of natural gas heating at 0.02 € per kWh, the amortisation time is as shown in Fig. 7.
Fig. 7: Amortisation time as intersection for the investment costs and the energy cost saving.
As the amortisation time lies clearly under the service life of a ETICS, the measure is economical. The annuity profit is determined in order to determine the economic optimum thickness of the thermal insulation. In so doing the extra or reduced costs of 1.25 € per cm thickness of thermal insulation material and per m² are applied (Fig. 8).
Technical Improvement of Housing Envelopes in Germany
49
Fig. 8: Annuity profit
The annuity profit is at its highest in the range between 8 to 14 cm. This corresponds to the economic optimum thermal insulation thickness. It is recommend that the upper range, that is 14 cm thickness of thermal insulation material is fitted in view of further increases in power prices and the external costs for environmental pollution etc. that are not considered. 3.4 Enviromental Performances 3.4.1 Use of Resources (non renewable, renewable) The proportion of renewable resources is very low in the case of the usual market system. This proportion only increases in the case of insulating materials made from sustainable raw materials – such as wood fibre boards. There is however insufficient experience to date in respect of the long-term resistance of these systems.
PEI [kWh], GWP [kg-CO2 ], AP [g-SO2 ] per m² and year service life
3.4.2 Energy Consumption (non renewable, renewable) – production / assembly – heating / cooling The proportion of renewable energies in the production of ETICS is low. Fig. 9 shows the overall energy content from primary energy content for the production and primary energy requirement due to the transmission heat losses dependent on the insulation thickness for a PS-ETICS
50 PEI
40
AP 30
GWP
20 10 0 0
50
100
150
200
thickness of thermal insulation [cm]
Fig.9:
Overall energy content, global warming potential and acidification potential over the life cycle of a PS-ETICS dependent on the insulation material thickness.
50
Technical Improvement of Housing Envelopes in Germany
It shows that when the insulation material thickness continues to increase to approx. 50 cm, the overall primary energy content reduces further. Therefore the energetic optimum is not yet achieved by the present insulating material thicknesses. 3.4.3 Environmental impacts, (GWP global warming potential, AP acidification potential, NP nitrification potential, EP eutrophication potential, ODP ozone depleting potential, POCP photochemical ozone creation) Fig. 9 shows the global warming potential as well as the acidification potential over the whole life cycle of the ETICS dependent on the insulation material thickness for the above mentioned example. In this example the optimum thermal insulation thickness in respect of the global warming potential at approx. 75 cm in respect of the acidification potential would be approx. 25 cm. 3.4.4 Waste and recycling and re-use potential There is little information on the contribution to waste made by the manufacturing phase. Pure uncontaminated polystyrene rigid foam plastics offcuts could be passed on for material recycling. In the case of external wall constructions using ETICS, which no longer meet the requirements for thermal protection, the existing systems do not necessarily have to be removed and replaced with new ones. Rather more procedures are offered which enable “over insulation” that is fitting an additional ETICS on to the existing ETICS. Apart from the thermal recycling of PS-ETICS, no other possibilities of recycling are known. 4 CASE STUDY 4.1 Residential Building in Frankfurt, Gallusviertel As an example for the refurbishment including the energetic improvement of the façade the area "Gallusviertel" in Frankfurt can be highlighted. Altogether houses with around 2500 apartments were refurbished with an insulation of 12 centimetres of ETICS (some even in the passivebuilding standard with 26cm). Besides new windows (double, coated and gas filled), insulation of roof floor 10 centimetres and cellar ceiling 8 centimetres were applied. In addition on some houses balconies with thermal separation to the façade system were fitted on the façade.
Fig.10: Houses before and after the refurbishment action.
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51
5 REFERENCES Cziesielski, E.; Vogdt, F.U.: Damage to thermal insulation composite systems, Stuttgart, Fraunhofer-IRB Verlag, 1999. Handbook Sustainable Construction from the Federal Ministry for Transport, Construction and Housing (publisher) Berlin, 2001. Vogdt, F.U.: Stress on thermal insulation composite systems as a consequence of hygric and thermal deformations on facing layers in large panel construction, Dissertation, TU Berlin, 1995.
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Technical Improvement of Housing Envelopes in Hungary A. Zöld Budapest University of Technology and Economics
T. Csoknyai Budapest University of Technology and Economics
ABSTRACT: The main problems of the post-war block of flats in Hungary are the poor thermal performance: thermal bridges, bad whether proofness and air-tightness and the related fabric damages, resulting in high operational cost and low quality of living standard. Uncontrollable heating systems increase the waste of energy. Although several good initiative can be referred to in the past as well as recently, some refurbishment attempt which neglected the complexity of the system further increased the problem, sometimes making disputable the rationality of the applied measures. False, simplified calculation concepts of pay-back time slowed down the decision making and the allocation of funds for added thermal insulation. On the other hand successful demo projects proved the great energy saving potential and positive side effect of thermal rehabilitation.
1 INTRODUCTION As it is described in the “State of the Art in Hungary” chapter the typical blocks of flats built in the post-war period are made with prefabricated sandwich panels. With regard to the huge number of flats in these blocks on one hand and the refurbishment programmes of the state, offering financial contribution exclusively for this building stock, on the other hand, the recent analysis encompass this type of buildings. The thermal performance of these buildings is not acceptable any more. The heating energy consumption is very high (150-220 kWh/m2year), accompanied with fabric damages. In the period of their erection the minimising the in situ work, high level of prefabrication meant the priority and the energy price was 1% of that of the recent figure. 1.1 Main characteristics of exposed walls Based on an overview of the available constructional plans five characteristic periods can be distinguished from the point of view of thermal performance and fabric protection. The periods are presented in Table 1. Although these were typical values, they were not uniform. Certainly in all periods there were differences, because the building elements were produced in sixteen prefabrication factories and plants. The dates were also not so definitive. Thus, the figures presented in this paper are useful for good estimations. COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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Technical Improvement of Housing Envelopes in Hungary
Regarding the theoretical U-values one could think that these structures are rather acceptable and almost fulfil even the present requirements. Certainly, if these were real U-values the measured heating energy consumption of the buildings were much less. As a consequence it is obvious that either the U values are much higher or there are other components of heat loss not taken into consideration. Indeed, both are true and the unconsidered components are the thermal bridge losses.
Table 1: Characteristic periods of the industrialized constructions Period Period 1
-1965
Period 2
1960-67
Period 3
1967-74
Period 4
1974-82
Period 5
1982-92
Characteristics Medium blocks, generally slug concrete, no thermal insulaton Sandwich panels, 8 cm mineral wool insulation, no insulation at joints Sandwich panels, 8 cm mineral wool insulation, 2-3 cm insulation at joints Sandwich panels, 7 cm PS insulation, 2 cm insulation at joints Sandwich panels, 8 cm PS insulation, 8 cm insulation at joints
Theoretic air-to-air conductance U = 1,3..1,7 W/m2K U = 0,45..0,66 W/m2K U = 0,45..0,66 W/m2K U = 0,45..0,55 W/m2K U = 0,38..0,48 W/m2K
1.2 The real air-to-air conductance of sandwich panels One reason is the mistakes made during the prefabrication process when sandwich panel was treated with heat, water, vibration and the polystyrene layer was not protected from the negative influences of the regular technology. In addition the weight of the reinforced concrete layer represented significant pressure on the PS layer. As a consequence the PS plates have often broken and their insulating performance has significantly decreased. An example for this problem is shown by the infrared photograph in Figure 1. Measurements in the Laboratory of Building Physics at BUTE have proved that this prefabrication technology causes 50 % of deterioration in the insulating properties. In period 2 and 3 mainly mineral wool was used as insulation material. The last decades have proven that this material can easily move due to its fibrous and loose structure. Therefore in many cases the mineral wool has fallen down in the panel. Today in many of these panels the mineral wool layer is missing causing very high U-values and fabric degradation. In addition the insulating properties of mineral wool significantly decrease at high moisture content. It causes problem if the driving rain can enter along the edges of the panel to the insulating layer. Naturally this problem is not typical for period two when the panel edges were not insulated. Here the concrete rim has a protecting effect. On the other hand the thermal bridge losses here are the highest.
Technical Improvement of Housing Envelopes in Hungary
Figure 1. Thermal bridges caused by panel junctions and broken PS insulation (infrared photo)
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Figure 2. Thermal bridges caused at junctions, window and parapet installations (infrared photo)
The infrared photos give evidences on the constructional mistakes. On Figure 1 the insulation is broken in one of the panels. The thermal bridges at panel junctions and around window frames can clearly be seen in Figures 1 and 2. In addition to the poor performance of the applied insulation the thermal resistance is decreased also by the steel reinforcement crossing the insulation layer that fixes the external weather protection concrete layer to the load bearing concrete layer. 1.3 Point-like thermal bridges in the sandwich panels The problem is typical after the 2nd period, when the concrete connection at the edges of the to reinforced concrete layers was eliminated and substituted by steel reinforcement. The number and diameter of crossing-through steel elements depends on the licence of the technology. In a most frequent panel of Soviet type 2x7 = 14 crossing steel elements with a diameter of 8 mm were applied. Although the total cross section of the steel elements are almost neglectable compared to the insulated area, the heat loss is significant, because the heat conductance of steel is steel / insulation = 80 / 0,05 = 1600 times higher than that of the insulation. Furthermore the extra heat loss caused by the crossing steel elements cannot be calculated only from the ratio of the surfaces and conductances of steel and insulation, because the steel elements do not finish at the meeting plain of the concrete and insulation layers. They enter into the concrete layer and turn in order to ensure the necessary holding stability. Therefore exact calculation can only be made using finite elements’ method. To simplify the calculation procedure the Passive House Institute has developed a diagram that can be seen in Figure 3.
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Technical Improvement of Housing Envelopes in Hungary
Heat loss of point-like thermal bridge
Steel Wood Screw GFK steel Diameter
Figure 3: Determination of extra heat loss caused by poctual thermal bridges (eg. steel elements crossing through the insulation) (Source: Passive House Institute)
It can be read from the diagram that the most frequently applied crossing steel elements with 8 mm diameter has a heat loss of 0,03 W/K, that means 14 x 0,03 = 0,42 W/K heat loss per panel. Let’s consider a panel of 2,65x3 = 7,95 m2 with 7 cm insulation including a window of 2,1x1,5 = 3,15 m2. The laboratory U-value of the panel is Ulab = 0,5 W/m2K, thus the laboratory specific heat loss (not including he linear and ponctual thermal bridges) of the panel is (7,953,15)x0,5 = 2,4 W/K. Adding the 0,42 W/K extra heat loss caused by the steel elements the result is 2,88 W/K and the increase is 17,5%. In general the extra heat loss is 10-20 % depending on the panel type and the additionnal elements (windows, balconies, loggias, etc.). Now it is clear that determining the exact U-value of a panel installed decades ago is impossible with calculations, because it depends on several stochastic parameters: the quality of fabrication and the climatic influences during its lifetime. The realistic value can be estimated from measured heat consumptions or laboratory measurements of panels. According to laboratory measurements at BUTE Laboratory of Building Physics the U-values of the uninstalled panels are between 0,8-1,1 W/m2K depending on the age, the applied system and the stochastic effects.
Figure 4. Example of a junction typical for buildings made with medium-sized blocks
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2 HEAT LOSS OF PANEL JUNCTIONS Parallel to the layers the junctions have also being developed with the time. In the followings the junction types are presented in the order of construction time. The thermal bridge losses were determined by a computer aided model based on the finite elements’ method. 2.1 Period 1: Single layer, uninsulated structures In the first period ended around 1965 slug concrete structures had a dominating role. Slug concrete is a relative light porous material with a lower U-value than that of the concrete (Oslug concrete = 0,5..0,7 W/m2K, Oreinforced concrete = 1,55 W/m2K). These structures were built without any insulation and the U-values of the facades are high: U = 1,3-1,7 W/m2K. Two technologies were applied: cast structure made at the construction site and siteassembly using prefabricated blocks. Due to the homogenous structure the significance of the thermal bridges is lower than that of the following periods, the typical <-values are 0,15….0,4 W/mK. Junctions at floor slabs and facade elements are made with reinforced concrete crowning with a thin slug-concrete „thermal insulation”. Certainly here the thermal bridge losses are higher. 2.2 Period 2: Sandwich panels with no insulation at joints The first construction factory was built in 1965 that was followed by 9 others. The medium sized blocks were substituted by sandwich panels with the dimensions of the rooms. The sandwich panels generally consisted of a 15 cm reinforced concrete holding layer, a 5-8 cm insulation layer and another 7 - 9 cm reinforced concrete weather protection layer.
3 8 Figure 5 Example of a junction in period 2
In the first buildings the Soviet example was taken: light concrete (ceramsit) was used as insulation material. It resulted in a very high laboratory U-value: U = 1,7 W/m2K. In a short time it was substituted by mineral wool. The two concrete layer was connected by a continuous reinforced concrete band at the panel rims. It means that the insulation was interrupted at the panel rims in a band of a width of 15-30 cm. Therefore these structures have the highest thermal bridge losses among all periods. Typical <-values are 0,6..1,3 W/mK. These are much higher values than the ones used in regular calculations.
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2.3 Period 3: sandwich panels with mineral wool insulation, decreased to 2-3 cm at the junctions Due to the frequent mould growth these structures were modernised to a new system where the junctions were insulated with 2-3 cm mineral wool. It was supposed to be thermal bridg free, but naturally it wasn’t. The 2-3 cm insulation was much less than that in the zones far from the joints and the two concrete layers were connected by steel. It means that the thermal bridge losses are still high, < = 0,1..0,8.. W/mK. 2.4 Period 4. Sandwich panels with polystyrene insulation along the edges The mineral wool insulation was followed by polystyrene and uniform systems were introduced. For instance in Budapest all the four construction factories started to apply the „Budapest uniform system”, namely the insulation thicknesses and joints were uniform. The thicknesses do not change significantly: in Budapest the previous 8 cm insulation thickness decreased to 7 cm and at the joints it decreased from 3 cm to 2 cm. Thus the the thermal bridge losses didn’t really change (< = 0,1..0,8 W/mK), the steel reinforcement neither. The most critical part of this system is the thin thermal insulation band, to be put on the edge in situ, to the welded edge of the panel. This system was applied in the period whe most of the panel flats were built (approximately 260.000 dwellings).
2 PS
8 Figure 6. Example of a junction in periods 3 and 4
2.5 Period 5. andwich panels with continuous insulation By the end of the seventies, in the early eighties it became clear that the thermal bridge losses are more significant than they previously thought. Furtermore the increase of the energy prices made it necessary to build more energy conscious structures. The so called „thermal bridge free structures” have been introduced where the insulation was not interrupted and the thickness at the edges was the same as in the panel. On the other hand the steel reinforcement and thus the point-like thermal bridges remained, so this system is not thermal bridge free at all. Nevertheless the thermal bridge losses became much lower, < = 0,1..0,4 W/mK. In several construction factories in the country the previous system was applied until the end of the panel period, not everywhere was adapted the „thermal bridge free” system.
PS
8
Figure 7 Example of a junction in period 5
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It is clear now that the thermal bridge losses of panel buildings is very high,much higher than the standard losses taken into account in the practice. The reason is that the materials are not homogenous at the joints, so they are not only geometric thermal bridges. 2.6 Resultant air-to-air conductance The impact of thermal bridges is illustrated by the two examples of table 2 where two panels are examined with typical geometries with the thermal insulation level of the five characteristic periods. For the single layer structures the thermal bridge losses represent „only” 30 % of the onedimensional heat loss. It is certainly much higher than the value used in practice: usually thermal bridge losses are considered as 5-10 % of the losses calculated from the U-value. It means that the usual approach is useless for buildings made with industrialised technology. Furthermore in the later periods the thermal bridge losses are equal or even two-times higher than the one-dimensionnal heat loss. It can be stated that the thermal bridge losses can be much higher than the heat loss calculated from the U-value.
Table 2: Heat losses and U-values of two panels with typical geometries according to the thermal insulation level of the five characterictic periods
U laboratory U real
Period 1 Period 2 Period 3 Period 4 Period 5
Period 1 Period 2 Period 3 Period 4 Period 5
ª W º «¬ m 2 K »¼
ª W º «¬ m 2 K »¼
1,5 0,55 0,55 0,45 0,4 U laboratory
1,5 0,8 0,8 0,8 0,7 U real
ª W º «¬ m 2 K »¼
ª W º «¬ m 2 K »¼
1,5 0,55 0,55 0,45 0,4
1,5 0,8 0,8 0,8 0,7
Q1dim >W @ Q TB >W @
U Q TB >%@ 1dim TB Q1dim ª W º «¬ m 2 K »¼
209 112 112 112 98 Q1dim >W @
75 317 156 193 106 Q TB >W @
36% 2,03 284% 3,07 140% 1,92 173% 2,18 109% 1,46 U 1dim TB QTB > %@ Q1dim ª W º «¬ m 2 K »¼
325 173 173 173 152
90 397 198 235 132
28% 229% 114% 135% 87%
1,91 2,63 1,71 1,88 1,31
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Technical Improvement of Housing Envelopes in Hungary
3 EFFECT OF ADDITIONNAL THERMAL INSULATION ON TRANSMISSION LOSSES 3.1 Added external thermal insulation The typical and only rational solution to improve the thermal characteristics of the exposed wall is to add external insulation, covered with thin plaster (the DRY-WIT or Thermohaut /=thermal skin/ system). The insulation itself is PS or mineral wool, the thickness was 6 – 8 cm before, nowadays 10 – 12 cm becomes typical, due to the new national regulation. The effect of thermal insulation on the laboratory U-value is shown by the diagrams of Figures 8 and 9 for a typical panel. The first centimetres of the insulation cause a dramatic improvement and then it becomes more and more modest. If the insulation is put on the external side of the wall not only the one-dimensional U value decreases but also the thermal bridge losses, because the insulation covers the free way of the „escaping” heat. Using the thermal bridge model the <-value of typical junctions were analysed in function of the insulation thickness (Oins = 0,035 W/m2K in all cases). Results are presented in Figure 10. The curves are similar to the ones of the U-values, a dramatic positive effect at the beginning and modest improvement at further increase of insulation thickness. The highest savings can be achieved at those joints where the original heat loss was very high (figure 11). U
U/Uo
[W/m 2K]
0,60 0,50 0,40 0,30 0,20 0,10 0,00
100% 80% 60% 40% 20% 0%
0
2
4
6
8 10 12 14 16 [cm]
Figure 8 Effect of additional thermal insulation to the laboratory air-to-air conductance (Uo = 0,5 W/m2K)
0
2
4
6
8 10 12 14 16 [cm]
Figure 9 Effect of additionnal thermal insulation to the laboratory air-to-air conductance [%]
3.2 Additional thermal insulation and average U-value for the panel including thermal bridge losses Figure 11 also shows that for panel structures the influence on the thermal bridges is higher than on the U-values. For one-layer structures (period 1) where the thermal bridge losses are relative low the case is the opposite. A most characteristic panel (the second panel of table 2) was examined in function of thermal insulation. In fact the thermal bridge free zones of the panels are relative small and the total length of the thermal bridges is high, because the rooms are small and there are windows, loggias, balconies in most of the panels in addition to the outside boundaries. As a consequence the thermal bridge losses have a dominating share in the panel’s heat loss. Precise figures about the selected panel can be seen in figure 13. Interesting to notice that in order to go below U = 0,6 W/m2K 6-8 cm additional thermal insulation is needed and below U = 0,4 W/m2K the necessary thicknesses are 10-14 cm in function of the construction period.
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61
< [W/mK] 1,0 0,9 II_pos_corner
0,8
III_pos_corner
0,7
IV_pos_corner
0,6
III_T
0,5
IV_T
0,4
V_T I_pos_corner
0,3
I_T
0,2 0,1 0,0 0
2
4
6
8
10
12
14
16[cm]
Figure 10: <-values in function of the additionnal insulation thickness (pos_corner: positive corner of facades, T: joint of facade and internal wall, I-V: construction periods)
100% 90%
II_pos_corner
80%
III_pos_corner
70%
IV_pos_corner III_T
60%
IV_T
50%
V_T
40%
average I_pos_corner
30%
I_T
20%
U labor
10% 0% 0
2
4
6
8
10
12
14
16 [cm]
Figure 11: <-values and laboratory U-value in function of the additionnal insulation thickness [%] (pos_corner: positive corner of facades, T: joint of facade and internal wall, Ulabor: laboratory U-values, IV: construction periods, average: average of all<-values )
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2,00 1,80 1,60 1,40
Period 1
1,20
Period 3
1,00
Period 4
0,80
Period 5
0,60 0,40 0,20 0,00 0
2
4
6
8
10
12
14
16
Figure 13: Average U-values (including <-values) of the second panel in table 2 in function of the additionnal insulation thickness
4 THE THERMAL PERFORMANCE OF BUILDINGS 4.1 The components of the heat loss The share of the heat loss components depends on many parameters like, period of construction, complexity of geometry, number of floors, type of construction. Therefore seven typical buildings were chosen that are supposed to characterise the most frequent building types. The buildings were selected considering the following requirements: 1. The buildings cover all significant panel-periods: the first five buildings are typical for period 3 and 4, the seventh is from period 5 and the sixth building is from period 2. 2. All typical layouts are taken representing different A V values: point-type buildings,
¦
band-type building, H-form layout, etc. 3. Typical floor numbers are covered: two are 4-5 storey and five are 10-11 storey buildings. 4.In Hungary all construction factories bought sowiet licence, ecxept the 2nd Construction Factory of Budapest that bought the Danish Larsen-Nielsen technology. Building Kf/10 is built with the latter one. 5. Finally all selected buildings were built in high numbers all over the country. The analysis was made with software-tool developed for this purpose in Department of Building Energetics and Service Systems, BUTE. The software tool is based on a statistic analysis of the Hungarian building types. Results are summarized in table 3. The seventh column of the table shows the average of the first six columns. The seventh building is not taken into the average, because its heat loss is much lower than the average. In the followings „average” means the average of the first six building excluding the seventh.
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Table 3 Results of the heat loss component calculations for seven characteristic buildings based on statistical method Number
1
2
3
4
5
6
Type
A10
B10
TB-51
KB-512
Kf/10
Period 2
Average 1032
30.60
34.42
39.48
31.01
36.02
33.94
20.04
40.2%
28.6%
31.2%
39.7%
34.2%
35.4%
43.0%
59.8%
71.4%
68.8%
60.3%
65.8%
64.6%
57.0%
8.4%
9.2%
12.0%
10.4%
8.6%
9.5%
20.2%
24.6% 2.8% 5.3%
23.3% 5.5% 10.5%
25.1% 2.4% 1.5%
22.8% 2.8% 5.3%
22.9% 5.3% 5.0%
23.9% 3.6% 5.5%
18.7% 5.5% 5.9%
18.6%
23.0%
27.6%
19.0%
24.0%
22.2%
6.7%
20.1%
10.7%
15.6%
19.8%
17.1%
17.1%
12.3%
34.9%
42.9%
39.0%
35.0%
39.4%
37.9%
27.9%
4.3%
4.7%
6.1%
5.3%
4.7%
4.9%
10.3%
13.8% 1.8% 4.1%
13.0% 3.5% 8.0%
14.0% 1.5% 0.8%
12.7% 1.8% 4.1%
12.8% 4.1% 3.8%
13.3% 2.4% 4.1%
7.7% 2.9% 3.0%
11.0%
13.7%
16.6%
11.2%
14.0%
13.1%
4.0%
55.0%
53.6%
54.6%
54.9%
56.5%
54.9%
40.2%
Specific heat loss [W/m3] 32.13 Filtration heat loss 38.3% (61.. Transmission heat 5) loss 61.7% 1 Facade panels (excl. thermal bridges) 8.2% 2 Windows (transmission) 24.7% 3 Roof 2.7% 4 Cellar ceiling 5.1% 5 Thermal bridges 21.0% Savings on filtration 19.1% (66.. Savings on trans10) mission 35.9% 6 Savings facade panels (excl. TB) 4.2% 7 Savings windows (transmission) 13.8% 8 Savings roof 1.7% 9 Savings cellar roof 3.9% 5 Savings thermal bridges 12.3% Total savings
55.0%
7
In order to make them comparable the same energy saving measures on the building envelope were considered for all buildings. These measures are enough to reach the requirements of the current building regulations that is generally required by the state subsidies, but does not mean the technical or economical optimum. - 8 cm of additionnal thermal insulation of facades (O = 0,035 W/mK), - 10 cm of additionnal thermal insulation of on the roof (O = 0,035 W/mK), - 5 cm insulation on the cellar ceiling (O = 0,035 W/mK), - installing new windows (U = 1,3 W/m2K), - as a consequence of the window exchange the ACH will be appr. 0,5 1/h. Before renovation a higher share of the losses are the transmission losses (60-70 %), the filtration losses are about 30-40 %. After renovation the share of filtration is higher (40-45 %), if ACH = 0,5 1/h is kept. It means that in a renovated building a balanced ventilation system with heat recovery can save relative more energy than in a building in its original state. It is clear from the figures that the thermal bridge losses are often higher than the facade losses calculated from the U-value. The thermal bridge losses are 18-28 % of the total heat loss that is in average 34 % of the transmission losses.
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Technical Improvement of Housing Envelopes in Hungary
The only exemption is the 7th building built in 1983 („thermal bridge free” type), here the share of thermal bridges is 6,7 %. Most of the thermal bridge losses are caused by the ones around the windows, T-joints and facade-slab joints, because their total length is very high. Only the transmission losses of the windows are higher than the thermal bridge losses, 23,9 % of the total in average. The share of the roofs and cellar ceilings are low (3,6 % and 5,5 % in average), because the buildings are usually high and these exposed surfaces are less significant. In smaller buildings the values are higher. The roof insulation is calculated with design thicknesses that are probably a bit underestimated but the real values are unknown. The average transmission losses can be seen in Figure 14. 30% 25% 20% 15% 10% 5% 0% Window s
Thermal bridges Facade (excl. TB)
Cellar ceiling
Roof
Figure 14: Components of transmission losses in average for the first six buildings
In the first six buildings the average saving is 55 %, for the originally better insulated sixth building it is less, 40 %. If regarding only the transmission losses the measure with highest saving potential (18 %) is in the facade insulation from that the higher share is due to the reduction of thermal bridge losses (13,1 %) and the share of the one-dimensional losses is much less (4,9 %). Il also means that the external insulation is much better than the internal one. The facade insulation is followed by the window exchange with 13,3 % decrease of the total, but if also the decrease of the filtration losses is considered this saving measure is the most efficient (30,4 %). The lowest saving potential is in the roof and cellar, but in many cases this saving can be underestimated because of the already mentioned reasons. The achievable savings are in figure 15. In the building built in period 5 change of windows is definitely the best measure.
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18% 16% 14% 12% 10% 8% 6% 4% 2% Roof insulation
Cellar ceiling ins.
Facades excl. TB
Facade thermal bridges
Window exchange transmission
Window exchange filtration
0%
Figure 15: Decrease of heat loss per energy saving measures (average of buildings 1-6)
4.2 Effects and side effects of added thermal insulation Misleading would be (as it was many times in the past) the calculation of the rationality of added thermal insulation if only heat losses would be taken into account: the added external thermal insulation has several positive side effects, all improving the thermal performance of the building. These are the followings: Covering the building shell with a continuous insulation layer not only the thermal bridge losses will be decreased but the internal surface temperature in general and especially along the edges will be increased. As a result the ventilation losses will be less: on one hand higher relative humidity of indoor air can be tolerated without the risk of fabric damages, on the other hand lower air temperature will provide the same operative temperature at the higher mean radiant temperature. These together mean less air change rate and lower air temperature. The temperature of the original layers will be higher, thus the stored heat increases. Better heat storage improve the utilisation factor of the solar gains, decreases the risk of summer overheating. The balance point temperature of the building will be lower, thus the heating season will be shorter, the degree-days to be covered by the heating system will be less. Due to these facts the energy saving may be the double of the value calculated simply on the base of the U value. Besides of the energy aspects further favourable consequences are to be mentioned, as - less risk of fabric damages, - better thermal comfort, - prolonged physical life time (the most critical constructional detail is the joint of the panels with in situ welding, exposed to moisture, driving rain – the corrosion here is slowed down with the external insulation and water repelling surface finishing). Last but not least the new surface finishing facilitate to improve the aesthetic quality of the ugly looking buildings. It is to be emphasized that only complex retrofit measures, including the simultaneous insulation of walls, change of windows and renovation of heating systems provide better thermal performance and less risk of fabric damages. Missing one or two items from these will not result in energy saving, moreover the risk of fabric damages may become higher.
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4.3 Legislative aspects According to the new national regulation, implemented in 2006 together with other rules of the Energy Performance of Building Directive the U value of walls must not exceed 0,45 W/m2K. It should be emphasized that this is only a possibility, because on the higher levels of the regulation the specific heat loss coefficient of the building and the specific primary energy consumption is limited, too. The last requirements can often be met only with lower U value. In the case of major refurbishment of buildings beyond 1000 m2 floor area the same requirements are applied as for new buildings! 4.4 Social and organisational background The importance of energy efficiency among panel buildings is more and more know by the public. In the last six years the government announced programs supporting especially energy saving measures among panel buildings. The structure and the requirements of the programs changed several times during this period, but the maximum of the governmental subsidy was about one third of the costs. Some ambitious local governments offered another third of the costs for their applicants, but even this wasn’t enough encouraging. One main reason of the problem can be explained by socio-economic aspects. In Hungary the majority of the flats are owned by the tenants, thus any renovation can be accomplished only by the agreement of many people with different social background, financing situation, energy consciousness and level of education. The supporting programs required 90-100% of participation that turned to be very difficult. There were always tenants who found even the 30% too expensive. In the recent years subsidised loans were introduced to cover the own share, which has turned to be very successful. As a result in a significant share of the panel buildings some renovation measures can be seen by today: exchanged windows, insulated facades (often only one façade per building) or modernised heating systems. However there are still two main problems. First, unfortunately the technical requirements of the programs still allow renovations resulting fabric degradation. Although the necessity of the complex retrofit is already realized by the proposing authorities, but the implementation is still often shows incompetence. For instance it is not allowed to exchange windows only (which is correct), but it is allowed to exchange the windows and insulate the cellar ceiling, which doesn’t make a difference from the point of view of fabric protection. Another significant problem is the instability of the supporting programs. They are often connected to political intentions and events, there are long periods when the programs are stopped without any information about the future continuation. It leads to the block of demand and the market. Finally it should be mentioned that in Hungary the gas prices (and as a consequence the district heating prices) are pushed down artificially by the government compared to world prices. This stabile subsidy is not favourable for energy efficiency measures and renewable applications which are supported in an instable way. The competition is simply unfair. However, this situation seems to change, because the artificially decreased gas prices cannot be kept any more. 5 CASE STUDY: THE SOLANOVA BUILDING In the Solanova project the special characteristics of the panel buildings were examined and the already worked out passive house measures were applied with a demonstrative purpose. The original state and the impact of the renovation are examined by a scientific supervision and a computer aided monitoring. The renovation process ended in October 2005, but the scientific research and the demonstration are running until December 2006.
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The goals of the project to significantly decrease the heat consumption of the building regarding both heating and DHW production and to improve thermal comfort based on an eco-efficient optimisation and social research. The results of the long-term monitoring prove that the heating energy saving is approximately 85%. In order to achieve this target the building envelope has been insulated (16 cm added externally) and new energy efficient windows (double and triple glazed, low-E coating) were installed. The flat roof was covered with 21-34 cm thermal insulation and the cellar ceiling 10 cm. For architectural reasons and to create a recreation area for the dwellers a green terrace roof was constructed aiming an additional positive effect on summer comfort in the top floor dwellings. The ventilation losses are decreased by a flat-wise balanced ventilation system with heat recovery. The remaining heat demand is covered by a new traditional radiator system. Without any measures the heat demand of the DHW would be dominating after the retrofit. Therefore water saving equipments were installed and 72 m2 solar collector array support the DHW production. The collector field serves double function: in addition to the DHW production they perform as a canopy for the southern ground floor shops providing shadow and rain protection
6 REFERENCES Hermelink A.: Ultra efficient refurbishments of panel flats – introducing the Solanova project, Climate Change – Energy Awareness – Energy Efficiency, IV. International conference, Visegrad, 8-10 June 2005, pp. 51-56 Pfluger R.: Importance of dynamic simulation and dynamic elements, Climate Change – Energy Awareness – Energy Efficiency, IV. International conference, Visegrad, 8-10 June 2005, pp. 79-84 Kalmár F. Heat gains influence on balance point temperature and thermal comfort, 7th Nordic Building Physics Symposium, 13-15 June 2005, Reykjavik, Iceland.pp. 953
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Technical Improvement of Housing Envelopes in Italy Silvia Brunoro Department of Architecture “Biagio Rossetti”, University of Ferrara, Italy
1 INTRODUCTION 1.1 Standard envelopes in Italy The post-war housing sector in Italy accounts for a large amount of waste, mostly owing to the poor technical performance of the envelopes. Building technology from 1950 to 1980 in Italy can be summarized as follows: Three main types of structure: reinforced concrete beams and pillars system, tunnel technologies and prefabricated panels; External walls: generally constructed in perforated brickwork or prefabricated concrete panels with no thermal insulation. External and internal layer is, for the most part, plaster; Windows: The most common materials used for window frames are aluminium and plastic. The majority of housing was built before the first petrol crisis in 1973 and the consequent law no. 373/1976, so have single-glazed window panes; Roofs: pitched and flat roofs. In general, flat roofs are used in the south of Italy, due to the rare incidence of rain, while sloping roofs are used in the North of the Italy. The structure is generally trestle floor beams and hollow floor blocks or prefabricated concrete panels. Flat roofs are usually finished with two layers of asphalt paper and 4 cm of gravel. Sloping roofs are finished with roof tiles. The main problems associated with Italian buildings envelopes are the lack of thermal and acoustic insulation and the poor quality of the windows (single-glazed windows and window frames with low air-tightness). The lack of performance and the consequent inability to make use of the climatic resources cause a high level of heat loss in winter and overheating in summer. 1.2 Requirements in Italy, that enforce a reaction to refurbish envelopes Italy has a temperate Mediterranean climate with well-defined seasons: cold winters, rainy springs and hot, dry summers. As a Mediterranean country, the principal problem is that of hot temperatures and rain action, so the main requirements of envelopes can be summarized as: Improvement of thermal insulation and thermal inertia; Reduction of overheating in summer; Protection from moisture, atmospheric agents and prevention of condensation. COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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Most existing envelopes do not comply with current insulation standards. In general, global heat loss (U value) exceeds 1.5 W/m2 °C. Windows are, in most cases, single–glazed, and sometimes the sections under the windows are thinner and therefore the heat transfer coefficient of the façade is much greater than required. Building deterioration increases negative consequences both in terms of the health of the residents and greater energy waste. In recent years the regulations on thermal insulation and comfort in working and residential units have become restrictive, due to the intervention of the “Energy saving law” 10/1991 and the subsequent implementation of Decree DM 27/07/2005. This has been recently upgraded by Decree 192 19/08/05 “Energy efficiency of buildings” which has promoted the “energetic certificate” in order to evaluate and control the performances of buildings in terms of energy, valid for new and refurbished buildings over 1000 m2. This law establishes the maximum values for energy requirements (Tab 1) in kWh/m2 per year in relation to the volume (V) and the surface area (S) of the building.
Table 1: Energy requirements of a building in winter according to Decree 192/05
Degrees/day S/V 0.2 0.9
A B C <600 >600<900 >900<1400 Energy requirements (kW/m2 year) 10 10 - 15 15 - 25 45 45 – 60 60- 85
D >1400<2100
E >2100<3000
F >3000
25 - 40 85 - 110
40 - 55 110 - 145
55 145
This decree establishes standard energy transmission values (U – values) for opaque façades and windows are fixed (Tab.2). These values will become more restrictive from 2009.
Table 2: Standard U values for façades and windows according to Decree 192/05 Climatic Zone A B C D E F
Opaque Façades U (W/m2K) From 1/01/2006 0.85 0.64 0.57 0.50 0.46 0.44
U (W/m2K) From 1/01/2009 0.72 0.54 0.46 0.40 0.37 0.35
Windows U (W/m2K) From 1/01/2006 5.5 4 3.3 3.1 2.8 2.4
U (W/m2K) From 1/01/2009 5.0 3.6 3.0 2.8 2.5 2.2
The Italian standards on noise insulation is defined by Law 447/1995 and decree DPCM 5/12/1997 n.297. This decree establishes seven categories of buildings and the corresponding values in Decibels (Db) of thermal insulation for each part of the building. Table 3: Acoustic insulation standards for residential buildings established by DPCM 297/97 Value (Db) RW D2m,nT,W Ln,W LASmax LAeq
RW D2m,nT,W Ln,W LASmax LAeq 50 40 63 35 35 Description Soundproof power index for walls between two rooms, to be calculated according to UNI regulation 8270 (1987 part 7, chapter 5.1). R is defined by EN ISO 140-5 (1996) Standardized noise insulation index for facades to be calculated as with Rw Tread noise index, to be calculated according to UNI regulation 8270 (1987 part 7, chapter 5.2). Ln is defined by EN ISO 140–6 (1996) Maximum sound pressure level considered “A” with slow time constant Continuum of equivalent value of sound pressure, considered “A”
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2 SPECIFICATION OF THE TECHNICAL SOLUTION The most common solutions for the refurbishment of façades in Italy are: External Thermal Insulation Composite Systems (ETICS), Ventilated Façades and replacement of existing windows with high - performance ones. The potentialities of ventilated façades will be assessed in this datasheet. 2.1 Ventilated façades The application of a ventilated façade is an optimal solution for improving the technical performance of envelopes. It is most commonly used to improve thermal and acoustic insulation and to protect against moisture and atmospheric agents. Furthermore, the new cladding can change the architectural image of the building. The system is composed of external cladding, dry mounted, that could be of a variety of shapes (slabs, panels, ceramic tiles, slats) and materials (stone, brick, ceramics, concrete, wood, metal, plastic). Glass façades are a special case. The cladding is fixed to the existing wall by means of metallic devices (stainless steel, carbon steel or aluminum) that also supports insulating panels. Between the cladding and the insulating layer, the air cavity (10-15 cm) allows natural air circulation, activated by the difference in temperature between the cavity and the entering (the so-called “chimney effect” – Fig.1). The air flow is regulated by the external climatic conditions, achieving a reduction in heat gain during the summer and a reduction in heat loss and in water vapour and condensation in winter. Since the combined action of rain and wind can cause drops of water to penetrate the cavity, use of a waterproof layer (bitumen pasteboard, synthetic layer) to protect the insulating panels is required. The main components that constitute a ventilated façade, from internal to external layer, are shown in Fig.1.
Figure 1. Elements that compose a Ventilated Façade. 0. Existing Wall 1. Regularization layer, a wet layer created in case of lack of evenness of the existing wall; 2. Insulating layer (rock wool, glass wool, polystyrene, polyurethane or cork panels); 3. Sub-structure of anchorage to the existing wall, usually in stainless steel; 4. cladding/sub-structure fixing elements; 5. Air cavity; 6. Cladding.
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3 THE IMPACT OF THE MOST COMMONLY REFURBISHMENT ACTIONS ON SUSTAINABILITY TOPICS 3.1 Technical Performances 3.1.1 Structural integrity The construction of a Ventilated façade does not increase the stability of the whole building. The façade is dry–mounted: this means that all the fixing operations are carried out with mechanical devices (screws, bolts, clamps) integrated, in the most effective solutions, by gluing or sealing with resins. The design principle of a ventilated facade lies in the static autonomy of each single slab of the facing and in the elimination of the mortar core. Not directly adhering to the supporting structure, the cladding slab is free to move according to its own coefficient of expansion, independently of the supporting structure’s movements, and to follow the settling and oscillations of the load-bearing structures thanks to the anchor’s elasticity. The absorption of elastic movements between the supporting structure and the cladding is generally resolved through the presence of joints, which permit free expansion without the slabs interfering with one another. The stability of the whole system is almost totally dependent on the anchorage devices. Principal factors that affect the installation and influence the stability performance are: The type and condition of the surface. Sometimes poor condition of the existing wall (i.e. bricks) can represent an obstacle to the fixing operations; The nature of the anchorage systems of the sub-structure to the wall and of the cladding to the sub-structure; The material proprieties and dimensions of the cladding. Most of the responsibility for stability is delegated to the sub–structure, generally made from stainless steel, carbon steel or aluminium, forming a modular grid. The vertical frame is usually prevalent, because in this way it is easier to obtain a connection between the load-bearing structures of the building (i.e. border beams of each floor plan). An important factor to the stability of the technical system is the connection between the sub-structure and the cladding elements, which can be made using two main categories of intervention: Iso-static systems, with punctual fixing for each element (i.e. anchorage with four pivots) with a Safe Life design, which takes in consideration the simultaneous relationships between cladding and fixing elements; Hyper-static systems, which request a Fail Safe design taking into account the diffused bonds of the façade. This system can prevent falling but involves a large number of forces and tensions. 3.1.2 Fire protection Ventilated façades are permitted in all types of building. All the components of the structure (external cladding and internal layers) must have fireproof characteristics. It is recommended that the cavity is divided into different section, which can be achieved using the metallic sub– structure profiles. This division into separate compartments could reduce the spread of fire by creating a physical barrier, and the division of the facade into several independent chimneys optimizes ventilation. 3.1.3 Noise Insulation The cladding of ventilated façades favours the reflection of the sound waves because the external joints, the cavity and the insulating layer provide significant acoustic absorption. This solution significantly improves noise insulation, depending on acoustic reflection, absorption and transmission characteristics that are specific to each technical solution. Superimposing a new multi-layered envelope permits a reduction in acoustic values in accordance with the new standards prescribed by D.P.C.M. 5-12-1997.
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3.1.4 Weather and moisture protection The creation of a ventilated façade can protect the building against the combined action of wind and heavy rain. The technique of anchoring the cladding and the presence of the air cavity can prevent infiltrations, drops and rivulets of water on the façade and keep the insulating layer dry. This increases the durability of the wall and in its energy efficiency. The cladding material, in fact, is freer to contain its own hygrometric dilatations and it is not affected by tensions due to volumes of humidity in the wall (increase and reduction due to the water absorption and elimination). Furthermore, if the thermal insulation and the wall are dry, the building does not suffer heat loss typical of wet materials (usually insulating panels increase their conductivity when wet, because they offer the absorbed water the necessary heat to evaporate). A high-resistance cladding can be beneficial in severe weather conditions (i.e. resistance to wind and hail). With the use of a permeable insulating layer, the diffusion of water vapour, which is the most important factor in avoiding dampness, is assured. The combination of an insulating layer and a waterproof layer permits water to vaporize from the wall while protecting from outside weather agents. 3.1.5 Conductivity (U-value), Heat flow (g-value), radiation, convection In view of the heat- and energy-saving characteristics of ventilated façades, there are various factors that favour the use of this solution. In the first place, its capacity to reduce, during summer season, the solar intake of the envelope. This is possible thanks to the partial reflection of solar radiation on the façade by the cladding, and also thanks to the air flow. The phenomenon of solar reflection is maximized when high–reflective claddings are used, mainly consisting of light, shiny and smooth materials. The ventilation effect is optimized, and it is effective on the whole façade, when the design of the cavity is careful and takes into account the dimensions of inlet and outlet air vents in relation to the thermodynamic variables. The second issue is the possibility of creating a homogeneous and continuous thermal insulation layer that can be easily joined to the crucial nodes of heat loss of the façade (i.e. nodes of vertical/horizontal structure or in correspondence with the window frames). The improvement of the thermal insulation depends principally on the thermal conductivity (U value - W/m2 K) of the wall that is closely related to the thickness of the layers. This technical solution makes it possible to greatly increase the thermal performance of both the thermal panels and the air cavity. The insulating layer envelops the building like a coat, and the presence of the air cavity helps in the reduction of the thickness of the panels in comparison to traditional external insulating coatings and adds an active insulating layer that works both in winter and in summer (Fig.2-3).
Figure 2: Functional diagram of a ventilated façade in summer: reduction of solar heat gain through the combined effects of solar reflection and ventilation
Figure 3: Functional diagram of a ventilated façade in winter: the air flow helps the elimination of condensation and the occurrence of water vapour which can damage the insulating panels
Incidentally, the presence of a ventilation cavity triggers a complex system of thermal exchanges (active insulation), difficult to evaluate in terms of the traditional regulations. Taking as a reference an even façade system with a closed air cavity, the design conditions of a ventilated façade in winter must take into consideration that air movement contributes to the decrease in
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the thermal proprieties of the system. Consequently, to ensure the same thermal conditions of the reference case, thermal resistance of the insulation layer must be increased as follows [Lucchini 2000]: Low ventilation of the cavity (1-10 l/s/m2): 2-4% Medium ventilation (10 -90 l/s/m2): 6-8% High ventilation (more than 100 l/s/m2): 10-12% Otherwise, by choosing advanced systems, it is possible to seal the air vents during the winter. During the summer, the difference in performance between a ventilated and closed air cavity system must be evaluated considering both thermal transmittances (U) and solar energy (N). The solar energy factor for a ventilated wall (NIV factor) is always less than the solar energy factor for a closed cavity wall (NI) and this is truer where the flow through the cavity is greater. This means that the contribution of solar radiation to the thermal balance is less when the amount of air in the cavity increases, and this is helpful in reducing heat when the temperature of the façade is high. Generally speaking, the difference in performance of the façade design depends above all on the context (urban texture and climatic conditions). There is no single solution suitable for all situations, but: The thickness of the layers and their properties; The height, thickness and typology of the air cavity; The position and dimensions of the inlet and outlet air vents; The exposure to the sun and orientation are the variable parameters to be considered in every single situation. An evaluation of the thermal-physical performance of this technical solution has been obtained through a simulation application carried out by the Energy Department of the University of Florence [Bazzocchi 2003]. A ventilated façade in Florence was taken as a case study, consisting of 5 cm polystyrene insulating panels, a 15 cm air cavity and hollow brick tile cladding. Environmental data: Orientation: South; Climatic temperatures on typical summer and winter days: 21st of June (summer) and 21st of December (winter) provided by CNR; Permanent temperature of internal room: 20°C for winter and 26°C for summer. The application permits the calculation of thermal exchanges by convection between layers from inside to outside considering the overall resistance. The use of the application requires knowledge of some fundamental values, such as: the temperature of the internal and external surfaces, the external cladding temperature towards the cavity, and the average temperature inside the air cavity. Other parameters to be considered are: the speed and the humidity of the air flowing through the cavity, the convection coefficients (internal or external) which indicate whether the flow is laminar or turbulent (Reynolds number). In Figures 7-8 the thermal flow per hour from inside to outside for the two typical conditions (21st of June – summer, and 21st of December - winter) is taken into consideration, comparing four different conditions: - The above mentioned ventilated façade; - The same façade with a closed air cavity; - 5 cm Etics; - Original façade (concrete wall).
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Figure 4: Thermal flow from inside to outside (21st June – summer - reference day)
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Figure 5: Thermal flow from inside to outside (21st December – winter - reference day)
It is easy to observe the positive effect of the natural air cooling in summer and the consequent internal cooling. This phenomenon increases at the middle of the day (from 13:00 to 15:00). The only positive thermal flow from inside to outside is obtained through the ventilated façade, which is about 7 W/m2 (Fig.4). The other thermal flows are negative, which means that the heat enters in the room (undesirable in summer). In winter, it has been assumed that the air cavity is closed, which contributes positively to the power of the thermal insulation compared to the original façade, as shown in Fig. 5. The thermal flow of the original wall without an air cavity is about 10 W/m2 while the thermal flow of the ventilated façade is –2.5 W/m2 . The negative value indicates that heat is gained. 3.1.6 Durability (service life) There is a wide range of claddings available for a ventilated façade, but all offer the possibility of removal during the Total Life Cycle of the building. As these are industrial products, their performance in terms of finishing, water absorption and resistance can be controlled. It is possible, quickly and at a minimal cost, to periodically wash the cladding, and to dismantle and replace it in a timely manner if decay occurs. The maintenance of a ventilated façade is very easy, considering that each element is independent of the others, and can be periodically planned. This greatly increases the durability of the refurbishment. 3.2 Functional/social performances 3.2.1 Flexibility A ventilated façade cannot help to increase the living space of habitations but, since the procedure is an alternative method of insulation and is created from the exterior, it does not reduce internal space. In some cases the cladding layer can be used as solar shading to cover external areas like loggias or balconies. In the case of glass façades, the enclosure of balconies can increase the surface area of the habitation by creating winter gardens which are helpful in solar energy gain in winter and in the reduction of energy consumption. The flexibility of the system depends principally on the installation and all aspects of design, industrial production, and building site organization (carriage and storage). 3.2.2 Comfort (thermal, acoustic, visual) A ventilated façade can improve the thermal comfort of habitations. The surface temperature of the walls is high, and this is fundamental to the reduction of heat loss from the inside. 3.2.3 Health (air quality, TVOC etc., mould & fungal growth) As described in the sections above, the application of a ventilated façade helps to increase thermal insulation and surface temperature and to reduce condensation and avoid the occurrence of mould. All these factors are essential to the health of the inhabitants.
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3.2.4 Safety, security In comparison to other refurbishment solutions, the use of a ventilated façade, even if does not contribute to the security of the whole building, can reduce dangerous maintenance due to the ease of assembly and management of the operations. Another benefit is the fact that this kind of technical solution enables people to remain in their accommodation without creating an unbearable situation during the refurbishment operation. 3.2.5 Barrier free, accessibility in use This does not apply to the creation of a ventilated façade. 3.2.6 Aesthetic perception The use of a ventilated façade is not restricted to one type of building. The wide range of claddings available on the market makes it possible to find a solution to each specific problem, and to optimize design for the different building envelopes. The main function of the external cladding is to protect the building structure from atmospheric agents as well as to redefine the aesthetic qualities of the building from an architectural point of view. The most commonly available materials for cladding are: natural stone, ceramics, concrete, brick, plastic, metal and glass (transparent or opaque). 3.3 Economic Performances 3.3.1 Building costs The cost of a ventilated façade can differ considerably depending on the type of system used, taking into consideration the types of supporting structure, insulation panels and cladding. The building cost (Bc) must be considered as the cost of the total construction, which depends on a large number of design choices, such as: Preparation of the support layer; Installation of the anchorages; Installation of the sub-structure (in one place or spread out); Placement of the insulating layer; Cladding material and the type of elements; Placement of the cladding, with regulation of the anchorage elements. As it will be difficult to check every single situation, the principal requirements that must be met by a ventilated façade have been analyzed. For every function, the utility cost was calculated, intended as a minimum cost of the component in that function [Bazzocchi, 2003] (Tab.4) Table 4: Principal functions of a ventilated façade and their utility, intended as minimum current value of the components which perform them Function and utility of the systems which constitute a ventilated façade Architectural aspect Bricks Metal cladding Glass panes Thermal insulation Ventilation Substitution and maintenance of the cladding With dry-mounted elements With glued elements
€/m2 20 30 100 20 90 140 20
An average cost for a ventilated façade can range from 100 to 500 €/m2. Naturally, the more complex the façade the higher the cost.
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3.3.2 Running costs (heat loss, cooling, cleaning, inspection, maintenance, etc.) The Running cost plays an important role in the definition of a refurbishment procedure, since it is the element that highlights the advantages of applying an innovative technical solution, the practicality of which must be evaluated as a long-term investment. The addition of a ventilated façade increases the thermal insulation of the wall, reduces heat transmission, cools and reduces solar intake in summer. All these factors contribute to the reduction of operating costs, due to the reduced use of HVAC (Heating Ventilation Air Cooling) systems. The Running Cost must be considered, taking in account the actual maintenance cost of the façade (replacement and repair of the various elements), and the reduction in consumption. As a reference, the maintenance cost for a ventilated façade constructed with hollow flat tiles is about 10% of the Building costs over 5 years (ordinary maintenance), added to the cost of replacing the façade at the end of the Total Life Cycle (extraordinary maintenance). It has been proven that the addition of a ventilated façade can reduce HVAC consumption by about 20-25%. 3.4 Environmental Performance 3.4.1 Use of resources (non-renewable, renewable) Compared to other refurbishment solutions, a ventilated façade can use renewable resources such as passive energy gain from sun (heat gain into the air cavity in winter) and ventilation (cooling the air in the air cavity in summer). After the refurbishment procedure, the energy required in order to guarantee the user’s comfort will be much lower, because the heat loss and gain through the wall is about 40-50% of the initial value. This contributes to a decrease the total U value (thermal transmittance) of the wall. 3.4.2 Energy consumption (non-renewable, renewable) - production / assembly – heating/cooling There is no data available in Italy about the amount of energy needed to produce materials, assembly on construction sites, or maintenance and demolition during construction of a ventilated façade. It has been proven that the addition of a ventilated façade helps to reduce heating and cooling costs. Incidentally, the environmental performance depends above all on the type of materials used. As demonstrated by a recent study [Ciampi, Leccese, Tuoni, 2002], the principal factors which influence energy saving through the addition of a ventilated façade are as follows: I= incidence of solar radiation. The percentage of energy saved increases when the solar radiation is more intense. This means that the addition of a ventilated façade is more beneficial for façades with greater exposure to the sun. d= air cavity thickness. The S value increases as the air cavity thickness increases. L= air cavity length. The length of the air cavity is a negative factor in the overall performance. The S value decreases as the L increases. W0= air cavity speed, which increases the percentage energy saved. Comparing four types of ventilated façades (aluminium panels [F1], hollow brick tiles [F2], concrete panels [F3], and ceramic tiles [F4]), the best performances are obtained by the hollow brick tile façade due to the metallic reflection of cladding which considerably reduces the effects of solar radiation (Fig. 6-7).
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Figure 6: Energy saved (S) by ventilated façades (d=10 cm; L= 15 m) with regard to solar radiation (I)+
Technical Improvement of Housing Envelopes in Italy
Figure 7: Energy saving (S) of ventilated façades (L= 15 m; I= 400 W/m2) in function of the air flow speed W0
3.4.3 Environmental impact, (GWP global warming potential, AP acidification potential, NP nitrification potential, EP eutrophication potential, ODP ozone depletion potential, POCP photochemical ozone creation) There is no data available in Italy on the environmental impact of the construction materials. 3.4.4 Waste and recycling and re-use potential The potential for recycling a ventilated façade is very high. This technical solution is totally dry–mounted which favours partial or total dismantling and recycling of the components . Thanks to the high grade of industrialization of the components, the dry installation, high energy performance and possibility of planning the procedures, we can say that, through the use of a ventilated façade, very high energy efficiency values can be obtained associated with a favourable Life Cycle Cost and a low environmental impact evaluation (LCA – Life Cycle Assessment). The demolition cost of a building and its parts will have a greater influence in the environmental evaluation of a sustainable design. Building waste must be classified as special waste and eliminated using selective demolition. There are two main solutions for recycling a ventilated façade: The sub structure components, recycled as raw materials in new production cycles; The cladding, recycled as part of a new building, (re-using it in a less important function such as horizontal cladding or inert in other buildings). 4 CASE STUDIES 4.1 Residential Building in Sassuolo, Modena The building is a multi–family apartment block built in the 1970s, in a typical post–war residential area of the first suburbs of Sassuolo, a small town near Modena, Italy. The building is five, and in some parts six, storeys high. On the ground floor there are garages and shared services. The structure is constructed using a concrete frame . The façade, unusually for Italian post–war housing, comprises a double wall formed by, from outside to inside, a solid brick wall (25 cm), a cavity (12 cm) and perforated brickwork (10 cm). The external and internal layers are of plaster. The east and west façades are characterized by a number of large projecting balconies. The roof–garden and the balconies are a simulation of the rationalistic style. The building, which contains 10 apartments of 60-70 square meters each, with a multitude of problems mainly relating to dampness and water penetration, visible in the decay of the façade (mould and plaster detachment).
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Furthermore, it has been necessary to improve the architectural image and to upgrade the installations and layout. It was decided to add a hollow brick tile ventilated façade to the north and south façades, which were most affected by the decay. To the east and west façades, the balconies are covered by a copper cladding. Next to the windows, two wooden shelters have been added to avoid water penetration. The refurbishment procedure was carried in the following phases: Percussion and demolition of the dilapidated parts; Construction of a layer of reinforced plaster to create an even layer to which to anchor the façade; Addition of a metal sub–structure composed of: a. mechanical plugs with Grower M8 and 8x24 washers b. single symmetric stirrups, 60/60, and asymmetric stirrups, 60/120 c. aluminium profiles d. stainless steel AISI 304 devices to sustain hollow bricks equipped with lateral e. wing rubber joints Positioning of hollow brick tiles. Thermal insulation was not a major problem, thanks to the sufficient thermal resistance of the existing double wall. For this reason it was decided it was not necessary to add a thermal insulation layer. In spite of this, the thermal behaviour of the wall has been improved. The operation was completed in 7-8 months, and the inconvenience caused to the inhabitants was tolerable. The building cost of the ventilated façade was 122 €/square meter (€ 89.705 in total) added to the cost of 3,800 € for special elements of the façade (e.g. special profiles, wire anti-bug nets), and € 6,000 for the scaffolding. The cost of other ordinary and extraordinary operations (replacement of plaster; positioning of copper cladding around the balconies and so on) was approximately € 82,000. The overall cost of the procedure was € 182,000.
Figure 8: The building before the refurbishment
Figure 9: The building during the refurbishment
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Figure 10: Detail of the new ventilated façade
Technical Improvement of Housing Envelopes in Italy
Figure 11: Technical section of the façade From the external to the internal: hollow brick tiles 25x50 cm; stainless steel devices to sustain the cladding; aluminium profiles; stainless steel stirrups; existing wall
4.2 Residential Building in Turin This building is a typical high–density residential block in the suburbs of Turin containing 80 apartments on 10 storeys. The building was built in 1960, with an envelope of concrete prefabricated panels (U=2.34 W/m2K) and aluminium-framed single-glazed windows. The envelope panels of 25 cm were severely deteriorated, especially in the brick tile external cladding, due to rainwater action. Furthermore, the insulation level was much lower than modern requirements. Heat losses were very consistent especially around the windows and the junctions between the pillars and beams . The procedures used to improve the thermal performance of the external envelope were: addition of a new ventilated façade; replacement of the external windows and doors to improve their thermal insulation characteristics (this also helped to characterise and enrich the external façades); The façade system is composed of a series of stainless steel elements fixed to the wall (Fig.15) and supporting insulation panels (polystyrene panels 3 cm in thickness) and slabs. The external cladding is composed of marble slabs and other inert agglomerated materials , pressurized and combined with thermosetting adhesives to advanced temperatures (200° C). The product is almost identical to natural stone, with some enhanced characteristics, such as: Zero water absorption; High permeability; High mechanical resistance; Lower building costs.
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The air cavity is about 10 cm wide. The refurbishment phases were: 1- Cleaning and replacement of the deteriorated parts of the surface to be covered; 2- Squaring of the surface; 3- Assembly of the modules. This operation was carried out by positioning the first module on the left part of the surface, then proceeding toward right attaching the modules one after another; 4- Once the first row of panels had been applied, attachment of the second row was begun, following the same procedure as before until the entire surface was completely covered. Around the windows, a water drainage system was constructed before the application of the covering. In these areas, it was necessary to pay particular attention to the cladding cuts; 5- Mounting of window coverings. It has been proven that the overall thermal transmittance value of the façade (U = W/m2K) after the refurbishment procedure has been reduced by almost a quarter. The thermal performance of the building before the refurbishment was very poor (R=0.427m2 °C/W; K (U) =2.34 W/m2K) The thermal performance of the building obtained after refurbishment is: R=1.89 m2 °C/W; K (U)=0.53 W/m2K. The total investment was about € 400,000. The building costs of the ventilated façade were 100 €/m2. The payback for incremental investment in energy efficiency has been estimated at 8 years.
Figure 12: The building before the refurbishment
Figure 14: Detail of the new envelope around the window frames
Figure 13: The building after the refurbishment
Figure 15: Technical section of the façade: A–Aluminum Embrasure; B-Slab; C-Windowsill; D-Thermal Insulation: Polystyrene; E-F- steel anchorage device; G-bolt; H-air cavity; N-Marble and agglomerated stone slab
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5 CONCLUSIONS The use of a ventilated façade in the refurbishment and upgrading of existing buildings is recommended in a wide variety of scenarios. The procedure must be carefully designed and planned in order to evaluate which will be the most appropriate and successful solution. A specific design, relating in particular to the individual situation in question can be beneficial to the technical and architectural quality of the building with reasonable costs and positive environmental effects. 6 REFERENCES AA.VV., UNI 11018/2003, Ventilated facades Acocella A., 2000. Involucri in Cotto – Sistemi innovativi per il rivestimento in architettura, Sannini Impruneta, Firenze Bazzocchi F. (courtesy of), 2003. Facciate Ventilate. Architettura Prestazioni e Tecnologia, Alinea, Firenze. Brunoro S., 2006, Efficienza Energetica delle facciate. Standard, requisiti, esempi per l’adeguamento e la riqualificazione architettonica, Maggioli, Rimini. Ciampi M., Leccese F., Tuoni G., 2002. Sull’impiego delle pareti ventilate per la riduzione dei carichi termici estivi, in: Costruire in Laterizio, n. 89. Daniels K.,1997, The Technology of Ecological Building, Birkhauser, Berlin. Lucchini A., 2000. Le Pareti Ventilate – metodologia di progettazione e messa in opera di materiali e componenti, Il Sole 24 Ore, Milano
Technical Improvement of Housing Envelopes in the F.Y.R. of Macedonia Strahinja Trpevski Institute of Civil Engineering “Macedonia”-Skopje, Macedonia
ABSTRACT: Buildings make a large contribution to the energy consumption of a country therefore a very large potential for energy savings exists in the residential and tertiary sectors. Given the low turn-over rate of buildings (lifetime of 50 to more than 100 years) it is clear that the largest impact for improving energy performance in the short and medium term is in the existing stock of buildings. Major renovations of existing buildings above a certain size should be regarded as an opportunity to take cost effective measures to enhance energy performance by meeting minimum energy performance standards tailored to the local climate. Over the past 2025 years, in many cases standards have been reinforced two to four times, including some very recent revisions. The effort is not yet finished. Reducing the energy consumption in buildings built in 50’s and 60’s is, at first, a complex issue in reduction of energy consumption in a technical sense, as well functional, social, economical and environmental aspects. Therefore for refurbishment of the facades as the most appropriate technical solution is selected “Externally Insulated Façade System”- EIFS. In this paper the impact of this technical solution regarding refurbishment of the facades and improving the energy efficiency of the buildings will be discussed.
1 INTRODUCTION 1.1 Standard envelopes in Macedonia This paper is built upon the report of our national representatives in WG2, related to the collective multi-story family houses of socialist type built in the period of 50’s and 60’s which is 30% (73.688 up to 50’s and 136.418 from 1960-1970) of the total dwelling stock in the country. In that period of construction extensive classic building systems of massive solid brick work were used with thickness of 25-38cm for perimeter and structural walls and 12 cm for internal partition walls rendered with 2,5sm external mortar and 1,5cm internal mortar ( Figure 1 ).As far as for slab (floor and ceiling ) construction matters, mainly cast reinforce-concrete thin-rib system or semi-prefabricated thin-rib system “Avramenko” were used . Immediately after the 1963 earthquake new rigorous seismic regulations and building standards were introduced by means of use the high quality R.C. skeleton systems with high security coefficient (Cs=3) and clay blocks with the holes and bought side plaster rendered ( 25sm+2x2,5cm) as materials for external and inside dividing wall constructions ( Figure 2 ). In that respect it can be said that the building stock of multi-storey family houses after 1963 was much better quality and safe to future possible seismic activities in the region. Also, beside new introduced R.C. skeleton systems, some totally prefabricated, pre-cast R.C. heavy-panels systems were introduced in the local building industry too such as “Karpos”system, donation of USSR government Its external pre-cast RC walls, besides the built-in Styrofoam insulation of 4 cm, manifested pour thermal comfort conditions caused by presence of many thermal bridges. The thickness’ of the perimeter wall panels is 25 cm consisting of three COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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basic stratums; External pre-cast R.C. panel thick 5 cm, internal (structural) pre-cast R.C. panel thick 14 cm and Styrofoam or fiberglass thermal insulation thick 6 cm in-between ( Figure 3 ). External and internal panels are structurally connected with concrete ribs, horizontal and vertical perimeter wall panel joints are usually visible and sealed with special sponge hose from inside and elastic sealant from outside. Internal structural pre-cast R.C. panels are thick 12 and 14 cm Such envelopes of the houses built in the period of 50’s and 60’s are extremely big “consumers” of energy for heating and cooling and as well are not able to provide adequate thermal comfort. Therefore the improvement of the quality of these types of housing envelopes must be a real task.
( Figure 1 )
( Figure 2 )
( Figure 3 )
Annual new construction and reconstruction represents less than 1% of existing housing stock, while the costs for constructing new units to meet energy performance standards will be relatively low, compared to the costs of retrofitting existing housing stock to comply with energy performance standards. However the energy savings potential is much greater if existing house stock is also covered by an energy performance standard, and the energy efficiency strategy does suggest that some retrofitting could be cost effective. According to the 2002 Census there are 697.529 dwelling units in Macedonia totaling 49,671,709 m2. Distributed within the stock of 446.235 single buildings of different type of which 60-62% are mainly one or two storey single family houses or double ones, and relatively small percentage of row houses or other types. The rest of 38-40% are multifamily houses. The main problems identified in the building envelopes built before early 80’s were low thermal insulation with the high U-values of the envelopes and high air permeability of window frames. About 70% of the total actual residential unites belongs to this group. 1.2 Requirements in Republic of Macedonia that enforce a reaction to refurbish envelopes Macedonia has become part of a negotiating process to enter the European Union. As such it will be expected to bring its own laws into line with EU directives as stipulated under Aquis Communitaire provisions. Therefore some activities are planed to reform it building codes to reduce energy consumption. It may make sense to adopt the structure proposed by EU directive 2091/EC. The EU directive sets minimum energy performance standards for new buildings and large existing buildings subject to major renovation, energy certification of buildings and regular inspection of boilers and air conditioning, and in addition and assessment of heating installation in which boilers are more than 15 years old. The approach of the directive is to look at the energy consumption at the building level, rather than its component parts, and as such should include: thermal characteristics of the building; heating installations; air conditioning installa-
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tions; ventilation air flow; built-in lighting installation; building orientation and outdoor climate; solar systems; natural ventilation; indoor climate conditions. Many EU standards exist for measuring the performance of these component parts (although there are some gaps), so in theory it would not be difficult for Macedonia to adopt the approach recommended by the EU directive. In 1970’s, a part of the building physics that deals with the problems in the field of thermal insulation in civil engineering, as relatively new scientific discipline has officially entered in Republic of Macedonia, through "Book of rules for technical measures and conditions for building thermal protection The book of rules was mandatory during the phase of design, construction, reconstruction and current maintenance of housing and business facilities up to day. The group of below mentioned standards was part of calculations for any related building. In the stage of the building permit application process the calculations for thermal insulation of the building should be submitted, preferably supported with data from thermal insulation measurement of the buildings. The climate in Macedonia is continental, with cold winters and hot summers. For the calculations of the relevant physical values needed for thermal protection effects analysis (heat losses during the winter period, heat gains during summer, water vapor flow rate process, etc.) among the other, the inside and also the outside project microclimatic conditions are needed as input data. From that aspect and from the global point of view, the climate in the Republic of Macedonia is characterized with sharp differences between the winter and the summer period In the standard MKC U.J.5.600, inherited from the former SFRY, on the constructive-climatic zones map, the territory of Republic of Macedonia is divided into 3 zones. The given average values of the lowest annual temperatures during winter and the relative air moisture are input data for thermal transmittance calculations that is the heat losses. On the map of winter outside project temperatures the territory of Republic of Macedonia is divided into climatic "islands", with temperatures, which move from -9 C to -21 C. These temperatures are being used during calculations of the risk of appearance of internal surface condensation. In the moment, Legislation remains from the 1980’s setting thermal insulation standards for buildings in former Yugoslavia with obligatory usage with prefix MKS such as: Requirements for design and manufacturing of buildings - MKS U.J5.600, Coefficient of heat transfer in buildings - MKS U.J5.510, Calculation of water vapor diffusion in buildings - MKS U.J5.520 and Characteristics of thermal stability of buildings - MKS U.J5.530. , corrected by innovating the standards MKS U.J5.600 and MKS U.J5.510 in 1987 .
Since that time the following U(W/m2K) values have been used: type time period 1.Outside wall 2. wall at dilatation 3.flat or pitch roof above heated space 4. RF floors above unheated space
from 1987 proposed from 2006 0,90 0,70 1,85 0,80 0,80 0,40 0,60 0,50
Furthermore government regulation No. 32/1999 adopts the relevant ISO and EN standards as national standards (ISO 6946, 7345, 9246, 9251, 9229, 1011-1/2, 13789, 14683), developed by the Institute for Standards and Metrology. However these standards relate mainly to methodologies for calculating energy efficiency. They have not yet been applied to the specific (climatic, use categories and building age in Macedonia) conditions in Macedonia, nor have energy consumption norms been developed based on these calculations. A recent review of building related standards and codes in Macedonia indicates that there is no explicit legal requirement for developers to meet energy performance standards.
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The Institute of Standards and Metrology, is currently responsible for the development of standards and it is now preparing a law on maximum energy consumption for heating, Low on construction products and new Regulation on building thermal insulation. Macedonia is a net energy importer, and is therefore keen to reduce its energy consumption, to improve energy security and its balance of payments. The recently prepared Energy Efficiency Strategy of Macedonia indicates that the energy consumption in the building sector represents 39% of the overall energy demand (2001); the residential sector uses nearly 80% of the energy consumed in all buildings and is responsible for some 71 % of the annual CO2 emissions in Macedonia (based on 1997 statistics) (Figure 4). The strategy goes on to indicate that consumption in this sector could be reduced by 30%. These figures could be drastically reduced through energy conservation, providing a reduction of imported fuels and thus an improvement of the balance of payments.
Transport 24%
Agriculture 4% Residential Building 81% Buildings 39%
Industry
Comm./Inst Building 19%
33%
(Figure 4)
(Figure 5)
About 87 per cent of Macedonia’s electricity is derived from fossil fuels (Figure 5). This corresponds to CO2 emissions of 2.5 million tones. These year, the Macedonian Parliament ratified already signed Kyoto Protocol for reduction of emission of CO2 and therefore the future activities related to the improvement of housing envelopes are very much in line with the obligations which come out from the signing of this document. 2 SPECIFICATION OF THE TECHNICAL SOLUTION Since housing envelopes-perimeter walls from the collective multi-story family houses built in the period of 50’s and early 60’s which is 30% of the total dwelling stock in the country can’t meet the present standards for thermal insulation the most adequate solution for this problem is to reconstruct them with the "Externally Insulated Facade System" EIFS. 2.1 Externally Insulated Facade System “EIFS” In this case it will be Stotherm Classic (figure 6) facade as a technical solution which guaranties fulfillment of the demands from the present and forthcoming standards. The guaranties are based on the attests for the materials used for the implementation of the system and experience gained in the process of implementation in the last 20 years in our country as a system for facades on new constructed buildings. The first multistory dwelling house in Macedonia was built 1984 with this system. Since than it has proven as the most successful composition of facade isolation without any visible problem although was affected in its exploitation time with three
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Existing wall
earthquakes in magnitude of 3-4 Richter degrease. This system has an external insulation with which the inside wall works like a thermal accumulator. Outside insulation minimize the interior temperature "up and downs" (amplitude). In opposite rooms with an internal insulation system loose the inside temperature as soon as they got it. It’s recommended only in rooms with seldom use (f.e. once a week for only some ours) or where external insulation is impossible to put.
( (figure 6 )
The structure of the StoTherm 8Classic façade isolation prevents loss of heat energy during the heating season or protects from the heat of sun rays and as well protects the construction structure.. It escapes the heat bridges such as gaps for radiators, concrete beams, reinforced beams, ceiling connections and etc. in the process of the refurbishment of the housing envelopes. This system of EIFS protects the construction structure by maintaining a constant temperature in the wall. If heat strains are lower then cracking of walls caused by temperature is prevented. The advantages of the “contact facades”- StoTherm Classicfor the refurbishment of the housing envelopes is in organic composition of a façade with polystyrol isolation with cement less ready made integral components which could be used for old and new buildings. For the climate of our region for the facades which has been used cement in their system components some damages occurred which lead to the collapse of the parts of facade. The system could be used on different wall constructions: concrete, silicate brick, solid bricks, porous concrete and est. which are unplastered walls and panel construction (three-ply panels) with uneven surfaces up to ± 1 cm (±3 cm mechanical attaching). The comprehensive detailed solutions which are offered by the system are the most important for efficient and long lasting exploitation .For the implementation of the system for improvement of the housing envelopes needs very low logistic on the work-site. This is the technology for damp and cold seasons for which diagonal reinforcement is not necessary neither previous evening coatings. 2.1.1 Steps of implementation Adhering. A mineral adhesive, organically enriched and reinforced with fibers, characterized by its high level adhering power. It is suitable for static even and uneven, an organic and organic surfaces. It can be processed manually and by machine and stick to the existing wall. Isolation. Thermal-isolation board of expandable polystyrol firm foam is used for this system which Allows CO2 and steam to pass through. It is lightweight without (F) CKW, nonflammable and with no traction. The board has a heat conductivity of 035/040. Fabric for reinforcement, Sto-Glasfasergewebe. The previously stretched fabric for reinforcement, resistant to alkali with an absolutely even acceptance of the strength satisfies the highest requirements for resistance to breakage and shocks. It is also easy and simple to process.
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Mass for reinforcement: StoArmat RC. Cementless organically fixed ready made mixture for reinforcement. Very elastic non-precasted, resistant to breakage. Very resistant to mechanical shocks. StoArmat RC clearly differs from mineral mixtures for reinforcement purposes. Details: StoArmat RC shows extraordinary performance during its application. The mixture is applied simply and without any difficulties. The endurance of the StoArmat RC mixture is unbeatable in the area of paste products. The exceptional content of fills guarantees lowest layer thickness, hence greater protection. The material for reinforcement is always sufficiently protected and its connecting points are always fully bridged. The organically upper layers (reinforcing coat and finish render) has an impact strength and crack resistance which is up to 10 point better then EIFS with mineral coats. Silicon facade paint with Lotus – Effect. Lotus Effect has been discovered in the lotus flower and has been transferred into Lotusan as a finalization of facades with colors. Lotusan combines the renowned water resistant “Sto” silicon paint with a micro structural surface, obtained from the lotus leaf. In this way, the area exposed to water and dirt is significantly decreased (figure 7). Binding is also greatly reduced. As a results, the water along with dirt is immediately swept away, whereas the façade remains dry in a great degree and nice looking. Even on sides of façade under direct atmosphere exposure. The problems with ordinary façade paints is that with time dirt becomes very apparent on facades (figure 8). Microorganisms tend to inhabit precisely the windier side due to the sufficient damp present there. The effect of Lotusan façade colors laid in a micro structural surface. Thus, the area exposed to particles of dirt and water is significantly reduced. Besides this, the surface is exceptionally hydrophobic. Rain drops immediately roll off and drag dirt particles which are harder to attach along with them, without any problem. The surface of ordinary façade paints is not very hydrophobic and lacks the microstructure the lotus leaf has. Therefore, it gets soaked more easily and dirt particles can attach easier.
(figure 7)
(figure 8)
3 THE IMPACT OF REFURBISHMENT ACTIONS ON SUSTAINABILITY TOPICS 3.1 Technical performance 3.1.1 Structural integrity (covering minor cracks) The advantages of the “contact facades”- for the refurbishment of the housing is that is able to cover all minor cracks and is highly mechanical resistant. The tests are showing very high elasticity and resistance to crashing. 3.1.2 Fire protection The system is Non- flammable which gives to the building additional value regarding fire resistance
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3.1.3 Noise insulation The system directly do not improve noise protection (only in a cases when polystyrol is with thickness above 15cm)but indirectly improvement is very high after the process of improvement of housing envelope. For improving of housing envelopes it is necessary to replace old wooden windows-single gazed with new AL or plastic framed double glassed thermo -pan windows which have much hire protection of noise. From physical/energetic point of view the protection of noise indirectly is increased in double ratio. 3.1.4 Weather protection Very great resistance to water and dirt immediately after dry coating is applied. It has ideal. protection, especially for sides which are exposed to wind. The structure of the StoTherm Classic façade isolation guarantees atmospheric protection resistant to rainfalls while at the same time allowing steam to pass through. This results to a significantly longer life of the façade. 3.1.5 Moisture protection Exceptionally well resistance to weather influence and moisture. This system allows steam and CO2 to easily pass through which positively influence to the thermal comfort of the ambient within the house. Resistant to microorganisms (seaweed and fungus) thanks to the last layer with Stolit and StoDilco 3.1.6 U-value, g-value, radiation, convection The proposed system shows stability to UV exposure and reference value to brightness up to >20% (upon request below 20%) 3.1.7 Durability (service life) The system has been attested on the for season climate changes in duration of 20 years and presents no changes in the structure of any of the layers of the composed system. 3.2 Functional / social performance 3.2.1 Flexibility The system shoves great flexibility in the improvement of the housing envelopes with a number of additional accessories and elements which allows to be solved any problem that appear during the refurbishment of facades with the most adequate long lasting solution 3.2.2 Comfort (thermal, acoustical, visual) There is no doubt that thermal, acoustical and visual comfort will be increased. This will depend of the applied parameters used from the standards. 3.2.3 Health (air quality, TVOC etc., mould & fungus growth) Very big problem was condensation of moisture within the old buildings. The study that was performed in early 80,s in the town of Skopje related to thermal comfort in some residential buildings shows very high percentage of allergies, and respiratory sickness within the chiliads. With this system of “Contact facades” will be eliminated possibility of raising mould & fungus growth at the inside walls, or at the corners of the constructive elements. Appearance of condensation within the existing housing envelopes with implementation of such system will be eliminated. 3.2.4 Safety, security The system shows safety and security during the exploitation time of at list 20 years.
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3.2.5 Barrier free, accessibility in use This system in our country is mostly consisted of imported components from original producer Sto Austria or Germany. There is free accessibility to this system on our market. The intendancy is nowadays to start with production of some of the components in our country. 3.2.6 Aesthetical perception The "Externally Insulated Facade System" EIFS represented by StoTherm Classic opens all free spaces for molding of the façade. It creates conditions for attractive facades of old and new constructions. The range of plasters and colors with StoDeco Profile contents proved aesthetical competency of the facades. 3.3 Economical performance 3.3.1 Building costs The implementation of the EIFS StoTherm Classic at the new buildings will increase the investment insignificantly. The investment for improving of the envelopes with this system cost 36EUR/m2. With the existing price of electricity approximate return of the investment in saving energy is 5-7 years. It would be worth to mention the enormous potential of passive house technology implementation with this system. 3.3.2 Running costs (heat losses, cooling, cleaning, inspection, maintenance, etc.) The running costs for heating and cooling are expected to be decreased minimum 30%. 3.3.3 Increased rent potential vs. vacancies through building action The multi-storey family houses built in 50’s and early 60’ have more than 40% lower market value price compared with new buildings. It is expected that with improvement in urban and housing envelopes that existing price on the market will be increased with 20%. 3.4 Environmental performance 3.4.1 Use of resources (non renewable, renewable) After the implementation of the EIFS for improvement of the housing envelopes the non renewable and renewable energy recourses will become more affordable due to the fact that there consumption for heating and cooling will be decreased 3.4.2 Energy consumption (non renewable, renewable) - production / assembly - heating / cooling The EIFS - StoTherm Classic reduces heating and cooling costs with a professionally built in structure of façade isolation which can save up to 60% energy. in addition, the emission of waste materials is also reduced. There is no doubt that those who use the façade isolation show environmental awareness. 3.4.3 Environmental impacts, (GWP global warming potential, AP acidification potential, NP nitrification potential, EP eutrophication potential, ODP ozone depleting potential, POCP photochemical ozone creation) The implementation of the Directive requires a whole set of activities mainly comprising legal, regulatory and support measures, institutional strengthening and awareness raising. Energy savings and CO2 reductions on a building by building basis will be easy to track, but the benefits in terms of national energy savings and CO2 emission reductions would only be evident after some 5-10 years when the accumulative volume of occupied new construction and renovated buildings represents 10-15% of the total building stock. For this reason, the implementation of EIFS system facades assumes projected energy savings and CO2 reduction benefits by the year 2020 as the measure of impact potential for each measure. The rate of new construction in Macedonia is less than 1%. Through current legislation and building practices, new construction typically
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has space heating requirements about 40% lower than the average required by the existing building stock. If we project the status quo to the year 2020, new buildings built between 2006 and 2020 will account for less than 10% of the building stock by volume and less than 4% of the energy consumed in the building sector. Depending on the set levels, minimum energy performance requirements for new buildings may further lower consumption levels in these new buildings by the year 2020, but the impact on energy consumption (and related CO2 emissions) in the building sector will be limited to about 0,4% (assuming a 40% penetration rate of application of the measures to new construction and an average of 10% reduction in new buildings energy consumption levels compared to current building practices) or an estimated 23,700 metric tons of CO2 per year by the year 2020. However, there is significant potential for energy consumption reduction and related CO2 emission reductions through profitable investment in EE and RE measures for existing buildings in Macedonia. The implementation of the directive with appropriate coordination and methodologies for existing buildings would be imperative within a broader programme of promoting and implementing EE and RE investment in the building sector. The advantages of these renovations are multiple: profitability in terms of maintained lower energy costs long after the payback period of the initial investment. increased energy independence both at the building level and at the national level. increased value and life-expectancy of the building stock. improvement of interior comfort and health levels. appropriately administered, related CO2-emission reductions qualify for CDM carbon trading programmes. Improvements in the existing stock generated by the implementation of the Directive could bring energy savings of 27,000 MWh per year. In the residential sector, assuming that the implementation of the Directive will target multi family housing with space floor over 1,000 m² (as requested in the Directive in the Member States), the potential of energy savings for the year 2020 is estimated at 4,725 MWh per year, leading to a reduction of CO2 of 2,200 tons per year. Should all measures proposed here be developed, and depending on the time needed for each measure to be effective, the country could reach overall energy savings of 304,851 MWh per year and 214,300 metric tons of CO2, which would signify a total saving of approximately 1,676,680 MWh over the period up to 2020, corresponding to a cumulated reduction of 1,178,700 tons of CO2. 3.4.4 Waste and recycling and re-use potential At this moment there is a limited possibility for recycling and re-use potential of the different components of the “Contact façade” system. 4 CASE STUDY The case Study is related to the refurbishment of the facades of the Row houses built in 1960’s, nowadays in a very attractive location in the central area of the town of Skopje (figure 9). Each row house has 6 two storey apartments with basement. and 75m2 leaving area in total. The characteristic plane is shown on (figure 10). For building of Row houses was used extensive classic masonry building systems based on massive solid brick structural walls thick 25cm. For slab construction are used prefabricated thin-ribs slab system called “Avramenko”, stiffened with perimeter and internal R.C. strips cast over the parallel and orthogonal structural walls. Within structural walls there aren’t vertical R.C. supporting pillars or strips. Although have pour seismic performances, the respective row buildings are not badly damaged during the 1963 earthquake and they were not subject to structural rehabilitation and strengthen-
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ing by means of inserting new extra horizontal and vertical R.C. strips and throw-in supporting pillars within massive structural walls. It can be said that thermal insulation in the Row houses was not a subject of any serious consideration during their construction. Practically, within this period all residential buildings (multifamily or single ones) lack thermal insulation which generally implicates some other, more or less, serious physical handicaps such as high coefficient of thermal conductivity (Ctc=1-15), significant heating losses, many thermal bridges, moisture, and energy unfits. The respective computer program calculations based on existing standards confirm that maximum permitted heat transfer coefficient is exceeded in all Structural elements . (external wall Umax=0,90W/m2K/Calculated U=2,16W/m2K, slab above unheated basement Umax=0,60W/m2K,/Calculated U=2,02W/m2K, under roof slab Umax=0,80W/m2K,/Calculated U=1,52W/m2K) with thermal conductivity of the windows above 3,3 W/m2K.
(figure 9)
Row houses plan
(figure 10)
In regard to this, serious thermal reconstruction project for proper energy efficiency was made and offered to the owners of the of the apartments in the row building. This was the most critical because offered solution must be balance between expensive part in the eventual future refurbishment and improvement of the quality of building envelope and saving energy. Therefore a Sto- EIFS was proposed for external walls and to avoid thermal bridges (figure 12). Double glazed thermo pan windows were suggested with thermal conductivity of 2,6 W/m2K with plastic frame to solve the problem of daylight and sun incomes into the dwellings as very important factors of commodity and health that should be improved by windows replacement . The PVC foil on the roof slab is used as a vapor barrier and 15cm rock wool placed over as thermal insulation. Underneath of basement slab, a vapor barrier is added with 5cm rock wool (figure 11).
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With such interventions the calculations in all thermo physical aspects shows satisfactory results according to the current standards (external wall Umax = 0,90W/m²K, / Calculated U = 0,51W/m²K, slab above unheated basement Umax = 0,60W/m²K, / Calculated U = 0,56W/m²K, under roof slab Umax=0,80W/m²K, / Calculated U=0,16W/m²K)
( Figure 11)
(figure 12)
The calculations shows that before refurbishment of envelope of the row houses for the heating season of six months is needed 24,37tons. After the proposed refurbishment the row house should consumed 9,5 tones oil for heating. According to that there is a savings of 14,8tones which is equal 9.800 EURO yearly savings.
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5 REFERENCES Nexant et al (2003) – Energy Efficiency Strategy of Macedonia, USAID Technical commity report,2002 - MKS standards, Prof Stojkov.T, 2004- The multifamily housing construction in Republic of Macedonia-State of the Art Karner Andreas, GEF Agency, 2005,- Support for the implementation of the EC Directive on energy performance in buildings in Macedonia Prof.Serafimov,Trpevski,PhD,Nikolovski , 2001, - Energy Efficiency in construction in Republic of Macednia, Deutche Gelellschaft fur Techishe Zusammenarbeit (GTZ) GmbH Vichner S, 2002 - Energy-Efficient building design-Macedonia, German federal ministry of economic cooperation and development & (GTZ) GmbH Black see regional energy Center,2003- Report of European network for the promotion of energy Technologies in the building sector, Sofia-Bulgaria Vekemans.G, 2002, Towards a common European approach for energy labeling and assessment of existing dwellings, Flemish institute for technological research – Vito Belgium Statistical Yearbook of Macedonia 2003
Technical Improvement of Housing Envelopes in Malta Vincent Buhagiar Faculty of Architecture and Civil Engineering, University of Malta, Malta.
ABSTRACT: The principal problem of residential building envelopes in Malta is that there was never a deliberate effort to use insulation in cavity walls, be it for thermal or acoustic isolation. However there was always a concern for moisture isolation by the use of cavity walls against rain penetrating the external porous limestone skin and using a damproof course to isolate the lower damp foundations from the rest of the building. This paper looks at the various technical improvements that could be implemented to the building envelope that could achieve improved energy efficiency as well as a notable upgraded comfort level for a better quality of life.
1 INTRODUCTION 1.1 Standard envelopes for housing units in Malta In Malta, since time immemorial practically all buildings have been erected in the local limestone, an abundantly quarried relatively inexpensive material. This brings with it certain problems associated with its porosity, namely rising damp and water penetration from driving and trickling rain, especially if not well protected. In view of the available natural resource, local stone, better known as globigerina limestone, has always been used in abundance since the earliest inception of vernacular dwellings ranging from rural settlements to farmhouses and townhouses. It was only in the 1960s with the onset of concrete that buildings in Malta started going to a high-rise category (essentially moving from two-storey row houses to three or four floors, considered as medium height in Europe). This called for the need for elevators and larger public spaces both within and immediately outside the block, attracting vandalism among other abuses. The standard system of construction was based on an external double wall comprising a twin skin of 230+230mm with an average 50mm cavity. Internal partitions are typically load bearing walls with the earlier standard width of stone blocks of 230mm. Today, due to lack of building space and the ever-diminishing natural resource (and the cost to quarry it), external walls have been drastically reduced to 150+150mm skins with only a nominal cavity of no more than 10mm, if at all. This is often bridged over immediately by the oozing mortar as each heavy stone is manually laid by the mason. (Average density is 20kg/m3). Externally for higher buildings, a twin skin is used composed of 230+150mm practically touching, with cross bond stones. The intention is merely structural stability, with builders and owners often oblivious to the heavy thermal and moisture bridging that is to ensue; figures 1 and 2 refer. COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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Figures 1,2: Stone Quarrying & Double skin external wall, zero cavity.
Internal partitions are today typically 150 mm, also load bearing at ground floor and upper levels. This has also reduced the average weight of a stone from 7.4kg to 4.8kg in dry conditions. Since the local stone is highly porous, when the moisture content increases the weight is considerably higher. This depends on the bedding plane of the stone itself in the quarry. In fact by observing a historic building’s flaking crust one can predict what will happen to even relatively modern buildings built in stone, experiencing such humidity exposure problems. Figures 3, 4 refer.
Figures 3, 4: Stone Deterioration – effects of rising damp & rain exposure.
2 REQUIREMENTS IN MALTA THAT REINFORCE THE NEED TO REFURBISH THE BUILDING ENVELOPE Climate is one primary natural mover raising the need for an energy conscious design (but not refurbishment) of local housing stock in Malta. With its mild winters, yet hot dry summers, the electricity demand for cooling has risen through the years, superseding the energy demand for heating in winter. Moreover, in winter heating can be diversified to various forms of primary energy, namely, firewood, coal, gas (LPG), paraffin or electricity. Cooling in summer is through air conditioning, employing only electricity, the least efficient of them all, since only around 33% derived electrical power arrives at the domestic meter, after
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33% inefficiencies from burning fossil fuels at the stations and another 33% are transmission losses through the grid. A need to reduce carbon dioxide emissions therefore exists. On the other hand there is certain lethargy to refurbish buildings for energy efficiency since to date building activity is still not regulated by a carbon tax or any other form of disincentive to burn fossil fuels. The prime motive behind a refurbishment is following the purchase of an old possibly derelict farmhouse or townhouse in order to transform it into a showpiece of original trades, masonry craftsmanship and features typical of its epoch. One other unspoken aspect is also the lack of available land for new residential buildings, and the exuberant forbidding price of the only remaining plots. Adding insult to injury, the long-winding treacherous process to obtain a development permit from MEPA is also a deterrent to further development outside scheme, perhaps a sustainable measure in its own right. A refurbishment to an existing building, typically an old dated non-listed farmhouse or townhouse, is essentially concerned only with the cosmetic renovation and re-planning as opposed to energy conservation in use. This does not augur well for the ever-increasing electricity bills, stemming form higher oil prices on the international markets. Use of masonry in facades is no longer enforced by MEPA (Malta Environment & Planning Authority), the only national planning authority. In fact most architects and developers have taken the liberty of using concrete blockwork extensively nowadays, particularly in areas close to the coast where a justified argument arises given the fact that our sedimentary stone (globigerina limestone) deteriorates rapidly and severely when exposed to a marine environment. This is often further aggravated with the lack of a damproof course, or one poorly laid, with the consequence of rising damp and cold bridging, hence unwarranted energy use for heating in winter. Blockwork is normally preferred especially since it is easier to plaster over with a sandcement mortar, also opening up a broad palette of colours for rendering on different textures (graffiato, frakas, xkumat, etc.) as opposed to the standard sober yellow ochre of the indigenous stone. It is also much lighter in weight, standing at approximately 18kg/m3 for a standard unit of 460x 230x 267mm high. It comes in two weights, namely with varying cavity widths. Price is also an issue. Building walls in concrete block is much more expensive than local stone. But it is only because local quarried stone is still relatively cheaper rather than blockwork being so expensive. Although admittedly all raw materials are imported hence pushing the price of a local concrete block as against foreign made products. The issue of cement production in Malta has already been raised but all efforts died down due to environmental lobbying against it. There has always been a reaction against refurbishing external building envelopes as an energy saving measure since at face value this presents no real return to the property. Developers have realised that customers, namely prospective buyers rarely appreciate this since electricity was until recently relatively cheap, especially since it has always been considered as a social commodity. Prospective buyers or tenants merely look at the upgrade in the finishes and services provided by the building. After all Government’s own Housing projects have never been taken through such a refurbishment. Also in private developments it is always the top floor owner who is responsible for roof maintenance, as opposed to Government projects which tie up the tenants/owners with a private agreement obliging all parties to contribute towards maintenance & any refurbishment exercises through the setting up of an ‘Owners’ Association’. Today with the latest Energy Directive (2002/91 EC), effective from 06 January 2006, action is almost imperative in order to conform to the legislation. At this stage the Directive only enforces member states to improve the performance of both new buildings as well as in major refurbishments. Historic buildings and minor refurbishments will eventually have to comply at a later date. Admittedly there is a fine line between major and minor refurbishments. Energy certification of public buildings will hopefully raise an awareness of both the financial aspect as well as the environmental benefits of such retrofits. The upcoming building regulations now have a specific section (part F) dedicated to conservation of heat and power. However to date (September 2006) no decision has been taken as to who is to enforce these regulations, particularly the energy certification aspect. It will kick off with a self-regulation ap-
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proach where all architects will be expected to learn the regulations and interpret the directive accordingly. Therefore only when such building regulations come into force – and enforced – can there be any real drive for a refurbishment with an energy efficient design intent.
3 SPECIFICATION OF THE TECHNICAL SOLUTION In Malta there no such thing as a specification of a single specific technical solution. In general buildings have to adhere to a set of standards dictated by standing legislation, some old, established under British rule (Sanitary Laws), others updated or stripped and rewritten or revised according to the needs of the times, since the post-war era of depressed and demolished Malta, today rebuilt anew practically without a trace (except for the National Opera House). The principal legislations which governs building activity in Malta are the following Sanitary laws of Malta (1936) Energy Directive (2002/91EC) Building Regulations, 2005, Part F, specifically deals with energy use in buildings, influenced by the same energy directive. The Planning Act (1992). [The latter had established the setting up of the Planning Authority, now revamped and incorporating an Environment monitoring unit, renamed as the Malta Environment & Planning Authority (MEPA). All building permits issued have a standard set of conditions which over rule any legal notices, such as the use of stone on facades. Other conditions are tailored to the site and project under the lens]. Accessibility audits of public buildings are dictated by the National Commission for Persons with Disability (NCPD), to which MEPA refers all such cases for vetting. Fire Health & Safety Regulations are normally vetted internally through MEPA itself in the case of minor jobs; for major projects, a specialized fire engineer’s report is required by MEPA. EIAs for major projects are normally requested by MEPA, with the EIA report drawn up by an independent consultant approved by the MEPA. Planning statements are also requested for projects of a localized influence or if they are extensions or phases of previous EIAs. Updates of such EIAs are also requested by MEPA from time to time as the project develops. Considering that the local stone, Malta’s best natural resource – albeit even if finite – has had the greatest influence on the building industry. As typical of Mediterranean climates, buildings and their immediate outdoor spaces have always focused on an outdoor type of social life. In general buildings are composed of standard block on block of stone, with both external and internal walls taking their share of load-bearing. External walls comprise two skins with a nominal cavity, always considered an asset in descending importance for overall structural stability, humidity barrier and finally a thermal barrier. Today roofs are typically constructed as reinforced concrete slabs. These have replaced the former soft stone flagstones laid on timber or steel beams. The main trend is that the local housing stock, private or public, has rooms typically around three to four metres span, limited by an economical slab thickness of a nominal 150mm concrete reinforced by a unidirectional C503 (BRC6) steel mesh. Any larger spaces require a tailored design attracting additional reinforcement, a thicker concrete slab and architects’ calculations and supervision fees. Elevations for social housing or private apartments are treated differently from the former private residences. Today the design is much more simplified and except for a fascia perimeter to windows or cornice, all elaborate sculptural features have been obliterated, dominated by speed of construction and costs. Prestressed prefabricated hollow core slabs have also been introduced in the market over the last thirty years., although their use was primarily intended and idealized for gaping spans in in-
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dustrial buildings, these have been emulated in dwellings too. They are at most ideal for basement column-free garages. Associated problems emerging are typically deflection and nonuniform or unpredicted loading, causing flaking masonry and fissure cracks throughout the apartments above. These in turn attract moisture penetration and dislodging of finishes. The typical height of an apartment block is four floors plus basement, as governed by the MEPA policies. To date there are no formal obligations that buildings should be structurally designed for seismic loading, but the more cautious architect (who is also the structural engineer) would normally design for this or commission a specialized expert. The established Euro codes are normally adhered to. Foundations are in globigerina limestone, the standard building material, however for medium to high rise buildings (four storey or more) reinforced concrete frame structures are typically used. Basement and excavations work is hewn out of the monolithic relatively uniform limestone terrain as well. Although there is a potential for utilizing the excavated material in the form of building blocks for re-use as foundation stone or elsewhere, this option has not yet been tapped, as formerly used in early vernacular dwellings where the farmhouse was erected on a building site and combining such an excavation and building site en suite. Building materials used in the industry are to date not certified to be compliant with any CE markings, even though some may already be, as they are imported as isolated building components from abroad.
4 THE IMPACT OF THE MOST COMMONLY USED REFURBISHMENT ACTION ON SUSTAINABILITY TOPICS One major aspect which should push for the need to refurbish and upgrade buildings is the latest increase in the electricity tariffs due to the ever increasing price of oil in the global market. To compensate for this an initial surcharge of 18% was first introduced, now increased to 55%. This has sent ripples across the board in terms of people’s awareness of the need for saving energy (reinforces a cost-wise attitude rather than an environment-wise approach!) Energy saving measures include double-glazing, shading devices, cavity and roof insulation, choice of orientation, re-planning of uses within the building, landscaping around the building to control the external microclimate, among others. The latest upcoming building regulations should be the best ‘whip up’ for introducing such energy saving measures. Although still in draft form, as outlined earlier, Part F dealing specifically with energy conservation and natural resources. The typical technical solution from a building construction aspect is outlined: Facades: Presently, the external double wall is composed of two skins of 150mm limestone, with a nominal cavity of 20mm, if at all. The ‘run of the mill’ buildings have no cavity insulation and no ventilation to the same cavity. There is no concern for isolation of the porous damp external skin form the inner skin, hence conductivity is at its best. The technical solution would be to isolate these with an air cavity and insulation attached to the inner skin, possibly with an aluminum foil in between to contain any internal heat gains in winter. Roofs: Today’s standard roof comprises a reinforced concrete slab topped with a crushed limestone material (torba), to obtain the falls, covered with a lean concrete mix, finished trowel smooth, laid to falls . Again, the standard practice is that no insulation is included. Admittedly over the last ten years or so a damproof membrane has been introduced. It is often deemed to be the ‘quick fix’ solution if there is a leaky slab, unwittingly considered irreplaceable with another technical solution. In truth there is no real extensively designed façade refurbishment in Malta, which is purposely designed for energy efficiency, particularly in the housing sector. The only minor refurbishments that take place are those concerned with eliminating moisture penetration from neighbouring properties, rising damp or basic façade redressing, primarily intended for aesthetic purposes. Even if only a cosmetic treatment is applied (such as an external rustic skin adhered to
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an existing fair faced masonry wall) this is deemed insignificant in terms of the overall thermal performance of the building. In government housing projects there have never been any energy conscious refurbishments to social housing blocks. If anything these were merely intended for physical restoration purposes. In the private residential accommodation this has also gone amiss. The private sector entrepreneur aims for minimizing the capital outlay for his project, with a clear intention for an outright sale in the shortest possible time to minimize bank interest to be incurred. Such apartments once sold individually, are practically never offered for a major refurbishment of the entire block, as this has to be undertaken by a purposely set-up owners’ association, formerly considered a ‘condominium’. Therefore individual owners are normally disheartened to take any individual action to refurbish their own flat only, as there is the extra effort to come to an agreement with the rest of the block. Rented accommodation in Malta is still unpopular as tenants argue that the monthly rent paid could be better paid as a monthly installment to repay a loan to purchase the flat rather than rent it. Hence it is only after the rent laws are repealed that such a holistic refurbishment projects will start to emerge, even if cautiously. 4.1 Technical Performance Malta is one of the warmest member states, lying on the southern fringe of Europe. In spite of our mild winters requiring only minimal heating, often intermittently over a three month period, humidity levels are persistently high, practically all year round. This is attributed to the fact that Malta is an Island with a typical Mediterranean marine climate. Conversely, our summers are very hot and humid, sprawling into spring and autumn when temperatures are often uncomfortably warm too. Therefore in terms of building energy design, Malta in reality has two seasons, a hot summer and a mild winter. It is for this reason that architects and building services engineers are more concerned with keeping buildings cool and dry rather than continuously warm. Malta’s transposition of the Energy Directive (2002/91EC) will come into effect as from 02 January 2007 through Legal Notice 238/2006, dated November 2006, entitled "Minimum Requirements on the Energy Performance of Buildings Regulations, 2006" under the Malta Resources Authority Act. This specifically refers to the final version of ‘Technical Guidance Document, Part F’ of the Building Regulations that specifies the minimum requirements for the energy performance of buildings, giving specific U-values to be reached as the minimum performance requirements for individual building elements (floors, walls, glazed openings, roofs). Trade offs are possible between different parts or components of the same building such the single average U-value is achieved, as long as the new building’s minimum performance is achieved. Among other recommendations Part F specifies the: use of insulation in roofs. use of double or improved glazing in windows. limited size of apertures. storage of rainwater for re-use as second class water, typically flushing of toilets and irrigation. use of direct solar energy for hot water and photovoltaic cells and setting up of wind turbines; these are highly encouraged, but not mandatory. Beyond the Technical Guidance Document, Clause 1(3) of L.N. 238/2006 explicitly enforces that: "Technical Guidance Document F notified in the Gazette, shall apply to new buildings and existing buildings that undergo major renovation or alteration, whose building permit applications in terms of regulation 3(1) of the Development Permission (Method of Application) Regula-
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tions, 1992, is received by the Malta Environment and Planning Authority on or after the 2nd January,2007". Although the measures will become mandatory, there is no enforcement body designated to handle such a task yet (December 2006). There are indications however that this may be taken on board by the MRA or the MEPA. 4.2 Functional / social performance The functional performance of any building is considered to be based on three pillars namely to provide shelter (thermal comfort - exclusion of adverse weather conditions), flexibility in planning (form follows function), the structural stability of the building. Although seemingly distinct these have an inter-related role to provide a functional building, particularly in the context of residential or even more, in social housing. 4.2.1 Shelter Provision In mainland Europe, social housing is provided at local community level or through local councils or regional/district management. Unlike continental Europe, in Malta all social accommodation is provided by central government due to its geographical size, land availability and demographical distribution. Due to the post-war, job-starved depression the social mentality was that workers and their families had to be ensured a safe and secure shelter, an abode close to their place of work. Hence landlords were obliged to carry out major repairs and maintenance to such houses, without te possibility of getting the keys back for his own family’s use. This has instilled an acute mentality with such owners that they are better off if they leave the house vacant falling to ruins rather than letting it out with no hoe of retrieving it. This has resulted in the present situation where a good number of such old vacant houses can be found in the more established Maltese towns and villages. Therefore the non-refurbishment of these houses has a negative impact on sustainability issues. The only way forward is an overall change to the present rent laws. 4.2.2 Planning Flexibility Due to the fairly rigid monolithic limestone construction, planning norms have always been dictated by span limitations of cellular layouts, typically up to four metres minimum width. This has diminished the flexibility of use (and re-use in refurbishments) in planning. However in the early 1980s, with the introduction of prestressed concrete slabs, such spans were increasing drastically now only limited by the load-bearing capacity of columns and beams. These are typically built in reinforced concrete or steel or a composite structure of both. The limited spans are deemed to be unsustainable, being less versatile for future different uses. This is however being resolved today by use of frame structures, thus rendering the final product more flexible future planning. 4.2.3 Structural Integrity In the Maltese built environment the structural integrity of a post-war building is demonstrated through the robust traditional load bearing external wall structures, as outlined earlier. This system is still used to the present day, particularly in new apartment blocks where the external façade walls and inner partitions are load bearing. The use of soft stone, originally mandatory, is today being replaced by concrete blockwork, yet still load bearing. It is only in commercial and office buildings that frame structures are largely used. 4.3 Economical performance Admittedly we are all more aware at first instance of the economical dimension of a refurbishment (or new build) than on the reduction of CO2 emissions. Architects have a role to play, namely that of educating the client in favour of sustainability. Although to date in Malta no insulation was ever used in buildings due to its mild climate, this will become mandatory together
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with double glazing, as from January 2007. This immediately prompts a reaction by the developer that there will be an increase in the cost of construction that will be ultimately passed on to the buyers. 4.4 Environmental performance Currently a typical refurbishment exercise in mainland Europe employs the use of E.T.I.C.S. (External Thermal Insulation Composite Systems). This is non-existent in Malta. It would not only create problems with condensation forming inside the cavity, but moreover it would jar with the surroundings, especially if used in an old part of the village. Apart from the ‘hot issue’ of getting the necessary planning permission there is the integration of a refurbished façade with an existing masonry building. The overall structural integration with cantilevered beams may create instabilities in an exiting façade. Similarly flat roofs can be refurbished to take additional insulation or existing windows fitted with double glazing; this has to be investigated against the end benefits, against a time frame (longevity) of the finished product, better known as the lifecycle analysis(LCA or life-cycle costs (LCC). Hence such a potential for refurbishment is to be seen in a holistic view in the context of the new building regulations, as outlined above in section 4.1.
5 CASE STUDY In Malta & Gozo, to date, there are no case studies of housing projects, neither public nor private, that have been taken through a refurbishment of their façade specifically for improving the thermal performance of the building envelope. In this light there are no case studies to present.
6 CONCLUSION In all honesty there is no real extensively designed façade refurbishment in Malta, which is purposely designed for energy efficiency, particularly in the housing sector. The only minor refurbishments that take place are those concerned with eliminating moisture penetration from neighbouring properties, rising damp or basic façade redressing, primarily intended for aesthetic purposes. Even if only a cosmetic treatment is applied (such as an external rustic skin adhered to an existing fair faced masonry wall) this is deemed insignificant in terms of the overall thermal performance of the building. In government housing projects there have never been any energy conscious refurbishments to social housing blocks. In conclusion, as highlighted separately, Malta has no mineral or oil resources of its own, thus having to import all its fossil fuels for power generation at the two power stations located on mainland Malta. Perhaps the best natural resource which Malta has is its solar insolation level. This needs to be exploited to be fully utilised for domestic solar water heating and photovoltaic systems. A separate matrix of all relevant data related to the thermal environment highlights Malta’s characteristics of a hot dry summer and warm wet winters, which make the Islands a popular place, worthy to be all year round. 7 REFERENCES Government Central Office of Statistics (1995 population census) Building Construction & Maintenance Department Housing Authority Chairperson, personal conversation Malta Environment and Planning Authority, Malta, Annual Report, 2005. State of the Building Industry Report, Building Industry Consultative Council, November 2006.
Technical Improvement of Housing Envelopes in Poland Zbigniew Plewako Rzeszów University of Technology, Department of Building Structures, Poland
Aleksander Kozáowski Rzeszów University of Technology, Department of Building Structures, Poland
Adam Rybka Rzeszów University of Technology, Department of Town Planning and Architecture, Poland
ABSTRACT: Paper presents one of the first popular technologies widely used in Poland for upgrading thermal resistance of facades in multi family housing buildings made with the use of non traditional technology. As a reaction to more restrict requirements of energy consumption, it became popular in 1980s years of the last century due to its material and technological simplicity resulting in relatively low construction costs. The idea of External Thermal Insulating Dry System (ETIDS) consist in adding to existing facade insulating sheets covered by external layer panels with structural frame, and fixing it to original wall structure. Although system was developed as an original idea, it was based on commonly available materials. It was especially dedicated to improve the thermal insulation of pre-cast external walls in the large panel building technologies – the most popular technology of multi dwelling building in Poland. Description of the system contains basic data of system elements, installing technology, details and performance with pointed out impact of the refurbishment action with ETIDS system on sustainability topics Specification of ETIDS is complemented with examples of typical applications.
1 INTRODUCTION 1.1 Standard envelopes in Poland The most popular dwelling house technology in Poland in period 1965 – 1989 is based on large panel precast elements. Over 4 mln dwellings were build giving about 30% out of total dwelling stock. Typical external bearing walls, for most of building systems (Fig. 1), were three-layer panels with internal bearing layer made of plain or reinforced concrete 12 to 15 cm thick, thermal insulating (foamed polystyrene or mineral wool 5 to 6 cm, in later years upgraded to 8 cm) and surface (façade) reinforced concrete layer 6 or 7 cm thick with finishing. Curtain walls (selfbearing) have the same structure with thickness of bearing layer reduced to 8 – 12 cm. Façade layer is fixed to structural one by bearing steel hangers and stirrup pins. This connection is flexible to compass thermal strain differences in both concrete layers. Wall openings have assembled widows and doors. Early large-panel systems provides facade finishing with plain or parging plaster. Most typical for large-panel system was rough cast finishing of external concrete layer of elements, with sealing front side of element joints. In some systems, where external longitudinal strip walls were used, spaces between openings (windows or balcony doors) were filled with sandwich panels. These panels with timber frame were made of asbestos-cardboard with thermal insulating layer and chipboard inside. Sometimes precast concrete panels were used. COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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Figure 1. Typical three-layer panel external wall. Layout and structure. 1 precast concrete, 2 thermal insulation (foamed polystyrene), 4 lightweight concrete, 5 in-situ concrete, 6 insulating foil, 7 steel profile sealing strip, 9 mortar, 10 rubber sealing
1.2 Requirements that enforce a reaction to refurbish envelopes in Poland Centrally controlled energy production based on hard and brown coal did not force energy saving solutions of building heating and thermal insulation. Heating system was based on big central heat-generating plants. Also heat accounting was independent of particular heat consumption. These were reasons of omitting energy saving problem up to 1982 (Tab. 1).
Table 1 Standard requirements of heat transfer coefficient in Poland
Partitions Walls Roofs
Required heat transfer coefficient, W/m2K PN-64/B-03404 PN-82/B-02020 PN-91/B-02020 Valid to 1984 Valid from 1984 Valid from1992 1,16 0,75 0,55 0,87 0,45 0,30
8 cm
6 cm
7 cm
6 cm
8 cm
7 cm
W/m2K
0,8
8 cm
6 cm
6 cm
1
0,6
105
5 cm
Technical Improvement of Housing Envelopes in Poland
0,4 0,2 0 W-70
Wk-70
OWT-67
OWT-75
Figure 2. Tested heat transfer coefficient of wall-panels due to increase of insulation layer thickness
Thermal insulation requirements for walls and solid roof ceilings valid to 1984 (with slight change in 1974) were simply result of assumed principles of excluding vapour condensation on internal surfaces and snow melting on roofs. They were based on experience in traditional brickwall building. Most of the existing envelopes do not respect insulating standard values (Fig. 2) 2 SPECIFICATION OF THE TECHNICAL SOLUTION Presented in this paper External Thermal Insulation Dry System (ETIDS) for refurbishing of three-layers external wall panels in large panel buildings became most popular in end years of 80th decade. It is “simplified version” of ventilated façade systems popular in Western Europe. Its advantage laid in simple and fast installing works based on easy to reach materials. Additional façade consist of heat-insulating layer made of mineral wool sheets 40, 60 or 80 mm thick, and covering layer of folded steel sheets T35 or T55 made of 0,75mm steel protected with zinc coating and coloured . Horizontal bearing strips spaced resulting from insulation sheets (1000, 2000 or 3000 mm) made of steel “Z” or “C”shape zinc covered profiles are mechanicaly fixed to concrete facade layer with expantion bolts spacing ca 1000 mm. Then, mineral wool sheets are put on the wall and mechanicaly fixed with plastic hat-nails (Fig 3). Folded steel covering layer is then fixed to bearing strip with self-drilling screws or blind rivets. Sheets have appropriate horizontal and vertical laps (Fig. 4). Top, bottom and side edges as well as openings were covered with additional plain steel sheets or strips covering old facades (Fig. 5).
1- “old” façade concrete 2- mineral wool sheets 3- hat-cap nail 4- bearing strip (zinc coated steel “Z” or “C” profile Figure 3. Fasting of mineral wool sheets to existing concrete facade (Arendarski, 1988)
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1- “old” façade concrete 2- mineral wool sheets 3- folded steel sheet 4- fastener (self drilled-screw or blind rivet 6- expansion bolt 7-“Z” profile 8- PVC washer 9- millboard washer
Figure 4. Fasting of corrugated steel sheets to existing concrete facade (Arendarski, 1988)
a)
b)
c)
d)
Figure 5. Lay-out of ETIDS elements in corners –a) and in openings –b), c), d) (Arendarski, 1988) 1 “old” façade concrete, 2 mineral wool sheets, 3 corrugated steel sheet, 4 fastener (self drilled-screw or blind rivet), 5 corner steel strip, 6 expansion bolt, 7 “Z” or “C” profile, 8 PVC washer, 9 millboard washer, 10 window, 11 foamed polystyrene profiles, 12-flat steel profile, 13 closing profile, 14 screw, 15 window still, 16 steel profile with drip
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3 THE IMPACT OF THE REFURBISHMENT ACTION ON SUSTAINABILITY TOPICS 3.1 Technical performance The building solutions used in curtain façades should be certified as prescribed in EN 13830. According to this European Norm, the performance characteristics that should be accessed in curtain walls are: 1. Fire resistance; 2. Reaction to fire; 3. Fire propagation; 4. Watertighness; 5. Dangerous substances; 6. Wind load resistance; 7. Resistance to own dead load; 8. Impact resistance; 9. Resistance to horizontal loads; 10. Thermal shock resistance; 11. Acoustic performance; 12. Thermal resistance; 13. Water vapour permeability; 14. Air permeability. 3.1.1 Stability, capacity, (earthquake) ETIDS due to its elasticity is stabile and sufficient for expected loadings: self-weight, thermal deformation of building (horizontal), wind loads. Stability of ETIDS depends also on bearing capacity of anchoring to existing – concrete facade. Technical Approvals for fastening techniques ensure safety of all connections in the system but it was noted that under storm wind some connectors were broken off causing flattering of single steel sheets. External steel cover is to resist to moderate mechanical impacts or vandalism acts. 3.1.2 Fire protection All elements of ETIDS are non-flammable, so the system even improve fire protection of building. However, air channels between insulation (mineral wool) and folds of steel sheets in special cases can work as a chimney intensifying the fire located by external walls. 3.1.3 Noise Insulation Of cause, additional layer of thermal insulation increase noise protection of partition, for ca. 5y10dB, but effective acoustic insulation depends mostly on openings: windows and balcony doors. 3.1.4 Weather and moisture protection a) Protection to rainwater It is the one of main tasks for this system and, of cause, it improve weather protection for the wall in general. Anyhow, due to small but continuous gaps in sheet connections, unavoidable penetration of wind and rainwater through steel layer occurs, which could start corrosion of system steel elements; b) Protection to condensations As mentioned above, moisture could penetrate through external ETIDS barrier. Additionally, under specific thermal condition water condenses on internal surface of steel sheets. But thanks to good internal ventilation in folds, insulation layer and deeper layers of wall stay dry, or even internal moisture is removed.
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3.1.5 Conductivity, Heat flow, radiation, convection Two elements of ETIDS improve thermal insulation: mineral wool and air in vertical folds. Depending on thickness of insulating layer (varying typically from 40mm to 80mm) and original U-value, reduction ('U) varies from 0,14 to 0,37 W/m2K (Fig 6);
0,8
U0 = 0.69
0,8
0,6
0,6
U0 = 0.49
'U = 0.37 0,4
0,4
0,2
0,2
0
'U = 0.22
0
40
50
60
70
80
40
50
60
70
80
Figure 6. Improving of U-value related to heat insulation thickness for different original U0-values
3.1.6 Durability (service life) Service life of ETIDS is generally limited by durability of steel: folded sheets on wall areas, detail plain sheet profiles, strips on edges and on openings as well. After almost 20 years of service till now no significant durability problems occurred with the exception of local corrosion on sheet cut edges. It seems that horizon of 30 years of service life is expected. 3.2 Functional/social performances 3.2.1 Flexibility Presented system does not influence building interior. Particularly dedicated to concrete facades it could be applied on brick walls as well. Formally, there are not limits to facades shapes, but the best performance is reached on flat surfaces with minimum openings, balconies, edges, etc. 3.2.2 Comfort (thermal, acoustical, visual) Improving the thermal comfort by increasing the external walls thermal insulation (reduction of U-value) is the basic assumption of the system development. In addition, specific but rather not considered profits in acoustic insulation are obtained .From another point of view, stiff and elastic external steel sheets works as acoustic baffle, reflecting external noise such as traffic or others. This effect is reduced by steel folding. The system can also produce noise (vibrations) while storm wind, which is reduced by millboard strip washer (muffler) under support “Z” profile. Dwellers report troublesome noise produced by the inside dropping of condensed water. Considering visual effects, its hard to say something positive about ETIDS. Of cause aesthetic impression are always subjective, but I think, that buildings looking like huge refrigerators or containers are not friendly for an eye. New façades made of uniformly running folded surface give rather uninteresting architectural impression. It could be slightly enhanced by various colours and folding types, or combining it with other external thermal insulating systems (ETICS or others). 3.2.3 Health (air quality, TVOC etc., mould & fungus growth) From the point of view of health the system performance is very good. Due to possibility of specific ventilation, it keeps walls warm and dry, helping to eliminate formation of mould and fungus (when interior ventilation system works properly of cause). Unrespectable problem are various insects that find very good living conditions and reproduction environment inside ETIDS space.
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3.2.4 Safety Improper shaping or realisation of covering layer details leaving sharp steel edges could cause skin cuts. Very small risk is connected with potential fall down of steel elements as a result of accidental loadings on aged (corroded) structure. No such cases were reported. 3.2.5 Barrier free Not relevant. 3.3 Economical Performances 3.3.1 Building costs Actual market price is unknown because light-dry method is not popular now. Approximate building costs in Poland for 2002 varied ca. from 25€ to 35€ per 1m2. 3.3.2 Running costs (heat losses, cooling, cleaning, inspection, maintenance, etc.) No running costs occur or are expected, because generally system does not require any special maintenance works. Reported power requirement saving for large panel multi-dwelling buildings is presented in Tab. 2 (Koczyk & el., 2000) Table 2. Power requirement saving rate for light-dry method of thermal insulating in large panel multidwelling buildings related to application range and area/cubature A/V factor A/V [m-1] Gable Range of walls applic. All facade
0.37
0.35
0.29
0.28
4.9%
3.2%
2.7%
3.1%
19.1%
17.5%
17.9%
19.0%
Accessible data reports (ĝwiĊcicki, 2003) concerning limiting energy saving actions for building only to improving thermal insulation of external walls by ETIDS, result in SPBT (Simple Pay Back Time) value of 14 years, with negative value –31.11 for NPV (Net Present Value). This means that from the economical point of view application of ETIDS must be combined with other actions (new windows, improving of heating system, thermal insulation of roof etc.). 3.4 Environmental Performances 3.4.1 Use of resources (non renewable, renewable) No ETIDS elements can be reused as renewable resources.
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3.4.2 Energy consumption (non renewable, renewable) - production / assembly - heating / cooling Only approximate and theoretical energy consumption data are presented in Fig 7. below: 4000 3500 3000 2500 2000 1500 1000 500 0 -500 0 -1000
[MJ]
U0 = 0.69 ETIDS 8cm: DU = 0,37 ETIDS 4cm: DU = 0,26
5
10
15
20
25
30
[y]
Figure 7. Approximate energy consumption saving [MJ] for 1m2 walls with ETIDS 8 and 4 cm
3.4.3 Environmental impacts, (GWP global warming potential, AP acidification potential, NP nitrification potential, EP eutrophication potential, ODP ozone depleting potential, POCP photochemical ozone creation) Taking into consideration the fact that in Poland heating energy used in multi-dwelling large panel building is produced mainly by coal in district heating stations with production and transport efficiency 32.7%, reduction of environmental impacts for 30 years period is as follows (Tab. 3): Table 3 Environment factor saving for 30 years of ETIDS use Factor GWP [t CO2] AP [kg SOx] NP [kg NOx]
ETIDS 4cm 1,29 6,48 4,52
ETIDS 8cm 1,84 9,31 6,91
3.4.4 Waste 100% of steel can be potentially recycled, but the real value is about 40% now. The same potential is for mineral wool, but in Poland 0% of it is recycled now. 4 CASE STUDIES Some examples of typical ETIDS application on large panel multi dwelling buildings are presented below. 4.1 Residentials Building in Baranowka District, Rzeszow First presented group of building represents early applications of ETIDS technology. In these cases refurbishing actions were performed on all facades (fig. 8 to 11).
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Figure 8. Baranówka district in Rzeszów – general view
Figure 9. ETIDS on front facade
Figure 10. ETIDS arrangement
Figure 11. ETICS and ETIDS (background) on similar facades
Second example (Fig. 12 to 15) presents refurbishment solution, in which only “blind” gable walls were covered with ETIDS, then on façade walls with windows, balconies or loggias ETICS technology was applied. In this more economic solution large steel sheets were easy and fast to put on flat concrete gable walls, when ETICS technology allow to proper details shaping around openings and balconies. This or similar solution became popular when ETICS technology widely came into practice at the beginning of 1990s.
Figure 12. OWT building – original facades
Figure 13. OWT building with older ETIDS on gable wall and newer ETICS on front wall typical solution
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Figure 14. ETIDS and ETICS arrangement
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Figure 15. ETICS and ETIDS joint
4.2 Gwardzistów district – Rzeszów, Poland Another example where only ETICS system was applied, but only on flat surfaces of façades, leaving loggias in original construction (Fig. 16 to Fig. 21).
Figure 16. RWP –system: ETIDS on east facade
Figure 17. ETIDS on façade pilaster – closer view
Figure 18. ETIDS - detail
Figure 19. ETIDS as insects habitat (birds?)
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Figure 20. ETIDS: bottom end arrangement
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Figure 21. ETIDS: base for green wall
The figures above show the details of ETIDS technology, which is more difficult in shaping then the ETICS systems. This is the reason, why ETIDC technology was “displaced” from façade walls to gable ones. 4.3 Nowe Miasto district – Rzeszów ETIDS applied only on gable walls with fibre cement panels instead of steel sheets (Fig. 22 to 23). In this solution panels are fixed to original wall by timber profiles (Fig.24). This is another version of first ETIDS technology.
Figure 22. RWP system: ETIDS with fibre-cement panels on gable wall (under renovation – painting)
Figure 23. ETIDS with fibre-cement panels on gable wall
1- “old” façade concrete 2- vertical timber lath 3- vertical sealing rubber strip 4- fiber-cement panel 5- horizontal steel profile 6-waterproof plywood washer Figure 24. Structure of ETIDS with fibre-cement panels
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4.4 Praga-Poáudnie district – Warsaw Presented on Figure 25 to 27 „early” ETIDS technology uses short steel sheets fixed by timbre frame. As in majority of the solutions presented in previous chapters, the first refurbishing actions were limited only to gable walls. In following years, some of these buildings were covered by ETICS on façade walls, or ETICS was applied originally to other ones.
Figure 25. ETIDS on gable wall
Figure 26. ETIDS on gable wall– closer view
Figure 27. ETIDS – partial cover
Figure 28. ETICS as alternative
5 CONCLUSIONS Presented ETIDS system, thanks to its simplicity and economical efficiency, was used widely in Poland in 80th and 90th years of past century for upgrading of thermal resistance of facades in non traditional multi dwelling buildings. Its structure is a kind of simplified version of ventilated façades systems, popular in south-west Europe. Actually in Poland, for façade refurbishing actions almost exclusively ETICS system are in use, with higher aesthetic and operational performance with comparable to ETIDS installation costs. 6 REFERENCES Arendarski J., 1988. Thermal insulation improvement of dwelling buildings. Warszawa: ARKADY (in polish) Koczyk H. & el., 2000, Heating. Basics of heating and thermal upgrading design. PoznaĔ, Wydawnictwo Politechniki PoznaĔskiej (in polish) ĝwiecicki A., 2003. The factors influencing the economic efficiency of thermo-modernizating capital expenditure.: Scientific books of Bialystok University of Technology: Civil Engineering No 23. Politechnika Biaáostocka (in polish)
Technical Improvement of Housing Envelopes in Portugal L. Bragança University of Minho, Guimarães, Portugal
M. Almeida University of Minho, Guimarães, Portugal
R. Mateus University of Minho, Guimarães, Portugal
ABSTRACT: The main problems in multi-storey building envelopes in Portugal are the low thermal insulation and low airborne sound insulation. These problems are more relevant in buildings built before the publication of the first thermal code. The envelopes, mainly the façades of buildings built in that period, do not fulfill the actual users comfort requirements and construction codes. This way, it is necessary to find the most appropriate technical solutions to refurbish those façades. One of most used technical solutions is the ventilated façade. In this paper the impacts of this technical solution in standard envelopes are going to be discussed. The impacts will be assessed looking at technical, functional, social, economical and environmental proprieties.
1 INTRODUCTION 1.1 Standard envelops in Portugal Since 1950 the building technology in Portugal is based on a steel reinforced concrete beams and pillars system. In spite of existing few exceptions to this general rule, it can be assumed that 99% of the housing buildings envelopes built after the early 60’s has the following pattern: Structure: it is composed of steel reinforced concrete frames of columns and beams. Exterior walls: the non load-bearing hollow brick walls emerged in the 60’s and it continues to be the most used solution. Actually, the most used technique is the hollow brick cavity wall. The insulation layer on the cavity of the walls is standard on buildings built from the late 80’s (Fig. 1); Fenestration: until the 70’s the windows frames were in wood. Since the 70’s most of the windows frames are made of aluminum and in the middle of the 90’s the PVC windows frames appeared in the market. After early 90’s, most of the windows have double glaze (6+12+6 mm) and the glass is clear on both sides in all facades; Roofs: pitched roofs and/or flat roofs (mainly in the South). Until the 80’s the standard was the ventilated roof with ceramic tiles laid on a wooden frame structure, without any insulation. Actually the pendant of the roof is made of a pre-stressed T-beams and ceramic blocks slab, constituting a non-ventilated attic. The biggest part of roofs built after the early 90’s has an insulation layer. The main problems identified in the Portuguese building envelopes were the low thermal insulation and insufficient sound insulation, mainly in buildings built before the early 90’s. The poor thermal behaviour is related with the high U-values of the envelopes. The major part of the envelopes built until the early 90’s, about 80% of the total actual residential units, do not have insulaCOST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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tion and the window frames have high air permeability and are single glazed. The poor air born sound insulation of the façades is commonly related to the bad quality of the fenestration (single glaze windows and high air permeability window frames). This situation becomes significantly improved after the publication, in 1991, of the actual thermal legislation.
Figure 1. Evolution on the exterior walls construction solution in Portugal (APICER1, 1998).
Figure 2. Ceramic tiled roof laid on a wooden frame structure, constituting a ventilated attic (APICER2, 1998).
Figure 3. Pitched roof structure made of prestressed T-beams and ceramic blocks slab, constituting a non-ventilated attic (APICER2, 1998).
1.2 Requirements in Portugal that enforce a reaction to refurbish envelopes Actual regulations (i.e. thermal and acoustical) are more demanding and they imply new ways to design buildings. At the level of thermal comfort regulation, its satisfaction is not obligatory retroactive in all buildings built before its publication. Its fulfilment it is only required in buildings submitted to a refurbishing process in which the costs exceed more than 50% of its actual value. Although, buildings built until the publication of the actual thermal legislation do not satisfy the actual users comfort requirements and they need to be refurbished. Nowadays a new thermal legislation is being discussed in order to fulfil the European Directive 2002/91/CE. In the new thermal legislation, the requirements will be at least 40% higher than the actual one. This situation is enforcing to study and find new construction/refurbishing solutions that will meet these new requirements. Table 1 shows the standard and future requirements for the thermal insulation of building envelopes. Until 1991 there was no regulation about this issue. On the other hand, it will be necessary to refurbish the actual building stock in order to reduce the energy consumption on it and meet the aims and goals for sustainable development, particularly at the level of the CO2 emissions and economic sustainability. At the moment, the energy consumed in Portuguese buildings is about 25% of the total energy consumption, and in the last years this value is increasing a lot. Portugal signed the Kyoto Protocol and now, more than ever, it is necessary to refurbish these façades in order to archive its goals.
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Table 1. Standard and future requirements of heat transfer coefficient (U-value) in Portugal. ________________________________________________________________________________________________________
D.L. 40/90 D.L.(1) Valid from 1991 Valid from 2006 ________________________________________________________________________________________________________ Partition Maximum U-value Reference U-value Maximum U-value Reference U-value Element (W/m2.ºC) (W/m2.ºC) (W/m2.ºC) (W/m2.ºC) ________________________________________________________________________________________________________ Walls 1.80 1.40 1.80 0.70 Climate zone I1 1.60 1.20 1.60 0.60 Climate zone I2 Climate zone I3 1.45 0.95 1.45 0.50 ________________________________________________________________________________________________________ Roofs 1.25 1.10 1.25 0.50 Climate zone I1 1.00 0.85 1.00 0.45 Climate zone I2 0.90 0.75 0.90 0.40 Climate zone I3 ________________________________________________________________________________________________________ Windows 4.20(2)/5.80(3) 4.30 Climate zone I1 4.20(2)/5.80(3) 3.30 Climate zone I2 4.20(2)/5.80(3) 3.30 Climate zone I3 ________________________________________________________________________________________________________ (1)
The new thermal legislation will be published in the second half of 2006. Buildings that are used during the night (dwellings, hotels, hospitals, etc.). (3) Other buildings. (2)
2 SPECIFICATIONS OF THE TECHNICAL SOLUTION The most used refurbishing solutions for vertical envelopes in Portugal are: the External Thermal Insulation Composite Systems (ETICS), the Ventilated Façades and the replacement of existing windows by double glazed and low air permeability ones. In this paper, the potentialities of the ventilated façade as a refurbishing solution, mainly for buildings built from the 70’s, will be assessed. 2.1 Ventilated coated façades The ventilated façade is composed, from exterior to interior, by a floating covering material, after which there is an air cavity, where a layer of insulation is installed, and finally the support structure (existing wall). The covering material is fixed into the supporting structure using a steel frame structure and anchoring devices. The air cavity that exists between the cladding and the insulation creates, due to the “stack effect”, effective natural ventilation, with remarkable benefits to the entire system. Placing a floating covering material in the external surface of the existing vertical external envelopes is one solution to improve their thermal and sound insulation. Compared with the other refurbishing solutions applied directly to the wall structure, the advantages of a ventilated façade are: Reduced risk of cracking and detachment; Easy installation: elements are assembled “dry” on site without the use of adhesives, by means of mechanical-type fitting and anchoring devices; Lower maintenance: work may be carried out separately on each individual cladding unit; Higher durability: the wall structure is protected against direct climate loads. This way its durability is generally high; Higher energy-saving: all construction mass of the wall structure is available for the interior thermal inertia and there aren’t thermal bridges. Higher moisture control: elimination of surface condensations on the insulation (the presence of an air cavity helps expelling water vapour from inside, reducing dampness caused by infiltration).
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The functional elements that form the ventilated façade, as presented in figure 4, are: Support structure: existing wall. This system is best suited for load-bearing walls; Regularisation layer: 1-2 cm-thick plastering. It has the function of reducing all irregularities on the surface of the underlying layer; Insulating layer: 3 to 8cm thick layer applied directly to the wall structure using glues and/or mechanical elements. The most common used materials are: polyurethane foam; expanded polystyrene and extruded polystyrene; Ventilation layer (air cavity): 3 to 5cm; Anchoring system: composed by an integrated set of elements with the static function of attaching the floating cladding to the building structure. The anchoring system may be made up of metallic or wood structural frame (spread fixing) or of anchors located in certain points (local fixing), and visible and not-visible solutions are available (figures 5 to 7); Cladding layer: to protect the building structure from direct climate loads and to (re)define the building aesthetics. The most common materials are: natural stone, man-made stone, ceramic, terracotta, plastic or metallic materials, oriented strand board (OSB), glass (transparent and opaque) and wood fibre board with Portland cement.
Anchoring system Ventilation layer Cladding layer
Insulation Support structure Plastering Regularisation layer
Figure 4. Cross section of a typical ventilated curtain wall (Mateus, 2004).
Figure 5. Detail of a typical visible spread metallic anchoring system (APICER, 2003).
Figure 6. Detail of a typical visible local metallic anchoring system (APICER, 2003).
Figure 7. Detail of a typical not-visible spread metallic anchoring system (APICER, 2003).
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3 THE IMPACT OF THE REFURBISHMENT ACTION ON SUSTAINABILITY TOPICS 3.1 Technical performance The building solutions used in curtain façades should be certified as prescribed in EN 13830. According to this European Norm, the performance characteristics that should be accessed in curtain walls are: 1. Fire resistance; 2. Reaction to fire; 3. Fire propagation; 4. Watertighness; 5. Dangerous substances; 6. Wind load resistance; 7. Resistance to own dead load; 8. Impact resistance; 9. Resistance to horizontal loads; 10. Thermal shock resistance; 11. Acoustic performance; 12. Thermal resistance; 13. Water vapour permeability; 14. Air permeability. 3.1.1 Stability, capacity, (earthquake) The cladding of this wall is not load-bearing. Although it is designed to accommodate structural deflections, control wind-driven rain and air leakage, resist to wind horizontal loads, minimize the effects of solar radiation and provide for maintenance-free long term performance. Movements of the structural elements of a building must be determined prior to the design of an exterior wall system. Movements may be grouped into three types (Quirouette, 1982): 1. live load deflections due to occupancy loads or peak wind loads on the building façade, and dead load deflections of the building structure; 2. expansion and contraction of materials as a result of temperature, radiation and sometimes hygroscopic loading; 3. slow but inexorable movements due to gradual deformation, such as creep in concrete, foundation settlement, etc. This refurbishing solution can be used in any type of façade. Although, it’s necessary to have in mind that the material used as wall structure influences the stability of the anchorages, thus influencing the wall stability. Soriano (1999) studied the influence of the material used in the wall structure in the anchorage system stability, and the results are shown in Table 2. Table 2. Reliability degree of the material used as wall structure in the stability of the anchorage system (Soriano 1999). ______________________________________________ Material Reliability ______________________________________________ Reinforced concrete Excellent Solid brick Very Good Perforated brick Good Cement brick Good Light ceramic brick Good Hollow brick Unacceptable ______________________________________________ Although not a frequent cause of failure, building movements are not adequately considered in the design and construction of façades. As higher is the cladding and fixing system’s rigidity as bigger are the problems found at this level. In the glass panel cladding the problems related to the movements of the wall structure
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should be particularly studied in order to avoid the collapse of any cladding unit. The problems are also worst when the dimensions of the cladding units are higher. To avoid the problems related to the cladding’s expansion and contraction, the joints between the units should have a compatible thickness. When a sealant is used in the joints, its modulus of elasticity should be compatible to the movement requirements. Low modulus sealants (remaining soft after cure) are suitable when movement is required, as in the case of metal curtainwalls. High-modulus sealants are best suited in cases such as structural glazing where high strength is required and movement is limited. The building movement resulting in compression, expansion and parallelograming of the frames must be accommodated by the fixing system. In a typical curtain wall system of structural mullions, the fixing system should allow a differential movement of about 4 to 5mm on a floor to floor basis and between each vertical riser (Quirouette, 1982). If greater movements are expected, the fixing system must be compatible with it. This situation leads to more complex detailing and usually a disproportionate increase in the system cost. 3.1.2 Fire protection When a ventilated curtain wall is built, an air cavity is created at the intersection of the floor assembly and the wall structure (interior face) of the curtain wall. The air cavity is a way for fire propagation from lower to upper floors. In order to prevent this risk, this cavity must be sealed along the perimeter of the building. The material and system used in the perimeter must be capable of preventing the passage of flame and hot gases for a time period at least equal to the fire resistance of the floor assembly. Air cavities of a range of widths could be sealed with fire resistive non-combustible materials such as mineral wool blankets. Figure 8 illustrate a typical detail of the air cavity and the sealing material between the slab and the curtain wall (MCA, 2003).
Wall structure or existing wall (in case of refurnishing) Supporting clip Seal with fire retardant mastic Floor Mineral wool Suspended ceiling Curtain wall
Air cavity at floor level
Figure 8. Exterior curtain wall at the level of floor intersection (air cavity sealing)
3.1.3 Noise protection In this type of wall the cladding doesn’t adhere directly to the supporting structure. Therefore, the airborne sound insulation is greatly improved compared to other building solutions with the same mass. Some problems of vibrations were identified in these walls, mainly when the cladding material’s rigidity is high and or its mass is low (e.g. glazed curtain walls). In order to prevent this kind of problems, that could compromise the global sound performance, it’s necessary to introduce a resilient material between the cladding and the fixing system.
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3.1.4 Moisture protection a) Protection to rainwater The penetration of rainwater through walls depends on the following combination of conditions (Chown, 1997): 1. the presence of water; 2. openings in the assembly that permit water to enter; 3. forces that can move water through the assembly. The control of rainwater penetration depends on being able to control any one or all of these conditions. Over time, rain penetration has been controlled in various ways ranging from massive masonry construction to pressureequalized rainscreen (PER) curtain-wall assemblies. In curtain walls the moisture protection is improved through the rainscreen principle: the presence of a drained and ventilated air cavity between the cladding and the wall structure permits the reduction of moisture load on the back-up wall. The air cavity permits the removal of moisture transferred from both the exterior and interior. b) Protection to condensations Water in its gaseous phase (water vapour or humidity) always tries to migrate from a region of high water vapour pressure to a region of lower pressure. The migration of water vapour through a wall can be compared to heat flow; it moves through all materials at a rate that is dependent on both the resistance of the materials to water vapour flow and the difference in water vapour pressure on both sides of the material. In winter the water vapour migrates from inside to outside and it generally condenses to water in the exterior surface of the insulation. The stack effect on the air cavity removes the humidity and prevents long contacts with the wall structure materials. 3.1.5 Conductivity, heat flow The heat flow control is generally achieved through the use of insulation. This system uses considerable insulation, usually behind spandrel glass or any opaque panels, although it is not visible from the exterior. Due to the high conductivity of some materials used as cladding, p. e. glass and metal, the system must also contend with potential condensation on the interior surfaces. One of the biggest advantages of this system is that the insulation is continuous. Therefore the thermal bridges in the structural elements areas are avoided. Another advantage of this kind of insulation is that all the wall structure’s mass is available for the indoor thermal inertia. 3.1.6 Durability The solar radiation is one of the major external agents that influence the durability. On this system the most important concerns related with solar radiation are the thermal expansion and contraction of curtain wall components, in particular those forming the outside cladding. Therefore, the durability of this kind of wall depends, above all, in the type of material used as cladding: the longevity of aluminium panels is reduced by corrosive urban pollution, acid rain and salty air; the pre-cast concrete panels often cracks; fibberglass reinforced panels loose strength over time as the alkaline-rich cement attacks the glass reinforcement. The durability of the OSB panels is limited due the destructive effects of ultraviolet radiation in the organic materials. The biggest advantage of this system, at the maintenance level, is the possibility of replacing any cladding unit without moving the others. 3.2 Functional/social and economical performance As stated before, several solutions and different materials could be used to build this system. This way, its functional, economic and environmental performances depends above all on the type of materials that were used on it. This way, the performance of this system, at these levels, will be assessed in the case study.
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4 CASE STUDY 4.1 Description of the building solutions The building solution accessed in this study is one of the most used solutions in multi-storey building façades, built in Portugal from the 70’s until the early 90’s. The solution is a hollow brick cavity wall (11+11cm) with a 4cm thick air cavity. Each surface of the wall is covered by a 1,5cm thick layer of render. This solution doesn’t have the necessary performance to fulfil the actual user’s comfort requirements and the new thermal regulations. Figure 9 shows the wall cross section before the refurbishing process. Air cavity (4cm) Hollow brick (11cm) Render (1.5cm)
Hollow brick (11cm) Render (1.5cm)
Figure 9. Cross section of the wall (before refurbishing).
The assessed refurbishing process consists in the placement of a 4cm thick continuous thermal insulation layer of agglomerated cork and in the assembly of a 1,0cm thick ceramic cladding. The anchoring solution is a structural system composed by galvanized steel elements and the air cavity between the insulation and the cladding is 4cm thick. The joints between the cladding units are sealed. Figure 10 presents the wall’s cross section after the refurbishing process. Agglomerated cork (4cm) Anchoring system Air cavity Ceramic cladding (1cm)
Figure 10. Cross section of the wall (after refurbishing).
4.2 Functional/social performance 4.2.1 Flexibility This kind of refurbishing solution can be adopted in near to all building systems, therefore its flexibility it’s very high. In non load-bearing walls this system could be easily placed if the anchoring system is connected directly to the building’s beams and columns. In load-bearing walls or when it’s not possible to connect the anchoring system directly to the building’s structure it is necessary to verify if the original wall has the necessary structural stability to support it.
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Since the system is mechanical fixed to the existent wall, in this solution it’s easy to replace any cladding unit or the entire system. 4.2.2 Comfort a) Thermal The placement of an insulation layer turns the U-value lower after the intervention. Table 3 shows the U-value of this wall before and after the process.
Table 3. Heat transfer coefficient (U-value) of the wall before and after the refurbishing process. ________________________ U (W/m2. ºC) ________________________ Before(1) After ________________________ 1.40 0.62 ________________________ (1) In the evaluation of this value the thermal bridges were not considered. Considering it the difference would be greater. b) Acoustical The airborne sound insulation curve of the building solution, before and after the refurbishing, is assessed using the analytical methodology proposed by Meisser (1973). The airborne sound insulation index (Dn,w) was quantified adjusting a reference curve to the result, as prescribed in NP–2073 (Portuguese normalization). As shown in figures 11 and 12, after the refurbishing the Dn,w (f=500 Hz) is improved in about 4 dB.
Dn,w
Figure 11. Airborne sound insulation curve (before refurbishing).
Dn,w
Figure 12. Airborne sound insulation curve (after refurbishing).
4.2.3 Health In this refurbishing solution, no health hazards were identified during the construction phase: this intervention is made at the exterior of the building; therefore it doesn’t directly affect the indoor air quality. During the operation phase, the application of a ventilated façade is useful to increase the thermal insulation, superficial indoor temperature and to reduce the condensation and avoid the formation of moulds. These factors are important for the inhabitant’s health. 4.2.4 Barrier free Comparing to other refurbishing solutions (e.g. ETICS), the smaller number of companies specialized in this type of system and the lake of specialized workmanship, increases its cost and reduces its competitiveness.
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4.3 Economical performance Comparing this refurbishing technology with other technologies, its construction cost is much higher. Although, in the economical performance assessment it is necessary to evaluate, not only the cost of each building material and the related workmanship, but also all other costs and benefits related to the solution’s life cycle. This way, it must be enhanced that the higher construction costs could be compensated with lower maintenance costs (as presented before, the maintenance operations are easy in this solution). Another factor that might influence this comparison is the residual value: this solution as a great residual value, since the biggest amount of its elements could be directly reused in another building or easily recycled. An average cost for a ventilated façade in Portugal is bounded between 75€/m2 (ceramic cladding and local metallic anchoring system) and 500€/m2 (aluminium cladding). 4.4 Environmental performance 4.4.1 Energy consumption The amount of energy needed to produce materials, their assembly in construction site, maintenance and demolition, it is bounded between 6 to 20% of the total energy consumed during the entire life-cycle of a building, depending, among others, on the used building technologies, number of users, climate and comfort level demanded by the occupants (Berge, 2000). About 80% of this value corresponds to the materials Primary Energy Consumption (PEC), what means the energy resources spent for its production, including the energy directly related to the extraction of raw materials, their processing and the energy needed for their transport. The remaining 20% includes the energy consumed in the transport of the transformed materials to the construction site, the energy consumed during the building construction and the consumed energy during the dismantling and demolition processes. The assessment of the total embodied energy in building materials is one of the dimensions to consider in the environmental performance evaluation. Table 4 shows the building mass and the PEC, per each square meter of this refurbishing solution.
Table 4. Solution’s mass and total Primary Energy Consumption (PEC). ________________________________________________________________________________
Material
Curtain wall mass _________________
(1)
PEC ________
PEC _______
2
kg/m kW.h/kg W.h/m2 ________________________________________________________________________________ (2) Steel (50% recycled) 5 4.86 24.30 Agglomerated cork 5 1.11 5.55 Ceramic tiles 25 2.22 55.50 Total 35 85.35 ________________________________________________________________________________ (1)
Source: Berge, 2000 (presented values are for Central Europe). Estimated value. It depends on the type of the anchoring system (visible/not-visible and local/spread fixing). (2)
The energy needed to guarantee the users comfort level will be much lower, since, after the refurbishing, the thermal losses and gains through the wall are about 45% of their initial value (Table 3).
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4.4.2 Environmental impacts Table 5 presents the results found in the environmental impact assessment. In Portugal, up till now, local life-cycle inventory (LCI) data about building materials it is not available; therefore the results are based in values studied by Berge (2000) for Central Europe. For Portugal this values should be slightly different.
Table 5. Environmental impacts of the refurbishing solution _____________________________________________________________________________________________________
Environmental impacts ___________________________________________________________________________ Mass ______
(1)
Water _______
(2)
Waste _______
(3)
GWP _______
(4) AP _______
(5) (6) COD _______ POCD _______
Material kg/m2 m3/m2 kg/m2 kg/m2 kg/m2 kg/m2 kg/m2 _____________________________________________________________________________________________________ Steel (50% recycled) 5 17.00 1.50 3.15 0.03 2.11 2.11 Agglomerated cork 5 0.12 0.00 1.39 0.00 0.01 0.01 Ceramic tiles 25 10.00 0.25 14.28 0.10 1.28 1.28 Total 35 27.12 1.75 18.82 0.13 3.40 3.40 _____________________________________________________________________________________________________ (1)
Water = Water used in the production process. Waste = Waste from the production process. (3) GWP = Global Warming Potential in kilograms CO2 equivalents. (4) AP = Acidification Potential in kilograms SO2 equivalents. (5) COD = Chemical Oxygen Depletion in grams NOx. (6) POCP = Photochemical Ozone Creation Potential in kilograms NOx. (2)
4.4.3 Waste production The best way to deal with the residues in construction is, in first place, to avoid them. After, recycling the largest amount of material must be considered. Incineration and deposition in waste deposits should also be avoided. This building/refurbishing technology is characterized by a great industrialization of the building process, being most of its elements prefabricated. The controlled production process results in the reduction of residues. The elements are produced with the exact dimensions needed to carry out their functions, not giving place to wastes. Another major source of residues in construction takes place in the demolition/dismantling phase. In this solution the building materials/elements are punctually joined, being easy to separate during dismantling. On the other hand the biggest amount of materials can be easily reused or recycled, for instance, the steel profiles can be easily reused in another building or 100% recycled. 5 CONCLUSIONS There are few examples of technical solutions that are being adopted in Portugal to improve the quality of the multi-story buildings envelopes. Two examples are the external thermal insulation composite systems (ETICS) and the ventilated façade. This paper presented the potentialities and limitations of the ventilated façade as a refurbishing solution to upgrade the functionality of the conventional buildings façades. This study showed that this technical solution is suitable to improve several different functional aspects of the façade, e.g. thermal and noise insulation and moisture protection (from rainwater and condensations). The main limitation of this solution, compared for instance to the ETICS, is the higher construction cost. This limitation can be compensated with the higher durability and lower maintenance costs of this solution. Besides the functional and economic performance, the environmental performance of this technical solution was assessed in order to study its impacts in the different dimensions of the Sustainable Development.
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Analysing the data presented in this paper, comparing it with the data of other technical solutions, and weighting the different dimensions according to local constrains and objectives of the project, it is possible to evaluate the sustainability of the ventilated façade as a solution to improve the conventional façades. As a next step, it is necessary to make experimental evaluations to buildings submitted to this refurbishment solution, and surveys to its inhabitants, in order to evaluate the real impact and performances of this technical solution. 6 REFERENCES APICER1 (1998). Manual de Alvenaria de Tijolo, Associação Portuguesa da Indústria de Cerâmica, Coimbra. APICER2 (1998). Manual de Aplicação de Telhas Cerâmicas, Associação Portuguesa da Indústria de Cerâmica, Coimbra. APICER (2003). Manual de Aplicação de Revestimentos Cerâmicos, Associação Portuguesa da Indústria de Cerâmica, Coimbra. Berge, Bjorn (2000). Ecology of Building Materials, Architectural Press, Oxford – translated from the original “Bygnings materialenes okologi”, Universitetsforlaget, Norwege. Chown, G. A. et al (1997). Evolution of Wall Design for Controlling Rain Penetration, Construction Technology Update No. 9, IRC – Institute for Research in Construction. Quirouette, R.L. (1982). A Study of the Construction Process, Division of Building Research, National Research Council of Canada, Building Practice Note 32. Mateus, Ricardo (2004). Novas Tecnologias Com Vista à Sustentabilidade da Construção. MSc Thesis in Civil Engineering, University of Minho, Engineering School, Guimarães. Meisser, Mathias (1973). Acústica de los Edifícios. Editores Técnicos Associados, S.A., Barcelona translatated from the original “La Pratique de L’Acoustic dans les Batiments”, S.D.T.B.T.P., Paris. MCA (2003). Exterior Curtain Wall /floor intersection. MCA – Metal Construction Association (USA), March. http://www.metalconstruction.org/, online in 2005/04/27. Soriano, A.L.R. de (1999). Aplacados Pétreos en Fachadas Ventiladas, Collegi d’Arquitectes de Catalunya. http://coac.net, online in 2000/12/
Technical Improvement of Housing Envelopes in Slovenia M. Sijanec Zavrl Building and Civil Engineering Institute ZRMK, Slovenia
J. Selih University of Ljubljana, Faculty for Civil Engineering and Geodesy, Slovenia
R. Zarnic University of Ljubljana, Faculty for Civil Engineering and Geodesy, Slovenia
ABSTRACT: In Slovenia typical residential buildings from 1946 to 1980 have either masonry or reinforcement concrete structure. The envelopes built before 70-ties are without thermal insulation with double glazed box windows; but in 70-ties early thermal insulation materials were introduced. Nowadays, these buildings offer significant energy saving potential and often need repair because of inadequate maintenance. Since Slovenia is an earthquake prone zone interventions in envelopes in many cases comprise also additional strengthening. Recently, national regulation (2002) imposed some obligatory measures at envelope refurbishment, which are supported by subsidies for energy efficiency. Different technical solutions for envelope insulation improvement are common in Slovenia, but most frequently the external thermal insulation system with thin layer plaster is used, accompanied with multi-chamber PVC windows with low-e double glazing. In this paper the impacts of technical solutions in standard envelopes are discussed from technical, functional, social, economical and environmental aspects. The refurbishment case study reflects the contemporary approach to refurbishment.
1 INTRODUCTION 1.1 Standard envelops in Slovenia According to statistical data obtained from Census of 2002, roughly 18% of dwellings in urban settlements were built before year 1945, 61% in years 1946 to 1980 and 21% in years 1981 to 2000. Approx. 63% of dwellings constructed in 1945 to 1980 period are located in multidwelling buildings. Approximately 25% of all energy in Slovenia is used in the buildings’ sector. Residential buildings in Slovenia built before 1980 are considerable energy consumers because of the poor thermal insulation of the building envelope and therefore offer immense energy saving potential. The technical energy saving potential in 1945-1980 residential buildings is estimated to 60%, economically viable energy saving potential is 29% (payback bellow 10 years), whilst the socially available energy saving potential does nor exceed 10%-15%, (depending on the incentives). Buildings from early post war period were built without of thermal insulation. The situation was slightly improved after 1967 when new regulations defining minimum requirements of thermal insulating performance of the building envelope came into force. The performance requirements became harsher in 1970 (outer wall U value 1.2 W/m2K) which had a positive effect upon the thermal insulation installed in the envelopes of the buildings erected after that year. The first serious thermal insulation regulation (outer wall U value 0,8 W/m2K) was put in force in 1980.
COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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Figure 1. Present situation in outer walls U (former k) value (W/m2K) in Slovenian residential buildings stock, concerning buildingsc erection period.
The data about the actual building envelope insulation level were collected by a pole in a relevant statistic sample of apartment buildings, as given more in detail in WG1 report. It can be observed that in 60% of the 1945-1980 existing buildings outer wall U value exceeds 1.0 W/m2K. Following the construction period of the buildings one can observe (Figure 1) that poorly insulated buildings ratio has not been considerably reduced until 1980, when implementation of rigorous building insulation regulations increased the number of buildings with lower outer wall U value. Hence, nearly one third of the buildings from 80-ties still have U value higher than 1.0 W/m2K.
Full clay brick – 29 – 68 cm U = 1.9 – 0.9 W/m2K Hollow clay brick 29 – 55 cm, plaster U = 1.5 – 0.9 W/m2K
Concrete hollow brick, plaster, 19 – 29 cm U = 2.1 – 1.6 W/m2K
Slag -concrete hollow brick, plaster 25 – 29 cm U = 1.54 – 1.39 W/m2K
Fly-ash concrete hollow brick, plaster, 29 cm U = 1.43 W/m2K
Foam concrete brick, plaster, 17.5 – 30 cm U = 1.39 – 0.93 W/m2K
Figure 2. The typical envelope structures of 1945-1970 envelopes (Sijanec Zavrl, 2005).
Clay hollow brick19 – 29 cm, 3 cm insulation, plaster, U = 0.7 W/m2K
Clay hollow brick 19cm, insulation 3cm, plaster, U = 0,7 W/m2K
Conrete 20cm, cell conrete 10cm, plaster U = 1.2 W/m2K
Light mineral wool prefabricated panels 15 cm , PE foil, gypsum plate U = 0.26 W/m2K
Figure 3. The typical envelope structures of 1970-1980 envelopes (Sijanec Zavrl, 2005).
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The structure and envelope systems in Slovenia are influenced by geographic location, availability of local materials and Central European cultural environment. Geographically, Slovenia is located in earthquake prone area where the moderate to strong earthquakes can be expected every hundred years. Building external walls (i.e. envelope walls) were in earlier period constructed either of clay brick masonry or cast-in-place concrete. In later period prefabricated systems were introduced applying the elements pre-cast by normal or lightweight concrete. In earlier period internal walls were constructed in clay brick masonry mostly as non-load bearing partition walls with some load bearing ones. The timber structures were used mostly for non-residential buildings with some exceptions in Alpine regions of Slovenia. However, timber was until sixties of last century also used for floor constructions in masonry buildings. 1.2 Requirements in Slovenia that enforce a reaction to refurbish envelopes When accessing to EU Slovenia had to harmonize the national legislation with the European one. The Construction Products Law has already been accepted based on CPD Directive (89/106/EEC) in 2000. The Building Law has been changed and promulgated in Jan. 2003. The new technical regulation on thermal insulation and energy efficiency of buildings based on EN 832 calculation method was promulgated in May 2002. It also implies some requirements for windows and glazing to be implemented in case of refurbishment of existing buildings. The current technical regulation related to energy efficiency in buildings (2002) complies with the provisions of the EU Directive CPD and EU Directive SAVE (93/76/EEC). It sets the requirements on the level 4 (from ID 6 of CPD Directive), i.e. the heat demand for space heating is the key criteria. According to the regulation the form called “Summary of thermal characteristics of building” became an obligatory part of the planning documentation and it is thus precursor of energy certificates. In order to fulfill the 2002 requirements and thus to achieve 30% savings compared to old (1980) regulation there was a great need for education of planners and awareness raising of investors and users, and a good opportunity for wider implementation of technologies and approaches for increased energy efficiency in buildings. According to the SAVE Directive for reduction of CO2 emissions by increased energy efficiency in building sector Slovenia supported the implementation of energy auditing scheme, heat metering and billing in apartment buildings, performance contracting, and also preparation of more severe regulation on energy use in buildings as well as development of energy certification of new buildings. During the past ten years these programmes have noticeably influenced the building market, so that nowadays energy efficient (EE) building is treated as a priority and quite often a »must« on the real-estate market. This was a contribution of the 90-ties to the Kyoto target in Slovenia, which was set at 8% reduction of CO2 emissions.
Figure 4. Degree-days (20/12) for Slovenia.
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More recently, Slovenia started with a phased transposition of the EPBD Directive (91/2002/EC). In the end of 2005 the first draft of the regulation for energy efficiency of buildings was prepared (adoption planned for Dec. 06), including (a) a methodology for calculation of integrated energy performance of buildings, (b) more severe minimum requirements for new buildings and (c) minimum requirements for buildings that are subject of major renovation. In average 30% less heat demand is expected after adoption of 2006 regulation (also due to anticipated Uwall = 0,3 W/m2K, compared to Uwall = 0,6 W/m2K in 2002), depending on the climate (2400 DD in Mediterranean climate, 3300 DD in continental climate and up to 4000 DD in Alpine climate, thermostat set temperature 20 oC, base 12 oC). The regular inspection of boilers has partly already been established in Slovenia on the basis of Environmental protection act, through the existing chimney-sweeping organisations. Due to the lack of qualified experts Slovenia will ask for a prolongation for (a) energy certification of buildings and (b) for regular inspection of air conditioning systems. Energy certification will be implemented in Jan. 2008 for new buildings and for large public buildings, in Jan. 2009 for existing buildings when sold and/or rented out. 2 SPECIFICATIONS OF THE TECHNICAL SOLUTION The most common refurbishment actions are described in the Figures 5 and 6 (see existing envelope structures in Fig. 2 and 3); two scenarios are presented: “standard” refurbishment level and “advanced” insulation level scenario. External Thermal Insulation Composite Systems (ETICS) is the most frequently used refurbishment system, in early 90-ties expanded polystyrene was most commonly used (contact thin-layer facades - DEMIT system, DEMIT PLUS, JUBIZOL), later the mineral wool insulation gained the popularity, most recently the mineral wool insulation elements with fibres perpendicular on the wall surface are implemented, due to better physical characteristics and easily increased thickness of the insulation. The above measure is normally accompanied by replacement of existing double glazed windows by multi-chamber PVC low-e double glazed, argon filled (Ugl = 1,1 W/m2K), low air permeability windows. Especially in the apartment building sector existing windows also lack in regular maintenance. Insufficient air-tightness and poor thermal properties of glazing result in a high heating energy demand and low level of thermal comfort in such buildings. Double-glazing is most commonly used in existent windows. Typically, older buildings are equipped with double or coupled windows while for the last two or three decades single frame windows are being built in. In old buildings the so-called double insulating glazing (Ugl = 2,9 W/m2K) is used in single windows. Its advantage is that the condensation on the inner glass panes is prevented, but the thermal characteristics remain the same or even worse compared to double-glazed coupled and double windows.
Full clay brick – 29cm Existing U = 1.9 W/m2K a) add 5cm thermal insulation, U = 0,55 W/m2K b1) add 10cm thermal insulation, U = 0,33 W/m2K b2) add 14 cm thermal insulation, U = 0,24 W/m2K
Hollow clay brick, plaster, 19 – 29 cm U = 2.1 – 1.6 W/m2K a) add 5cm thermal insulation, U = 0,55 W/m2K b1) add 10cm thermal insulation, U = 0,33 W/m2K b2) add 14 cm thermal insulation, U = 0,24W/m2K
Timber floor construction a) add 15cm thermal insulation, U = 0,33 W/m2K b) add 20cm thermal insulation, U = 0,20 W/m2K
Clay hollow (“monta”) floor structure with concrete structural layer a) add 15cm thermal insulation, U = 0,33 W/m2K b) add 20cm thermal insulation, U = 0,20 W/m2K
Figure 5 The typical refurbishment measures for envelope structures of 1945-1970 envelopes (Sijanec Zavrl, 2005).
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Clay hollow brick19 – 29 cm, 3 cm insulation, plaster, Existing U = 0.7 W/m2K a) Add 2cm ext.TI U = 0.56 W/m2K b) Add 10cm ext.TI U = 0.24 W/m2K
ETICS
Clay hollow brick 19cm, insulation 3cm, plaster, U = 0,7 W/m2K
Conrete 20cm, cell conrete 10cm, plaster U = 1.2 W/m2K
a) Add 2cm ext.TI U = 0.56 W/m2K b) Add 10cm ext.TI U = 0.24 W/m2K
a) Add 5cm ext.TI U = 0.56 W/m2K b) Add 14cm ext.TI U = 0.24 W/m2K
ETICS
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Light mineral wool prefabricated panels 15 cm , PE foil, gypsum plate U = 0.26 W/m2K a) Add 5cm int.TI U = 0.19 W/m2K b) Add 10cm int.TI U = 0.15 W/m2K
Figure 6. The typical refurbishment measures for envelope structures of 1970-1980 envelopes (Sijanec Zavrl, 2005).
Figure 7. The typical refurbishment measures for envelope structures of 1970-1980 envelopes - External contact thermal insulation system, windows - PVC frames, 2-glazed, low-e, Ar.
3 THE IMPACT OF THE REFURBISHMENT ACTION ON SUSTAINABILITY TOPICS 3.1 Technical performance 3.1.1 Stability, capacity, (earthquake) In traditionally used polystyrene thermal insulation systems stability and capacity are not very relevant issues, since in the majority of cases the insulation system is installed on the load bearing envelope. The building envelope plays a major role in providing the load-bearing capacity and stability of a building, as well as its earthquake resistance. If the strengthening is needed due to the insufficient earthquake resistance, the partial replacement of weak lime mortar with stronger cement mortar, and the application of reinforced concrete coating to entire outer surface of masonry envelope is done before the protection of envelope with thermal insulation and render.
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3.1.2 Fire protection Building structures insulated with rock wool provide better fire safety comparing to more often implemented expanded polystyrene insulation systems, i.e. in a case of fire, flames do not easily propagate to neighbouring rooms, or even more important, to higher storeys of apartment blocks. Thus the residents have more time to safely evacuate the building and the fire fighters more time to effectively extinguish the fire, while the impacts of fire are less severe. 3.1.3 Noise protection The prevention of the noise coming from the outdoors is rather achieved by high quality windows (glass layers of different thickness, SF6 in-fill gas, good air-tightness) than by ETICS itself. 3.1.4 Moisture protection ETICS with their silicate, acrylic and/or silicon plaster layer successfully repel the rainwater and keep the thermal insulation material in good condition with unchanged thermal conductivity. In the early years ETICS systems suffered from bio deterioration and mould growth on the weather exposed, mostly north oriented surfaces. The additives in the final layer of render reduced this problem. ETICS if proper designed and installed offer good moisture protection in case of diffusion of water vapour. In recent common practice the ETICS as a whole is considered as a building product. The contractors have the licence for the execution of certain ETICS system, so the risk of combining the incompatible materials has been significantly reduced. In refurbishment with ETICS the prevention of thermal bridges and consequently surface condensation with mould growth (balcony plates, window shelves) has to be planned in advance.
Figure 8: When ETICS are implemented thermal bridges should be analysed and prevented.
3.1.5 Conductivity, heat flow In refurbishment ETICS with 8-12 cm of polystyrene and/or mineral wool insulation is used. Taking into account the slightly increased thermal conductivity of the insulation material in real conditions (comparing to declared and design values) the U value of the refurbished walls remains in the range of 0,35 – 0,5 W/m2K. ETICS offer substantial reduction of heat flow (caused by solar radiation) through the opaque part of the building envelope. The intensive time-lag and the reduction of the amplitude is the result of the massive load bearing layer and light insulation layer, respectively. It is very important that the insulation layer in this system is continuous. Therefore the thermal bridges in the structural elements areas have to be avoided by detailed design.
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3.1.6 Durability Refurbishment with ETICS and energy efficient windows may occur 1 - 2 times in a theoretically planned service life of a building. According to the Slovenian regulation about maintenance of residential buildings from 2004, the service life of the ETICS is 25 years and the service life of PVC framed windows is 20 years. Early ETICS systems often suffer from mould growth on north oriented facades. If proper installed and maintained the durability is not a problem. 3.2 Functional/social performance 3.2.1 Flexibility ETICS as well as PVC windows exhibit great flexibility and can this be implemented in also in more complexes architectural envelopes. 3.2.2 Comfort (thermal, acoustical, visual) Due to many options for the structure and colour of the top plaster layer there are extensive design choices available. Refurbishment with ETICS significantly improves thermal comfort, while the implementation of new energy efficient PVC windows contributes to better acoustical comfort. The impact of above refurbishment actions has no major impact in visual comfort. 3.2.3 Health Mould & fungus growth may only occur due to the mistake in design and execution of works (thermal bridges) and due to improper use of the flat (high relative humidity, insufficient ventilation rate). In normal use there are no harmful emissions form ETICS and PVC windows, but in case of fire polystyrene gives off CO and CO2 as well as smoke and water; when burning PVC releases toxins such as dioxins, furans and hydrogen chloride, as well as CO and black dense smoke. 3.2.4 Other – quality labeling In mid 90-ties “National quality mark in Civil Engineering” was developed for building products and services, and used for voluntary quality certification of energy efficient windows since 1997. ”National quality mark in Civil Engineering” for windows is awarded to energy efficient windows, produced by companies that concern about the environmentally friendly production and quality of their service. The evaluation scheme covers different criteria pondered according to their relevance to Slovenian situation. The evaluated criteria are: measurable technical criteria (U values, air-permeability, water tightness, mechanic characteristics), not measurable technical criteria (convenience of technical solution, functionality of the product) environmental criteria, efficiency and quality of production processes, satisfaction of buyers, fulfilment of the company’s business plan, global impact on the society and environment. The windows proved with quality mark were automatically accepted for subsidising under the national grant subsidy scheme. The payback of the incremental investment in energy efficiency (i.e. pay back of insulation required for the improvement of U value, excluding works needed due to the restoration) is 4-8 years.
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Figure 9. “National quality mark in Civil Engineering” was introduced in 1997 for labelling of energy efficient windows in Slovenia.
3.3 Economical performance 3.3.1 Building costs The buildings costs of ETICS depend mainly on the quality and the thickness of the covering plaster. The insulation material itself represents between 10%-20% of the total investment costs of the insulation. The average price for ETICS (contact polystyrene thin covering layer system installed in a multi storey building) is between 30 and 40 EUR per m2 of the insulated envelope. The payback depends on various factors: energy price (0,05-0,1 EUR/kWh), U value before the refurbishment, physical condition of the envelope before the refurbishment, level of the thermal comfort before and after the works done. Normally the pay back time for ETICS is 12-20 years. The average price of PVC framed windows is 20-25 EUR/ m2. Correspondingly, the pay back time of the entire investment in exchange of windows is 10-15 years. But since the aesthetic and functional reasons are as much important as energy efficiency, the pay back time may not be the most relevant indicator for such a refurbishment measure. On the other hand, the pay back of the incremental investment in low-e coating and Ar filling does not exceed 2 years! 3.3.2 Running costs The running costs are reduced by 20-30% due to ETICS, and by 20% due to the installation of energy efficient windows (less heat losses, less uncontrolled ventilation due to low airpermeability of new window frames) 3.4 Economical performance 3.4.1 Use of resources Polystyrene as well as PVC for window frames are produced of non-renewable sources (crude oil). (Alternative to polystyrene the mineral wool can be used in ETICS, made of non-renewable source but will less hazardous production process.) 3.4.2 Energy consumption For the production of polystyrene and PVC the non renewable energy is used. Although the energy for the production of polystyrene is high in average 600 kWh/m3 (200 kWh/m3 for PVC), this is compensated by good insulation properties (when insulation is properly used, PB of production energy is less than 2 years).
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3.4.3 Environmental impacts The restoration of existing buildings using ETICS and new PVC windows my significantly contribute to Kyoto goals (8% reduction of CO2 per base year 1986 was accepted as Kyoto target in Slovenia. The CO2 saving potential due to envelope measures in 1945-1980 apartment buildings was estimated to 58.000 t CO2. The estimated cost of CO2 reduction due to envelope improvement is 0,08 EUR/kg CO2. 3.4.4 Environmental impacts Recycling and re-use of polystyrene insulation is limited due to difficult separation of layers in ETICS. Also the PVC recycling opportunities are limited as recycled PVC can only be used for low grade products. Beside the technological there is also and economically barrier for recycling of polystyrene and PVC. 4 CASE STUDY 4.1 General information The case study is related to energy refurbishment of an apartment building on Sisenska 42-44 in Ljubljana, built in 1960. The building consists of 40 apartments with totally 95 residents. The heated floor area of the building is 1.860 m2. The total area of the building envelope in contact with the outer environment is 1.191 m2 (including opaque and transparent parts of the envelope). The area of the windows is 189 m2. The existing envelope structure consists of prefabricated concrete plates (total thickness 16 cm) with a core of concrete mixed with wooden chips (“betocel”) in thickness of 8 cm as a moderate thermal insulation. This project was one of the apartment buildings refurbishment projects co-financed by the Ministry of environment and physical planning in the framework of state subsidies for energy efficient renovation of buildings (built before 1980) with minimum expected energy savings of 10.000 kWh (i.e. calculated reduction of heat demand, equivalent to 1000 l of oil). The ministry allocated 0,3 mio EUR in 2004 and 0,42 mio EUR in 2005 for subsidies for apartment buildings. The maximum subsidy per project is limited to 21.000 EUR and 10% of the investment, respectively. 4.2 Technical data The building block has got reinforced concrete bearing structure. The architectural form of a building with a ground floor and 4 storeys is very frequent in post war building stock. 4.2.1 Problems Two main problems of the building were identified: insufficient thermal protection and dilapidated façade. The building was designed and built in the period when there was no regulation and no requirements regarding the thermal insulation and energy efficiency in buildings. The building codes related to brick structures resulted in U values of approx. 1,3 W/m2K for outer wall and the window technology normally applied in that time (double glazed cast windows) resulted in U values of approx. 2,7 W/m2K with normally high air leakage.
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4.2.2 Strategy for improvement An examination of energy efficiency of the building was carried out. The examination revealed that potential energy savings due to the building envelope improvements could be as high 40%. The recommended measures were the following: thermal insulation of the outer walls and replacement of existing windows with energy efficient windows, according to the requirements for new buildings, set in the Regulation for thermal insulation and energy efficiency of
buildings from 2002. 4.2.3 Actions The following restoration measures were done: Outer wall: thermal insulation of outer wall with 8 cm thick polystyrene layer. Windows: installation of energy efficient windows with low-e double glazing (Uglazing=1,1 W/m2K with six chambers PVC window frames, where the U value for the entire window is
1,1 W/m2K.
Figure 10. Non-renovated apartment house Sisenska 42-44 in Ljubljana. IR thermography detected cold bridges in the envelope: (joints of concrete panels).
FLIR System s
6.5 °C 6
4
Sp1 2
0 -1.5
Figure 11. The envelope of refurbished building with IR thermography showing the improved thermal insulation after the implementation of ETICS.
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4.3 Performance The presented case study demonstrated the performance as follows: After the refurbishment the U value of the outer wall was Uwall_new=0,35 W/m2K (before Uwall_old=1,3 W/m2K). After the refurbishment the U value of the windows was Uwall_new=1,1 W/m2K (before Uwall_old=2,7 W/m2K). Improved external paint layer increased weather and moisture protection; however, no quantitative assessment was carried out.. New paint layer offers better resistance to atmospheric influences. Prolonged service life can be expected in duration of 20 years (expected service life of the new envelope). Better thermal insulation of the building envelope resulted in the increased level of thermal comfort due to higher surface temperature of the inner wall temperature. New PVC multi-chamber framed windows and low-e , sound protective glazing (double glazing with different thickness of glass layers) ensured an improved acoustic comfort. No quantitative data were available. Energy efficiency project investment costs: The cost of the total renovation was 23,600.000 SIT (100.000 EUR). Windows’ cost 7,500.000 SIT (31.300 EUR), and wall insulation cost is 16,100.000 SIT (67.100 EUR) (65% of the total cost). Energy savings per year (heat consumption decrease) are 125.520 kWh, expected money savings 7000 EUR/year (district heating). Simple pay back of total investment is 14 years. Simple pay back of incremental investment in energy efficiency is 3-4 years. 5 CONCLUSIONS The refurbishment of building envelopes has become one of the most important tasks in maintenance of buildings from 1945-1980 period. The paper presented various envelope refurbishment approaches and described the performance of the most frequently used technology for building refurbishment in Slovenia. External thermal insulation composite system (ETICS) either with polystyrene or with mineral wool thermal insulation in thickness between 8 cm and 10 cm has become a general practice in building refurbishment. Low-e, argon filled glazing has been a prevailing technology in replacement windows since mid 90-ties, and it also became obligatory since 2002. Recent regulation on energy efficient buildings already imposed the requirements for building refurbishment, mainly in case of replacement of windows and renovation of the opaque envelope elements. The EPBD regulation (expected in Dec. 2006) will prescribe even more severe targets for major renovation. For further uptake of insulation systems technologies as well as replacement of windows in existing buildings refurbishment the technical, social and economic performance is important. This study showed that ETICS can demonstrate good balance between technical and environmental performance. The durability of thin layer plaster ETICS may not be as high as in case of ventilated insulation system, but this limitation can be compensated with far lower investment costs. IR thermography of refurbishment with ETICS showed the need for careful approach in prevention of thermal bridges, that can lead to surface condensation problems. To overcome the general financial barriers for renovation of building envelopes for major renovation the state subsidies are available, if the energy efficiency targets are met.
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6 REFERENCES Sijanec-Zavrl, M., 1996. Expectations and reality in attaining energy saving potential in Slovene residential building stock. Goetzberger, A. and Luther, J. (edt.). EuroSun'96, Freiburg, Germany, 1996. EuroSun'96:proceedings. München, DGS-Sonnenenergie, str. 1131-1135. Sijanec Zavrl, M. 2002, Approach to energy conscious retrofit of Slovenian building stock, p. 95-101, Proceedings of Workshops Newly Associated States EnerBuild RTD, Ed.: A.Zold, M.Lain, S.Petruszko. Sijanec Zavrl, M. et al., 2005, Control of energy costs in the apartment buildings of Housing fund of Ljubljana, Final report of research project, BCEI ZRMK. Soerensen, C., 1997. Waermedaemstoffe im Vergleich, Umveltinstitut Muenchen, Germany. Zarnic, R. & Sijanec Zavrl, M. & Selih, J., 2003. Envelopes of multi-store residential buildings in Slovenia, COST C16 workshop, Delft. Wolley, T. et al., 1997, Green Building Handbook, E & FN Spon. Sijanec Zavrl, M., 2003. Thermal insulation energy and efficiency of multi-storey residential building envelopes in Slovenia, COST C16 Workshop, Delft Žarniü, R., 2001. Building regulations for rehabilitation works and their application in Slovenia. In Carlo Blasi & Luca Giorgi (ed.). The application of existing building regulations in rehabilitation works: proceedings of the workshop, Florence, 2 and 3 December 1994. Luxembourg: Office for Official Publications of the EC, p. 63-76.
Technical Improvement of Housing Envelopes in the Netherlands Christoph Maria Ravesloot Delft University of Technology, Faculty of Civil Engineering and Geosciences Delft, the Netherlands
ABSTRACT: Renovation of high rise apartment buildings in The Netherlands has just been executed, is at hand now or is planned for the nearby future. Typical problems are lack of thermal comfort, loss of functionality of the floor plan and social deterioration of the neighborhood. Changes of the dwellings in the housing complexes should include energy saving, alteration of the floor plan functionality in more differentiated housing types and upgrade of socio-economic services in the immediate neighborhood of the high rise housing complexes. The technical improvements are not that difficult to make, considering that the standard in comfort, energy saving and functionality of the floor plan for newly build houses has been proved being technical and economical feasible. The problem is the organizing of the existing inhabitants, with their small budgets and many differentiated expectations. Financing the insecurities of this kind of logistical processes is forming the bottle-neck. In this paper the existing standard in functionality of dwellings in relation to comfort and energy saving will be addressed. In comparison with this standard the technical problems of high rise building stock will be addressed. Next the paper will shortly address the socio-economical problems concerning the organization of large scale renovation of high rise complexes in The Netherlands. Two exemplary case studies in the Amsterdam South-East Quarter and in the Delft Quarter of the Poptahof will be elaborated to illustrate the practical meaning of improvement of comfort and energy saving in high rise building stock in The Netherlands.
1 INTRODUCTION 1.1 Standard envelopes in The Netherlands In The Netherlands there are approximately 6.600.000 houses. 30 Percent of these houses are apartment flats. Almost 200.000 of the dwellings are situated on the fifth floor or higher. Most of the houses are from the sixties and seventies of the twentieth century. Post-war housing sector in The Netherlands accounts for a big energy loss, mostly because of a poor technical performance of the building envelope. Most of high rise building in The Netherlands was built before the building code included norms considering thermal comfort, functionality of the floor plan and energy saving. Therefore high rise building technology in The Netherlands can be characterized by the following aspects: The construction is mostly of reinforced concrete beams and pillars system, of concrete tunnelling techniques and of some kind of prefabricated elements; The external walls generally consist of brickwork, with or without cavity, or prefabricated concrete panels without thermal insulation. Internal finishing mostly is plaster; The windows are of wood and sometimes of steel or plastic containing single or double glazed window panes; The roofs of most high rise apartment buildings are flat. The construction is comparable to the main construction of the different storey floors. Flat roofs are usually finished with bitumen covering of some kind. Sometimes roofing materials like PVC, EPDM or some other
COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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polyolefin-based product is used. Sometimes the roofing is protected and fixated by some gravel. Even the use of green covered layer is used. The main problem of Dutch building envelopes is the lack of thermal and acoustic insulation and the inferior quality of the windows and the fact that double glazing will not fit in the existing window frames. The combination of low income of the inhabitants and their habits of insufficient ventilation cause indoor air problems and unhealthy indoor climate. An organizational problem is also that the maintenance of the windows is part of the duties of the inhabitants when the inside is concerned. The outside is the responsibility of the owner of the complex. Since many high rise buildings also have balconies along side the façade, the design of a second elevation outside the balconies will change the outside single glazing windows into inside walls of so called glass houses. This changes the responsibility of the maintenance but also changes the thermal comfort of the dwelling drastically. More than 20 % of the Dutch building stock consists of multi-family housing, most of them as high rise apartment buildings. These buildings represent a part of 1.3 million tons of a total of 7 million tons of CO2 reduction potential in the housing sector (Ecofys 2005). 1.2 Requirements in The Netherlands The Dutch climate is characterized by moderately wet winters and moderately warm summers. This is called a sea climate. The influence of this climate on the energy performance of buildings is especially working out in winter, from October to May, the heating season. Due to climate change however, the winters are warmer and the summers can get hot for longer periods of time than it used to be. During winter and summer the amount of rain during one downpour of rain has also drastically increased. This leads to three measures to be taken in renovation of apartment buildings (Apon et.al. 2005): Improvement of thermal insulation in heating season; Reduction of summer overheating; Protection from excessive rainfall, moisture and condensation phenomenon. Most of the existing envelopes in high rise building do have too little insulation to guarantee comfort and low energy bills. Generally u value exceeds 1.0 W/m2K. Windows are seldom double layer. Due to the high wind velocity at the higher stocks, inhabitants keep their ventilation openings closed during winter. This leads to high indoor air humidity and because of that to the contamination of the indoor air with toxic gases and pollution. The Dutch building code for existing apartment blocks represents not a very high standard. The minimal requirements are only 1,0 W/m2K for thermal insulation. In practice no requirements for glazing have to be considered, since the replacement does not require approval or inspection of authorities. From the first of January 2007 a Dutch legislation for the existing building stock is extended by the introduction of the Energy Performance of Buildings Directive (EPBD). The formal introduction was introduced last 6 years by the offer by authorities to make an Energy Performance Calculation and Advise on a voluntary basis. According to Sunnika the Dutch situation is only partly complying to the articles 3-10 of the EPBD (Sunnika 2006). In surveys with projectmanagers in renovation projects it was found that during the nineties of the twentieth century, seldom energy saving measures were taken (van der Waals et.al. 2000; Elgersma 2001). According to European research regarding the introduction of the EPB directive for existing building stock, the u-values in the moderate climate zones, like in The Netherlands, have to be raised. The u value of the roof has to become 0.23 W/m2K, the building envelope 0.38 W/m2K,, the ground floor 0.41 W/m2K and the windows minimal 1.68 W/m2K (Petersdorff P., et.al. 2004).
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2 SPECIFICATION OF THE TECHNICAL SOLUTION The most used solutions for the refurbishment of façades in The Netherlands are: the External Thermal Insulation Composite Systems (Etics), the filling of ventilated cavity walls with insulation and the replacement of existing windows by high - performing glazing. However, considering the roof also as an elevation, the insulation of roofs as the most commonly executed technical solution. 2.1 Etics One of the advantages of renovating masonry building envelops is that the deteriorated finishing, for instance because of the wearing out of the cement, does not have to be treated. New outside insulation will cover these problems. It saves a lot of money. Masonry walls have to be cleaned and newly fixed once every 30 tot 40 years. Many masonry walls in Dutch apartment buildings can use an overhaul these years. By using Etics as finishing, the wall will extend the life time for at least one or two decades. I minor problem is that the Dutch architecture often is characterized by masonry techniques. Sometimes you just do not want to change the architectural image of a building by covering masonry with Etics. However, in high rise apartment buildings, this mostly only accounts for the heads of the building, since most of the building envelop consists of glass and panels of some kind.
Figure 1 and 2: The elements of two typical Dutch Etics wall after adding insulation during renovation. The left one can also be constructed by demolishing one of the two cavity masonry walls. 0 Finishing with plaster and tapestry (inside) 0 Finishing with plaster and tapestry (inside) 1 Existing wall 100 mm masonry 1 Existing wall 100 mm masonry 2 Old finishing layer 2 Cavity 3 Anchorage to the existing wall, with 100 mm insulation 3 Anchorage to the existing wall 4 Cladding, new Etics wall 4 Existing outside masonry wall 5 Finishing with some kind of mineral or polymer plaster 5 New insulation 100 mm 6 Cladding, new Etics wall 6 Arbitrary top layer of moisture regulating (open) Arbitrary top layer of moisture regulating and rain resistant chemical or mineral finishing
2.2 Cavity Walls Many outside walls in The Netherlands are cavity walls with two walls of masonry. The cavity used to be only 25- 40 mm, just wide enough to keep a slow ventilation air going. This air provides ventilation to dry the inner and outer walls adjacent to the cavity. The easiest method to insulate these kinds of walls during renovation is to fill the cavity with some kind of insulation material. However, the transportation of humidity out of the masonry must be kept functioning and rain from outside must be blocked by some kind of coating on the outside wall.
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2.3 High Performance glazing High performance glazing in The Netherlands is almost as cheap as double glazing. The amortization time of high performance glazing is short. In most cases only the technical potential of the window frame can be hindering. Of all measures, substitution of single and double glazing by high performance glazing is most popular. However, if the glazing is put in an environment where the cooling down outside is severe, there can be cases where there is condensation of humidity on the outside of the glazing in the early morning. Normally this will disappear as soon as the outside temperature is rising and the condensate vaporizes. But it can cause some hindrance to people that are used to early rising with a free vista out of the window. 2.4 Roof insulation Roof insulation is, after substitution of glazing, the most common energy saving measure in renovation of Dutch houses. There are two ways of renovating roofs for energy saving purposes: 1 to add insulation under a new roofing or 2 to add insulation on top of old or new roofing. The second is cheaper and easier to execute. When insulation is put under a new roofing layer, mostly a vapor barrier is needed. On top of both alternatives a green roof can be put. The problem with renovating roofs of apartment buildings are especially the height of the roof, the wind impact at those heights, and the fact that there are always many pipes and tubes penetrating the roofing. If penetrations of the roofing can be avoided, the quality will increase significantly and the cost will reduce. More and more flat roofs on Dutch apartments buildings are covered with vegetation. The roofs are protected against erosion of wind, rain, ice and extreme temperatures. This will extend the lifespan and will reduce the negative impact to the environment. Green roofs can also contribute to a lower energy use by air conditioners in case of summer overheating. On the other hand can the city profit from noise reduction, clean air, decrease of extreme rain volumes and reduction of the average air temperature in summers. The typical Dutch solutions in renovating apartment buildings are well known and well documented. There should not be any technical questions left. However, incidentally detailing can be difficult. The costs of renovation normally are lower than the costs of demolition and new building. The obstructing factor is the justification of raise of rents for tenants.
Figure 3: The elements of a typical Dutch roof renovation, on a concrete construction, after adding insulation during renovation. Figure 4 with insulation on top of the roofing. 0 Construction of concrete, wood or steel 0 Construction of concrete, wood or steel 1 Existing roofing, or newly fixed vapor barrier 1 Existing roofing or protection sheet 2 Insulating layer (rock wool, foam glass, polystyrene) 2 New roofing, rubber or bitumen 3 New roofing, rubbers, PVC, ECB bitumen etc 3 New layer (gravel) for fixation 4 Possible new added green roof construction 4 Possible new added green roof construction 5 In case of green roof, some plants and herbs 5 In case of green roof, some plants and herbs
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3 THE IMPACT OF TH E MOST COMMONLY REFURBISHMENT ACTION ON SUSTAINABILITY TOPICS 3.1 Technical Performances 3.1.1 Structural integrity The structural integrity of apartment buildings in The Netherlands is seldom at stake. The buildings were built with reliable concrete techniques and are mostly well maintained during the decades of use. With the existing buildings structure most common changes can be executed easily. The obstructing factors are fire protection and noise insulation. Especially noise reduction via ventilation shafts is a problem that has to be fixed during transformations. 3.1.2 Fire protection All four types of measurement can easily be practiced, according to fire protection standards. The Dutch authorities provide information and quality systems to maintain safe practicing in building renovation. Fire protection demands also have become strict in the last decade. Apartment buildings from the twentieth century seldom have problems in complying with standards. 3.1.3 Noise Insulation In The Netherlands noise from traffic and noise between neighbors is the most commonly heard complaint from inhabitants of apartment buildings. Noise standards have therefore been raised in the last ten years. The apartment buildings that are under renovation now, will possibly not comply with newest standards. The costs for adjusting floor and wall constructions would be too high. The noise travel through the ventilation shafts however can be addresses properly, if treated in relation to the general ventilation problems in these apartments. 3.1.4 Weather and moisture protection Because of the relatively simple construction and detailing of high rise apartment buildings, the weather conditions seldom give large problems in renovation. However, the not insulated areas in the roof, ground floor and building envelop give raise to several moisture problems, due to condensation during winter season and due to bad ventilation habits of the inhabitants. These moisture problems, can, if properly designed and constructed, be solved by putting insulation to the outside construction and by renovating the ventilation system. Extra effort can be put in instructing the inhabitants of the dwellings about ventilation practices and to inform them about causes of moisture problems. 3.1.5 Durability (service life) Most apartment buildings in The Netherlands will be renovated during this decade. Only few will be replaced by new buildings. From the point of view of sustainability reuse and upgrading to contemporary standards of energy use and comfort are preferred. 3.2 Functional/social performances 3.2.1 Flexibility The flexibility of dwellings in high rise apartment buildings is mostly suitable to a few family configurations. Consider that in most Dutch quarters of apartment buildings many single households, young and elderly people, many kinds of family’s, coming from many different cultures inside and outside Europe, are supposed to live. Then it is easy to understand, that the floor plans from the sixties and seventies of the twentieth century will not fit all circumstances. Renovation of the blocks often also leads to more differentiated floor plans, with more flexible inner walls. Flexibility is limited by structural integrity demands and limitations of the available surface (Dorsthorst Durmicevic 2003). The most commonly used design solution is differentiation per level. Elderly people and families with small children are best situated on the lower storey’s. single family and couples can best be situated on the upper floors.
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Figure 5: Influence of air leakage and heat recovery from ventilation air on the energy performance in stairway oriented apartment buildings and in hallway oriented apartment buildings in The Netherlands.
3.2.2 Comfort (thermal, acoustical, visual) A well designed, detailed and installed insulation of apartment buildings can improve the thermal comfort of the dwellings. This accounts for the winter situation as for the summer situation. The superficial temperature of the walls is less extremely cold or warm. Although there are no specific demands for overheating of dwellings, overheating in summer has to be considered as a possible negative side effect of insulating measures. Heat-insulation often also contributes to better acoustical insulation, as long as the air tightness of the building envelop is also properly addressed. Air leakage often also is an acoustical leakage. 3.2.3 Health (air quality, TVOC etc., mould & fungus growth) The question of how healthy the Dutch dwelling is, was recently answered by Hasselaar. He investigated cases of polluted houses and cases of so called not polluted houses and came to some disturbing conclusions (Hasselaar 2006). Especially in the apartment buildings, were many different households with different domestic habits live, ventilation and hygiene are not at peak efficiency. By renovating the apartment buildings, measures can be taken to prevent health problems. Ventilation systems should be easy accessible for periodic maintenance, inhabitants should be cautioned in their responsibilities for a healthy indoor environment. Generally moisture from within the dwelling is the cause for many unhealthy situations in dwellings. Due to the cultural back ground that differs from the average Dutch culture, many inhabitants of low cost high rise apartment buildings have their own way in heating and ventilating the dwelling. Direct effects of bad ventilation regimes are growth micro-organisms like fungus. Indirect effect of bad ventilation and high humidity is the start of chemical reactions with compounds in interior decoration such as carpets and curtains. Chemicals like formaldehyde and mono-ethylene can vaporize into the air. Second important source of unhealthy situations is open gas firing in hot water CV kettles and hot water supplies in the kitchen. The combustion process exhausts CO and CO2 as well as smoke and again humidity. Possible future factors are radiation of all kinds and evaporation of chemical compounds in the houses. Research in this area focuses on cocktails of humidity, chemical compounds and micro-organisms (Hasselaar 2005). 3.2.4 Safety, security Most of the times safety and security is provided with an audio system so the inhabitant can hear the visitor and make a choice to let him enter or not. In most cases of renovation of apartment buildings also a camera system is installed to improve the social security in the buildings. The front door can always be opened by the inhabitant from within his or her apartment. Be-
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cause of the vulnerability of these kinds of apartment buildings to vandalism, special care is given to the entrances of the building. Bright colours, activities at the entrances and some kind of visual control over the entrances are often introduced after with the transformation. 3.2.5 Barrier free, accessibility in use The typical Dutch high rise apartment building with hallway access and a central staircase, is always provided with an elevator. Accessibility however is not always provided due to differences in height between the inside floor and the balcony floor. Even if they would have the same height, a threshold would make access difficult. Putting insulation on top of the outside hallway and pathway, covered by some hard material cover, would make a difference. The importance of adjusting the entrance of an apartment flat towards sufficient accessibility often has a bigger priority than insulation and increase of thermal comfort. 3.2.6 Aesthetical perception Part of the renovation of apartment buildings is the upgrading of social safety in and around a complex of buildings. One of the measures taken is better lighting, better and alternative routing from and to the building and the use of bright colors and smooth finishing on the floors and walls. The aesthetic perception of especially the entrances has been more important during the last years, mainly because of increased social safety. Aesthetical perception of these kind of building can improve very quickly just by breaking the repetition of the same building parts by variations on this theme (Ravesloot 2005). 3.3 Economical Performances The economical performance of apartment buildings is embedded in the social function of providing low rent housing for lower income groups. Transformation to higher levels of comfort and environmental performance must be judged in that perspective. 3.3.1 Building costs The cost of energy saving measures can be calculated very precisely in Dutch building industry. In case of larger contracts for large areas of high rise apartment buildings, the costs can be reduced downward to 30 %.
Table 6: Costs of specific measures in renovation of large areas of high rise apartment complexes (Ecofys 2005). Function and utility of the systems which compose a ventilated elevation (inclusive VAT) Brick or concrete elements with Etics Cavity wall Genuine roof insulation Flat roof insulation Ground floor insulation 21 Double glazing with Argon gas filling Double glazing with Argon gas filling and thermal reflective coating
€/m2 72 13 26 26 98 123
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An average cost for a ventilated cavity wall or massive wall with Etics can range between 100/500 €/m2. The complexity of the details is leading in the estimation of the final costs. The average amortization time for these kind of investments in apartment buildings can be considered to be until five years for less than 39 % of the cases (140 kTon CO2 reduction potential), between five and ten years for approximately 17 % (60 kTon CO2 reduction potential), between 10 and 20 years for approximately 31 % (110 kTon CO2 reduction potential) and only 13 % (50 kTon CO2 reduction potential). From these numbers you can conclude that investments in the Dutch existing building stock of high rise apartment buildings, can be justified (Ecofys 2005). 3.3.2 Running costs (heat losses, cooling, cleaning, inspection, maintenance, etc.) However, most of these apartments are rented for families and households with minimal income. Higher rents can not be afforded, unless compensated by lower energy bills. The running costs for the installations are not always included in amortization calculations. In case of private rent, the owner is responsible for the maintenance of the building and its outer construction. The interior is part of the maintenance responsibilities of the tenant. However, some housing associations deliver maintenance services that keep the installation in top condition, thus compensating the expenses for these services by more energy savings because of the enduring high efficiency of the installation. This counts especially for the ventilation units with or without heat recovery. 3.3.3 Increased rent potential vs .vacancies through building action There are no numbers know of the increased rent potential due to better maintenance and more investments in energy saving. The housing associations normally do not have any problems renting high rise apartments buildings. There is still a shortage for cheap housing in the housing market in The Netherlands. 3.4 Environmental Performances The use of land of high rise apartment buildings is not optimal. The highest density with the most dense population occurs with building blocks of 4 to 5 storey’s high. Because of the compactness of the dwellings and the relatively small outside surface compared tot the floor surface, apartments are quiet energy efficient. By adding insulation to this surrounding building envelop and by installing a new efficient and healthy ventilation unit, environmental performance can be boosted. 3.4.1 Use of resources (non renewable, renewable) The use of energy resources, renewable and non renewable can be balanced into an energy neutral concept. Energy neutral apartment buildings have a very low use of heat and electricity due to extreme saving measures. On the other hand are there solar collectors or heat pumps to produce renewable energy for domestic use in the apartments. Solar cells (PV) can produce electricity also for use in the apartments. According to Apon et.al. apartments in high rise buildings can, if transformed cleverly and according to minimal standards, function properly and comfortable within energy neutral concepts (Apon et.al. 2005). The bottle neck for such an energy neutral concept is formed by the ventilation system, the risk of overheating in summer situations and the possibility to avoid heat leakage in difficult connections in the building envelop. Especially the balconies at both sides of the building can be difficult to insulate. 3.4.2 Energy consumption (non renewable, renewable) - production / assembly - heating / cooling The energy consumption of a high rise apartment building has to be seen in the perspective of the situation that nothing will be changed with the building. The existing situation of bad comfort, even worse energy use and insufficient functionality of the floor plans can be consolidated for a long time. Rents stay low and the social segregation of the neighbourhood will keep get-
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ting worse. If the owner of the buildings and the municipality do want to change this problematic situation, there are basically two choices: 1 Transform the building by renovating; 2 Demolish the building and build a new one. Klunder has made some Life Cycle Analysis (LCA) calculations for these kind of buildings. She concludes that from the perspective of environmental performance the best choice is to transform the buildings towards more energy efficient and comfortable apartment buildings. Consolidating would cost to much energy in the long run, building new apartments would cost too much new materials, while the old ones would have to be wasted (Klunder 2005).
Figure 7: Flows of material, energy and water of consolidation, transformation and new construction (Klunder 2005).
Figure 8: Flows of material per building element in transformation and in new construction for one building (Klunder 2005).
Most important environmental beneficial factors in case of transformation are: 1. The component and the building can serve longer; demolition is avoided for a longer period of time 2. During this time less fossil energy is lost 3. The thermal comfort has improved 3.4.3 Waste and recycling and re-use potential The potential for re-use of high rise apartment buildings is mostly high. This is because of the excellent technical condition of most of the buildings. Furthermore can these buildings be modified in functionality of the floor plan, without compromising the structural integrity (Dorsthorst, Durmisevic 2003). On the other hand is the demolition of such buildings very expensive. Sometimes demolition also is complicated and therefore more expensive because of the use of asbestos in the building. As long as it is untouched, there are no costs for re-using the building. The recycling of demolition waste, in case high rise apartment flats have to be demolished anyway, is technically very well possible. On the lowest level of aggregation, which is in form of gravel, iron and glass, the reuse in The Netherlands has been organized very well. By law it is regulated that all demolition waste has to be reused, mostly for roads and concrete construction works.
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4 CASE STUDIES The technical improvements mentioned above are elaborated in two case studies. The Dutch quarters of Bijlmermeer in Amsterdam and Poptahof are both exemplary for the genuine Dutch context of technical improvement in housing. Both cases have been researched and archived thoroughly. Many cases of technical improvement in Dutch high rise apartment buildings are similar to these cases. 4.1 Residential High Rise Building in Bijlmermeer, Amsterdam South-East The Amsterdam Quarter of The Bijlmer in Amsterdam South-East is famous for the high ambitions and high expectations with which the quarter was built in the late sixties and early seventies of the twentieth century. The Bijlmer Quarter is even more famous for its social problems during its life time afterwards. Municipality and building associations have been trying for years to alter the situation and to improve the living conditions in the quarter by changing the high rise buildings. On October 4th, 1992, an EL-AL 4X-AXG3 Boeing 747-400 freight carrier fell down from the sky, ending many lives and destroying part of an apartment building at Kruitberg. Only 363 dwellings could be saved from this disaster. During the years 2002-2004 these dwellings are upgraded to contemporary comfort and energy standard. This refurbishment is an exemplary worst-case study for other projects in The Netherlands, despite its history of high ambitions and disaster. The building is a ten storeys high multifamily apartment block built in the sixties, in the famous post – war residential area of Amsterdam-South-East Bijlmermeer (Donze et.al. 2004). The goal of the large scale renovation is to increase social safety and thermal comfort. The floor plans are still functional, despite the large differentiation in family composition. This project is part of a European demonstration project called Regen-Link. The major changes concerning energy conservation are in renovating the building envelope, adjusting the ventilation-system and in renewing the heating-system. There were no severe problems with moisture or condensation. The building envelop existed of not insulated outside walls, under the windows as well as else ware. Although the glazing was double, this was still not comfortable due to the leaking facade and due to the bad window frames. The roof however was already insulated up to the standard of u-value of 2,6 W/m2K. Both facades at the end of the building were insulated from the outside until a u-value 0,35 W/m2K of was reached. Only the dwellings behind these end walls had new glazing installed. This way the energy performance of these eighty dwellings levels with the energy performance of the dwellings inside the building. As a special improvement 35 balconies of dwellings were transformed in to glass houses by closing the outside with a large frame with glazing. The selection of these special improvements was done on basis of the argument if the functionality of the dwelling would significantly improve and if the inhabitants could give their consent to this enlargement. As is stated before, the balcony would become part of the interior and because of that the inhabitant would become responsible for the maintenance of this part of the building. Fife of these balconies even has got PV panels, producing electricity, in the lower glass panes.
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Figure 9: View of the old façade at the end of the building block
Figure 10: A 42 m3 storage buffer for the solar energy is installed.
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Figure 11: The new façade covered with PV panels, producing electricity.
Consolidation of existing situation • No floor insulation • No cavity walls nor insulation • U value = 10 W/m2K • Limited roof insulation u value = 2,6 W/m2K • Double glazing • Collective heating and hot water facility with end heating by local gas-heating Transformation to new situation • Floor insulation with u value = 0,35 W/m2K • Etics u value = 0,35 W/m2K at end of buildings, u value of 0,45 W/m2K for other envelop • Roof insulation 0,35 W/m2K • 720 m2 solar-collectors on the roof providing warm water for heating and showers • new high performance gas-heating • 200 m2 PV solar cells at the end of the building and in the fencing of the balconies • Heat recovery via heat-pumps • Building energy system optimizing software The costs per dwelling were a total investment of €80.000,– (inclusive VAT). The project was subsidized by European Funding, national EPR subsidy, EPA subsidy, EP-plus funding, Urbun funding (subsidy for a policy dependence), national subsidy for the elevator). As a consequence there was no need to raise the rents for the inhabitants. The energy use however decreased with 40 %, from which 15 % was caused by a individual meter for heat use, in stead of a collective arrangement as before. 4.2 Residential Building in Poptahof Delft This building is a typical high – density residential block in the suburbs of Delft. This area is the most densely populated area in The Netherlands. The eight apartment buildings consist in total of 794 dwellings. After renovation there will be 605 dwellings left for rent. The buildings were built in the sixties and seventies, with an envelope of concrete panels (Apon et.al. 2005). Changing the floor plan would improve the functionality of the dwellings. The most interesting modification would be the differentiation of the number of rooms in apartments and the surface.
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In the design-research of Apon et.al., one of the apartment buildings was transformed into an energy neutral apartment building. This case in Delft is seen as a representing type of housing for many of the 200.000 apartments in high rise buildings. From the modelling in this research some lessons for the renovation were learned (Apon et.al. 2005): The risk of overheating in summer is very high, especially when a heat recovery system is installed in the ventilation system, without the possibility of by passing the heat-recovery unit, shading from the outside would help most; The thermal comfort in winter can be secured by putting insulation of 10 cm in or to the outside walls, replacing the double glazing with double glazing with coating and by installing a heat recovery system for balanced ventilation of the dwellings. If the insulation and the glazing improves, the energy use decreases; The positioning of glass houses, by adding a window frame outside the balconies, would improve winter comfort, but would decrease summer comfort drastically; By exaggerate the insulation quality down to u-values below 0,15 W/m2K, the energy use for heating becomes low. The remaining electricity should be covered by green energy, supplied by PV panels on the outside walls and the roof or by solar collectors, providing hot water for the hot water system. In a similar study of the same apartment building by Klunder (Klunder 2005) it is concluded that the overall environmental impact can decrease significantly. Klunder also concludes that this the renovation approach can be seen as representing many of the 200.000 dwellings in apartment blocks throughout The Netherlands. Klunder remarks about the floor plan that the construction of the building leaves enough space for alterations and differentiation in floor plans and types of dwellings. This would not affect the environmental impact in a considerable amount. 5 CONCLUSIONS The technical improvements in high rise building stock can be motivated by differentiation the floor planning toward more flexibility. As long as the improvements in energy performance can be situated in or near the building envelope, the future changing the floor plan and of changing the functionality of the dwelling is more likely to happen. The problem is in organizing the logistics of such a large scale renovation. The challenge lies in financing the technical improvements and the process costs within realistic frames of pay back time. Thorough value management and alternative risk assessment are most likely to be the key factors for success of the renovation in the long run. Exemplary case studies show that already by installing outside wall insulation and double glazing with spectral coatings, the energy use of dwelling is minimized to a level were energy neutral building comes within reach. The production of sustainable heat and green electricity can not always be executed. There is not always enough room to mount the PV panels and solar collectors on the roof or at the south elevation. Building envelopes must be refurbished because of wearing and damages during use. Then it is technically and economically interesting to include wall insulation to increase energy efficiency and thermal comfort. If feasible use a technical solution with low environmental impact. The benefits from not demolishing the building already form a gain because of avoidance environmental effects. The saving of fossil fuel, due to the energy saving, is the most important beneficial environmental impact.
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6 REFERENCES Apon L,Castro Boelman E de, Ravesloot CM, & Dijk, E van (2005). Energy use and overheating risk in zero-energy renovation. in M van den Voorden, L Itard, & P de Wilde (Eds.), Proceedings of the conference building performance simulation : a better support for the practice of today and tomorrow? (pp. 1-8) 2005; Donze G., Nuiten P., Brouwer C., Metamorfose karaktersitiek Bijlmercomplex, projectbeschrijving Europees Voorbeeldproject, in (ed) Verwarming en Ventilatie, January 2004; Dorsthorst, BJH te, & Durmisevic, E, Building's transformation capacity as the indicator of sustainability; transformation capacity of flexible housing. In A.R. Chini (Ed.), Deconstruction and materials reuse CIB publications 287 (pp. #1-#16). Florida: University of Florida 2003; Ecofys, Kosteneffectieve energiebesparing en klimaatbescherming, De mogelijkheden van isolatie en de kansen voor Nederland, Ecofys Utrecht 2005; Elgersma P.S., Een warm gevoel bij minder verbruik, wat bepaalt de keuze van woningcorporaties voor energieebesparing?, Aedes Hilversum 2001; Hasselaar E., Hoe gezond is de Nederlandse Woning, Duurzaam Bouwen en Beheren 5, Delft University Press 2001; Hasselaar E., Health indocators and criteria, OTB Delft University of Technology 2006; Petersdorff C., Boermans T., Stobbe O., Joosen S., Graus W., Mikkers E., Harnisch J., Mitigation of CO2 Emissions from the Building Stock, Beyond the EU Directive on the Energy Performance of Buildings, ECOFYS GmbH, Koln 2004; Ravesloot C.M., Rombo tactiek, English Abstract page 26-1, Eindhoven University of Technology, Bouwstenen 90, Eindhoven 2005; Ravesloot CM, Social demands and stakeholders participation in Dutch sustainable housing policy. in C Schaur, F Mazzolani, G Huber, G De Matteis, H Trumpf, H Koukkari, J.P Jaspart, & L Braganca (Eds.), Improvement of buildings' structural quality by new technologies (pp. 511-518). Leiden: A.A. Balkema Publishers 2005; Ravesloot CM,Aesthetics in Urban Design seen from the Perspective of Sustainability,. in C Schaur, F Mazzolani, G Huber, G De Matteis, H Trumpf, H Koukkari, J.P Jaspart, & L Braganca (Eds.), Improvement of buildings' structural quality by new technologies (pp. 511-518). Leiden: A.A. Balkema Publishers 2005; Sunnika M.M., Policies for improving energy efficiency in the European housing stock, Delft Centre for Sustainble Urban Areas, Delft University Press 2006; Waals van der et.al.,,Energiebesparing en stedelijke herstructurering, DGVH Nethur, Den Haag Utrecht 2000;
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Comparison of Design Criteria Christian Wetzel CalCon Holding GmbH, Munich, Germany
INTRODUCTION During the work in the working group 3 in the Cost action C16 the members showed interest in comparing the actual state of the building envelopes and also to compare the actions that are normally done when refurbishing the envelope. Thus the group built a "matrix" where all participating countries filled in national information. COST-actions are European projects, where only travel cost is being reimbursed. Thus the national experts simply contributed what they already know but the experts did not perform research for that action. The data collected in that matrix shall therefore be understood not as an elaborated full survey of national representative data, but as an ad-hoc interview of these experts giving their opinion about the state of the envelopes in their countries. The matrix is structured with columns: for the participating countries with national abbreviations, e.g. "F" stands for France and lines with the specific information about different topics in each country. After an overall information about each country like the typical heating and cooling degree days, the national regulations etc- the matrix is in general separated into the two segments of the "envelope" of a building: facade and roof. Furthermore these segments are sub-diveded in 2 groups: Current state of individual components of the envelope today (and not the original state when the building was erected) and Conventional refurbishment actions. Accordingly the following tables can be found:
COST C16 Improving the Quality of Existing Urban Building Envelopes – Facades and Roofs. L. Bragança, C. Wetzel, V. Buhagiar, L.G.W. Verhoef (eds) IOS Press, 2007 ©2007 IOS Press and the Authors. All rights reserved.
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Comparison of Design Criteria
General information (heating degree days, national regulations etc. in each country Façade: Current state of façade covering load bearing structure windows weather protection and shading devices façade insulation used other components of the façade Refurbishment actions of: Insulation of the façade Windows including weather / solar protection Other measures Roof: Current state of Type of roof Type of roof covering Type of insulation Refurbishment actions of: Insulation of the roof Other measures The national experts were asked to either give certain numbers, e.g. for the thickness of the most commonly used insulation of flat roofs or to answer with "Y" for "Yes" or "n" for "No". Most questions are answered even more accurate by asking if this technical solution of the envelope is: "C" = "Common" i.e. it is found in over 20% of the building stock (e.g. wooden frames for windows instead of metal or plastic frames "S" = "Seldom" i.e. less than 20% and more than 1% of the building stock and finally "N" = "Not existing" i.e. only a very few not representative cases exist and the total number is lower than 1% of the whole building stock. It shall also be emphasized that the project regarded post WWII apartment buildings and therefore all buildings erected before that time were not taken into account.
Comparison of Design Criteria
1 1.1
155
COUNTRY CRITERIA MATRIX WITH SALIENT FEATURES General information
Table 1: Country criteria matrix
GR IT
FR
S
PT DE DK MT NL MK HU SI CY PL
GENERA L INFORMATION Commonly used inside air temperature to calculate energy demand for cooling
25
25
26
25
25
25
26
23
24
24
25
26*
24
N
Number of climatic zones for cooling
N
N
4
N
3
0
1
1
0
N
1
N
4
N
Range of external design-temperature for cooling systems [°C]
26 to 37
N
N
N
26 to 37
N
27-
35
-
30 to 38
16 to 32
N
28 to 40
N
National regulation exists for the cooling demand for residential buildings [Y/N]
N
N
N
N
Y
N
N
N
N
N
N*
N
N
N
Specified number of months for cooling season in national regulations
3
N
N
0
4
N
0
6
N
0
N
N
4
0
Heating degree days based on (18°C) 1257
20
18
4375
776 to 3034
-
2906
619
3088
N
3000
20
710
N
Cooling degree days based on (18°C) 684
20
N
N
52 to 875
N
70
1021
-
N
no
20
1091
N
Commonly used temperature to calculate heating degree days
18.3
20
18
12
20
12
17
18
10
12
12
20/12
20
12
Average external temperature for heating season
9
4 to 13,5
N
10
7,5
3,6
4,9
13,8
5,8
5
3
7,6
11 to 14
2,87
range of external design temperature for heating system [°C]
-8 to +6
-5 to 5
-11
-11
-5.8 to 7.6
-15 to -5
-12 to 20
10
-12 to -10
-12 to -18
-11 to 15
-7 to -19
12 to 20
-16 to -24
Specified number of months for heating season in national regulations
4-6
3,5 to 6
7,5
7
4.3 to 8.0
7
8
4
7
6
5
9
6
7 to 8
Number of climatic zones for heating
3
6
3
1
3
1
1
1
1
3
3
10*
4
4
Maximum heating degree days [Kd]
702
3000 2420 3150 3000 4623 4200 1737
x
2647 3300 4000
900
4200
Minimum heating degree days [Kd]
361
600
2023 2900 2400
600
3400
787
3605
1330 2730
960
3178 3000
214
x
EUROSTAT: Average (or commonly 1732 2085 2494 5423 1302 3244 3478 used) heating degree days (12°C) [Kd]
564
2905
-
2917 3044
Legislation to reduce energy consumption exists for new buildings since ...
1979, 1991/ 1974 1999 1990 1973 1961 2006 1974 1987 2006 1970 2007 1984, 2006 2005 1992
Legislation to reduce energy consumption exists for refurbishment actions on existing buildings since ...
1979, 1991/ 2006 2005
N
1999 1990 1985 1966 2009 1988 1987 2006 2002/ 2007 1984, 2007 1992
156
Comparison of Design Criteria
Regulations concerning heating exist all over Europe, while regulations for cooling and according energy saving measures are not clearly defined. Even in southern European countries like Greece, Cyprus or Malta no regulations exist. The only exception is Portugal, where there is a national regulation to reduce energy consumption through cooling.
Figure 1: Average heating degree days for the EU-25 representing the climatic variety of Europe
1.2
Current state of facades
The participating experts were interviewed about the current state of the façade in their country. The current state of facades can be subdivided into the following parts that are shown in the tables below: External covering Load bearing structure Windows Weather protection and shading devices Insulation already used Other components of the facade
Comparison of Design Criteria
157
Table 2: Description of the current state of the façade external covering. GR
I
F
S
P
Rendering
C
C
Exposed masonry (natural stone, brick)
S
S
Exposed concrete
S
C
S
Prefabricated concrete elements
S
C
C
Artificial stone veneer
S
S
N
DE DK MT NL MK HU SI CY PL
C
C
C
C
S
C
C
C
C
C
C
C
N
C
S
C
C
C
C
S
C
S
N
S
C
S
S
C
N
C
S
S
S
S
N
C
N
C
C
S
C
C
C
S
N
C
C
N
S
S
N
S
N
N
S
N
N
FAÇADE DESCRIPTIONOF THE CURRENT STATE (POST II-WW APARTMENTBUILDINGS) CURRENT STATE: Type of external covering:
Curtain-wall façade
S
N
S
S
S
S
S
S
S
S
S
S
S
S
Light (concrete) elements
S
C
N
C
N
C
S
N
C
S
S
S
N
S
Wooden elements
S
N
N
C
N
S
S
N
S
S
S
N
N
N
Metal elements
S
N
N
S
N
S
S
N
S
S
S
N
N
N
Most participating countries have as a common façade covering rendering. Prefabricated concrete elements are not only common in eastern European countries but except for Portugal and Cyprus also in all other participating countries. Wooden elements are found commonly in Sweden, while these elements are not existing at all in Slovenia, Cyprus, Poland, Malta, France and Italy
Table 3: Description of the current state of the façade load bearing structure. GR
I
F
S
P
DE DK MT NL MK HU SI CY PL
Light masonry block with reinforced concrete slabs
S
S
C
C
N
C
N
C
C
C
C
S
N
S
Masonry with hollow block flooring (waffle beam flooring)
S
S
C
C
S
C
S
C
C
S
C
C
S
N
Reinforced concrete (frame structure) and clad/infilled with material other than masonry
S
C
C
C
S
S
C
C
C
C
S
C
S
C
Concrete columns with masonry and concrete floors
C
C
S
C
C
C
S
C
C
C
S
S
C
C
Timber constructions
S
N
N
C
N
S
C
N
S
S
S
N
N
N
Natural stone with wooden flooring
S
N
N
N
N
S
N
N
N
S
N
N
N
N
Natural stone with reinforced concrete slabs
S
N
N
N
N
N
S
C
N
S
N
N
N
N
FAÇADE CURRENT STATE: TYPE OF LOAD BEARINGSTRUCTURE
158
Comparison of Design Criteria
Natural stone that was (beside brick) all over Europe the most common type of load bearing structure is commonly used after WWII only on the island of Malta, where the natural resources of limestone are used instead of importing expensive brick or concrete materials.
Table 4: Description of the current state of the windows on the façade. GR
I
F
S
P
DE DK MT NL MK HU SI CY PL
FAÇADE CURRENT STATE: WINDOWS wooden frame
C
S
C
C
C
C
C
S
C
C
C
C
S
C
plastic frame
C
C
C
C
S
C
S
N
C
C
C
S
N
N
steel/aluminium frame
C
C
C
C
C
S
S
C
S
S
S
S
C
N
single-Glazed
C
C
C
C
C
S
S
C
C
S
N
N
C
S
double-Glazed
C
S
C
C
C
C
C
S
C
C
C
C
S
C
double-Glazed and coated
S
N
S
S
S
C
C
S
C
C
C
S
N
N
double-Glazed and coated and gas-filled
N
N
S
S
N
C
C
S
S
C
S
C
N
N
triple glazing etc.
N
N
N
C
N
S
S
N
S
S
N
S
N
N
Steel and aluminum frames are common in southern Europe (and Sweden?), while in Poland Cyprus and Malta plastic frames are unknown. Single glazing is not used in Eastern European countries like Hungary and Slovenia.
Table 5: Description of the current state of the weather protection and shading devices on the façade. GR
I
F
S
P
C
S
S
S
N
DE DK MT NL MK HU SI CY PL
FAÇADE CURRENT STATE: WEATHER PROTECTIONAND SHADINGDEVICES
Shutters
C
S
S
S
S
S
S
S
N
Roller shutters
C
C
C
C
C
C
S
S
S
C
C
C
C
S
Venetian Blinds
C
C
S
C
S
C
S
C
S
S
C
S
C
N
Interior sunshades
C
S
C
C
C
C
S
C
C
C
C
C
C
S
Interpane sunshades
S
N
N
C
N
S
S
S
C
S
S
S
N
S
Exterior sunshades
C
N
N
S
N
S
S
S
C
S
S
S
S
N
Canopies (light weight material)
C
N
N
C
N
S
S
C
S
S
N
N
S
S
Weather protection is seldom or not at all used in Poland. Sunshading devices are more used in southern European countries. This shows, that glare protection that is a common European topic is not regarded as important enough in living areas (unlike in office space) and the more important reason for installing solar shading devices is for thermal reasons to avoid overheating through solar radiation. Another interesting result from the comparison: roller shutters do not exist in Poland and Portugal.
Comparison of Design Criteria
159
Table 6: Description of the current state of the insulation used on façades. GR
I
F
S
P
DE DK MT NL MK HU SI CY PL
FAÇADE CURRENT STATE: INSULATION USED Exterior insulation (ETICS, ETIDS)
C
S
S
C
S
C
C
N
C
C
C
C
N
S
Cavity insulation/Insulation inside the wall
C
C
N
C
C
C
C
S
C
S
C
S
N
C
Interior insulation
S
S
C
C
N
S
S
S
S
S
S
N
N
N
Except for Malta and Cyprus all other European countries used exterior insulation. Interior insulation is common only in Sweden and France while in other countries it is only seldom or not used (P, SI, CY, PL)
Table 7: Description of the current state of other components on the façade. GR
I
F
S
P
DE DK MT NL MK HU SI CY PL
Balconies up to 5m²
S
C
C
C
C
S
C
Balconies, bigger than 5m²
C
S
S
S
S
C
Loggias
S
S
S
S
S
S
Access to apartments through galleries attached to one side of the facade
S
S
S
S
S
S
FAÇADE CURRENT STATE: OTHER COMPONENTSOF THE FAÇADE C
C
C
C
C
C
C
C
S
S
C
C
S
S
S
S
C
S
C
C
C
C
C
C
N
C
S
C
S
S
S
The gallery access to apartments is common only in DK, NL and HU and not at all existing in Malta 1.3
Refurbishment actions on facades
Besides an evaluation about the current state of facades also the typical and commonly used refurbishment and retrofit actions in each country were evaluated. Emphasis was put on the fact, that not the newest results from scientific research or experiments are listed but commonly used actions that can be regarded as the "standard" refurbishment/retrofit action in each country. The refurbishment actions listed in the matrix were subdivided into the following groups: Insulation on the façade Windows including weather and solar protection Other refurbishment measures
160
Comparison of Design Criteria
Table 8: Description of the commonly applied refurbishment action for opaque parts of the facade. GR
I
F
S
P
Simply painting/refurbishing the façade without doing any energy efficient improvement
C
C
C
C
C
C
C
C
C
C
C
C
C
C
Refurbishment measure: Increased thickness of the wall, additional layer with conductivity higher than 0,1 [W/mK]
N
S
C
C
S
S
S
S
C
N
S
N
N
C
ETICS (ETIDS) Insulation Material Polystyrene / Mineral Wool
C
C
C
C
C
C
C
S
C
C
C
C
N
C
ETICS (ETIDS) Recycled or “Ecological” Material (Wool, Paper)
S
S
S
S
N
S
N
N
S
N
S
N
N
N
Ventilated Façades
S
C
N
N
S
C
C
N
S
S
S
N
N
Insulation from inside
S
S
C
C
N
S
S
S
S
S
S
N
N
N
Insulation inside the wall (e.g. cavity walls with inside insulation layer, blowing insulation into the gap)
S
N
S
S
N
C
C
S
S
N
N
N
N
N
4 to 5
4 to 6
6 to 8
8 to 10
4 to 6
10 to 12
15
5 to 7
10
5 to 8
8 to 12
8 to 10
3 to 5
(5)810
Insulation material depends on the height of the building or other restrictions (fire protection, gross habitable area, public/private use, etc.)
N
Y
N
Y
N
Y
Y
S
N
Y
Y
Y
N
Y
Insulation is not allowed because of regulations to preserve building envelopes (listed/classified buildings)
Y
C
Y
Y
Y
Y
S
Y
N
Y
Y
Y
Y
Y
Additional cost for implementing Insulation are reduced through local or national support measures, based on actual political situation (lower interest rates, certain amount of money paid by authority, allowance to increase rent, etc.)
C
Y
Y
Y
N
Y
Y
C
Y
N
Y
Y
Y
Y
REFURBISHMENT ACTIONS
DE DK MT NL MK HU SI CY PL
ON
THE FAÇADE
REFURBISHMENT ACTION: I NSULATION OF THE FAÇADE:
Commonly used thickness of insulation-layer [cm]
For refurbishment actions of the façade including (additional) insulation the following conclusions from the survey can be taken: Besides Cyprus where no insulation is used for refurbishment action and seldom application in Malta all participating countries are commonly applying insulation on the façade when refurbishing the envelope. Ventilated facades are only common in Denmark, Germany and Italy while insulation from inside is only common in France and Sweden. In all other countries it is only used seldom or not at all. The commonly found thickness of existing insulation layers (with conductivity lower than 0.1 [W/mK]) varies from south to north in Europe between 3cm (Cyprus) to 15 cm in Denmark. Of course in especially North and middle European countries also insulation systems with an insulation layer of more than 15 cm can be found. But once again it shall be highlighted that it was asked not for the technical possible but the commonly used solution.
Comparison of Design Criteria
161
Table 9: Description of the commonly applied refurbishment action for transparent parts of the facade. GR
I
F
S
P
Replace old windows by single glazed new ones
S
N
N
N
S
S
N
C
S
N
N
N
C
N
Replace old windows by double glazed, gas filled ones
S
C
C
C
C
S
C
N
S
S
C
N
N
C
Replace old windows by double glazed, coated and gas filled ones
S
S
S
C
N
C
C
N
C
C
C
C
N
S
Replace old windows by triple glazing
N
S
S
C
N
S
C
N
S
S
N
S
N
S
Breaking holes in the façade to implement new windows
S
S
S
S
N
S
S
C
S
S
N
S
N
N
Adding external (roller) shutters
C
C
C
S
S
S
S
S
S
C
S
C
N
N
Adding external solar protection: flexible devices, e.g. shades, Venetian blinds
C
C
S
C
C
S
S
C
S
S
S
S
S
N
Adding external solar protection: permanent constructions e.g. concrete or metal overhangs
S
S
S
S
N
S
S
S
S
N
N
N
N
N
REFURBISHMENT ACTIONS
DE DK MT NL MK HU SI CY PL
ON
THE FAÇADE
REFURBISHMENT ACTION: WINDOWS INCLUDINGWEATHER/ SOLAR PROTECTION
Triple glazing is found only in North European countries as a commonly used refurbishment action. In Greece, Portugal, Malta, Hungary and Cyprus this type of glazing is not even seldom used for refurbishment.
Table 10: Description of other commonly applied refurbishment actions for facades. GR
I
F
S
P
Enlarging the living space by adding a conservatory to the façade
C
S
S
S
S
S
C
C
S
C
S
S
N
N
Glazing balconies to create winter gardens
S
C
S
S
C
S
C
C
S
C
S
C
C
N
Adding balconies to the façade
S
S
S
S
N
S
S
S
S
C
N
N
N
S
Stairwell with gallery access to the apartments: Glazing of the galleries
S
S
S
S
S
S
S
N
S
N
N
N
N
N
REFURBISHMENT ACTIONS
DE DK MT NL MK HU SI CY PL
ON
THE FAÇADE
REFURBISHMENT ACTION: OTHER MEASURES
A measure to enlarge the living space and also to increase thermal efficiency is the measure to glaze unheated balconies. Except Poland this measure can be found all over Europe.
162
1.4
Comparison of Design Criteria
Current state of roofs
Analogous to the survey of the current state of the facades also the current state of existing roofs was analyzed. The matrix was subdivided into the following parts: Type of roof Type of roof covering Type of insulation
Table 11: Description of the current existing types of roofs. GR
I
F
S
P
C
C
C
C
C
DE DK MT NL Mk HU SI CY PL
ROOF DESCRIPTIONOF THE CURRENT STATE (POST II-WW APARTMENTBUILDINGS) CURRENT STATE: TYPE OF ROOF Pitched roof
C
C
N
S
C
S
S
N
S
Pitched-Mansard roof
S
C
S
C
S
C
S
N
S
C
S
S
N
S
Flat roof with access
C
C
S
C
S
C
S
C
C
C
S
C
C
N
Flat roof without access (to residents)
S
C
C
C
C
C
C
S
C
C
C
C
C
C
Some of the participating countries have a majority of flat roofs or even do not have pitched roofs at all. These are: Malta and Cyprus with no pitched roofs and Poland with only a few pitched roofs in the existing apartment building stock built after 1945. Table 12: Description of the current existing types of roof coverings. GR
I
F
S
P
DE DK MT NL Mk HU SI CY PL
concrete tiles
C
C
N
C
S
C
C
C
S
S
C
S
N
N
ceramic glazed tiles
N
S
N
C
S
C
C
S
S
Y
C
S
N
N
ROOF CURRENT STATE: TYPE OF ROOF COVERING:
brick (klinker) tiles
S
C
C
N
C
C
C
N
N
C
C
C
N
N
bituminous tiles
S
C
N
N
N
S
N
N
S
C
S
S
N
N
copper/metal roof covering
S
C
N
N
S
S
S
N
S
S
S
S
N
S
S
C
N
N
S
C
N
S
N
S
N
N
N
N
N
N
N
N
N
N
S
S
N
N
N
N
slate roof wood
S
concrete with protective paint
S
S
S
N
S
N
N
C
S
N
N
N
C
N
bituminous layers
S
C
C
C
C
C
C
C
C
C
C
C
C
C
bituminous layers with gravel layer
S
C
C
C
C
C
C
C
C
C
C
C
S
S
concrete cast in situ screed (flat roof)
C
S
N
N
N
S
C
C
S
S
N
S
C
N
green roof
S
S
S
S
S
S
N
N
S
N
S
S
N
N
foils e.g. PVCs
S
N
N
N
S
C
C
N
C
S
C
N
N
N
corrugated fibercement
S
S
N
N
C
S
C
S
S
S
C
S
N
N
Comparison of Design Criteria
163
Pitched roofs in the participating countries are mainly covered with concrete or brick tiles. Bituminous tiles are only a common roof covering in Italy and Macedonia. Copper or metal roof coverings are only common in Italy while in other countries this type of roof covering is only seldom or not used. Flat roofs in the participating countries are covered mostly with bituminous layers with or without gravel layers (except for Greece where concrete cast in situ screed is commonly used). Green roofs, foils or corrugated fibre cement are only common in some of the participating countries.
Table 13: Description of the current existing types of roof insulation. GR
I
F
S
P
DE DK MT NL Mk HU SI CY PL
Pitched roof: insulation of the upper floor (unheated attic)
S
S
C
C
C
C
C
S
S
C
C
C
N
S
Pitched roof: insulation under/between/ over the spars
C
C
C
C
C
C
C
S
S
C
C
S
N
C
Flat roof: Cold roof (ventilated)
S
N
N
S
N
C
S
S
S
C
S
S
N
C
Flat roof: Warm roof
C
C
C
C
C
C
C
C
C
C
C
C
C
N
Flat roof: Inverted roof membrane system
C
S
S
N
C
C
C
S
C
S
S
S
N
N
ROOF CURRENT STATE: TYPE OF INSULATION:
While insulation of the façade is not found in all participating countries, the insulation of the roof is commonly found in all participating countries. Flat roofs are except for Poland commonly built in the warm roof system, while in Poland only the (ventilated) cold roof system is state of the art. For pitched roofs the insulation of the upper floor in unheated ceilings as well as the insulation under/between/over the spars can be found. 1.5
Refurbishment actions on roofs
As for facades the commonly used techniques and not the optimum solutions are listed in the matrix, subdivided by the following topics:
164
Comparison of Design Criteria
Table 14: Description of the commonly applied insulation on roofs. GR
I
F
S
P
No additional insulation is applied when refurbishing the roof
S
N
S
S
S
C
S
C
S
S
N
S
C
C
Pitched roof: Insulation is put under/between/over the spars
C
C
C
C
C
C
C
S
C
C
C
C
N
C
Pitched roof: Insulation is put on the floor of the attic
C
S
C
C
C
C
C
N
C
C
C
C
N
S
Pitched roof: Commonly used thickness of insulation-layer [cm]
5 to 7
4 to 8
4 to 6
18
10
10 to 15
6 to 12
16 to 22
5
15
REFURBISHMENT ACTIONS
DE DK MT NL Mk HU SI CY PL
ON
THE ROOF
REFURBISHMENT ACTION: I NSULATION OF THE ROOF
20 to 16 to 25 18
10 to 50 to 20 70
Pitched roof: Vapor barrier used
C
Y
C
C
S
Y
Y
S
Y
Y
Y
C
N
C
Pitched roof: Ventilated insulation
S
Y
C
C
N
C
C
N
S
C
C
C
N
C
Flat roof, ventilated roof: Additional insulation is put
C
Y
S
S
C
C
C
S
S
C
C
C
N
S
Flat roof, warm roof: New (increased) insulation is applied on the roof
C
C
C
C
C
C
C
S
C
C
C
C
S
S
Flat roof, warm roof: Inverted membrane system with insulation is put on the façade
N
S
?
?
C
C
-
N
C
N
C
S
N
N
5
4 to 8
4 to 6
7 to 8
4 to 6
16
10 to 20
5 to 10
10
10
3 to 5
10 to 16
Flat roof: Commonly used thickness of insulation-layer [cm]
10 to 10 to 16 18
In Italy and Poland a refurbishment action of the roof is always coupled with an additional insulation layer, while in other countries also refurbishment actions without addition of insulation layers can be found. The thickness of the insulation layer again as for the façade increases by moving towards the north starting with 4 cm in Italy and Portugal to 25 cm in France. For flat roofs the same trend can be observed with 3 cm in Cyprus up to 20 cm in Denmark.
Table 15: Description of other than insulation measures that are commonly applied on roofs. GR
I
F
S
P
Change unheated attic to heated one (implement e.g. new living space)
C
C
C
C
N
C
C
N
C
C
C
C
N
N
Add additional glazing (fixed or open able on the roof)
S
C
C
S
N
S
S
S
C
C
C
C
N
N
Break down chimneys, that are not any more used
S
C
N
N
N
C
S
N
C
C
S
S
N
N
Close interior guttering system, add exterior guttering system
S
C
N
N
N
C
S
N
S
C
S
S
N
N
REFURBISHMENT ACTIONS
DE DK MT NL Mk HU SI CY PL
ON
THE ROOF
REFURBISHMENT ACTION: OTHER REFURBISHMENTMEASURESON THE ROOF
Comparison of Design Criteria
165
Looking at other refurbishment actions at the roof the creation of new living space can be seen as the most common measure. Only in Portugal, Malta, Cyprus and Poland the unheated attic is not commonly but not at all changed into a heated attic by simultaneously insulating the attic. This can be explained by the construction of the building. Flat roofs in many cases so not have no unheated attic, as the highest floor is situated directly under the roof construction or in some cases the unheated attic is not as high as the other floors and without sufficient glazed areas and therefore only used for storage area of the tenants.
CONCLUSION Especially looking at refurbishment actions it can be seen, that Europe is growing together adapting measures techniques and material from other countries. Exceptions are mainly seen on the islands of Malta and Cyprus. Looking at the lack of regulation and knowledge about the reduction of the cooling energy load regulations and support for planners and craftsmen is necessary. Otherwise the primary energy consumption for cooling will more and more contribute to the greenhouse gas emissions in Europe.
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COST C16 Management Committee
Belgium Prof. Andre de Naeyer Hogeschool Antwerpen Univ. College Henry vande Velde Design Sciences Mutsaardstraat 31 B-2000 Antwerp +32.3.231 6200 +32.3.231 9604
[email protected]
Cyprus Mr. Christos Efstathiades Public Works Department Republic of Cyprus Ministry of Communication & Works Lefkosia +35799597362 +35725332094
[email protected]
Cyprus Mr. George Hadjimichael Town Planning & Housing Department Demostheni Severi Avenue 1454 Nicosia +357 22 30 65 92 +357 22 30 65 01
[email protected]
Denmark Mr. Jesper Engelmark DTU - Technical University of Denmark Dept. of Civil Engineering Planning and Management of Building Processes DTU Building 118, Brovej 2800 Lyngby +45 45251932 +45 45883282
[email protected]
Denmark Prof. Ebbe Melgaard Royal Academy of Fine Arts School of Architecture Philip de Langes Allé 10 1435 København K +45 49147850 +45 32686111
[email protected]
F.Y.R. of Macedonia Prof. Kiril Gramatikov St Cyril & Methodius University Faculty of Civil Engineering Dept. of Concrete and Timber Structures UL. Partizanski odredi 24 POB 560 1000 Skopje + 389 2 3116066 ext. 148 + 389 2 3117 367
[email protected]
168
COST C16 Management Committee
France Prof. Francis Allard Université de La Rochelle Pôle Sciences et Technologie LEPTAB ave Michel Crépeau F-17042 La Rochelle cedex 1 +33 546 45 82 04 +33 546 45 82 41
[email protected]
Germany Mr. Franz Georg Hofmann Federal Ministry of Transport Construction and Housing Merler Allee 11 53125 Bonn +49 228 252500 +49 228 9259 554
[email protected]
Germany Mr. Christian Wetzel CalCon Holding GmbH Management Goethestr. 74 80336 Munich +49-(0)89-552698-0 +49-(0)89-552698-75
[email protected]
Greece Prof. Charalampos Baniotopoulos ARISTOTLE UNIVERSITY OF THESSALONIKI CIVIL ENGINEERING UNIVERISTY CAMPUS GR-54124 Thessaloniki +302310995753 +302310995642
[email protected]
Hungary Dr. Tamás MezĘs University of Budapest for Technology and Economics Muegyetem rkp 3 1111 Budapest +36 1 463 2303 +36 1 463 1638
[email protected]
Hungary Prof. György Sámsondi Kiss Technical Committee Monitor Szent Istvan University Thököly Str 74 1146 Budapest +36 1 252 1270 +36 1 252 1278
[email protected]
Hungary Ms. Agnes Novak Budapest University of Technology and Economics Budapest +36 1 3060 394 +36 27 347 237
[email protected]
Italy Prof. Roberto di Giulio University of Ferrara Department of Architecture Via Quartieri 8 44100 Ferrara +39 348 3856993 +39 055 244042
[email protected]
Italy Mr. Eugenio Arbizzani Universita degli Studi di Roma "la Sapienza" Facolta di Architettura Valle Giulia Via Gramsci 53 00197 Roma +39 06 49919291 +39 06 49919290
[email protected]
Malta Dr. Vincent Buhagiar University of Malta Faculty of Architecture & Civil Engineering Environmental Design Department of Architecture & Urban Design Tal-Qroqq MSD 06 Msida +356 2340 2849 +356 21 333919
[email protected]
COST C16 Management Committee
169
Malta Mr. Ruben Paul Borg University of Malta Faculty of Architecture and Civil Engineering Mediterranea, 161, Triq Luigi Billion, Pembroke, Msida, Malta (00356)79055680 (00356)21375185
[email protected]
Netherlands Prof. Leo G.W. Verhoef (Chairman) Delft University of Technology Berlageweg 1 2628CR Delft +31.152784179 +31.152781028
[email protected]
Netherlands Mr. Frank Koopman (Technical Secretary) Delft University of Technology Faculty of Architecture (room 2.05) Chair Restoration Berlageweg 1 2628 CR Delft +31152784133 +31152781028
[email protected]
Poland Prof. Aleksander Kozlowski Rzeszow University of Technology Building Structure Civil Engineering W. Pola 2 Rzeszow Poland 35-959 Rzeszow +48 178541127 +48 178542974
[email protected]
Poland Dr. Adam Rybka Rzeszow University of Technology Faculty of Civil and Environmental Engineering Department of Town Planning and Architecture W. Pola 2 35 959 Rzeszow +48 17 8651624 +48 17 8543565
[email protected]
Portugal Prof. Luís Bragança Lopes University of Minho School of Engineering Building Physics and Construction Technology Laboratory Azurem 4800-058 Guimaraes +351253510200 +351253510217
[email protected]
Slovenia Prof. Roko Zarnic (Vice Chairman) University of Ljubljana Faculty of Civil and Geodetic Engineering Jamova c. 2 1000 Ljubljana +38641777517 +38614250681
[email protected]
Slovenia Dr. Jana Selih University of Ljubljana Faculty of Civil and Geodetic Engineering Jamova 2 1000 Ljubljana + 386 1 4768575 + 386 1 2504861
[email protected]
170
Sweden Prof. Dr. Satish Chandra Gothenburg University Institute of Conservation Box 130 St. Nygatan 23-25 40530 Gothenburg +46 31 7734709 +46 31 7734703
[email protected]
COST C16 Management Committee
United Kingdom Mr. Stephen Ledbetter University of Bath Centre for Window & Cladding Technology Bath +44 1225 826506 +44 1225 826556
[email protected]
COST C16 Working Group Members
Working Group 1 Cyprus Mr. Petros Lapithis Intercollege Art and Design Department 46 Makedonitissas Avenue Lefkosia CY, Cyprus +357 22 841 571 +357 22 353 682
[email protected]
Denmark Mr. Torben Dahl Institute of Technology School of Architecture Royal Danish Academy of Fine Arts Philip de Langes Allé 10 Dk-1435 Copenhagen K, Denmark +45 32 68 62 04
[email protected]
F.Y.R. of Macedonia Prof. Kiril Gramatikov St Cyril & Methodius University Faculty of Civil Engineering Dep of Concrete and Timber Structures UL. Partizanski odredi 24 POB 560 1000 Skopje + 389 2 3116066 ext. 148 + 389 2 3117 367
[email protected]
France Mr. Dominique Groleau Ecole Nationale Supérieure d'Architecture de nantes Laboratoire CERMA rue Massenet 44300 NANTES +33 2 40 59 21 22 +33 2 40 59 11 77
[email protected]
Germany Mr. Christian Wetzel CalCon Holding GmbH Goethestr. 74 80336 Munich +49-(0)89-552698-0 +49-(0)89-552698-75
[email protected]
Greece Prof. Ted Stathopoulos Concordia University / Aristotle University Engineering / Computer Science Centre for Building Studies Building, Civil Engineering 541 24 Thessaloniki
[email protected]
172
COST C16 Working Group Members
Hungary Dr. Tamás MezĘs University of Budapest for Technology and Economics Muegyetem rkp 3 1111 Budapest +36 1 463 2303 +36 1 463 1638
[email protected]
Italy Prof. Roberto di Giulio (Chairman) University of Ferrara Department of Architecture Via Quartieri 8 44100 Ferrara +39 348 3856993 +39 055 244042
[email protected]
Italy Ms. Silvia Brunoro University of Ferrara Faculy of Architecture via Quartieri 8 44100 Ferrara +39 347 1497462 + 39 0532 293627
[email protected]
Netherlands Ms. Marie Therese Andeweg Delft Universiry of Technology Faculty of Architecture Berlageweg 1 2628 CR Delft +31152787912
[email protected]
Poland Dr. Zbigniew Plewako Rzeszów University of Technology Faculty of Civil and Environmental Engineering Department of Building Structures ul. W. Pola 2 35-959 Rzeszów +48 602759595 +48 178542974
[email protected]
Portugal Prof. Luís Bragança Lopes University of Minho Building Physics and Construction Technology Laboratory School of Engineering Azurem 4800-058 Guimaraes +351253510200 +351253510217
[email protected]
Slovenia Dr. Marjana Sijanec Zavrl Building and Civil Engineering Institute ZRMK Dimiceva 12 1000 Ljubljana +386 1 280 8342 +386 1 280 8451
[email protected]
Sweden Prof. Dr. Satish Chandra Gothenburg University Institute of Conservation Box 130 St. Nygatan 23-25 40530 Gothenburg +46 31 7734709 +46 31 7734703
[email protected]
COST C16 Working Group Members
173
Working Group 2 Belgium Prof. André de Naeyer Hogeschool Antwerpen Mutsaardstraat, 31 2000 Antwerpen +323 231 6200 +323 231 9604
[email protected]
Cyprus Mr. George Hadjimichael Town Planning & Housing Department Demostheni Severi Avenue 1454 Nicosia +357 22 30 65 92 +357 22 30 65 01
[email protected]
Denmark Prof. Ebbe Melgaard (Chairman) Royal Academy of Fine Arts School of Architecture Philip de Langes Allé 10 1435 København K +45 49147850 +45 32686111
[email protected]
F.Y.R of Macedonia Mr. Tihomir Stojkov St Cyril & Methodius University School of Architecture Partizanka b.b. 91000 Skopje
[email protected]
France Dr. Gerard Guarracino ENTPE CNRS Department of Civil Engineering & Building Rue Audin 69518 Vaulx en Velin +33472047030 +33472047041
[email protected]
Germany Mr. Franz Georg Hofmann Federal Ministry of Transport Construction and Housing Merler Allee 11 53125 Bonn +49 228 252500 +49 228 9259 554
[email protected]
Greece Prof. Dimitrios Bikas Aristotle University of Thessaloniki (AUTh) Structural Engineering/Building Construction Dept. of Civil Engineering 541 24 Thessaloniki +(30)2310 995763 +(30)2310 420628
[email protected]
Hungary Ms. Agnes Novak Hungary University of Design and Crafts Budapest University of Technology and Economics Budapest +36 1 3060 394 +36 27 347 237
[email protected]
Italy Mr. Paolo Civiero Universiy of the Studies of Rome “La Sapienza” Dept. ITACA Via Flaminia, 70 00196 Roma +39 3286223091 +39 0644363083
[email protected]
Netherlands Mr. Frank Koopman Delft Universiry of Technology Faculty of Architecture Berlageweg 1 2628 CR Delft +31152784133 +31152781028
[email protected]
174
COST C16 Working Group Members
Poland Dr. Adam Rybka Rzeszow University of Technology Faculty of Civil and Environmental Engineering Department of Town Planning and Architecture W. Pola 2 35 959 Rzeszow Poland +48 17 8651624 +48 17 8543565
[email protected]
Portugal Prof. Manuela Almeida 23/05/2006 University of Minho School of Engineering Building Physics and Technology Group Civil Engineering Department Azurém 4800-058 Guimarães +351 253 510 200 +351 253 510 217
[email protected]
Slovenia Prof. Roko Zarnic University of Ljubljana Faculty of Civil and Geodetic Engineering Jamova c. 2 1000 Ljubljana +38641777517 +38614250681
[email protected]
Sweden Prof. Solveig Schulz Chalmers University of Technology Architectural Conservation SE-41296 Göteborg +46(31)7722441 +46(31)7722489
[email protected]
COST C16 Working Group Members
175
Working Group 3A Belgium Dr. Filip van Rickstal Catholic University of Leuven Civil Engineering Department Div. Building Materials Kasteelpark Arenberg 40 3001 Heverlee +3216482797 +3216321976
[email protected]
Cyprus Mr. Christos Efstathiades Public Works Department Republic of Cyprus Ministry of Communication & Works Lefkosia +35799597362 +35725332094
[email protected]
Denmark Mr. Jesper Engelmark DTU - Technical University of Denmark Planning and Management of Building Processes BYG.DTU - Dept. of Civil Engineering BYG.DTU, DTU Building 118, Brovej 2800 Lyngby +45 45251932 +45 45883282
[email protected]
F.Y.R. of Macedonia Prof. Kiril Gramatikov St Cyril & Methodius University Faculty of Civil Engineering Dep of Concrete and Timber Structures UL. Partizanski odredi 24 POB 560 1000 Skopje + 389 2 3116066 ext. 148 + 389 2 3117 367
[email protected]
F.Y.R. of Macedonia Mr. Zivko Bozinovski (Vice Chairman) St Cyril & Methodius University Institute of Earthquake Engineering and Engineering Seismology P.O.B. 101 Salvador Aljende 73 91000 Skopje +389 2176155 +389 2112163
[email protected]
France Prof. Francis Allard Université de La Rochelle Pôle Sciences et Technologie LEPTAB ave Michel Crépeau F-17042 La Rochelle cedex 1 +33 546 45 82 04 +33 546 45 82 41
[email protected]
Germany Mr. Claus Asam TU Berlin Institut für Erhaltung und Modernisierung von Bauwerken Berlin +4930399216 +493039921850
[email protected]
Hungary Dr. Tamás MezĘs University of Budapest for Technology and Economics Muegyetem rkp 3 1111 Budapest +36 1 463 2303 +36 1 463 1638
[email protected]
176
COST C16 Working Group Members
Italy Prof. Roberto di Giulio (Chairman) University of Ferrara Department of Architecture Via Quartieri 8 44100 Ferrara +39 348 3856993 +39 055 244042
[email protected]
Malta Mr. Ruben Paul Borg University of Malta Faculty of Architecture and Civil Engineering Mediterranea, 161, Triq Luigi Billion, Pembroke, Malta Msida, Malta +35679055680 +35621375185
[email protected]
Netherlands Prof. Leo G.W. Verhoef Delft University of Technology Architecture/ Restoration Berlageweg 1 2628CR Delft +31.152784179 +31.152781028
[email protected]
Netherlands Ms. Marie Therese Andeweg Delft Universiry of Technology Faculty of Architecture Berlageweg 1 2628 CR Delft +31152787912
[email protected]
Poland Mr. Alexander Kozlowski Rzeszow University of Technology Building Structure Civil Engineering W. Pola 2 35-959 Rzeszow Poland +48 178541127 +48 178542974
[email protected]
Slovenia Dr. Jana Selih University of Ljubljana Faculty of Civil and Geodetic Engineering Jamova 2 1000 Ljubljana + 386 1 4768575 + 386 1 2504861
[email protected]
Sweden Ms. Sonja Vidén School of Architecture Royal Institute of Technology Stockholm Sweden
[email protected]
COST C16 Working Group Members
177
Working Group 3B Cyprus Mr. Petros Lapithis Art and Design Department Intercollege 46 Makedonitissas Avenue Lefkosia CY, Cyprus +357 22 841 571 +357 22 353 682
[email protected]
Denmark Mr. Torben Dahl Institute of Technology School of Architecture Royal Danish Academy of Fine Arts Philip de Langes Allé 10 1435 Copenhagen +45 32 68 62 04
[email protected]
France Mr. Dominique Groleau Ecole Nationale Supérieure d'Architecture de nantes Laboratoire CERMA rue Massenet 44300 NANTES +33 2 40 59 21 22 +33 2 40 59 11 77
[email protected]
Germany Mr. Frank Ulrich Vogdt TU Berlin Institut für Erhaltung und Modernisierung von Bauwerken Berlin +4930399216 +493039921850
[email protected]
Germany Mr. Christian Wetzel (Vice Chairman) CalCon Holding GmbH Goethestr. 74 80336 Munich +49-(0)89-552698-0 +49-(0)89-552698-75
[email protected]
Greece Prof. Ted Stathopoulos Concordia University / Aristotle University Engineering / Computer Science Centre for Building Studies Building, Civil Engineering 541 24 Thessaloniki
[email protected]
Hungary Mr. András Zöld
[email protected]
Italy Ms. Silvia Brunoro University of Ferrara Faculy of Architecture via Quartieri 8 44100 Ferrara +39 347 1497462 + 39 0532 293627
[email protected]
Malta Mr. Vincent Buhagiar University of Malta Faculty of Architecture & Civil Engineering Environmental Design Department of Architecture & Urban Design Tal-Qroqq MSD 06 Msida +356 2340 2849 +356 21 333919
[email protected]
Netherlands Mr. Christoph Maria Ravesloot Faculty of Civil Engineering and Geo Sciences Department of Design and Construction Section Design and Construction Processes PO Box 5048 2600 GA Delft 31 15 2781472 31 15 2787700
[email protected]
178
COST C16 Working Group Members
Poland Dr. Zbigniew Plewako Rzeszów University of Technology Faculty of Civil and Environmental Engineering Department of Building Structures ul. W. Pola 2 35-959 Rzeszów +48 602759595 +48 178542974
[email protected]
Portugal Mr. Ricardo Mateus University of Minho Civil Engineering Department Azurém 4800-058 Guimarães +351 253 510 200 +351 253 510 217
[email protected]
Portugal Prof. Luís Bragança Lopes (Chairman) University of Minho School of Engineering Building Physics and Construction Technology Laboratory Azurem 4800-058 Guimaraes +351253510200 +351253510217
[email protected]
Slovenia Dr. Marjana Sijanec Zavrl Building and Civil Engineering Institute ZRMK Dimiceva 12 1000 Ljubljana +386 1 280 8342 +386 1 280 8451
[email protected]
Sweden Prof. Dr. Satish Chandra Gothenburg University Institute of Conservation Box 130 St. Nygatan 23-25 40530 Gothenburg +46 31 7734709 +46 31 7734703
[email protected]
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