epfl_th4258

POUR L'OBTENTION DU GRADE DE DOCTEUR ÈS SCIENCES

PAR

acceptée sur proposition du jury:

Prof. A. Mermoud, président du juryProf. J.-L. Scartezzini, directeur de thèse

Prof. A. Bassi, rapporteur Prof. A. G. Hestnes, rapporteur

C. Roecker, rapporteur W. Weiss, rapporteur

Architectural Integration and Design of Solar Thermal Systems

Maria Cristina MUNARI PROBST

THÈSE NO 4258 (2008)

ÉCOLE POLYTECHNIQUE FÉDÉRALE DE LAUSANNE

PRÉSENTÉE LE 17 DÉCEMBRE 2008

À LA FACULTE ENVIRONNEMENT NATUREL, ARCHITECTURAL ET CONSTRUIT

LABORATOIRE D'ÉNERGIE SOLAIRE ET PHYSIQUE DU BÂTIMENT

PROGRAMME DOCTORAL EN ENVIRONNEMENT

Suisse2009

I

A Léonard e François:

ce l'abbiamo fatta!

III

ACKNOWLEDGMENTS

This work would not exist without the fundamental contributions of outstanding professionals who shared with me their competences, precious friends that offered me their warmest moral support, family and institutions that made this research compatible with my family duties.

I wish to express my deepest gratitude to all these generous persons, in particular to:

My thesis director, Professor Jean-Louis Scartezzini, for constantly ensuring the best working conditions to carry on this research in his great laboratory;

Christian Roecker, moral co-director of this thesis, for his constant support, precious suggestions, constructive discussions, and true friendship during all these years;

All the members of the jury, Andrea Bassi, Werner Weiss and Anne Grete Hestnes, and the jury president André Mermoud, for having accepted to dedicate their time to this thesis, for their precious inputs and for having made the exam discussion an enjoyable moment;

The EU and the Federal Office of Energy for funding my research activities within the projects SOLABS and Coloured Glazing, and the projects partners for the fruitful collaboration and constructive discussions;

All the architects, facade manufacturers, engineers and friends who took part in the surveys; in particular all the professionals who spent time answering and commenting the questionnaires in person;

Anne Grete Hestnes for her major contribution in spreading the results obtained within this research;

Jean Bernard Gay, for his friendship and his generosity in sharing his knowledge (and for making me truly understand the building physics!);

Vesna Kosoric for her contribution in collecting the data needed to carry on the analysis of the products available on the Swiss market;

Pierre Loesch for his highly professional technical support, but even more for his true friendship, kindness and daily moral support, during all these years of office sharing;

My dear friend Paola Tosolini, for her unremitting presence in all the toughest moments, and for bringing a therapeutic Venetian breeze in the Lab;

The LESO secretaries Suzanne L'Eplattenier, Sylvette Renfer and Barbara Smith, for their constant kindness and understanding;

Laurent Deschamps and all computer scientists for their effective technical support;

IV

All the "Lézards" for the unique friendly atmosphere they contribute to create in this Lab;

Pierre-Alain Probst and my husband for patiently re-reading this manuscript;

Farnaz Moser for having managed to obtain an outstanding day nursery at EPFL;

Christine Wuillemin and all the educators of Polychinelle for the great day care quality they offered to my children, without which I would have never been able to concentrate on this work;

My parents, who crossed the Alps a crazy number of times to help me dealing with all my responsibilities. My mum in particular for all her last minute rescuing and all the hours she spent in the Cisalpino train to come here;

My parents-in-law, Pierre Alain and Claude, for their constant, kind availability, and their fundamental help in taking care of the children;

Finally my warmest thanks goes to my three beloved men Jérome, Léonard and François for their encouragements, their constant support, their good humour, and for reminding me daily what is really important in life.

V

ABSTRACT

Although mature technologies at competitive prices are largely available, solar thermal is not yet playing the important role it deserves in the reduction of buildings fossil energy consumption. The generally low architectural quality characterizing existing building integrations of solar thermal systems pinpoints the lack of design as one major reason for the low spread of the technology. As confirmed by the example of photovoltaics, the improvement of the architectural quality of building integrated systems can increase the use of a solar technology even more than price and technique. This thesis investigates the possible ways to enhance the architectural quality of building integrated solar thermal systems, and focuses on integration into façade, where the formal constraints are major and have most impact. The architectural integration problematic is structured into functional, constructive and formal issues, so that integration criteria are given for each architectural category. As the functional and constructive criteria are already recognized by the scientific community, the thesis concentrates on the definition of the formal ones, yet underestimated or misunderstood. The results of a large European survey over architects and engineers perception of building integration quality are presented, showing that for architects formal issues are not a matter of personal taste, but that they relate to professional competences, and consequently can be described. The solar system characteristics having an impact on the formal quality of the integration are identified (formal characteristics), the related integration criteria are assessed, and finally integration guidelines to support architect integration design work are given. The limits imposed by the collectors available in the market are pointed out, showing that the lack of appropriate products is nowadays the main barrier to BIST (Building Integrated Solar Thermal) architectural quality. A methodology for the development of new solar thermal collectors systems responding at the same time to energy production needs and building integration requirements is defined. The importance to ensure, within the design team, the due professional competences in both these fields is stressed. Three progressive levels of system “integrability” are defined in the path leading to the concept of "active envelope systems" and the main role of facade manufacturers is highlighted. The methodology is applied to unglazed and glazed flat plate systems, and new façade system designs are proposed that show the relevance of the proposed approach.

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Key words: Solar thermal I Architectural integration I Active facade I Integration quality I Facade integration I Solar architecture

VII

RESUME

Bien que des technologies éprouvées et fiables soient aujourd'hui largement disponibles à des prix compétitifs, le solaire thermique ne joue de loin pas le rôle qu'il mérite dans la réduction de la consommation d'énergies fossiles des bâtiments.

La très faible qualité architecturale qui caractérise de façon générale l'intégration du solaire thermique au bâtiment, montre du doigt le manque de "design" comme une des raisons principales de la faible diffusion de ces technologies. Comme l'exemple du photovoltaïque le confirme, les aspects formels liés au développement d'une technologie solaire doivent aussi être attentivement traités pour que le système solaire devienne réellement intéressant aux yeux des utilisateurs et des architectes.

Cette thèse explore les voies possibles pour améliorer la qualité architecturale des systèmes solaires thermiques intégrés au bâtiment, et se concentre sur les intégrations en façade où les contraintes formelles sont majeures et ont un impact fondamental.

La problématique de l'intégration architecturale est structurée en questions fonctionnelles, constructives et formelles; des critères d'intégrations sont donnés pour chacune des trois catégories architecturales. Puisque les critères fonctionnels et constructifs sont déjà reconnus par la communauté scientifique, cette thèse se concentre sur la définition des critères formels, encore sous-estimés ou mal compris.

Les résultats d'une large enquête Européenne sur la façon dont architectes et ingénieurs perçoivent la qualité d'intégration sont présentés. Les jugements des architectes ont été cohérents ce qui indique que les questions formelles ne sont pas une affaire de goût personnel, mais qu'elles sont liés à des compétences professionnelles et peuvent en conséquence être décrites. Les caractéristiques du système solaire ayant un impact sur la qualité formelle de l'intégration sont identifiées (caractéristiques formelles), les critères d'intégrations y relatifs sont établis, et finalement des conseils d'intégration sont donnés comme appui au travail d'intégration de l'architecte.

Les limites imposées par l'apparence des capteurs actuellement disponibles sont mises en évidence.

Une méthodologie pour le développement de capteurs solaires répondant en même temps aux besoins de production d'énergie et aux exigences d'intégration au bâtiment est définie. L'importance d'assurer à l'intérieur du groupe de développement les bonnes compétences dans ces deux domaines est mise en évidence.

VIII

Trois niveaux progressifs d'intégrabilité du système sont définis sur la voie menant au concept de "systèmes de façade actifs", et le rôle fondamental des façadiers est souligné. La méthodologie est appliquée aux systèmes solaires vitrés et non vitrés, et des exemples de développement de nouveaux systèmes sont proposés qui montrent l'intérêt de l'approche proposée. Mots Clés: Solaire thermique I Intégration architecturale I Façade active I Qualité d'intégration I Intégration en façade I Architecture solaire

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CONTENTS

Acknowledgments III

Abstract V

Summary IX

0. STRUCTURE OF THESIS 3

1. INTRODUCTION 7

1.1 Solar thermal in building 9

1.2 Solar thermal technologies 13

1.3 The interest of facade applications 23

2. STATE OF THE ART 27

2.1 Solar thermal technologies 29

2.2 Architectural integration issues 30

2.3 The case of photovoltaic 32

2.4 Outlook 34

3. ARCHITECTURAL INTEGRATION QUALITY 37

3.1 Facade integration functional aspects: "UTILITAS" 40

3.2 Facade integration constructive aspects: "FIRMITAS" 42

3.3 Facade integration formal aspects: "VENUSTAS" 43

3.3.1 Defining formal aspects of architectural quality: web survey 46

3.3.1.1 Survey methodology 46

3.3.1.2 Survey results, best to worst. 49

3.3.1.3 Survey highlights 53

3.3.2 System characteristics affecting formal integration quality 54

4. ARCHITECTURAL INTEGRATION REQUIREMENTS 55

4.1 Field(s) positioning and dimensioning 58

4.2 Collector material and surface texture; absorber colour 59

4.3 Shape and size of the modules 62

4.4 Type of jointing 63

4.5 Examples of good integration 63

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5. EXISTING COLLECTORS "INTEGRABILITY" 73

5.1 Product flexibility on the Swiss market 75

5.1.1 Size and position of collector field 77

5.1.2 Collector material, surface texture and absorber colour 77

5.1.3 Shape and size of the modules; type of jointing 77

5.2 Available innovative products 78

6. DEVELOPMENT METHODOLOGY FOR NOVEL SOLAR THERMAL SYSTEMS 101

6.1 Collector as part of multifunctional envelope systems 103

6.2 Building integration requirements: "UTILITAS", "FIRMITAS", "VENUSTAS" 104

6.2.1 UTILITAS - functional integration 105

6.2.2 FIRMITAS - constructive integration 106

6.2.3 VENUSTAS - formal integration. 107

6.2.3.1 Basic level of integrability 107

a. module shape and size 107

b. Module visible jointing 110

c. Collector colour 113

d. Visible surface textures and finish 114

6.2.3.2 Medium level of “integrability” 117

6.2.3.3 Advanced level of integrability 118

6.3 Market trends /users preferences 118

6.4 Production feasibility and eco-impact. 119

7. METHODOLOGY VALIDATION FOR AN UNGLAZED SOLAR THERMAL SYSTEM 121

7.1. Methodology validation framework 123

7.2 Design approach 124

7.3 Evaluation of users' wishes 125

7.3.1 Module shape, size, jointing. 125

7.3.2 Surface texture and finish 128

7.3.3 Surface colour 129

7.3.4 Application to buildings 131

7.3.5 Visibility 133

7.4 The resulting collector 135

7.4.1 Characteristics of the new collector 135

7.4.1.1 Module shape and size, module jointing 135

7.4.1.2 Surface colour, texture, and finish 136

7.4.2 Wall and cladding systems 138

a - Sandwich plank collector for wall systems 138

b - Cladding plank collector 138

7.4.3 Development into a façade system 138

7.4.3.1 The Demosite facade prototype (approach1) 140

7.4.3.2 Approach2: adapt collector to an existing facade system 145

XI

7.5 Architectural integration guidelines applied to Solabs planks 146

7.5.1 System position and dimension 146

7.5.2 Collector colours and materials 146

7.5.3 Module size and shape; module jointing 146

7.6 Application examples 148

7.6.1 Survey examples 148

7.6.2 Commercial buildings: a new Ikea standard 152

7.6.3 Office buildings: new MSI headquarters in Lausanne-Vidy 154

7.6.4 Residential building retrofit, Préverenges. 156

7.6.5 Residential building retrofit in La-Chaux-de-Fonds 160

8. METHODOLOGY VALIDATION FOR A GLAZED SOLAR THERMAL SYSTEM 163

8.1 Context of study 165

8.2 The approach: working on glazing transparency 166

8.3 One solution: combining selective filters and diffusing treatments 167

8.3.1 Thin film selective interference filters 168

8.3.2 Diffusing glass treatments 169

8.3.3 Full glass treatment and up scaling 172

8.4 Addressed key integration issues 177

8.4.1 Glass surface colour 177

8.4.2. Glass surface texture 178

8.4.3. Non active elements (dummies) 180

8.5 Next steps 182

8.6 Integration simulations 182

9. CONCLUSIONS 191

ANNEXES

Annexe: IEA TASK draft "Solar energy and architecture" 195

Annexe 2: web survey architectural integration quality of B.I.S.T. 203

Annexe 3: E.U. project SOLABS 211

Annexe 4: web survey: users wishes for unglazed collector formal characteristics 217

Annexe 5: survey : users wishes for glazed collectors formal characteristics 231

Curriculum Vitae 237

STRUCTURE OF THESIS

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SOLAR THERMAL IN BUILDINGS I SOLAR THERMAL TECHNOLOG-IES I THE INTEREST OF FACADE APPLICATIONS

TECHNICAL ELEMENTS ARCHITECTURAL APPLICATIONS

FIRMITAS

UTILITASARCHITECTURE = NEED ALSO FORMAL CONTROL

CLEAR NEED OF NEW PRODUCTS CONCEIVED FOR BUILDING INTEGRATION !

CONCLUSIONS

CONSTRUCTIVE ASPECTS (FIRMITAS)FUNCTIONAL ASPECTS (UTILITAS) FORMAL ASPECTS (VENUSTAS)

WHAT'S FORMAL QUALITY?

INTEGRATION GUIDELINES

INTEGRATION CRITERIA

PRODUCTS FLEXIBILITY IN SWISS MARKET

AVAILABLE INNOVATIVE PRODUCTS

REQUIRED SYSTEM FLEXIBILITY

ARCHITECTURAL INTEGRATION QUALITY

THE FACADE APPLICATION: ARCHITECTURAL ISSUES (PROBLEMATIC AND STATE OF THE ART)

FIRMITAS: CONSTRUCTIVE ISSUES UTILITAS: FUNCTIONAL ISSUES VENUSTAS: FORMAL ISSUES

WEB SURVEY

METHODOLOGY VALIDATION FOR A GLAZED SOLAR THERMAL SYSTEM

METHODOLOGY VALIDATION FOR AN UNGLAZED SOLAR THERMAL SYSTEM

FIELDPOSITION &DIMENSION

MODULESHAPE

MODULEJOINTING

MATERIALS&

TEXTURES

ABSORBERCOLOUR

CHARACTERISTICS AFFECTING INTEGRATION QUALITY

DEVELOPMENT METHODOLOGY: COLLECTOR AS PART OF MULTIFUNCTIONAL ENVELOPE SYSTEMS

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MariaCristina Munari Probst Chapter 1 I Introduction

THESIS STRUCTURE I 0

The objective of this thesis is to investigate possible ways to enhance the architectural quality of building integrated solar thermal systems (BIST) in order to help spreading the use of these technologies, by making them appealing to both users and building designers. In the perspective of an increased solar energy demand in buildings, a special attention is dedicated to facade integration.

The architectural issues related to the integration of solar thermal collectors into building facades are structured into functional issues, construction issues and formal issues. Functional and construction integration issues, already recognized by the scientific community, are resumed in chapter 2 and related integration criteria are given in the first part of chapter 3. The formal aspects, yet not duly treated, are rather the object of an extensive research presented in chapter 3, 4 and 5.

To make all further considerations relevant, a shareable definition of formal quality is searched at first (chapter 3). To counter the widespread thought that formal issues are a matter of personal taste and to help avoiding subjective interpretations, this part of the work is supported by a large European survey over architects’ perception of BIST formal quality.

The collectors characteristics having an impact on this quality (i.e. formal characteristics) are identified (field position and dimension; collector visible material(s) and surface texture(s); absorber colour; module shape and size; module jointing). Integration criteria are then given for each of these characteristics together with practical guidelines to support architects dealing with the low formal flexibility offered by the products now available on the market (chapter 4).

The formal flexibility offered by available collectors is analyzed showing a clear need for new products conceived for building integration (chapter 5).

Chapter 6 is the heart of this thesis and presents a methodology for the development of novel solar thermal collectors systems able to answer at the same time to functional, constructive and formal integration requirements while ensuring energy efficiency and dealing with production constraints.

The methodology is validated through two real research and development projects, one in the field of unglazed flat plate collectors and the other in the field of glazed collectors, presented respectively in chapter 7 and chapter 8.

In the conclusions major outcomes are presented, together with a critical overview of the results obtained, both theoretical and practical.

6


7


INTRODUCTION

8


9


INTRODUCTION I 1

Abstract. The great potential of active solar thermal technologies to help reduce CO2 gases emissions in the building field is highlighted. The urgency to improve the integration quality of BIST (building integrated solar thermal) to support the spread of these already efficient and cost effective technologies is emphasized. The various available technologies are presented and the most promising for building applications are identified as glazed and unglazed flat plates, as well as evacuated tubes. The interest of facade application is discussed in terms of added exposed surfaces and energy production specificities.

1.1 Solar thermal in building

Present world energy demand is growing continuously, together with the related CO2 gas emissions in the atmosphere resulting from the use of non renewable energies.

FIG1.1: Global world primary energy consumption from 1980

and 2007 in Million tonnes oil equivalent.

Data from BP Statistical Rewiew of World Energy, June

2008 [1].

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In such a context the role of renewable energies will be crucial to help reaching, or at least getting close, to the Kyoto protocol objectives asking for a global reduction of greenhouse gases emissions of 5.2% compared to the year 1990 (corresponding to a cut of about 30% if compared with the emission levels that would be expected without the Protocol by 2010!) (fig1.1 and 1.2) [1.2][1.3][1.4].

Among renewables, solar energy is an enormous resource in comparison to fossil energies: the sun radiation energy reaching the earth in one hour is higher then the actual energy demand of the whole world for one year! (fig.1.3) [1.5].

Within solar technologies, the greatest role is played by solar thermal (heating and cooling), a high efficiency, though simple and proven technology, with a payback time

Fig 1.3: Annual solar energy radiation that reaches the earth, proven fossil fuel reserves and annual global consumption of commercial energy. Data from BP Statistical Rewiew of World Energy, June 2006.

Fig: 1.2 Global averages of the concentrations of the major, well-mixed, long-lived greenhouse gases - carbon dioxide, methane, nitrous oxide, CFC-12 and CFC-11 from the NOAA global flask sampling network since 197 Source: NOAA Earth System

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much shorter then lifetime. Its efficiency is about 4 times higher than the one of photovoltaic, with a cost per kWh of 6 to 10 times cheaper. Even if in the last years the market is growing fast (+10% worldwide in 2005, +23.5% in EU in 2005 and +44% in EU in 2006) solar thermal is really not playing the impor-tant role it deserves in the reduction of buildings fossil energy consumption [1.6][1.7].

The 20,4 millions m2 of solar thermal (about 2GWth power) installed in EU at the end of 2006 are still very far from the goals set by the White Paper on Renewables in 1997, asking for 100 millions m2 by 2010 (i.e. 70GWth) [1.6][1.8].

One reason for the low spread of solar thermal can certainly be found in the lack of appropriate promotion policies, issue that EU is finally facing by trying to set common

Fig. 1.4: Million m2 of solar thermal installed in EU:

comparison between current trend and the European Union

objectives set in the White Paper (in m2). Source:

EurObserv'ER 2007

Fig. 1.5: Total capacity of glazed flat plate and evacuated

tube collectors in operation at the end of 2005 in kWth per

1'000 inhabitants (only countries with more than

2kWthermal per 1000 inhabitants are considered). Data from IEA, Weiss et all,

2007[7].

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targets and new rules*[1.9] [1.10] [1.11]. The cost effectiveness and simplicity of solar thermal, though, indicate that this is not the sole reason for the general lack of interest for these technologies by building professionals. The generally low architectural quality characterizing existing building integrations of solar thermal systems pinpoints the lack of design as one main reason for the low spread of the technology. As confirmed by the example of photovoltaic, the formal aspects related to the development of a solar technology also have to be carefully treated to make solar systems appealing to both users and building designers (fig 1.6 and 1.7) [1.12][1.13][1.14][1.15][1.16][1.17][1.18]. For solar thermal, building integration is crucial: whilst PV can be installed far from the consumption place (electricity can be transported and stored easily in the grid with very low losses), solar thermal energy requires on the contrary to be produced and stored near the consumption place, i.e. in the building itself. This thesis intends to investigate the possible ways to enhance the architectural quality of building integrated solar thermal systems, and focus on integrations into façade, where the formal constraints are major (see next section 1.2).

Fig. 1.6 and 1.7: Passive solar house integrating a multifunctional photovoltaic cantilever roof, south facade and PV system detail. St.Sulpice (CH), 2000-01. Arch. MC Munari Probst

*This is changing, and the gap should be reduced, thanks to a new trend characterizing thedecisions of the European Parliament in the last 2 years. In 2006 The EU Parliament voted with a very large majority a Resolution asking for a strong new directive to promote RES-H (Renewable Heating and Cooling). In January 2007 the EUpublished the Renewable Energy Roadmap setting an overall binding 20% renewable energy target which includes fully for the very first time the RES-H ( Renewable Heating and Cooling) [1.11] The Roadmap has very recently become a law draft (January 2008). This lets really hope for the best since it is demonstrated that when policies are appropriates, objectives can easily beattained. If all Europe would actually use solar thermal like Austria, where policies of promotionhave been effective and continuous, we would count 130milions m2 of collectors installed: 30%more than the objectives set by the White Papers.

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1.2 Solar thermal technologies

Solar thermal energy can be collected in several ways and can be used for different building applications: space heating, domestic hot water production (DHW), and soon also for building cooling. It can be collected passively, through the transparent parts* of the building envelope, storing the gains in the building mass itself [2.19]. These systems can only be used for space heating, and will not be further considered in this research. Or it can be collected actively on surfaces optimized for heat collection (solar absorbers) placed on the outside of the building envelope and transported by a medium either directly to the place of use, or to a storage to be used when needed. Among active systems, two main families can be identified according to the medium used for the heat transport: air collectors systems and hydraulic collectors systems. - Air systems are characterized by lower costs, but also lower efficiency mainly due to air low thermal capacity (0.32Wh/K m3). Solar thermal gains are generally used immediately and without storage for pre-heating the fresh air needed for building ventilation (fig.1.8). The heat can be stored by forcing the air to circulate in a stones bed underneath the ground, or using the solar air as cold source in a heat pump air/water; such applications can be quite expensive, and are rare. Like passive systems, air systems can only be used for space heating and will not be further considered in this work. - Hydraulic systems, as opposed to air systems, allow an easy storage of solar gains and are suitable both for domestic hot water (DHW) production and space heating (soon also for cooling). Being also cost effective, they are by far the most promising systems in relation to the goals set by the White Paper and are the focus of this research (figs.1.9 and 1.10). Their medium consists mainly in water charged with glycol in variable percentages to avoid freezing according to the specific climate. The great thermal capacity of water (4.16 MJ/K m3, i.e. 1163 Wh/K m3) ensures a very good quality of heat exchange

Fig. 1.8: Example of air collector system

(Solarwall). Credits:

www.sustainabledesign-update.com

* With the exception of Trombe wall and transparent insulations.

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both with the absorber and the storage. The solar gains can then easily be stored in insulated water tanks and used for domestic hot water (DHW) or/and space heating on demand. If used only for the space heating, solar gains can also be stored directly in the building mass, but their use in relation to the energy demand is less flexible.

Hydraulic solar thermal systems can be divided according to their technology into: a. Evacuated tubes collectors; b. Glazed flat plate collectors; c. Unglazed flat plate collectors;

Concentrating collectors do also exist but they are not really relevant for the topic of building integration treated in this research. This is also true for unglazed plastic collectors which, due to their very low working temperatures, are only useful for swimming pool or aquaculture process water heating.

The different solar technologies are characterized by different basic forms of collectors, different working temperatures, different applications, and different costs and are presented hereafter (fig.1.11)[1.20][1.21].

Figs. 1.9 and 1.10: Share by technology of the World solar thermal market in 2005 and of the European solar thermal markets in 2006 (EU 25) Data source: IEA -W.Weiss 2007 for world share [7]; EurObserv'ER2007 for EU [6].

WORLDWIDE EU25 2006WORLD 2005

Δ

Figs. 1.11: Efficiencies and suitable applications of unglazed, glazed and evacuated tubes collectors in relation to required working temperatures.

a. Evacuated tubes collectors

Evacuated-tubes collectors are composed of several individual glass tubes, each containing an absorber plate bonded to a heat pipe and suspended in a vacuum.The great insulation power of vacuum allows working at very high temperatures even in cold climates. Evacuated tubes are suitable for all applications needing high working temperatures like industrial applications, solar cooling, but also domestic hot water (DHW) production.Their peculiar structure allows to orientate the inner absorbers independently from the module mounting angle (see figure below, right).

1 . glass tube

2 . absorber

3 . hydraulic system

4 . vacuum

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Inner absorbers orientation is independent from the module mounting angle

Suitable working temperatures 120°C

Main applications DHW, solar cooling, industry

Energy production (Switzerland -field surface: 6m2) 480 -620 kWh/m2 per year

Average cost in Switzerland per m2 (referred to a 6m2 field, data 2007)

800.- CHF/m2 (price variation 500.- to 1300.- CHF)

b. Glazed flat plate collectors

Glazed flat plate collectors are the most diffused in EU. They usually consist in boxes of about 2 m2 containing a selective metal absorber, an hydraulic circuit heated up by the absorber, a back insulation, and a covering glazing, that produces a greenhouse effect and insulates the absorber. Suitable working temperature are between 50 and 100°C, but they can rise up to 200°C in summer. Overheating risks should be taken into consideration and avoided since damages could occur on sensible parts (rubber jointing for instance). Suitable applications are DHW production and space heating.

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Suitable working temperatures 50 - 100°C

Main applications DHW, space heating

Energy production (Switzerland -field surface: 6m2) 450 - 600 kWh/m2 per year


450.- CHF/m2 (price variation 200.- to 600.- CHF)

c. Unglazed flat plate collectors

Unglazed flat plate collectors are composed of a selective metal plate (the absorber), an hydraulic circuit heated up by the absorber, and by a back insulation. Differently from glazed collectors, the absorber is not insulated by a covering glazing. Working temperatures are consequently lower than glazed collectors ones, but higher that plastic unglazed thanks to the higher conductivity of the metal absorber and higher absorption/lower emission values of the selective layer. These collectors can easily reach temperatures of 60-65° C, and can be used for swimming pools, for low temperature space heating systems, and for DHW pre-heating.

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Average cost in Switzerland per m2 (referred to a 6m2 field, data 2007) 350.- CHF/m2

d.Unglazed plastic collectors

Unglazed plastic collectors are usually made of rubber or ultraviolet (UV) stabilized polymers, and are not insulated. Due to their very low working temperatures they are only useful for swimming pool tempering or aquaculture process water heating, and are not further considered in the frame of this research.

1 . glazing

2 . absorber


4 . back insulation

combined in one

element


Main applications swimming pools



250.- CHF/m2

7


1.3 The interest of facade applications

Most solar collectors are designed as pure technical components for implementation on rooftops where the visual impact is minor and the energy efficiency maximized by the tilted mounting (fig 1.12). Plants for domestic hot water (DHW) are then usually installed on the roof and are undersized to avoid over production and the consequent overheating risk in summer-time: they cover for this reason 30 to 60% of the annual DHW needs (corresponding to about 1 to 2m2 per person in residential buildings).

If for unglazed collectors this is not a main issue, overheating represents the main risk for glazed flat plate and evacuated tubes systems. The absorber temperature of a 45° tilted glazed collector can exceed 200°C in summer in case of over production and consequent collector stagnation; this temperature can rise up to 300°C in an evacuated tube. Such temperatures can damage plastic and silicone parts (fig 1.13) [1.22].

Fig. 1.13: Measured example of frequencies of different system

temperatures during summer months (May to September) of a combisystem with a collector with poor emptying behaviour.

A frequency of 1% corresponds to about 40 hours, 0.01%

corresponds to 22 minutes.Data from IEA SHC-Task 26, R. Hausner and C. Fink, 200 [21].

Fig. 1.12: Example of undersized roof integrated solar

thermal system. Credits: www.smrhs.co.uk

23

8


The constant increase of the oil price, the general enhanced citizens’ awareness of global warming consequences, together with the clear cost-effectiveness of solar thermal technologies and the latest EU promotion policies let foresee a real boom in the market demand in the near future. In this context the envelope surfaces interesting for this application will not be just the roofs, but also the building facades. In the perspective of a growing solar fraction demand in buildings, the implementation of solar thermal collectors into facades becomes very interesting. Facade use increases the available exposed surfaces, and vertical mounting reduces the overheating risk in summer, allowing the dimensioning of the plant according to real heat needs.

In EU mid latitudes solar energy production of vertical solar thermal collectors is in fact almost constant during the whole year, which eases system dimensioning. Even if the global yearly production is reduced by about 30%, the difference is actually concentrated in summer months, when only part of this heat is used. Facade mounting does help avoiding overheating, while winter and mid season productions are not relevantly affected (fig.1.15).

Fig. 1.14: Facade integrated solar thermal system. Sport centre in Graz, Austria.

Fig. 1.15: Comparison of the monthly sun radiation available on a 45° south oriented tilted surface vs. a vertical south oriented surface in Graz, Austria (47°latitude). Data from W.Weiss, I.Bergmann, AEE-Intec.

Cf

FACADE ( 90°)

production more

constant

- 30 % ROOF ( 45°)

s u m m e r t i m e

AVAILABLE MONTHLY IRRADIATION [ k W h / m2 ]

24

9


If implementing solar thermal into building facades has definitely some interesting advantages in terms of energy production profile and surfaces availability, its integration in the facade design is particularly delicate and can easily become problematic considering the formal characteristics of collectors presently available.

References

[1.1] Data from BP Statistical Review of World Energy, June 2008.

[1.2] United Nations Environment Programme. "Industrialized countries to cut greenhouse gas emissions by 5.2%". Press release, 1997-12-11.

[1.3] Kyoto protocol to the united nations framework convention on climate change, united Nations 1998, on http://unfccc.int/resource/docs/convkp/kpeng.pdf

[1.4] The Kyoto protocol- a brief summary on http://ec.europa.eu/environment/climat/kyoto.htm

[1.5] Oliver Morton Solar energy: A new day dawning?: Silicon Valley sunrise, Nature 443, 19-22 (7 September 2006) |doi:10.1038/443019a

[1.6] 7th report EurObserv’ER: State of Renewable Energies in Europe, edition 2007, p. 2 William Gillett, Head of Unit for Renewable Energy, Executive Agency for Competitiveness and Innovation[European Commission]

[1.7] W.Weiss, I. Bergmann and G. Faninger, Solar Heat Worldwide, IEA Solar Heating and Cooling Programme, 2007.

[1.8] European Commission, Energy for the future: renewable sources of energy - White Paper for a Community Strategy and Action Plan, COM(97)599 final (26/11/1997)

[1.9] EU Solar Thermal Industry federation: Solar thermal action plan for Europe, 2007

[1.10] C. Philibert, Barriers to Technology Diffusion: The Case of Solar Thermal Technologies, International Energy Agency, Organisations for Economic and Development, 2006.

[1.11] A Renewable Energy Roadmap: paving the way towards a 20% share of renewables in the EU's energy mix by 2020, EU MEMO/07/13, Brussels 10.01.2007 http://europa.eu/rapid/pressReleasesAction.do?reference=MEMO/07/13

25

10


[1.12] Irene Bergmann, Facade integration of solar thermal collectors- A new opportunity for planners and architects, Renewable energy world, May/June 2002

[1.13] W. Weiss Editor “Solar Heating systems for Houses - A design handbook for solar combisystem”-James and James 2003: Book prepared as an account of work done within the Task26”Solar Combisystem” of the IEA Solar Heating and Cooling Programme.

Chapter 5. Building-related aspects of solar combisystem, Peter Kovacs, Werner Weiss, Irene Bergmann, Michaela Meir, John Rekestad.

[1.14] R. Krippner “Solar Technology – From Innovative Building Skin to Energy-Efficient Renovation”, in Solar Architecture, Christian Schittich (Ed.) Birkhauser, Edition Détail 2003.

[1.15] R. Krippner “L’enveloppe productrice de chaleur et génératrice d’électricité”, in Enveloppes - Concepts, Peaux, Matériaux. Sous la direction de Christian Schittich. Birkhauser, Edition Détail 2003.

[1.16] T. Herzog, R. Krippner “Synoptic description of decisive subsystems of the building skin, proceedings building a new century”, in the 5th European Conference Solar Energy in Architecture and Urban Planning, Bonn, Germany. 1998.

[1.17] A. G. Hestnes “Building integration of solar energy systems”, in Solar Energy vol.67, n.4-6, 2000.

[1.18] A.G. Hestnes “The integration of solar energy systems in architecture”, in Proceedings Eurosun 1998

[1.19] E. Mazria, The Passive Solar Energy Book (Expanded Professional Edition), Rodale Press 1979.

[1.20] M. Santamuris Editor “Solar thermal technologies for building - the state of the art”,

James and James, 2003.

[1.21] Data from Jean-Christophe Hadorn, responsible fro the solar thermal energy program at OFEN (Office Féderale de l'Energie) 2008.

[1.22] R.Hausner and C Fink, Stagnation behaviour of solar thermal systems, A report of IEA SHC – Task 26, nov. 2002.

26

Chapter 2 I State of the art

27

MariaCristina Munari Probst

STATE OF THE ART


28



29


STATE OF THE ART I 2

Abstract. The architectural issues related to the integration of solar thermal collectors into building facades are structured into functional issues, construction issues and formal issues. The state of the art in relation to the three aspects of the problematic is presented revealing major lacks in the definition of formal issues and related requirements. Similitudes and differences with the case of Photovoltaic are considered. The state of the art of available solar thermal collectors systems, fundamental to this research, is not presented here, but in Chapter 5 (Existing collectors systems integrability).

2.1 Solar thermal technologies

A comprehensive state of the art in solar thermal technologies for building is summarized in the first book of the series “Building, Energy, and Solar Technology” published by James and James and edited by M. Santamuris [2.1] - In the second chapter of the book A.M. Papadopoulos of Aristotle University Thessaloniki focuses on active solar technologies for buildings, presenting in a very comprehensive way a classification of the different solar thermal systems and the current state of the art. [2.2] Active solar thermal energy systems are classified according to the produced energy form and application, and the current status of the technologies for each application is briefly described. The various solar collector types as independent components are described and classified as 1. Flat plate collectors; 1.1. Fluid Collectors; 1.2. Air collectors, air heating collectors; 2. Vacuum-tube collectors water heating collectors; 3. Concentrating collectors; 4. Low-temperature solar collectors (unglazed collectors). - M.G. Hutchins of Oxford Brooks University, provides in the third chapter an excellent review of the advances made in the field of spectrally selective materials for solar thermal conversion and use in the building envelope with emphasis on transparent glazing. [2.3]

A.M. Papadopoulos

M.G. Hutchins

M. Santamuris


30


2.2 Architectural integration issues

Even though a specific and comprehensive study on all architectural issues related to facade integration of solar thermal collectors has not yet been conducted, a few research groups have approached the subject, either as a marginal part of a wider research topic, or by exploring some specific aspects of the problem (mainly constructive and functional aspects): - Thomas Herzog and Roland Krippner from TU Munich suggested a good approach to the problematic by structuring the architectural issues related to the building integration of solar technologies in general into the three Vitruvian categories of architecture: Functional (utilitas), construction (firmitas) and aesthetic issues (Venustas) [2.4]. They point out a general “randomness and lack of style” in "solar“ buildings, despite the high efficiency of available solar energy systems and components [2.5] [2.6] [2.7]. They remind how solar architecture is a “pars pro toto” of Architecture in general, and how as a consequence the integration of solar energy systems has to be thought as part of the global architectural design [2.8] (taking all constructive, functional and formal aspects into account). Being at variance with those asking for integrated installation, these authors state that the question of additive versus integrated installations is secondary, the most important aspect of architectural integration being to fit the elements harmoniously into an overarching visual concept. [2.8]. Practical examples of different collectors formal integration possibilities are given for different typologies of roof and facade.[2.9] - Anne Grete Hestnes from the Norwegian University of Science and Technology in Trondheim, Norway, considered the integration of solar technologies into building within IEA SHC Task 23 “Optimisation of Solar Energy Use in Large Buildings”, starting with building needs rather than from a specific solar technology. The “holistic approach” she defines consists in evaluating the different forms of energy required by the building in each specific case, finding then the most appropriate combination of passive and active solar systems [2.11]. The importance to work on conceiving solar components as multifunctional standard building elements is stressed in order to facilitate architectural integration efforts and reduce total costs [2.11] [2.12]. - Werner Weiss group from AEE INTEC - Gleisdorf, Austria – focused on building related aspects of solar combisystems within International Energy Agency TASK 26 “Solar Combisystem”. Werner Weiss group stresses the importance of providing successful building integrations in order to reach a full market penetration. The example of photovoltaic (PV) development is used to demonstrate how “good

T. Herzog and R. Krippner

A.G. Hestnes

W.Weiss et all


31


integrations can have a greater impact even than price and technique”, in the spread of solar technologies [2.13]. Particular attention is dedicated to integration of solar collectors arrays into facade where large areas can be found, highlighting the thermal advantages related to the vertical use of collectors (see section 1.3) [2.13] [2.14] [2.15] [2.17]. Improving the appearance of the collectors is therefore fundamental for Werner Weiss, which states that the new solar collectors should be developed as multifunctional building elements providing both shelter and heat (functional integration - utilitas). The application into facade of thermal glazed collectors used as shielding elements and applied to the wall structure without air gap has been deeply explored in terms of building physics (vapour diffusion through the wall) (construction aspects: firmitas). The study demonstrates that this type of application is possible even if the details need to be carefully studied and limits can be found depending on the type of wall structure [2.13] [2.14] [2.16]. A survey over 50 Austrian architects’ and town planners’ general wishes on solar thermal collectors for façade pointed out the wish of freedom in design for the shape and the colour of the absorber (even if that would mean a loss in collector yield), as well as the need to improve the design of modules’ fixing details and joints (formal aspects- venustas). Finally, they stress the importance of joining the professionals efforts of architects and engineers in order to achieve a successful integration of solar collectors into building envelopes [2.14]. - Thomas Matiska and Borivoj Sourek from the Czech Technical University in Prague show the energetic interest of facade application of solar thermal for domestic hot water (DHW) production. They have investigated the thermal behaviour of facade collectors in comparison with roof collectors for DHW production in mid latitudes, coming to very positive results. They verified that if to cover the usual DHW solar fraction of 60%, facade collectors should have an area increased by about 30% compared to a 45° tilted roof collectors, increasing the solar fraction above 70% leads to a required area comparable with roof collectors, but with greatly reduced stagnation problems. They also demonstrated that, when sufficient insulation layers are used, the application of facade solar collector affects the summer indoor comfort in building in a very reasonable way: the indoor temperatures increased by no more than 1°C in all the investigated configurations. [2.18] - In the first part of his recent civil engineering thesis, Talal Salem conducted a study on possible technical solutions for the integration of solar thermal collectors into selected types of wall structures starting from the functional analysis of both the solar collector system and the building construction system. The selected building

T. Matiska and B. Sourek

T. Salem


32


construction systems are representative of the French construction habits, and only glazed flat plate collectors are considered. The study does not include the externally insulated masonry wall option, relevant for the low energy buildings market, especially when it comes to the main renovation market. The functionally compatible integration propositions are based on considerations over production, mounting and accessibility for the maintenance of the system. Their formal impact on the building is classified according to its visibility: visible system or invisible system. The integration suitability is assessed through a prospective multicriteria analysis which takes into account technical, economical, environmental, and architectural aspects covering all the phases of system life cycle (Production; Mounting; Exploitation and Maintenance; Dismantling). Amongst the 44 criteria identified to evaluate the integrated system suitability, only 11 are architectural criteria and 3 classified as "aesthetic criteria": System visibility; System modulation; System acceptation. The obtained analysis results are used to highlight the weaker aspects of the proposed integration, and some consequent improvements are proposed. In general weakest aspects are found in the multifunctional aspects of the system, while the aesthetic is considered satisfactory. As said by Salem himself the limits of this assessment methodology are in the subjectivity of the criteria selection. This being a research conducted by civil engineers, the architectural aspects of the integration represent only a minor part of the whole integration issue, and aesthetic criteria in particular have not been detailed. Even if not explicitly stressed, the importance of architectural aspects is indirectly recognised: in the classification of the 44 criteria in a influence-dependency scale, 4 out of the 6 criteria considered "very influent" are architectural criteria: positioning optimisation (formal issue); structural function (construction issue); insulation function (functional issue); system modularity (formal issue) [2.19].

2.3 The case of photovoltaic

The development of PV is certainly an interesting reference for the further formal developments of solar thermal, as it deals with the same building skin frame, and is concerned by similar surfaces and orientation needs. Nevertheless some major differences need to be highlighted:

- The basics shape, thickness and weight of the PV modules are fundamentally different than the ones characterising thermal collectors. Photovoltaic (PV) systems already offer to users and designers an important formal freedom mainly thanks to the small size of the cells and the flexibility of the electrical cabling, that greatly broaden the integration possibilities;


33


- While solar thermal absorbers require to be back insulated to avoid heat losses, photovoltaic cells requires to be back ventilated for their efficiency to be optimized;

- Photovoltaics can be easily integrated into the transparent parts of the envelope thanks to the large availability of sun shading elements, translucent cells, semitransparent modules. In the field of solar thermal this option is offered only by evacuated tubes*.

- Due to the easy transportation of electricity and the possibility to store the gains into the grid, the problem of over production does not exist for photovoltaic. Unlike solar thermal, the irregular energy production over the year resulting from the tilted mounting is not an issue; it leads on the contrary to a maximized annual production, highly recommended in consideration to Photovoltaic low efficiency and high cost (see also section 1.3);

- If for solar thermal the heat losses resulting from shadows are just proportional to the shadow size and don't bring any particular problem, photovoltaic electricity production is greatly affected by shadows, with risks of modules damage if the shadow impact is not well studied during the system design phase;

- Architectural integration possibilities offered by PV are listed in Ingo Hagemann’s book “Gebaudeintegrierte Photovoltaik” [2.20]. Available PV technologies and existing products are carefully listed and described showing how products conceived for building integration are in this field largely available and widely accepted by users and building designers. Possible integration options are identified for each of the following integration types: flat roof integration, inclined roof integration, wall façade integration, glass façade integration, skylight integration, sun protection integration. The different integration possibilities are described through over 100 existing buildings’ examples. - The architectural integration of Photovoltaic was explored also within IEA Photovoltaic Power System Programme, Task 7. The objective of Task 7 was to enhance the architectural quality, the technical quality and the economic viability of PV systems in the built environment in order to reach the successful integration of PV systems, and to spread in this way the use of this technology. Within this Task architect Tjerk Reijenga worked on the definition of architects “needs”, coming to the conclusion that a PV system “should have the correct dimensions and colour to fit the design, and should be easily mounted and made watertight in a short time”. [2.21] PV integration criteria were identified and were summarized as: - Natural integration - Architecturally pleasing - Good composition of colours and materials - Fit the gridula, harmony, composition - Matching the context of the building - Well engineered - Innovative new design [2.21] [2.22].

IEATask VII - Photovoltaic in the buildt environment

I. Hagemann


34


Key characteristics like colours, materials, module dimensions, building grid and context are considered to define the criteria. Nevertheless the limits of these criteria are in the use of words like pleasing, natural, good, which are based on a subjective appreciation of a quality and do not define the integration characteristics leading to this appreciation. Some precise requirements are actually given like fit the gridula and use innovative new designs, but they cannot be valid for all cases: decision can be taken by the architect not to fit the gridula and not to use innovative new designs and still design a coherent integration. Within the same Task an international demonstration centre for building elements called Demosite was established by the International Energy Agency and run by the Laboratory for Solar Energy and Building Physics at EPFL. Dismantled in 2008, Demosite hosted a wide set of demonstration stands showing building integrated systems from several countries: a group of about twenty pavilions hosted facade and tilted roof products from various manufacturers, while a flat roof hosted other few systems specific to that environment. This demonstration centre was an effective way to provide comprehensive information on photovoltaic integration for architects, builders, authorities and other interested parties. [2.23]

2.4 Outlook

The state of the art shows that the crucial need to improve the architectural quality of building integrated solar thermal has been generally recognised as one key issue to spread the use of solar thermal technologies. A systematic study of the problematic has not been conducted yet, and the ways leading to an enhanced architectural quality of building integrated solar thermal are still to be traced that consider all aspects of architecture: functional , constructive and formal ones. The topical importance to thoroughly explore these issues and give appropriate answers is, among other indicators, confirmed by the planning of a new IEA Task "Solar Energy and Architecture" dedicated to the architectural aspects of solar technologies application, including solar thermal: it must be noticed that the word "Architecture" appears for the first time in the title of one planned task, after 30 years of IEA researches and 40 Tasks mainly focusing on solar technologies for building application [see Task draft in annexe1]. The example of photovoltaic shows the importance to provide products conceived for building integration to support the spread of solar technologies. The state of the art of available solar thermal collectors systems (presented in chapter 5) shows a clear lack of this type of products in the solar thermal market (also due to the characteristics of solar thermal collectors, formally less flexible then photovoltaic ones).

IEATask7 -Demosite


35


References

[2.1] M. Santamuris Editor “Solar thermal technologies for building - the state of the art”,

James and James, 2003.

[2.2] A.M. Papadopoulos, Active solar heating and cooling for buildings, in Solar thermal technologies for building - the state of the art, James and James, 2003, M. Santamuris Editor.

[2.3] M.G. Hutchins, Spectrally selective materials for efficicnt visisble, solar and thermal radiation control, in Solar thermal technologies for building - the state of the art, James and James, 2003, M. Santamuris Editor.

[2.4] Marcus Vitruvius Pollio, De Architectura, 30-20 bC, Pierre Gros editor, Einaudi, 1997.

Also available on-line: www.penelope.uchicago.edu/Thayer/E/Roman/Texts/Vitruvius/home.

[2.5] R. Krippner, T. Herzog “Architectural aspects of solar techniques – Studies on the integration of solar energy systems”, in Proceedings Eurosun 2000, 3rd ISES-Europe Solar Congress, Cophenagen, Denmark.

[2.6] T. Herzog “Solar Design”, in Detail n°3/1999, ed. Birkhauser.

[2.7] R. Krippner “L’enveloppe productrice de chaleur et génératrice d’électricité”, in Enveloppes - Concepts, Peaux, Matériaux. Sous la direction de Christian Schittich. Birkhauser, Edition Détail 2003.

[2.8] R. Krippner “Solar Technology – From Innovative Building Skin to Energy-Efficient Renovation”, in Solar Architecture, Christian Schittich (Ed.) Birkhauser, Edition Détail 2003.

[2.9] R. Krippner “Endbericht Soleg- Solar gestüzte Energieversorgung von Gebäuden”, Verbundprojekt mit der bayerischen Industrie gefördert von der Bayerischen Forschungsstiftung, 2001, par.3.12 “Architeknoische Aspekte solarer Energietechnik”, Roland Krippner]

[2.10] T. Herzog, R. Krippner “Synoptic description of decisive subsystems of the building skin, proceedings building a new century”, in the 5th European Conference Solar Energy in Architecture and Urban Planning, Bonn, Germany. 1998.

[2.11] A. G. Hestnes “Building integration of solar energy systems”, in Solar Energy vol.67, n.4-6, 2000.

[2.12] A. G. Hestnes “The integration of solar energy systems in architecture”, in Proceedings Eurosun 1998.

[2.13] I. Bergmann “Facade integration of solar thermal collectors – A new opportunity for planners and architects”, in Renewable Energy World, June 2002.

[2.14] W. Weiss Editor “Solar Heating systems for Houses - A design handbook for solar combisystem”-James and James 2003: Book prepared as an account of work done


36


within the Task26”Solar Combisystem” of the IEA Solar Heating and Cooling Programme.

Chapter 5. Building-related aspects of solar combisystem, Peter Kovacs, Werner Weiss, Irene Bergmann, Michaela Meir, John Rekestad.

[2.15] W. Weiss “Solar heating systems – status and recent developments”, in Proceedings ISES 2003 (Plenary session presentation).

[2.16] I. Bergmann, W.Weiss“Fassadenintegration von thermischen Sonnenkollektoren ohne Hinterlüftung”, AEE Intec, Arbeitsgemeinschaft ERNEUERBARE ENERGIE, Institut für Nachhaltige Technologien, march 2002.

[2.17] JM Suter, T Letz “IEA SHC Task 26 “Solar Combisystem” is completed – a fruitful international 4 –years co –operation between researcher and industry with a number of practical results”, in proceedings CISBAT 2003.

[2.18] Thomas Matiska and Borivoj Sourek, Facade Solar Collectors, in Solar Energy 80 (2006) 1443-1452

[2.19] T. Salem Intégration des composants solaires thermiques actifs dans la structure bâtie, PhD thesis, Laboratoire des Sciences de l'Habitat de l'Ecole Nationale des Travaux Publics de l'Etat, Départemant Génie Civil et Bâtiment (DGCB), URA CRNS 1652.

[2.20] Ingo B. Hagemann “Gebaudeintegrierte Photovoltaik – Architektonische Integration der Photovoltaik in die Gebäudehülle”, Ed. Rudolf Müller 2002.

[2.21] Tjerk Reijenga “What do architect need?”, in Proceedings of the IEA PVPS Task VII, 2000.

[2.22] Tjerk Reijenga “Architectural quality of building integration of solar energy – case studies in The Netherlands”, in proceedings of 2nd World Solar Electric Building Conference, Sydney, March 2000.

[2.23] C.Roecker; P. Affolter; A. Muller, F.Schaller, Demosite : The Reference for Photovoltaic Building Integrated Technologies, In 17th European Photovoltaic Solar Energy Conference - Munich (2001).

37

MariaCristina Munari Probst Chapter 3 I Architectural integration quality

ARCHITECTURAL INTEGRATION QUALITY

38


39


ARCHITECTURAL INTEGRATION QUALITY I 3

Abstract. The architectural issues related to the building integration of solar thermal collectors are investigated, structuring them into functional, constructive and formal issues. Functional and constructive integration criteria and guidelines are given. Formal issues, less recognized, are investigated to define formal quality. A large European survey addressed to experienced architects, engineers and façade manufacturers is presented that backs up this investigation. The first key result is the definition of the collectors’ characteristics having an impact on the formal integration quality (formal characteristics). The integration requirements for each of these formal characteristics, together with guidelines to support the work of architect, will be given in Chapter 4.

As discussed in chapter 2, the architectural integration quality can be defined as the result of a controlled and coherent integration of the solar collectors simultaneously under all functional, constructive, and formal (aesthetic) points of view * [3.1] [3.2]. If the functional and constructive requirements for the integration of solar thermal collectors into facades have already been given attention, the formal requirements, fundamental for their acceptability, have not yet been duly explored and remain largely underestimated. The main reasons are the very marginal role played by architects in solar thermal development, and the lack of engineers’** professional competences over formal issues they often perceive as mainly subjective and consequently hard to define.

*Vitruvius, architect, engineer and writer at the time of Emperor Augustus (1th century BC), gives in his treates “De Architectura” (the sole ancient treatise on architecture surviving from classical antiquity) the first known definition of architecture that is still relevant today. Architecture is defined as a coherent whole fulfilling at once functional, constructive and formal requirements (Utilitas, Firmitas Venustas). If one of these aspects is missing, or is not considered enough, the global architectural quality of the building will be affected. ** The word Engineers is intended to cover all technical professions in the field of solar thermal and building construction.

40


3.1 Facade integration functional aspects: UTILITAS

The need for a functional integration of solar thermal collectors into the building envelope and the related concept of collectors as multifunctional building elements, providing both shelter and heat, have been theorized by several researchers. The main stressed advantages are the reduction of the overall cost and the ease of the architectural integration effort (see state of the art, chapter 2). The integration of solar thermal collectors in the building envelope means, from the functional point of view, to integrate the solar heat collection function (active production of solar thermal energy) while preserving/ensuring the other envelope functions. The building envelope has to fulfil a wide and complex set of protection and regulation functions, with the following objectives: - It has to protect from intrusion, rain, wind and noise; - It must insulate from winter cold and excessive summer heat; - It has to regulate the visual relations inside/outside and outside/inside, the supply of

fresh air, of daylight and of passive solar gains; - It has to ensure users’ comfort while reducing the use of non renewable energies

for heating, cooling and lighting to the minimum. To comply with these different needs, the envelope is articulated into different parts, each of them being able to fulfil a specific set of functions*: opaque and transparent/translucent parts, composed by fixed and/or mobile elements [3.3][3.4].

- The opaque parts fulfill mainly protection functions (from intrusions, rain, wind, noise, heat, cold)

In buildings responding to the new energy standards, opaque parts are mainly composed by multilayer systems. The optimization of the protection function from heat and cold makes it a common practice to use an insulation layer and to place it outside the carrying structure of the building. This helps avoiding important thermal bridges and related condensation problems, it is more effective against summer overheating and allows optimizing the use of passive thermal gain: solar gains in winter and night free cooling in summer can be stored into the mass of the building structure.

The external positioning of the insulation layer requires the use of new layer(s) to protect insulation from weather and mechanical solicitations, i.e. external cladding with or without waterproofing, according to cladding type.

The protection functions fulfilled by the opaque envelope parts imply mainly the use of fixed elements (with the exception of doors and – rarely – opaque ventilation elements).

- The transparent (or translucent) parts are meant to collect daylight and passive solar thermal gains, to provide the visual contact with the outdoor, while still

* This is clearly a simplification. For more details regarding the possible articulations of facades, please refer to “Facade Construction Manual”, Herzog Krippner, Lang [3.3].

41


ensuring the whole set of protection functions. Transparent parts are mainly composed of mobile components and systems: to regulate day lighting and passive

solar gains, to regulate the visual relation inside/outside, and in most cases to also regulate natural ventilation.

Integrating the new function "solar collection" into the building envelope requires to understand where (opaque parts, transparent parts, fixed/mobile elements), how, and if the latter can be made compatible with the other envelope elements, materials, and functions. The compatibility level will be different according to the functional characteristics of the selected solar thermal technology (glazed flat plate, unglazed flat plate, evacuated tubes ...) and the functional characteristics of the specific envelope element (transparent/opaque, mobile/fixed, multilayer/single layer, ...)

As far as evacuated tubes are concerned, the most promising applications seem the use of the collector as balcony eave, or as sun shading in front of transparent envelope surfaces (Fig.3.1 and 3.2).

Due to the characteristics of their absorbers, glazed and unglazed flat plate collectors seem on the contrary to be less compatible with the functions of the transparent envelope parts, but possible implementations as sun shading should not be excluded. The modules dimensions and thickness together with the presence of hydraulic connections, are certainly a handicap to this kind of applications and would probably restrict them to fixed sun shadings (generally not ideal)*. The multilayer composition of flat plates is clearly suitable for the integration in the multilayer composition of the opaque envelope parts. The insulation behind the absorber plate and the insulation of the building envelope can potentially become one single element or complete each other; the absorber for unglazed collectors and the glazing for glazed ones can take, under a purely functional point of view, the role of insulation protection described above, replacing the facade cladding layer**. [3.5]

Fig 3.1: Evacuated collector with 2 added

functions: sun shading and daylight control.

Credits: Schott-Rohrglas company and Stuttgart

University; Fig 3.2: Evacuated tubes

as balcony fence. Residential building in Zurich, Architect Beat

Kaempfen.

* When combining solar energy and sun shading, photovoltaic would probably be more appropriate, as it is lighter, thinner, its module size and shape are much more flexible due to the reduced dimensions of the cells. The electric connections are also easier to deal with than hydraulic ones, which makes it possible to implement mobile devices. ** Constructive and formal aspects will be treated later.

42


3.2 Facade integration constructive aspects: FIRMITAS

While integrating solar collectors in a facade, it is fundamental to consider the construction characteristics of the specific technology to be integrated (described in section 1.2) together with the specificities of the constructive system hosting the collectors (loadbearing/non-loadbearing; single-layer/multiple-layers; single-leaf/multiple-leafs; non-ventilated air cavity/ventilated air cavity; low prefabrication level/high prefabrication level; made of masonry/concrete/wood/metal, etc.)*[3.3][3.4] In all cases it is important to check that the new multifunctional facade system meets safely all the standard facade constructive requirements: - The collector load should be correctly transferred to the loadbearing structure

through appropriate fixing; - The fixing should avoid thermal bridges and the global U value of the wall should

not be negatively affected; - The collector should withstand fire and weather wear and tear; - It should resist wind load and impact, and should be safe in case of damage; Beside these standard building construction constraints, the integration of solar collectors into facades implies considering other issues resulting from collector specificities, i.e. the presence of a hydraulic system and the high working temperatures of the absorbers: - The hydraulic system should be carefully studied to deal with water pressures

differences at the different facade levels (heights); It should be safely positioned within the envelope structure and should remain accessible; measures to avoid damages resulting from water leakage should also be taken;

- Envelope materials in contact with the absorber should withstand collector working temperature;

- Fixing details and jointing should make collector's materials expansions compatible with those of the other envelope materials;

- Safety issues should be considered for collectors within users' reach to avoid burning (ground floor, window and balcony surrounding...). This issue is particularly important for unglazed technologies where the absorber is not protected by the glazing;

- Risks of damage related to vandalism should be evaluated and appropriate measures taken;

- Vapour transfer trough the wall should avoid condensation layers, and allow the wall to dry correctly.

This last issue is probably the most delicate for integration of flat plate collectors as wall claddings without air gap, as described in section 3.1. In fact, the great range of temperatures occurring in the absorber modifies the normal physic characteristics of the vapour flow in a radical way.

* Please refer to “Façade construction manual”, Herzog, Krippner, Lang, for more details [3.3].

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In normal cases vapour migrates from inside (higher temperature) to outside (lower temperatures); vapour barriers are placed on the inner (warm) part of the wall structure to avoid condensation layers, with special attention to the protection of insulation materials and wood. Mounting solar collectors directly to the wall (without air gap), causes a fundamental modification of the vapour transfer: vapour will flow from inside to outside while the absorber is cold and would change direction when the absorber gets hot! This issue has been thoroughly studied by Werner Weiss team from AEE INTEC - Gleisdorf. The conclusions of this work is that thermal glazed collectors can be used as shielding elements applied to the wall structure without air gap, but the details need to be carefully studied and limits can be found according to the type of wall structure. Since in such configuration the absorber works as an external vapour barrier, water condensation must be able to dry towards the inside. Light timber wall are particularly vulnerable to condensation, so that careful attention must be paid to avoid trapping the water vapour between two vapour-tight layers, i.e. collector outside and vapour barrier inside (no tiles should be used for instance to cover the inner face of the wall in bathrooms and kitchens). Massive masonry walls are less sensible to humidity but are instead particularly sensible to the heat losses due to eventual thermal bridges in the fixing structure. [3.6] [3.7] [3.8]*

3.3 Facade integration formal aspects: VENUSTAS

Facades from the Latin facies, face, are the external side of the building, i.e. the public face of the architecture [3.9]. A coherent and controlled formal composition of the different architectural elements necessary to satisfy the constructive and functional requirements is crucial for the facade design.

In time, building components answering to functional and constructive needs have been developed into elements (windows, columns, chimneys, etc) conceived to answer to the whole set of architectural needs, including formal ones (Figg.3.3, 3.4, 3.5, 3.6). These architectural elements are often multifunctional, made of several construction components optimized to interface with each other, in a formally controlled composition.

* Personal discussions have been carried out on this topic with Pierre Renaud (Planair SA) and Philippe Papillon (INES) in the frame of the EU Project SOLABS, as well as with Werner Weiss and Thomas Muller at AEE INTEC Austria. The conclusion is that these types of applications are possible, but are delicates, and have to be carefully studied case by case.

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As solar thermal collectors are components of the building heating system, it is interesting to refer to older, heating system components that have with time dealt with building formal issues. From technical components, chimneys have evolved into architectural elements with specific formal characteristics, varying with place and time, and strongly characterizing the structure and the formal composition of the building, with an impact on the roof structure (figs 3.7, 3.8, 3.9, 3.10), but also on the facade composition (fig.3.11)

* Beauty of form is revealed in organisms which have developed perfectly according to their lawsof growth, and so give, “'the appearance of felicitous fulfilment of function”. John Ruskin, Thepoetry of Architecture, 1838.

Fig 3.7: Chimneys as architectural elements in Irish row houses. Credit: www.dublinblog.ie; Fig.3.8: Casa dei sette camini (house of the seven chimneys), Tolentini, Venice; Fig.3.9: John Ruskin* sketches of Chimneys from The poetry of Architecture, chapter 5: A chapter on chimneys [3.10]; Fig 3.10: Chimneys in Irish row houses; Fig 3.11 House in Santa Marta, Venice. Credit: Fotomacs, http://flickr.com/photos/8506323@N07/1447843458.

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Radiators for space heating have evolved from pure technical components to multifunctional design elements.

This architectural optimisation process has not yet taken place with the young solar thermal collection function, so that collectors still remain mainly independent

Fig 3.12: Radiator as pure technical component.

Fig 3.13: Example of radiators as multifunctional

designed elements.

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technical components, generally conceived just to optimize the solar heat collection function. This means that when these components have to be implemented into a facade, the architect’s task can become very difficult. However, considering the important size of a thermal system in relation to the façade scale, a strict formal control of solar collectors is mandatory for the facade to be architecturally acceptable. In the previous sections, studies over ways to improve functional and constructive integrability of collectors have been presented. In the following sections a research over possible ways to improve its formal integration quality is conducted.

3.3.1 Defining formal aspects of architectural quality: web survey

To understand how to improve the formal quality of Building Integrated Solar Thermal (BIST), a definition of formal quality is needed. To help define the formal quality as objectively as possible, a survey over the way(s) Architects perceive this issue was designed and conducted. Even if less represented, Engineers and Facade Manufacturers were also consulted, to identify possible differences with the Architects perception and to help improve the mutual understanding that is needed to enhance the cooperative work between these professions. Distinction was made between the three European climatic regions, Northern, Central and Southern amongst the Architects community.

3.3.1.1 Survey methodology

Web survey To reach enough people from various regions within a limited timeframe and budget, a Web based questionnaire was chosen as polling method. After consulting experienced specialists both in the architectural and in the Web domains, a draft questionnaire was set up, and tested through personal interviews with practicing architects and academics in architecture. To avoid a "climatic bias", interviewees were selected within all three European climatic regions. These interviews confirmed the interest and clarity of the concept, and provided a few suggestions and minor amendments. Moreover, they specifically offered the opportunity to openly discuss the topic, delivering an insight of the way the solar collectors were viewed by the contacted architects. In a Web survey, as opposed to personal interviews, innovative feedbacks such as proposals and new ideas are difficult to obtain. The feedbacks from the first interviewees confirmed the general approach as well as the arrangement of the questionnaire, and the final layout was adopted.

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Pool and questions The survey was proposed via the Web to a large pool of European architects, engineers and façade manufacturers, equally representing the different European climatic regions. Those questioned were asked to globally rate ten selected examples of existing BIST, using a five point scale (- - ; - ; + - ; + ; + +), concentrating on the integration quality, not on the building’s architectural value. The examples addressed both glazed and unglazed solar thermal collectors, with black and coloured absorbers. Four roof and six facade systems were proposed, comprising a variety of integration levels, building types, materials and colours. A detailed evaluation of the suitability of module sizes, shapes and colours in relation to the integration context was then proposed, to help clarify the bases of the global judgment [see questionnaire in annexe 2]. Over 1500 requests were sent out and 170 fully completed questionnaires were collected. As intended, the majority of responses came from architects, with engineers and façade manufacturers representing also an important fraction of replies. The vast majority (83%) of the respondents had more than five years of professional experience.

To summarize the appraisals, averages have been computed, converting the appreciation scale (- - ; - ; + - ; + ; + +) into a numerical scale (-100, -50, 0, +50, +100). In the following analysis the results are reported on a -100 to +100 scale to illustrate the "mark" obtained by the object by summing the individual marks and averaging them.

Survey analysis procedure The first step in the results analysis was to look for possible different approaches corresponding to the profession, the experience or the regional origin of the interviewee. A good consistency of the architects’ votes appeared quickly, independent of their climatic region of origin and the type or duration of their practice. By contrast, a different perception of the architectural quality was observed between architects and the other interviewees.

Fig 3.14: Professional activities of respondents;

Fig 3.15: European climatic region of origin of the contacted architects.

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good

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These different appreciations were taken into account in the further analysis, by treating separately the votes of two groups, with different objectives for each group: - Understand the judgements of the architects and extract the criteria defining a

good integration, admitting that Architects are the reference group for architectural quality.

- Understand the judgements of the engineers and façade manufacturers and identify the main differences with the architects, to improve the mutual understanding that is needed to enhance the cooperative work between them.

3.3.1.2 Survey results, best to worst.

The following analysis, based on the votes given by Architects, deals with both the global integration quality and the detailed appreciation of modules size, shape and colour in relation to the context. Crucial help came from the 20+ direct interviews with professors of architecture at universities and esteemed practising architects of various parts of Europe who accepted to take part in the survey and discuss it in person [3.10][3.11][3.12]. Facade integrations: - The best rating (+76 average architects rating) was given to the balcony integration presented in Case 6 (Fig.3.17). The solar modules occupy the whole breast wall of the upper stage centre, and are used as parapet external finishing. The size and shape of the modules fit the grid and match the rhythm of the façade. The collector glazing and the black colour of the absorber match the colour and material of the above window openings and are dimensioned to completely cover their area. The collectors appear as an integral part of the building.

- The Solarwall air collectors' integration into a Canadair Hangar in Canada (Case 8, Fig.3.18) is considered to be the second best integration (+54). The unglazed solar

Fig 3.17: Appreciation of the glazed collectors’ system integration of

building n°6: School in Gais (CH), Arch Gsell und

Tobler. Picture credit: Arch Gsell

und Tobler.

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system works both as a solar collector and façade cladding. It is placed on the non-carrying wall, underlining the structure of the building. The simultaneous use of the solar system as solar collector, façade cladding and composition element expressing the structure makes the integration fully successful, in spite of its rather basic building architecture.

- The Canadian school presented in Case 7 (Fig.3.19) also integrates Solarwall air-collectors into façades. The integration is considered acceptable (+29) though definitely not as good as the previous example. The solar collectors are used as façade cladding but the covering rules in relation to the building structure are not as clear as in the Canadair hangar. The square building symmetry is respected and equal facades are treated equally, but the wall surface of each façade is only covered in the upper part, making the cladding more of a decorative element than the upper layer of the wall system. The colour freedom allowed by solar wall collectors is not appropriately used as in this case the blue colour is rated between bad and a just acceptable choice, while the size and shape of the modules are considered, in accordance with the global appreciation, widely acceptable.

- Case 4 (Fig.3.20) presents a renovated building with façade integrated glazed collectors. The glazed solar modules of the system cover the whole blind wall of the lateral façade, but only that wall, characterizing and differentiating it from contiguous

Fig 3.18: Appreciation of the black Solarwall air collector system integration of building n°8: Canadair hangar in Canada. Picture credit: www.solarwall.com

Fig 3.19: Appreciation of the blue Solarwall air collector system integration of building n°7: gymnasium in Canada. Picture credit: www.solarwall.com

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façades. By contrast, in the original project (see simulation of the original building in chapter 7, p.148, fig.7.42-b) there was no solution of continuity at the angle between the two facades. In this example, the solar system fits the façade but is not part of the building composition logic. It is worth noticing that in this case the appreciations of the architects differ from those of engineers and façade manufacturers. While the last group considers the architectural quality of the integration as good (+57), for the architects it is just acceptable (+26). The size, shape and the colour of the module are considered an appropriate choice by the engineers, but for the architects the framed collectors and their black absorber are considered inadequate.

- Integrations presented in Cases 3 (Fig.3.21) and 5 (Fig.3.22) were considered definitely unsuccessful by the architects, even though the other actors of the construction process were less negative. In both buildings the solar collector is used as an added decorative element applied to the wall without any construction and/or composition logic.

The negative appreciations of Building 5 (-28) show how in architects’ understanding, the use of coloured absorbers alone is not a valuable answer to the integration design problems, considered more complex. On the other hand it is interesting to note that the same coloured absorbers had a remarkably positive impact on

Fig 3.20: Appreciation of the glazed collectors’

integration of building n°4: building renovation and

transformation into youth hostel (Austria) .

Picture credit: AEE INTEC, Austria.


integration of building n°3: single family house

(Austria). Picture credit: AEE INTEC,

Austria.

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engineers and facade manufacturers who rated the integration quality as positive (+48).

Roof integrated systems The appreciations of roof integration examples were consistent with those of façade integration. - The most appreciated integrations were the roof integrated unglazed solar collector systems presented in Ex. 9 (Fig.3.23) and 10 (Fig.3.24), both judged as very good (+54 and +57).

Fig 3.22: Appreciation of the glazed collectors’ integration of building n°5: residential building renovation (Germany).

Fig 3.23: Appreciation of the unglazed collectors’ integration of building n°10: Dwelling in Spain. Picture credit: Energie Solaire SA

Fig 3.24: Appreciation of the unglazed collectors’ integration of building n°9: Swimming pool in Switzerland. Picture credit: Energie Solaire SA

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In these examples the collectors occupy the whole roof area and have the double function of solar absorbers and upper layer of the covering system. The visible piping of Example 9 seems to disturb engineers and façade manufacturers more (!) than architects, who appreciate the controlled design of the technical elements, conceived as integral part of the building design.

- The integration presented in Case 2 (Fig.3.25) is considered as acceptable by the group of architects (+31), while the other group rate it as good (+55).

Like in the previous examples, the solar system occupies the whole roof surface of the building and has the double function of solar absorber and upper layer of the roof system, but in this case the collectors are glazed and “framed”. The size of these glazed collectors is considered acceptable, but not good; the blue colour is not considered to be appropriate. - The classic roof integration of Case 1 (Fig.3.26) is considered to be a failure. The approach reminds of the façade integration of Example 3: the collector is used only in its primary function, and is added to the building as an independent technical element.


integration of building n°2: School in Germany.


integration of building n°1 of the questionnaire:

Single family house in Germany.

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3.3.1.3 Survey highlights

Architects vs. engineers and façade manufacturers The architects consistently agreed on the value of the integration quality of the objects, be it good or bad, with only minor differences in the intensity. The consistency of architects' votes as well as the specificity of their approach, clearly different from the engineers’ one, confirmed the existence of general architectural integration criteria used as common judgement base. Engineers and façade manufacturers are generally less demanding regarding integration quality. Their responses tend to differ from those of architects in intensity, but also radically in the judgement of two examples (cases 3 & 5) (Fig.3.16). Apart from the standard bad roof application of case1, none of the remaining integration is considered unsatisfactory, indicating a general low level of criticism on formal issues. These differences in appreciation highlight that judging architectural quality rely on architects professional competences, showing the importance of using architects’ skills to deal with formal issues.

Multifunctionnality All well rated examples use the solar collectors as multifunctional elements, part of the envelope construction system. Clearly the multifunctionnality of the collector makes it easier to deal with the formal aspects of the integration (venustas). It provides the decisive advantage for the designer to architecturally compose with fewer elements, as each fulfils several functions. On the other hand this result testifies the importance for architects of all architectural aspects of the integration including functional and constructive ones (utilitas and firmitas).

Colour issue Despite an Austrian survey [3.7] showing that 85% of architects would like to dispose of coloured collectors, even at the cost of a slightly reduced efficiency, many well rated examples integrate black collector modules (!). This of course does not mean that coloured collectors would not increase the integrability, but it demonstrates that integration issues are much more complex than just choosing an appropriate collector colour. 3.3.2 System characteristics affecting formal integration quality

In most cases the rating given to the global integration quality doesn’t represent the average of the two ratings of modules shape/size and absorber colour: except for two cases the global integration quality is either higher or lower than both other ratings.

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These results showed that the global integration quality depends not just on module shape, size and colour, and helped underline how all system characteristics affecting building appearance (i.e. all formal characteristics) have an impact on integration quality.

These characteristics are at the core of the present work, and can be summarized as follows:

1. Size and position of collector field

2. Collector material and surface texture

3. Absorber colour

4. Shape and size of the modules

5. Type of jointing

Each of these characteristics will be thoroughly discussed in the next chapter.

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References [3.1] Marcus Vitruvius Pollio, De Architectura, 30-20 bC, Pierre Gros editor, Einaudi, 1997. Also available on-line:

www.penelope.uchicago.edu/Thayer/E/Roman/Texts/Vitruvius/home.

[3.2] R. Krippner, T. Herzog “Architectural aspects of solar techniques – Studies on the integration of solar energy systems”, in Proceedings Eurosun 2000, 3rd ISES-Europe Solar Congress, Cophenagen, Denmark.

[3.3] T. Herzog, R. Krippner, W. Lang, Façade construction manual, Birkhauser, edition Detail, 2004.

[3.4] C. Schittich, Enveloppes - Concepts, peaux, matériaux, Editor Christian Schittich. Birkhauser, Edition Détail 2003.

[3.5] T. Salem Intégration des composants solaires thermiques actifs dans la structure bâtie, PhD thesis, Laboratoire des Sciences de l'Habitat de l'Ecole Nationale des Travaux Publics de l'Etat, Départemant Génie Civil et Bâtiment (DGCB), URA CRNS 1652.

[3.6] T. Muller et all, Colourface- Coloured Collector facades for solar heating systems and building insulation, Eurosun 2004

[3.7] I. Bergmann, W.Weiss “Fassadenintegration von thermischen Sonnenkollektoren ohne Hinterlüftung”, AEE Intec, Arbeitsgemeinschaft ERNEUERBARE ENERGIE, Institut für Nachhaltige Technologien, march 2002.

[3.8] Personal discussions have been carried out on this topic with Pierre Renaud (Planair SA) and Philippe Papillon (INES) in the frame of the EU Project SOLABS, as well as with Werner Weiss and Thomas Muller at AEE INTEC Austria.

[3.9] Definiition of facade from N.Pevsner, J. Fleming H.Honour, Dizionario di architettura, Ed italiana R.Pedio, Giulio Einaudi Editore, 1981, p.207.

[3.10] MC.Munari Probst, C.Roecker, Integration and formal development of solar thermal collectors, in Proceedings PLEA2005, Beirut, Lebanon, pp.497-502, 2005. Conference Best Paper Award.

[3.11] MC.Munari Probst, C.Roecker, Towards an improved architectural quality of building integrated solar thermal systems (BIST), in Solar Energy (2007), doi:10.1016/j.solener.2007.02.009.

[3.12] MC.Munari Probst, C.Roecker, Deliverable 1.1 EU Project SOLABS 2005.

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MariaCristina Munari Probst Chapter 4 I Architectural integration requirements

ARCHITECTURAL INTEGRATION REQUIREMENTS

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ARCHITECTURAL INTEGRATION REQUIREMENTS I 4

Abstract. Integration criteria are assessed for each collector characteristic affecting building appearance, as defined at the end of the previous chapter. Guidelines are given to support architects dealing with the low formal flexibility generally offered by the products available on the market.

The results of the web survey described in the previous chapter underlined the complexity of the architectural integration issue and helped identify the system characteristics affecting the formal quality of the integration. For the integration to be successful, size and position of collector field, collector material and surface texture, absorber colour, shape and size of the modules, type of jointing have all to be coherent with the overall building design logic. In the present chapter each characteristic will be thoroughly treated. Integration criteria related to the characteristic will be given in boxes at the beginning of each dedicated section. Architects' freedom and limitations in the application of the criteria will be then discussed in the light of available products. Finally the suitable level of flexibility that products should provide to help meeting the criteria will be described.

GLAZED COLLECTORS FIELD

Fig: 4.1: Example of building integrated glazed collectors field. Multifamily dwelling in

Gleisdorf, Austria. This building is taken as a base

to show the formal characteristics a solar system

having an impact on the integration quality

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The BIST system shown in fig.4.1 is taken as a base to help highlight the impact of the different formal characteristics on the overall building design perception.

4.1 Field(s) positioning and dimensioning

The parameters to play/work with to control the location, shape and size of the collectors' field are: - Position and dimensions of available exposed surfaces; - Energy production goals (targets); - Solar thermal technology; - Building architectural needs. Each of these parameters has a direct influence on the others. No hierarchy exists as each of them can be used as a starting point, but can also be influenced back by the others. Energy production goals can be defined or adjusted in relation to available exposed surfaces. On the other hand, if energy production goals are clearly set at the beginning of the project, available exposed surfaces can be also created on purpose. Both ways are open and valuable; however the first approach is probably more appropriate in case of building retrofit while the second can be used mainly for new buildings. The choice of a specific solar thermal technology affects the exposed surface requirements. For the definition of system location and size, conscious architects

The position and dimension of collector field(s) have to be coherent with the architectural composition of the whole building (not just within the related façade)

Fig: 4.2 Impact of field position and dimension on the global architectural composition of the building

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should consider that solar thermal energy can be produced using several different technologies, with different surface needs. In fact, each technology has different energy production characteristics, according to its specific efficiency, and consequently different needs in terms of collector area. (see chapter 1.2 Solar thermal technologies).

Possible combinations options in terms of "technology choice - surface requirements" and "available exposed surfaces -energy production goals" should be considered to find the best compromise in terms of building integration needs and energy production goals, possibly with the help of an energy specialist.

An effective approach to the positioning and dimensioning issue is to use collectors as multifunctional construction elements. The multifunctionnality of the collector brings the decisive advantage that the designer has to architecturally compose with fewer elements, as each fulfils several functions. Within this application mode, the use of dummy elements (non-active elements with a similar appearance, fulfilling only the construction function) is a key tool to decouple the geometric/architectural dimensioning of the system from its energetic sizing. Unfortunately, the market offer in this respect is quite poor (see chapter 6). Most of the time, such applications require the development of a tailored product specific to just one project, and are therefore very expensive.

4.2 Collector material and surface texture; absorber colour

The collector visible material(s) surface texture(s) and colour(s) interact with the same characteristics of other building envelope elements; as a consequence they should be compatible with the other building skin materials, colours and textures.

Fig: 4.3 Collectors’ materials surface textures and colours.

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In this perspective, the initial choice of collector technology is crucial, as it imposes the material properties of the external - visible- system layers.

In the case of glazed collectors, the visible layers are the covering glass and the metal absorber* located behind:

- The glass is usually extra white to optimize solar energy transmission. Its surface can be lightly textured, to become slightly diffusing, or it can be perfectly smooth and transparent, with anti reflection coating sometimes available to increase the energy transmission.

- The absorber is made of a thin (usually 0.3 to 0.5 mm), generally black, metal* sheet. It is mainly made of copper, aluminium or steel, and can either be in one piece or made of a row of metal strips.

The geometry and surface texture of absorbers can be quite diverse depending on the manufacturer, but usually no flexibility is offered within one specific product. Due to the heat collection function of the absorber, its colour is almost always black or dark blue. The absorber colour results most of the time from selective coatings used to optimize

* Polymeric materials applications start to be considered but are still very marginal. For this type of applications it is suggested to refer to IEA Task 39-Polymeric materials for solar thermal applications (2007-2010) [4.1]

Fig: 4.4 Different types of glass finishing: floated extra white glass on the left, and diffusing rolled glass, on the right.

Fig: 4.5 Strip absorber made by Winkler SA (Austria).

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absorption (α) and to reduce emission losses (ε). The colour of these coatings can change according to the angle of vision, so that a black absorber may look violet or blue or red depending on the incidence angle of the sun on the surface. The more the surface irregularities, the more the absorber may look iridescent. Some other very dark colour shades are starting to appear in the market, like dark brown and dark green, but remain rare exceptions.

- In the case of unglazed collectors, the absorber metal sheet is the only visible layer. In this case, though, the absorber is made of one sole sheet (no strips systems).

- In the case of evacuated tubes there are two or even three visible layers: the glass tube, the absorber metal strip inside, and in most cases also the back module sheet.

Fig: 4.6: Example of iridescent appearance of solar absorbers

gleaming under direct sun through extra white anti

reflective glass. S+H Solar manuactory building.

Fig: 4.8 Exemple of the different visible layers of

evacuated tubes collectors: glass tube, metal strip plate

absorber, back module sheet.

Fig: 4.7: Exemple of iridescent appearance of solar absorbers

gleaming under direct sun through extra white glass.

Gleisdorf football center, Austria.

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Within the chosen technology the different products available on the market should be considered to find the absorber colour and surface texture most suitable for the given application. Yet the level of freedom offered by the available products in this sense is very low. In new buildings, or in heavy renovations, one possible approach is to define the materials of the other envelope elements so as to be compatible with the materials, textures and colours of the chosen collectors.

4.3 Shape and size of the modules.

Once more the choice of the technology is crucial since it affects the basic form of the collector module: tubes for evacuated collectors, flat plates for glazed and unglazed systems. Within the chosen technology, the specific module size and shape offered by the

Module size and shape have to be compatible with the building composition grid and with the various dimensions of the other facade elements.

Fig: 4.9 Exemple of building cladding chosen to match the appearance of collectors’ colour and texture. Credits: AKS Doma, www.aksdoma.com

COLLECTORS’ FIELD

Fig: 4.10: Module shape and size in relation to building modular grid.

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available products should be considered to find the most adapted ones. Even though most of the products offer standard module sizes, a few producers of glazed flat plate collectors, coming from the advanced Austrian market, give a remarkable freedom in this respect, so that even trapezoidal collectors can be found.

4.4 Type of jointing.

Module jointing are mostly made out of black EPDM (Ethylene Propylene Diene Monomer) thermoplastic rubber. Collectors with a metal frame are also more and more available, but the frame is still quite thick and in general no choice for its shape is possible within the specific products. Sometimes a colour on demand for the frame can be chosen.

4.5 Examples of good integration

The following building integrations of solar thermal are examples of architecturally successful implementations of collectors into facades. One example per technology (glazed and unglazed collectors and evacuated tubes) is presented.

Jointing types must be carefully considered while choosing the product, as different jointing types differently underline the modular grid of the system in relation to the building.

Fig: 4.11: Impact of module jointing on the perception of

collectors modularity

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The integration quality is described according to each key quality characteristics: Field position and dimension; Visible materials; Surface texture; Surface colour; Module shape and size; Jointing options; Use of collectors as multifunctional construction element (i.e. functional/constructive integration quality).

The rating scale is +; +/- and -.

Glazed collectors: New school building in Geis, Switzerland, 1996

Architects Gsell und Tobler, Niederteufen SwitzerlandSolar collectors: Ernst Schweizer AG, Metallbau / Bahnhofplatz 11/ CH-8908 Hedingenwww.schweizer-metallbau.ch

Even though the integrated collector system allow a very low level of formal freedom (fixed module size of 2081x 1223 mm), this building fulfils almost all set of integration criteria, showing the great impact good architects can have even when dealing with formally limited products.The integration of solar thermal was clearly considered at a very early project phase, so that the design of the south façade, of the spaces behind it, and of the roof structure have all been influenced by both the size of the collectors field, and by the fixed modular dimensions of the collectors. The collector field (63m2) occupies the whole parapet area of the façade; its modular dimensions respect the rhythm of the window opening and of the vertical wooden structure carrying the sun shading; the glazing of the collector and its dark colour matches the glass and dark colour of the window, in contrast with the lateral blind facade in concrete bricks. Even if not ideal, the rubber jointing are acceptable. Their colour and thickness are not very different from the ones of the window frames. This example presents a new building project, that could be developed around the solar system. For building renovations the integration of a fixed dimensions module is clearly more problematic.

+Collector used as multifunctional construction element

+/-Jointing options

+Module shape & size

+Surface colour

+/-Surface texture

+Visible materials

+Field position and dimension

Unglazed collectors: New CeRN building, Bursins 2004-2007

Architects Niv-o, Simplon 4, CP 127, CH - 1001 Lausannehttp:// www.nivo.chSolar collectors: Solar Roof by Energie Solaire SA / Z.I. Ile Falcon/ CH-3960 Sierrehttp://www.energie-solaire.com

The Centre d' exploitation des Routes Nationales (CeRN) is a center for the maintenance of the Swiss motorways. It is composed of different parts: a big lorry garage, a salt storage, and an office area. The project won the first Swiss competition including sustainable development as a judgment criteria.The building integrates the Energie Solaire unglazed metal collectors in the south façade, using them as multifunctional façade claddings.Non exposed facades are covered by non active elements having the same appearance as active ones (only the external metal sheet is used rather than the double metal sheet normally used for the proper collectors).To deal at best with the fixed width of the Energie Solaire absorber (86 cm), the composition of the whole building is based on this modular dimension. Despite the absorber black colour, its peculiar surface structure, and the fact that this collectors have been conceived for roofs (Solar Roof), this building presents one of the best integration example of solar thermal in building facades (see also ch. 6: Available innovative products - Energie Solaire Solar Roof system).

© atelier niv-0


+Jointing options


+Surface colour

+Surface texture

+Visible materials


Evacuated tubes: Sunny Wood, multiple family house, 2002

Beat Kämpfen, Regensdorferstrasse 15, 8049 Zürichhttp://www.kaempfen.comSolar collectors: SWISSPIPE Balkone by Schweizer energie AG /Im Chnübrächi 36 / CH-8197Rafzhttp://www.schweizer-energie.ch/

This new residential building integrates evacuated tubes collectors in the balconies of the south façade, actually fulfilling all the integration criteria. Each of the 18 modular balconies of the south façade integrate a solar collector module, strongly characterizing the formal composition of this façade. The solar modules, composed of nine tubes each, are 90 cm height and ensure the double function of solar thermal heat producer and standard balcony parapet. Their length of 2,4 m, leaves the space for a wooden parapet of 90 cm wide, treated like the other wooden surfaces of the envelope and actually hiding one of the two collectors vertical jointing . The choice of the product played in this example an important role. The collector modules are in fact conceived by the manufacturer Schweizer EnergieAG as multifunctional elements for energy production and balcony fence (see also ch. 6.Available innovative products: Schweizer energie AG - SWISSPIPE Balkone)


+Jointing options


+Surface colour

+Surface texture

+Visible materials


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References

[4.1] International Energy Agency - Solar Heating and Cooling Program, Task 39: Polymeric Materials for Solar Thermal Applications (http://www.iea-shc.org/task39/index.html)

[4.2] M. Munari Probst and C. Roecker. Towards an improved architectural quality of building integrated solar thermal systems (BIST). Solar Energy, 81(9):1104-1116, 2007.

[4.3] M.-C. Munari Probst and C. Roecker. Integration and formal development of solar thermal collectors. In proceedings PLEA 2005, 2005.

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MariaCristina Munari Probst Chapter 5 I Existing collectors “integrability”

EXISTING COLLECTORS "INTEGRABILITY"

74


75


EXISTING COLLECTORS "INTEGRABILITY" I 5

Abstract. A systematic formal description of the products proposed on the Swiss solar thermal market is presented. The formal quality of the existing collectors is assessed by evaluating the potential applicability of the integration criteria given in the previous chapter. The general inadequacy of currently available products is shown, demonstrating that new concepts are needed to respond simultaneously to both thermal and architectural issues. Finally the -very few- innovative products available on the EU market are listed.

As underlined in the previous chapter, mastering all characteristics of the solar thermal system in both perspectives of energy production and building design is not an easy task for the architect. The formal characteristics of the system are strongly dependent from the specific solar thermal technology, which imposes the core components of the collector, with their specific shapes and materials: glazed tubes for vacuum collectors, flat glazing and metal sheet for glazed collectors, metal sheet for unglazed flat plates, etc. The more flexibility can be offered by the solar collector within these imposed forms and materials, the more are the chances of a successful integration.

To evaluate the current situation in this respect, the degree of flexibility offered by Swiss solar collectors systems’ manufacturers was investigated, focusing on the most relevant technologies for facade integration: glazed flat plate, unglazed flat plate and evacuated tubes.

5.1 Product flexibility on the Swiss market

A total of twelve manufacturers are presently active in Switzerland, nine producing glazed collectors, two evacuated tubes and one unglazed collectors. Seven of them do implement collectors into facades, even if marginally, but only two offer collectors that are especially conceived for facade application (only one in the field of glazed flat plate –resulting from a small scale, customized, production-) [5.1.1 to 5.1.12].

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(1) Producer 6.a is at present developing a novel collector module for facade use, characterized by easy facade fixing system andaluminium framed jointing. (2) Façade products are proposed in terms of solar shading and balcony parapets. (3) Dummies can beproduced on specific demand (4) Three collectors colours are available (black, blue and bronze).

* The author wish to acknowledge Mrs. Vesna Kosoric for her main contribution in the collection of the data needed to carry on the presentanalysis.

*

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The following analysis presents, for all system characteristic affecting the integration, the level of flexibility offered by each available product. The results are resumed in the tab 5.1 here beside [5.2].

5.1.1 Size and position of collector field

As already discussed in section 4.1, an effective solution is to use collectors as multifunctional construction elements. The market offer in this respect is clearly unsatisfactory. One producer of evacuated tubes proposes multifunctional collectors (balcony protection and solar shading as added functions) but doesn't supply dummies. The producer of unglazed collectors offers a system, originally developed for roof application, which can be used as facade cladding and provides dummies. Yet the appearance of the absorber is still not ideal for façade application. In the field of glazed systems, the multifunctional use is possible but depends on architect’s creativity, rather than availability of specific products. None of the manufacturers offer multifunctional elements or provide dummies as standard option.

5.1.2 Collector material, surface texture and absorber colour

Within each specific technology, a choice of different surface treatments (texture and colour), compatible with the energy production function, should be provided by the manufacturer, to give the flexibility needed for facade implementation. The market analysis shows a real lack of flexibility on these items too. No freedom at all is offered in the unglazed and in the evacuated tubes fields. In the glazed field the situation is not substantially different. Two manufacturers offer some freedom on the glazing texture, proposing two types of finishing. Only one manufacturer offers the flexibility to use a specific glass finish on demand and gives the option to choose between three absorber colours (black, blue and bronze).

5.1.3 Shape and size of the modules; type of jointing

The freedom offered by Swiss products in terms of size and shape is not completely satisfactory, but flexible products can be found in all fields. A major problem is still the total lack of adequate jointing options for facade in both flat plate technologies. Only one manufacturer offers an alternative to the standard rubber jointing, consisting of a continuous, quite wide, aluminium frame. In the field of evacuated tubes the situation is different since the manufacturer supplying facade modules provides a level of jointing flexibility compatible with the facade application. To these already globally unsatisfactory results we should add that the Swiss market is characterized by a large predominance of distributors (31, vs. 12 manufacturers) who can clearly supply even less flexibility then direct industrial producers.

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With such inadequacy of the market, no surprise that façade applications are so rare. Nevertheless the presence in the larger EU market of an Austrian pioneer manufacturer, offering glazed solar thermal collectors expressly designed for facade integration, shows that there is hope for this kind of application. This manufacturer works almost exclusively with own mounted, customised products, that are actually encountering a remarkable market success. This is the sole glazed collectors’ producer able to provide flexibility in the jointing system as well as in the absorber colour. However the system is not expressly designed as multifunctional construction system, and no dummies are provided as standard option (Table 5.2).

Interestingly, in the main domain of glazed collectors, no products are actually conceived as complete multifunctional façade systems providing dummies. The most common added building function in this field is the use of the collector as facade cladding. But the actual lack of dummies restraints the system positioning to the sole exposed areas and sees the energetic sizing imposing the geometric/architectural dimensioning. The fact that dummy elements have not been provided up to now, even by manufacturers aware of the problem, is due to the characteristics of the collector to be imitated. To have an appearance compatible with the system, dummies would require a glazing and an added metal sheet similar to the absorber used in the proper collectors. These complex, unproductive elements would clearly be too expensive in terms of cost and grey energy to be successful.

5.2 Available innovative products

The present section is dedicated to solar thermal collectors available in the EU market, that do present an innovative approach to the architectural integration issue compared to the standard collectors available in the respective field. Unglazed and glazed flat plate systems are presented, as well as evacuated tubes systems and one air system. Facade products are the main focus, but innovative roof collectors have also been considered. All the following specification sheets have been conceived starting from the manufacturer data to present in a synthetic way the formal characteristics of different products and summarize their “integrability” potential. Not all the innovations are proposed by flexible systems. In these cases the product is presented because the new approach may be promising in the frame of future developments.

Tab 5.2 Glazed collectors field: rating of one of the most flexible systems available in the innovative Austrian market (AKS Doma)

Energie Solaire SA- Solar Roof

Z.I. Ile Falcon3960 Sierre / Valais [email protected]://www.energie-solaire.com

The Energie Solaire Solar Roof is an unglazed solar thermal system characterized by its absorber: a flat fully irrigated heat exchanger made of two structured stainless steel sheets. The collector is conceived as a multifunctional element for roof covering, but can also be used on façades (as collector + cladding).Its peculiar structure allows the integration on all types of roof profiles, even curved ones.No flexibility is offered for surface geometry and colour, nor for module dimensions. Nevertheless the double sheet structure of the absorber allows the use of non active elements (made of the external metal sheet only) of any shape and size to complete the façade/roof covering system [5.3].

+/-Jointing options

-Absorber colour choice

-Absorber: surface texture choice

+/-Shape & size flexibility

+Availability of dummies

+Multifunctional element

SOLAR ABSORBERS:

Double structured metal sheet filled with liquid (fixed dimensions)

NON ACTIVE ELEMENTS (ROOF COVERING/FAÇADE CLADDING):

External metal sheet only (any dimensions)

Rheinzink - QUICK STEP Solar Thermie

RHEINZINK (SCHWEIZ) AGTäfernstrasse 185405 Baden-Dä[email protected]://www.rheinzink.ch

QUICK STEP Solar Thermie is a very innovative unglazed system for roofs, produced by the roof and façade manufacturer Rheinzink. The active modules have been developed to be integrated into the standard Rheinzink QUICK STEP roof covering system, so that active modules look exactly like the traditional non active ones: field positioning and dimensioning is not anymore an issue.The system is conceived as a proper active roof system. Its high integration potential shows the importance of involving building manufacturer in the development of new products for building integration [5.4].

+Jointing options

+/-Absorber colour choice

+/-Absorber: surface texture choice




SOLARWALL – Solar Air Heating System

Conserval Engineering, Inc200Wildcat RoadToronto, Ontario M3J [email protected]://www.solarwall.com

The Solar Wall unglazed air system is a perfect multifunctional façade system.Its appearance is very similar to the one of profiled metal sheet for façade cladding. Its low extra cost allows using the same profile both on exposed and non exposed envelope area solving the issue of dummy elements.The colour palette is as large as any standard façade cladding palette. It comprises both high and low efficiency shades, leaving to the architect the choice of using a more or less efficient colour according to building and context specificities [5.5].+Jointing options

+Absorber colour choice

+/-Absorber: surface texture choice

+Shape & size flexibility



Winkler Solar: VarioSol E collectors system

Winkler Solar GmbHRäterweg 17A-6800 [email protected]://www.winklersolar.com

Winkler VarioSol is a glazed flat plate system conceived for façades and is characterized by a very high level of freedom both in size and shape of the modules: 38 different standard formats up to 24 m2 are proposed, and almost any customized shape can be provided at a reasonable extra cost. This flexibility comes from the absorber structure made of strips of small width and length cut to measure up to 5 m. Collectors are produced on order so that individual details, like jointing, can be made to measure.No dummies elements are available, and no choice is given on absorber colour/texture [5.6].

+Jointing options



+/-Glazing: surface texture choice


-Availability of dummies


AKS Doma Solartechnik -Flex

Sonnenstrasse 16822 [email protected]://www.aksdoma.com

Like the Wrinkler VarioSol system, AKS Doma Flex system is a glazed flat plate system conceived for façades, and is characterized by a very high level of freedom in both size and shape of the modules: 30 different standard formats up to 20 m2 are offered. Customized module shapes and dimensions can also be easily provided. Like for Winkler collectors, this flexibility comes from the absorber structure made of strips of small width and length cut to measure up to6 m. Jointing of different colours are available.No dummies elements are available, and no choice is given on absorber colour/texture [5.7].

+Jointing options



-Glazing: surface texture choice




Eternit - SOLAR FORCE

Eternit (Suisse) SA CH 1530 Payerne [email protected] http://www.eternit.ch;http://www.soltop.ch; http://www.suntechnics.ch

This SOLAR FORCE system has been designed by Eternit (façade and roof manufacturer) together with SOLTOP (glaze flat plate solar thermal collectors) and SunTechnics Fabrisolar AG (Photovoltaic modules). The active solar modules (both thermal and photovoltaics) are conceived to be integrated into the Eternit INTEGRAL PLAN roof covering system.The module size and the jointing of the active solar modules are developed to match the ones of the standard Eternit INTEGRAL PLAN shingles.The colour and surface texture of the thermal modules are intended to match the dark grey and mat aspect of the shingles [5.8].

+/-Jointing options

+/-Absorber colour choice



-Shape & size flexibility



QUICKSOL compact system (solar thermal - SOLTOP) Photovoltaic INTEGRAL PLAN (SunTechnics Fabrisolar AG)

SOLARNOR AS collectors

Drammensveien 1260277 OSLONorwayhttp://www.solarnor.com

The SOLARNOR collector is a glazed flat plate collector with the absorber and the glazing made of polymeric materials. The collector consists of two twin-wall sheets of high temperature resistant plastics, fixed in an aluminium frame. The solar radiation is converted to heat in the absorber sheet. The collector is conceived as a standard building element that can replace other types of roof or facade coverings, with a weight of only 8 kg/m2 while filled (6.5 kg/m2 without water).The building modules come in 4 different lengths up to 6 metres and a fixed width of 60cm.No dummies are available, and no flexibility is allowed in the texture and colour of the absorber and the polymeric glazing. Yet the grey, mat appearance of the collector surface can be interesting for façade applications [5.9].

+/-Jointing options







H+S Solar GmbH - Produkt H+S Pa

H+S Solar GmbHFeldstrasse 51CH-9455 [email protected]://www.hssolar.ch www.hsserviceag.ch

H+S Solar GmbH - H+S Pa is a glazed flat plate system conceived for façades, and is characterized by its reduced thickness (38mm!) that eases the integration into the building skin. The glazing is glued by the glass manufacturer itself to the collector structure with the same technique used to glue double glazing. Being air tight, the gap is filled with argon gas which helps reduce heat losses. The gluing of the glazing allows the use of any jointing system providing a new level of freedom in the field of glazed flat plates. The reduced thickness and the gluing technique allow the mounting also on triple glazing window frames.No freedom is allowed in module shape and size, nor in absorber or glazing surface texture/colour [5.10].+Jointing options




-Shape & size flexibility



Schweizer energie - SWISSPIPE Balkone

Schweizer energie AGIm Chnübrächi 36CH-8197 Rafzhttp://www.schweizer-energie.ch/

Schweizer energie SWISSPIPE Balkone is an evacuated tubes system conceived as a multifunctional element for building façades. Starting from the peculiar vacuum collectors module structure made of parallel tubes, the manufacturer has developed a multifunctional balcony fence collector.The flexibility allowed in module size and jointing make this system a very good option for the integration of evacuated tubes in building façades [5.11].

+Jointing options







University of Stuttgart - Active facade research project

Dipl.-Ing. Tina VolzrungUniverität Stuttgart-Institut für Baukonstruktion 2http://www.uni-stuttgart.de/ibk2

solar collectors: Schott-Rohrglashttp://www.schott.com

This system integrates evacuated tube collectors (made by the manufacturer Schott-Rohrglas) into a global glazed façade concept targeted for office buildings.The collectors are multifunctional: they produce solar thermal heat and cool (solar cooling), and work as sun shading offering a partial protection against direct sun radiation over office glazing, while letting enter day light [5.12].

+Jointing options







Univerität Stuttgart/ Institut für Baukonstruktion

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References

[5.1.1] Agena Energies - http://www.agena-energies.ch

[5.1.2] Friap - http://www.friap.ch

[5.1.3] Soltop Schupisser AG - http://www.soltop.ch

[5.1.4] Ernst Schweizer AG Metalbau - http://www.schweizer-metallbau.ch/

[5.1.5] Frysol Solartechnik - http://www

[5.1.6] HPW Tec solartechnik - http://www.hpwtec.ch http://www.hassler-solarenergie.ch

[5.1.7] H.Lenz - http://www.lenz.ch

[5.1.8] Hassler energia alternativa GMBH -

[5.1.9] ZMOTEC Solartechnik - http://www.zmotec.ch

[5.1.10] Energie Solaire SA - http://www.energie-solaire.ch

[5.1.11] B. Schweizer Energie - http://www.schweizer-energie.ch

[5.1.12] AMK Solac Systems AG - http://www.amk-solak.com

[5.2] MC. Munari Probst, V. Kosoric, A. Schueler, E. De Chambrier, C. Roecker, Facade Integration of Solar Thermal Collectors: Present and Future, in Proceedings CISBAT 2007, Lausanne, 2007.

[5.3] Energie Solaire SA- Solar Roof. http://www.energie-solaire.com

[5.4] Rheinzink- QUICK STEP Solar Thermie. http://www.rheinzink.ch

[5.5] SOLARWALL –Solar Air Heating System. http://www.solarwall.com

[5.6] Winkler Solar: VarioSol E collectors system. http://www.winklersolar.com

[5.7] AKS Doma Solartechnik -Flex. http://www.aksdoma.com

[5.8] Eternit - SOLAR FORCE. http://www.eternit.ch; http://www.soltop.ch; http://www.suntechnics.ch

[5.9] SOLARNOR AS collectors. http://www.solarnor.com

[5.10] H+S Solar GmbH - Produkt H+S Pa. http://www.hssolar.ch www.hsserviceag.ch

[5.11] Schweizer energie - SWISSPIPE Balkone. http://www.schweizer-energie.ch/http://www.schott.com

[5.12] University of Stuttgart - Active facade research project. http://www.uni-stuttgart.de/ibk2; http://www.schott.com.

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101

MariaCristina Munari Probst Chapter 6 I Development methodology for novel solar thermal systems

DEVELOPMENT METHODOLOGY

102


103


DEVELOPMENT METHODOLOGY FOR NOVEL SOLAR THERMAL SYSTEMS I 6

Abstract. This chapter is the real core of the thesis. It presents a methodology (summarized in diagram 6.1, next page) for the development of novel solar thermal collectors systems able to cope at the same time with: - Energy production requirements; - Functional, constructive and formal integration issues; - Users expectations/market trends; - Production constraints (manufacturability, standardisation, costs...); Considering the very low level of formal integrability of available systems and the major improvements needed in this field, three steps are proposed in the path leading to the innovative concept of "active facades". This should help producers improve their offer in progressive steps. The importance to build design teams with the due competences in both energy production and building fields is emphasized. The new fundamental role of facade manufacturers is highlighted.

6.1 Development methodology - collector as part of multifunctional envelope systems

As seen in the previous chapter, most existing solar collectors were developed as purely technical elements, starting from the “thermal system” point of view only, sizing the collectors to optimise heat collection, manufacturability, handling and installation, but only giving a marginal attention to architectural integration issues. A typical development process would see an industrial designer just bring the last touch to the design, improving its look, not its “integrability”.

Collectors must be developed to respond to their own technical constraints, but should furthermore become an architectural element, conceived to be integrated into the building envelope. They should possibly fulfil more than one function,

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consequently supporting designers’ integration efforts and reducing the overall cost [6.1][6.2].

Bearing in mind that this new collector generation will be more “building oriented”, there might be unavoidable trade-offs on efficiency or cost, but this will be compensated by a broader acceptance and better implementation possibilities. This means also that there will be a new palette of collector types with a clear “building function”, each addressed to a specific building application, such as metallic cladding, glazed façade element, balcony fence, tilted roof shingle, etc.

Taking this approach implies following a new collector development procedure, radically different from the traditional one, its prerequisite being the appropriate composition of the design team. For the development of these multifunctional construction elements the design team must have competences in the fields of solar thermal energy production, architecture and building technology.

As seen in section 2 of chapter 1, three main characteristics distinguish the various solar thermal technologies, determining their temperature and efficiency range, and the related possibilities of heat use*: - the medium used for the heat transfer (air, water, ...). - the materials composing the collector (plastic, metal, glass, ...). - the intrinsic form of the collector (flat plate, multilayer flat plates, tubes, ...)

These main characteristics have a major impact on the architectural integration possibilities at all the functional, constructive and formal levels. The formal freedom compatible with their functioning should be explored to develop new designs able to meet not only energy production needs, but also: - building integration requirements (functional, constructive and formal ones) - users expectations/market trends - production constraints (manufacturability, standardisation, costs...)

To master correctly so many different domains, the design team should be composed not only of solar thermal engineers and collectors manufacturers, but also of building professionals, including architects and facade manufacturers.

6.2 Building integration requirements: utilitas, firmitas, venustas

As stated in chapter 4 the architectural “integrability” of solar thermal should be studied considering all the three basic architectural levels: functional, constructive and formal. Every integration level brings several constraints and possibilities that must be carefully considered (see also chapter 3). Relevant possibilities and constraints in relation to these three different architectural aspects of the integration will be highlighted in the coming sections . The specificities of the different

*(domestic hot water production, space heating, swimming pool tempering...)

FIG

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: CO

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TOR

AS

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T O

F M

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NA

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VELO

PE S

YSTE

MS

:

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ELO

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T M

ETH

OD

OLO

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-IMPA

CT

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IDER

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RK

ET T

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DS

/ U

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UTILITAS FIRMITAS

Conceive collectors as multifunctional envelope elements: Find an added envelope function compatible with the specific collector technology

* i.e. Glass tube and metal absorber strip for evacuated collectors; metal plate and back insulation for unglazed flat plates; glass sheet with metal plate and back insulation for glazed flat plate.

Ensure collector durability while following building construction standards** and regulations***

** Static; vapour transfer; u value; …*** Wind load resistance; fire regulations; safety…

BUILDING REQUIREMENTS

VENUSTAS

Provide:

1. Flexibility on all collector formal characteristics to make it adaptive to different contexts and buildings (new and retrofits):

2. Similar non active elements with the sole added function to help position and dimension the system according to building composition needs.

3. Complementary interface elements to offer a complete active façade system.

ENVELOPE

FUNCTION(S),

SPECIFIC

MATERIALS

AND FORMCOLLECTOR

FUNCTION,

SPECIFIC

MATERIALS*AND FORM

MULTIFUNCTIONAL COLLECTOR =

REDUCED COST ENHANCED INTEGRABILITY

PRODUCTION FEASABILITY

Manufacturability

Standardisation

Costs

SOLAR ENERGY

PRODUCTION

FUNCTION:

Ensure r

easona

ble co

llector

efficie

ncy

for the

speci

fic

solar t

hermal t

echnol

ogy:

Evacuated tubesUnglazed air collectors

Unglazed flat plate collectors

Unglazed plastic collectorsGlazed flat plate collectors

VISIBLE COLOUR

VISIBLE SURFACE FINISH

VISIBLE SURFACE TEXTURES

MODULE JOINTING

MODULE SIZE

MODULE SHAPE

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technologies (glazed flat plates, unglazed flat plates, and evacuated tubes collectors) will be considered.

Main recommendations are summarized in boxes.

6.2.1 UTILITAS - functional integration

The solar heat collection function should be considered as one of the functionalities of the building envelope system. In this perspective solar thermal collectors should be conceived as multifunctional envelope components. Developing multifunctional collectors requires finding envelope function(s) compatible with solar heat collection and consequently define how to combine the materials and form characterizing the collector technology* with the functions**, the structure***and the materials**** of the specific part of the envelope they will replace (diagram 6.1). Products will have given domains of application, in relation to the specific envelope functions they are taking over, and in relation to the constructive typology they are compatible with: the plain masonry wall very common in the field of building renovations will require for instance to develop different elements than those used for a prefabricated metal facade common in industrial buildings. The merging process may imply some compromise on collectors' efficiency or result in more expensive collectors, but this will be balanced by enhanced implementation possibilities, and by a reduced overall construction cost. (See relevant/promising crossed merging possibilities of different types of envelope with different technologies in section 3.1.Facade integration functional aspects. See also chapter 7 and 8 presenting the methodology validation on unglazed flat plate collectors and glazed flat plate collectors for facade).

As shown in chapter 3, in the case of flat plate hydraulic collectors for facade application, the most promising envelope function is the facade cladding, possibly using the collector insulation as wall insulation (or the wall insulation as insulation for the collector (!)).

Conceive collectors as multifunctional envelope components: Identify an added envelope function compatible with the specific solar thermal technology.

*i.e.glass tube and inner metal absorber strip for vacuum collectors; metal plate and back insula-tion for unglazed flat plates; glass sheet with metal plate and back insulation for glazed ones. **transparent/opaque, made of fixed /mobile elements. *** single layer/multiple layers; load bearing/non load bearing; single leaf/multiple leafs; no ventilated air cavity/ventilated air cavity; low prefabrication level/high prefabrication level... ****made of masonry, concrete, wood, metal, ....

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In the case of unglazed flat plate technology, the facade cladding function would be fulfilled by the metal absorber, while in the case of glazed collectors, this function would be ensured by the glazing. Evacuated tubes have already been used as balcony fence, or as solar protection (sun shading) in front of transparent envelope parts (see figs.3.1and 2 in chapter 3). Both are interesting implementations of the multifunctionnality concept (see section 1 of chapter 3).

6.2.2 FIRMITAS - constructive integration

The new multifunctional collector must fulfil the constructive constraints of both the solar heat production function, and the added building construction function(s). Its efficiency should be guaranteed, while the collector respects building construction standards and regulations. Special attention has to be dedicated to the following issues: - The multifunctional element should ensure a correct vapour transfer through the wall, avoiding condensation problems and allowing the wall to dry correctly (see details in chapter 4.2). [6.3][6.4] - Its insulation system should allow adapting to different building insulations standards and required U values for wall(s). - Summer overheating risks due to absorber high temperatures should be considered to define insulation needs [6.5] - The fixing points should meet static requirements while avoiding thermal bridges. - All jointing and fixing details should be able to cope with the dilatations of the different materials at collector working temperatures. - Surface temperatures should be compatible with safety regulations in the areas exposed to users’ contact, such as ground floor, window and balcony surrounding, etc.; particular attention is needed for unglazed systems, where the absorber is not protected by the glass. - Wind load resistance and fire regulations should be considered and respected, as well as any other specific safety regulation, in particular the material breaking behaviour in case of vandalism (very important for glazed elements). - Measures against winter freeze should be taken. - Eventual hydraulic system leakages should be traceable, fixable, and should not cause main damages to the wall. (see detailed requirements in section 3.2. Facade integration constructive aspects).

Ensure collector durability while following building construction standards and regulations

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6.2.3 VENUSTAS - formal integration.

Considering the very low level of formal integrability of available systems, and the major improvements needed in this direction (see chapter 4 and 5), three progressive levels of system formal integrability are defined: basic, medium and advanced (see diagram 6.1). This should help producers improve their offer in progressive steps.

6.2.3.1 Basic level of integrability

From a practical point of view, offering a total formal freedom can make the production process too complicated and the product uneconomical. To help offer a satisfactory level of flexibility within cost effectiveness, user's wishes and market trends should be evaluated, either trough market analysis end/or specific surveys (like in the case of the EU project Solabs, chapter 7, section 3).

a. Module shape and size

Module shape and size should definitely offer a maximum dimensional freedom to cope with the great variability of building dimensional constraints. For flat plate collectors the flexibility of module shape and size depends mainly on the level of flexibility offered by the hydraulic system that irrigates the absorber. Clearly the freedom in shape and size should not require reconsidering every time the pattern for the hydraulic system. The key issue is then to find a hydraulic system compatible with absorber shapes and size variability.

- For glazed collectors one possible way is to use absorbers made from standard, cut to length, strips. The small width of the strips and their length cut to measure makes it possible to compose absorbers of any form and shape, so that the limits in module dimensions are only to be found in the maximal dimensions of the glass, and its cutting process (fig 6.1). This is used by two innovative facade products in the field of glazed flat plate collectors, AKS Doma and Winkler (figs.6.1, 6.2-a, 6.2-b)(see also section 5.2: Available innovative products).

Ensure collector formal flexibility In order to be adaptive to specific contexts and buildings (both new and retrofits), solar thermal systems should be able to provide flexibility on all collector characteristics affecting building appearance: a. module shape and size; b. module jointing; c. collector colour; d. visible surfaces textures and finish.

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- For unglazed collectors, the absorber is not protected by the glass and has then to resist shocks and weather in order to protect the insulation layer. This requires the absorber plate to be thicker than the metal sheets commonly used in glazed collectors and makes the use of absorber strips less suitable. Other solutions should then be considered to provide the needed absorbers’ dimensional flexibility. One solution for this issue was proposed by the EU project Solabs (see chapter 7), which was to provide plank shaped elements (figs.6.3-, 6.3-b, 6.3.c). As for the absorber strips, plank elements are characterized by a given small width and a cut to

"Collectors available in 38 standard formats"

Fig 6.1 Winkler: glazed collectors system for facade: available in 38 standard formats, thanks to the use of absorbers strips.

Insulation

Underconstruction

Absorber

Solar glass 4 – 8 mm

Fig 6.2a and b: AKS Doma glazed collectors system for façade: detail of the absorber strips system. Left: cross section. Right facade detail.

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measure length, allowing covering surfaces of any dimensions while using a standardized system.

New solutions need still to be developed to provide cost effective cassette modules offering freedom in both dimensions. One promising path seems to be the use of the roll bond technology. Roll-bonded sheets are produced by rolling two aluminium sheets together under high pressure. Certain areas are deliberately not bond together and are subsequently ‘blown up’ in a similar manner to a balloon. In this way, channels with numerous branches can be produced, offering a very good heat transfer with the liquid (figs: 6.4-a, 6.4-b, 6.4-c).

- For evacuated tubes the modules should offer the possibility to choose the number of tubes per module, and the mounting distance between the tubes. Additional freedom would be to offer cut to length tubes, and diameter variability.

Fig 6.3a-b-c: Solabs: cut to lenght plank shaped collector.

a and c: back side b-front side

Fig 6.4a Solar absorber prototype with hydraulic

system made using the Roll bond technology developed

by Alcan and Fraunhofer ISE. Credit: Alcan.

6.4- b and c: Roll bond

technology offers the possibility to blow up the

hydraulic circuit on one side only of the aluminium plate.

a

b

c

a b

c

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b. Module visible jointing

The impact of module visible jointing is often underestimated, but has actually an important influence on the integration quality. Different jointing types (framed jointing, negative jointing, horizontal jointing profile, overlapping jointing...) underline differently the modular grid of the building. A building could be valorised by underlining the collector field modularity, in which case highly visible jointing, like framed jointing for instance, would be appropriate (in case of architectural composition approaches based on a clear modular control of the building). In other situations the use of modular elements may not respond to the building composition logic, and the use of more discrete jointing may be preferable. In any case, the proposed solution should consider the jointing systems currently used for the part of the facade replaced by the multifunctional collector. Some flexibility would clearly be suitable, even if not all technologies provide the same freedom potential. - Glazed collectors jointing requires coping with several constraints. The greenhouse effect on which the technology is based, requires firstly to keep the glass at an appropriate distance from the absorber (to minimize convection exchanges dues to air movement) and secondly to use a peripherical jointing avoiding fresh air to circulate in the module (or at least to limit it). The need for a peripherical module jointing that fixes the glass and ensures air tightness affects fundamentally the jointing between the modules themselves. The collector assembly process and its mounting on the building have a major influence on the type of solutions that can be offered to users (already assembled collector boxes to be fixed on facades, or assembling collector layers on the facade during building construction).

Already assembled collector modules generally use black EPDM rubber profiles as peripherical joints (fig 6.5-a and 6.5-b) fulfilling both functions of glass fixing and inside air control. Such ready to install modules are mounted on facade side by side,

each with his own rubber frame. The architect can then influence the module to module jointing only by deciding the horizontal and vertical distances between the modules composing the field, or by covering them with very large metal profiles.

Fig 6.5-a: Already assembled collector modules using EPDM rubber jointing to fix the glazing to the collector case. Fig. 6.5-b: Module to module jointing resulting from mounting side by side already assembled modules with EPDM joints.

a b

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Innovative manufacturers of facade collectors generally propose to mount the collector layers directly on the facades, separating the two functions of fixing and sealing, allowing more elegant solutions (Fig.6.6-a). The glass is fixed using standard

facade metal frames holding two modules' glass (or by punctual fixing), and the air tightness is ensured by much slimmer rubber profiles, eventually placed behind the glass or hidden by the fixing system (figs.6.6-b-c-d-e; fig 6.7-a-b).

Fig 6.6-a: glass fixing and jointing detail proposed by

AKS Doma (VarioSol system).

Credit: AKS Doma

Fig 6.6-b-c-e: AKS Doma frame jointing: profile

available in different colours Fig c and e: Diakonie Wohnheim, Salzbur.

Brandmüller& Brandmüller architects.

Credits: AKS Doma

Fig 6.7a-b: AKS Doma horizontal jointing profile.

Single family house in Nenzing(A), arch Achammer

& Partner OEG. Credits: AKS Doma

.

e

c

d

b

a

b

a

SOLAR COLLETCORS FIELD

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A novel solution to the glass fixing and sealing issue is proposed by the Swiss producer H+S Solar. With a process similar to the one used to produce double and triple glazing, the glass is glued to the collector box directly by the glass manufacturer (Schollglas). As for double and triple glazing, the perfect air tightness resulting from this process allows replacing the air in the cavity with a more insulating gas (argon for instance). The resulting collectors are free from any visible peripherical jointing and are only 4cm thick, which makes them very similar to the triple glazing commonly used in passive buildings (figs 6.8-a-b-c-d).

- Unglazed flat plate collectors are technically less complex than glazed or evacuated collectors: they are made of fewer layers and can be assembled without the need of peripherical jointing. The interface jointing between the modules can easily be developed in the form of a smooth negative jointing, very common in facade metal claddings. This jointing type can also be made compatible with the use of standard covering profiles, vertical, horizontal or framed, according to building specificities and architect’s approach.

Fig 6.8-a-b-c-d: s H+S Solar collector: the glazing is glued to the collector structure by the glass manufacturer itself (Schollglas) with the same technique used to glue double glazing. The gluing of the glazing allows the use of any jointing system providing a new level of freedom in the field of glazed flat plates.

dc

b

b

a

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c. Collector colour

Collector colour mainly results from the colour of the absorber plate, which is usually black to optimize heat collection. Black absorbers should remain an option, but should not be the only one. Other colours should be provided even at the cost of a slightly reduced efficiency. This would allow adapting to more sensitive urban contexts, permitting an otherwise unacceptable integration. Several research groups have been working on coloured absorbers with relatively low emissivity (ε<0.4) and high absorptions (α>0.6) coefficients, allowing combinations (α + ε) with reasonable performances. The thickness insensitive spectrally selective (TISS) paints developed by the National Institute of Chemistry of Ljubljana offer various colour shades and can be used both for spray and roll-to-roll coating (fig. 6.9. For more details see next chapter, pp.136-137)

Coloured selective coatings have been produced by Interpane (ex Alanod-Sunselect, today Blue-Tec): they are characterized by very good emittance (ε) and absorption (α) values. The selective layer is deposited by magnetron sputtering in a coil coating

Fig 6.9: Thickness insensitive spectrally selective

paints(TISS) palette, developed at the National

Institute of Chemistry Ljubljana , Prof. Boris Orel,

within EU project Solabs.

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line on the metal roll before cutting and forming the absorber plates/strips. Even if different colour shades can be provided, this process requires coating large amounts of material in the same colour. This results in reduced flexibility compared to the thickness insensitive paintings process that allows to apply the painting in small quantities to already formed absorbers. For glazed collectors, colours can be provided also by colouring the glazing. Spectrally selective coatings have been developed for this purpose at EPFL; they are able to reflect only a tiny portion of the visible spectrum and let the rest of the energy pass through (see details in chapter 8). Several colour shades have been provided with a reflection coefficient (i.e. a loss in efficiency) around 10% (fig.6.10). This is extensively detailed in chapter 8. Methodology validation on glazed solar thermal systems (Coloured collectors project).

Researches are also conducted which explore the possibilities offered by the silk printing process, offering interesting alternative, but showing less performing results at the moment (fig.6.11).

d. Visible surface textures and finish

Visible surface texture and finish should not just result from the optimisation of the heat collection function or production standardisation, but should be considered as characteristics for which formal freedom should also be explored.

Fig 6.10: Different shades of spectrally selective coatings developed at EPFL.

Fig 6.11: Different silk printed glazing over standard solar absorbers. Samples produced by Christoph Hutter, H+S Solar.

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Surface geometries (corrugated embossed, perforated, regular/irregular, etc.) and surface finishing (matt, glossy, structured, etc.) compatible with the materials composing the external layer of the collector should be considered. This is also true for the options concerning eventual patterns (standards, made to measure, etc.). The greater the choice, the easier it will be to combine the product with the other materials composing the envelope. The absorber surface texture/geometry is affected by the hydraulic system pattern and the associated welding technology. The reduced thickness of the absorber resulting in regular or irregular surface corrugations, clearly visible when exposed to the sun, has also an impact on the latter (fig.6.12 and fig.6.13-a-b-c-d).

Fig 6.12: Irregular absorber surface corrugations visible under direct sun (H+S Solar

Collectors).

Fig 6.13a-b-c-d: Different absorbers surface geometries (and hydraulic system welding

types) proposed by different manufacturers.

a b

c d

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If for unglazed collectors the different options should be considered only for the absorber surface, in glazed collectors this applies both to the glazing and the absorber.

Fig 6.15: Different surface textures patterns (obtained by lamination) offered by Saint- Gobain for the Albarino extra white glass. (Image made from Saint-Gobain pictures: http://nordic.saint-gobain-glass.com)

Fig.6. 14: Impact of different glass finishing over a standard Energie Solaire SA solar absorber: a- Standard extra-white floated glass. b- Structured (pyramidal) glassc and e - Acid etched with regular patterns. d- Homogeneous acid etching f- Tailored acid etching g and h - Silk printing

a b

c d

e f

g h

a b

c d

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6.2.3.2 Medium level of “integrability”.

Implementing thermal collectors with the added cladding function for instance means that the new multifunctional element has to fulfil the requirements of both a solar collector and a facade cladding. Now, for architectural coherence, areas of different solar exposure may need the same cladding type. Moreover, some parts of the building skin may require small elements that cannot be economically produced as solar collectors. This means that the availability, within the system, of elements providing the sole cladding function is fundamental to cope with facade integration issues. In the case of BIPV systems (Building Integrated Photovoltaic), non active elements having an appearance similar to the active ones have been called "dummies". The word "dummies", though, is slightly misleading in the case of the multifunctional collector, since the non active element fulfils a real function (e.g. the cladding). We will also call them "non active elements ", or to be more specific "non active claddings" (fig 6.16 a-b-c-d).

Provide non active elements. Non active elements similar to the collectors, but fulfilling only the added envelope function, should also be provided; they will help position and dimension the whole system field according to building composition needs

SOLAR ABSORBERS:

Double metal sheet filled with liquid

NON ACTIVE ELEMENTS (CLADDING):

External metal sheet only

Fig 6.16-a-b-c-d: Use of non active elements in CeRN

building in Bursins (Energie Solaire SA unglazed

collectors system): non exposed facades are covered

by non active elements having the same appearance

as active ones. Only the external metal sheet is used

in these parts rather than the double metal sheet normally

used for the proper collectors.

See also section 4.4.Example of good integration, and

section 5.2.Available innovative products.

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6.2.3.3 Advanced level of integrability

Providing active and non active elements is already a big step forward in the actual context of solar thermal systems. However, the requirements such a new system should meet in relation to its added function are wider. To become a proper, coherent, complete facade system, the multifunctional solar system should also comprise all the jointing components needed to interface the modules (active and non active) with the other envelope elements (windows, balconies, eaves, facade angles...). This would bring the additional advantage for the architect to deal with one unique partner for the façade. To develop such integral solar façade systems, two approaches can be considered:

1. To develop the necessary façade elements around the new multifunctional collector

This path gives the maximum freedom to designers, and might offer some additional functionalities in the non active elements, but at the extensive cost of developing a whole façade concept.

2. To adapt the new multifunctional collector to an already existing facade system.

This option will probably require some adaptations to the collector initial design and to the original façade system (piping transfer, colour on demand etc…), but it will be in most cases quicker to develop, more cost effective and offer access to an existing market (this approach was recently taken by the facade and roof manufacturer Rheinzink to develop its latest Quick Step Solar Thermie roof system, conceived to be compatible with the already existing Rheinzink Quick Step roof covering system – see 5.2 Innovative products, sheet page 81).

6.3 Market trends /users preferences

To ensure that the new collector will have a market, both the users’ desired level of freedom and aesthetic preferences have to be investigated. Existing market analysis and/or specific surveys can be used for this purpose.

Provide a complete facade system. Complementary interface elements (jointing/finishing/angular components) should be offered to provide a complete active facade system (cladding)

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Knowing users’ expectations would help decide which compromises can be made and which ones should be avoided regarding the level of formal flexibility to be offered by the new product.

6.4 Production feasibility and eco-impact.

Manufacturability and production cost of collectors and associated system elements also need to be considered. In this analysis, as mentioned above, the overall construction cost reduction resulting from the multifunctional use of the collector is to be taken into account. A key challenge lies in the careful balancing of standardisation needs and user’s will of freedom. As for the economic cost, the energy cost of the multifunctional system should also be evaluated. The embodied energy required for the production/distribution/ mounting/dismounting of the system should be considered. The global eco-impact of the system should then be evaluated in the light of the energy savings resulting from the solar energy production and also from the merging of several envelope functions in one element. The next chapters 7 and 8 present two practical cases of solar thermal systems developed as active facade systems according to the described methodology: the first in the field of unglazed collectors and the second in the field of glazed ones.

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References [6.1] A. G. Hestnes “Building integration of solar energy systems”, in Solar Energy vol.67,

n.4-6, 2000. [6.2] I. Bergmann “Facade integration of solar thermal collectors – A new opportunity for

planners and architects”, in Renewable Energy World, June 2002. [6.3] T. Muller et all, Colourface- Coloured Collector facades for solar heating systems

and building insulation, Eurosun 2004. [6.4] I. Bergmann, W. Weiss “Fassadenintegration von thermischen Sonnenkollektoren

ohne Hinterlüftung”, AEE Intec, Arbeitsgemeinschaft ERNEUERBARE ENERGIE, Institut für Nachhaltige Technologien, march 2002.

[6.5] Thomas Matiska and Borivoj Sourek, Facade Solar Collectors, in Solar Energy 80 (2006) 1443-1452.

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MariaCristina Munari Probst Chapter 7 I Methodology validation for an unglazed solar thermal system

METHODOLOGY VALIDATION: UNGLAZED SYSTEM

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METHODOLOGY VALIDATION FOR AN UNGLAZED SOLAR THERMAL SYSTEM I 7

Abstract. The methodology presented in the previous chapter is applied within a real R&D project in the field of unglazed collectors. The successive development phases are described. They lead to a novel system matching all technical and architectural (functional, constructive and formal) requirements, actually responding to the concept of active facade. The evaluation of the potential applicability of integration criteria to the new collectors systems gives a clear positive feed back on the reliability of the formal development methodology. Examples of architectural designs integrating new collectors and applying the defined integration criteria are presented.

This chapter describes the different steps of a successful application of the methodology to the development of an unglazed flat plate hydraulic collector. The work was carried out in the framework of an EU project, named Solabs (annexe 3).

7.1. Methodology validation framework

The EU project SOLABS (2003 - 2006) aimed at developing a novel unglazed solar thermal collector for building façades, resorting to coloured selective coatings on steel. The intent was to produce a novel collector conceived as a multifunctional construction element, facilitating the architectural integration (both in new buildings and in renovations), and able to meet users’ aesthetics expectations [7.1][7.2]. With the above mentioned challenge, the composition of the design team was crucial. It was set up around the competences of three main groups:

- Physicists: responsible for the absorber’s coloured selective coatings and the corrosion protection layers - Mechanical engineers: responsible for the actual industrial design of the product, its thermal efficiency and the heat use in buildings.

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- One architect (my role): responsible for architectural integration issues, the analysis of users’ wishes and their implementation in the final product. Initially this role was secondary and intended to just help implement the new collector in buildings. Following my proposal, the new collector had to become a building element inspired by existing building products, and this role became crucial for the final design.

The partners came from different organisations, comprising large manufacturers, small and medium sized companies (SMEs) as well as research institutions and consultant engineering companies. The resulting variety in the design approach was a key value to the teamwork.

In order to design and create this new collector, the methodology described in chapter 6 was followed with the following steps: - Definition of the technology type and associated materials and constraints. - Selection of potential collector concepts within these constraints. - Exploration of users’ wishes and preferences for the proposed options. - System finalisation combining integration needs, users’ expectations and technical requirements.

7.2 Design approach

As discussed above, any collector design has to be defined within the formal limitations imposed by the corresponding solar technology. In this case, the SOLABS design team had to work with the constraints of unglazed – hydraulic - flat plates - collector technology, with the additional constrain of using steel material for the absorber. Looking at the existing unglazed collector market, one can observe that if the Solarwall air heating system proposes a façade integrated collector, none of the unglazed water collectors is conceived to be used on façades, or as façade element. As from an architectural point of view unglazed solar thermal collectors for façades are de facto façade metal claddings, the original approach was to select options directly inspired by currently used façade metal claddings (already developed to respond to building needs), rather than by existing solar collectors. For detailed evaluation, these claddings were divided into three families: - Profiled sheets : very large, non modular metal sheets providing a homogeneous covering, thanks to the absence of visible jointing in the cladding (trapezoidal or corrugated sheets for instance) (Fig.7.1-a). - Cassette modules : modular elements of geometrical proportions varying from 1:1 to 1:4, with visible jointing, well-suited for cladding of large wall areas. Due to the high visibility of the jointing, the careful choice of the module dimensions is the key to a successful cladding design (Fig.7.1-b). - Panel planks : cut to length modules with a width ranging from 20 cm to 40 cm. The maximum length of individual planks is usually 4 meters. The variable width of the

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reveals (from 0 to 30 mm), added to the cut-to-length feature makes the use of this standard modular element more flexible, so that panel-planks can be used for cladding numerous architectural objects (Fig.7.1-c). Only cladding types easily adaptable to support a hydraulic system could be taken into account, consequently profiled sheets were put aside at an early stage, judged hardly adaptable from the technical point of view. Cassette modules and panel planks were both retained as valid solutions.

For both solutions, the feasible shapes, sizes and jointing and the possible texture, finishing and colours were proposed for evaluation by potential users.

7.3 Evaluation of users' wishes

A questionnaire was set up to explore users' preferences for collector formal characteristics, within the cassette and plank options (see full questionnaire in annexe 2). The latter was addressed to potential users by the way of the World Wide Web, to the same pool of professionals who took part in the survey over integration quality presented in chapter 3 (section 3.3.1, page 46). Both multiple choice questions and appreciations were addressed. To summarize the appraisal, averages have been computed, converting the five point appreciation scale (-- ; - ;+/- ;+ ; ++) into a numerical scale (-100; -50; 0; +50; +100).

7.3.1 Module shape, size, jointing.

The cassette option Starting by considering the cassette option, a definition of the level of acceptable module standardisation was requested first.

a. b. c. Fig 7.1-a-b-c: Currently used façade metal claddings

analysed to inspire the novel SOLABS multifunctional

collector: a.- Profiled metal sheets; b- Cassettes; c-Tongue

and grove planks.

Fig 7.2: Acceptable level of standardization for a cassette shaped solar collector module

01020304050607080

Architects Eng.+ Façade M .[%]

Made to measure

Cut to length

Range of standard modules

1 standard module

Cassettes: size and shape

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A series of standard modules would satisfy 43% of the architects, most of them asking for the freedom in one dimension with a cut to length module as minimum requirement. Moreover almost one third of the architects thought that a made to measure module is a prerequisite. On the other hand, 80% of the engineers and façade manufactures would be pleased with a series of standard modules; 20% of them even thought one standard module would be sufficient (fig 7.2.).

Regarding the jointing, the profile free module was the most appreciated by all questioned, architects and engineers. Frame jointing was less chosen, even though it was still acceptable according to both architects and engineers (fig 7.3 and 7.4).

The plank option. The survey regarding the panel-plank began with a question on the most suitable panel width, the plank length freedom being one of the features of this kind of cladding. The preferences were quite dispersed, but as a trend we can note that engineers and facade manufacturers would prefer to use wider elements than architects. The ideal size satisfying most of the interviewees was around 30cm, (29cm for architects, 32,5cm for engineers) (fig 7.5 and 7.7).

A variable width reveal was considered suitable by all interviewees, architects as well as engineers, in order to have a flexible panel plank solar system (fig 7.6 and 7.8).

Fig 7.3 (left): Appreciations of different jointing types: framed jointing; horizontal profile jointing; negative jointing [-100 to +100 scale]. Fig.7.4 (right): Different types of jointing (top to bottom): framed jointing profile, horizontal jointing profile; negative jointing.

C a s s e t t e s j o i n t i n g

-100

-80

-60

-40

-20

0

20

40

60

80

100

frame horiz. Jointing profile profile free module

Architects Eng.+ Façade M.

Cassette jointing

? 10mm

30mm

0mm

Fig 7.5 (left): Plank width Fig. 7.6 (right): Variable widths reveal form 0 to 30mm.

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All interviewees considered both the cassette and the plank to be valuable options for an unglazed collector within Solabs project constraints. Even so the plank got a slightly better rating than the cassette (67 to 56). It is interesting to note that the architects appreciation varied slightly with the region of origin. The architects from the southern European countries definitely preferred the plank (71 to 45), while for the other architects the two options were equivalent (fig 7.9). In one of the very few occasions where they disagreed, engineers clearly preferred the planks (63 to 43), as opposed to façade manufacturers who considered them equally interesting (65 to 65).

V a r i a b l e w i d t h j o i n t i n g

- 100

- 80

- 60

- 40

- 20

0

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rating


S u i t a b l e p l a n k w i d t h

0

10

20

30

40

50

60

70

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20-25cm 25-30cm 30-35cm 35-40cm

Architects Eng.+ Façade M.[%]

Fig 7.7 (left): Suitable plank width [%].

Fig. 7.8 (right): Suitability of a variable widths reveal for a

plank shaped, cut to length, collector [-100 to +100 scale].

C a s s e t t e s o r p a n e l p l a n k s ?

61 6463 61

45

71

43

6365 6556

67

-100

-80

-60

-40

-20

0

20

40

60

80

100

cassettes planks

Arch. North

Arch. Centre

Arch. South

Engineers

Façade m.

All

Fig 7.9: Appraisal of the two proposed shape options:

cassette shaped and plank shaped solar collectors

[-100 to +100 scale].

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7.3.2 Surface texture and finish

After the module shape and size topic, the questionnaire focused on the surface textures and finish preferences before dealing with the basic topic of colours. Marginal surface geometries options were also taken into account (fig.7.10 c and d), thinking that technical solutions to problems related to the project could suggest the use of less common surfaces (see example of Energie Solaire collectors in chapter 5, section 2). The selected categories of surfaces were flat, profiled, embossed and lenticular perforated (fig 7.10-a-b-c-d). As expected, preferences of both architect and engineers went for the most traditional geometries: flat and slightly profiled. The embossed and the lenticular perforated surfaces were not considered appropriate for façade use, but they seemed of interest for some people (fig 7.11).

The question regarding the surface finish left no doubts: 90% of the surveyed people preferred a matt rather than a polished surface (fig.7.12).

T e x t u r e : s u r f a c e g e o m e t r y

0

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Flat Profiled Embossed Lent. perforated


T e x t u r e : f i n i s h i n g

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Polished matt

Architects Eng.+ Façade M.[%] [%]

Fig 7.10-a-b-c-d: Proposed surface geometries (from left to right): flat, profiled, embossed and lenticular perforated.

Fig 7.11 (left): Recorded preferences over collector surface geometry [%]. Fig 7.12 (right): Recorded preferences over surface finish [%].

a b c d

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7.3.3 Surface colour

The questions related to the colours were difficult to define. The lack of realistic samples at this stage of the project, as well as the difficulty for Architects to select a colour out of context, led to define first the level of colour freedom expected for the collector. The colour topic was approached by asking first how many colours should appear in the colour palette, and to evaluate the importance of having custom colours.

The wishes concerning the number of colours presented a real challenge. Two thirds of architects as well as two thirds of engineers would not be satisfied by a choice of less then ten colours. Slightly more than half the architects would be pleased with 10 to 20 colours, while almost 90 per cent of the engineers believed this would be an acceptable palette. Forty per cent of architects, ten per cent of engineers and façade manufacturers even suggested a palette containing more than 20 colours (fig 7.13). Moreover, for more than 80 per cent of architects and engineers the possibility to choose a custom colour was considered to be important and for two thirds of architects this was even an essential requisite.

In order to guide the elaboration of a colour choice for unglazed solar collectors the interviewees were asked to point out three colours they thought should definitely be included in the colour palette. The questionnaire suggested 24 colours divided in 6 families (Green, Blue, Red, Brown, Yellow, Grey). Each colour family proposed four choices, from the pure colour to a very dark declination of it (fig.7.14).

0

1 0

2 0

3 0

4 0

5 0

6 0

7 0

8 0

9 0

1 0 0

3 to 5 5 to 1 0 1 0 to 2 0 2 0 to 4 0

A rc h ite c ts E n g .+ F a ç a d e M .

C o l o u r p a l e t t e : n u m b e r o f c o l o u r s

[%] Fig 7.13: Users wishes

concerning the suitable number of colours to be included in the

collector colour palette [%].

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In order to really understand the Architects' wishes and to avoid any "technical bias", the colour choice did not exclude the (thermally) non-realistic options, meaning that also light colours (like yellow for instance) were considered.

The results were clear: architects' most demanded colours were by far greys, independently of the regional origin of the architects, North, Centre or South of Europe. Blues and reds were also demanded options while greens, browns and yellows were less popular, even though a few yellows options were considered interesting by some architects from the Southern European countries (fig. 7.15). A clear difference in the colour choice between architects and engineers can be observed, with some slight differences being linked to the architects' origins. If engineers and facade manufacturers clearly chose the darker declination of the colours, sticking to the most realistic options, architects' choice were generally evenly distributed between the different levels of darkness. Even so, a trend related to the cultural origin of the architects can be observed: architects from the southern European countries preferred slightly brighter colours than their northern and central

Fig 7.14 (left): Proposed colours for the palette. Fig 7.15 (right): Recorded color preferences (three possible choices among the 24 proposed colours) [%].

C o l o u r s

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5

10

15

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25

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35

40

45

50


greens blues reds browns yellows jaune [%] greys yellows

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counterparts, while the darker options were mostly chosen by the architects coming from Central Europe (fig.7.16).

7.3.4 Application to buildings

The last part of the survey was dedicated to the actual integration into buildings. The south oriented facades of an existing building were the starting point of the questions related to the integration process. The chosen building is an office building in Morges (CH), built in the fifties, and needing a retrofit. The building is an example of modern movement architecture: concrete structure, blind lateral façade (B) and main façade (A) rhythmed by the carrying structure and by the rows of horizontal window openings. The composition scheme is characteristic of many buildings of the fifties-sixties-seventies existing in Europe, that need to be retrofitted soon (fig.7.17-a-b).

As the available surface with optimal sun exposure (south east-south west) is distributed between both the main façade (breast wall) and the blind lateral wall, questions were asked regarding the type of solar cladding that would be most appropriate for the facade covering.

C o l o u r s

0

5

10

15

20

25

30

35

40

45

50

greens blues reds browns greys yellows

Arch. North Arch. Centre Arch. South Engineers Façade m. All[%]

available South (S-E, S-W) exposed surface

A B

Fig 7.16: Detailed colour preferences in relation to the profession and the region of

origin of architects [%].

Fig 7.17-a: Existing office building in Morges (CH).

Fig 7.17-b: Available South

exposed surfaces.

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The preferred option was the plank cladding for all categories of interviewees: about 2/3 of engineers and architects preferred the planks and only 1/3 chose the cassette shape. It is interesting to note that as for the question on shapes and sizes, the most convinced by the plank option were the architects coming from Southern Europe, with a preference of almost 80% (fig.7.18).

The next question, based on the same building picture, was used to investigate the users’ attitude when choosing the size of the system: will they dimension the system according to technical requirements only or according to architectural composition rules? To the question "would you cover all the available south exposed surface with the solar cladding or just a part of it", 2/3 of the engineers and façade manufacturers answered they would use all the available surface. Less than half the architects chose this option, all the others preferring to cover only one of the facades, in majority the balcony area of the main façade (fig.7.19).

R e n o v a t i o n : c a s s e t t e s o r p a n e l p la n k s ?

0

10

20

30

40

50

60

70

80

90

100

cassettes panel-planks


S u r f a c e a v a i l a b l e : w he r e t o a p p l y t h e c o l l e c t o r s ?

0

10

20

30

40

50

60

70

80

South exposed façades (A+B) Fac A: parapects area Fac.B: lateral façade

Architects Eng.+ Façade M.[%]

Fig 7.18: Recorded users’ preferences over collector shape for the cladding of the building presented in fig.7.17 [%].

Fig 7.19: Recorded users’ preferences over building area to be covered with solar thermal collectors (Morges office building renovation, fig.7.17) [%].

133


Dummy elements were proposed as a mean to support the compositive integration of the solar system. This option was welcomed by architects. It was less significant for the engineers, while it was considered crucial by the façade manufacturers (fig.7.20).

7.3.5 Visibility

The final questions investigated the general approach regarding solar installations. Expectations regarding the visibility of the solar system were investigated: should a system express its solar function and be recognizable, or should it be disguised and non recognizable (fig.7.21)? If choosing the second option, would it be acceptable to see piping connections or should they be hidden (fig.7.22)?

I m p o r t a n c e o f h a v i n g d u m m y e l e m e n t s

-100

-80

-60

-40

-20

0

20

40

60

80

100

rating

Arch. North

Arch. Centre

Arch. South

Engineers

Façade m.

All

R e c o g n i z a b i l i t y o f t h e s o l a r f u n c t i o n

0

10

20

30

40

50

60

70

80

No Yes


Fig 7.20: Recorded users’ interest for dummy elements

[-100 to +100 scale].

Fig 7.21: Users’ expectations regarding the recognizability of

the solar heat collection function of the system [%].

134


Apart from the solar enthusiastic engineers, all others interviewees (architects and façade manufacturers) were divided: half of them wanting a perfectly integrated non recognizable system, the other half wanting to somehow recognize the solar function of the integrated system (fig.7.21). Regarding the piping visibility, the trend was clearer, with about 60% of the interviewees, architects, engineers and facade manufacturers, preferring hidden piping (fig.7.22).

The closing question attempted to quantify the level of interest of the participants for the Solabs project, and left room for comments and appreciations.

The very high level of interest recorded by the survey results confirm that the difficulty of finding solar collectors conceived for building integration does exist and that users are actually conscious of the problem.

V i s i b l e p i p i n g

0

10

20

30

40

50

60

70

80

No Yes

Arch. North Arch. Centre Arch. South Engineers Façade m. All

[%]

L e v e l o f i n t e r e s t i n t h e S O L A B S p r o j e c t

0

10

20

30

40

50

60

70

-- - 0 + ++


Fig 7.22: Users’ expectations regarding the visibility of solar system piping [%].

Fig 7.23: Recorded users’ interest in the project Solabs [%].

135


7.4 The resulting collector

7.4.1 Characteristics of the new collector

The results of the survey had a major impact on the design process. The design of the new collector was then a matter of finding the best trade-offs between architectural, energetic and economical constraints. Carefully balancing recorded users’ wishes (aesthetic preferences and need for formal freedom), production constraints, energy performances, and cost, the project partners finalized the design of a multifunctional collector that responds to building needs and to market demand. Its major formal characteristics (module shape and size, module jointing, surface colour, texture, finish) are described in the following sections.

7.4.1.1 Module shape and size, module jointing

Considering the high level of freedom requested by the users for the module dimensions, the cassette option was abandoned and the development focused on the plank. The final product is a cut to length plank collector of 29 cm width, with variable negative jointing ranging from 0 to 2 cm, very similar to the plank modules largely available on the façade metal cladding market. The hydraulic system is fixed (glued or riveted) to the back of the collector to ensure both an optimal heat transfer and a perfectly smooth front surface. The horizontal piping system is designed to be compatible with the cut to length dimension of the modules. Similarly, the hydraulic junction between the planks, ensured by a brass manifold, is designed to be compatible with the variable width of the horizontal jointing (Fig.7.24, 7.25-a).

Fig 7.24: Dimensional characteristics of the

developed solar collector.

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7.4.1.2 Surface colour, texture, and finish

The surface of the absorber is flat with a matt finish, as wished by 90% of the interviewees. The wishes concerning the large palette of colours to be provided, together with the clear architects' preference for grey shades (see section 7.3.3), represented major challenges for the design team. To be able to satisfy users’ desire of large colour choice, the decision was taken to use thickness insensitive spectrally selective paints (TISS), to be applied to the collector when already build. This option was preferred to the alternative of making the collector absorber using already coloured coil coated metal sheets. With the chosen solution, the production is not limited by the need to order significant quantities of the same colour as for coil coating, and a large colour palette (including grey shades) can be proposed. As the paint can be produced in small quantities and in short time, customers will also have the possibility to ask for a specific colour on demand. Moreover, the possibility to paint the dummies and finishing elements with the same paint (see below) is another argument in favour of that option (Fig 7.25-b). The coloured selective paintings used in the project were developed by the National Institute of Chemistry of Slovenia. Different absorptance (α) and emittance (ε) values characterize the various colours of the palette, the architects having to select the paint by balancing aesthetics and energy efficiency criteria (Fig.7.25-b). Energy losses linked to the colour choice should nevertheless remain within a reasonable range (α>0.7 and emittance ε<0.4).

Fig 7.25-a The developed TISS paint can be applied to the collector when already formed allowing to propose a large colour palette.

137


Fig. 7.25-b: Colour palette with specific emittance (ε) (right ) and absorptance (α) (left) values for each colour (TISS painting – NIC Ljubljana).

138


7.4.2 Wall and cladding systems

To be able to cover a broad range of applications, it was decided to decline the multifunctional plank in two different variants:

a - wall system, offering self supporting sandwich elements

b - cladding system, to be applied on wall structure

a - Sandwich plank collector for wall systems

The sandwich plank collector for wall systems was the first one developed within the Solabs project. Made of self supporting, bifacial metallic planks, it is mainly targeted at industrial new buildings (see application examples in section 7.6.2). It offers the triple functionality of solar collector, façade finish, and thermally insulated wall (Fig. 7.26-a). Its possible implementations match those of a standard planks sandwich system, as shown by the example of fig.7.26 –b, taken from TKS Bausysteme.

b - Cladding plank collector.

The cladding plank collector is a modification of the previously described sandwich plank for wall systems. Stripped down of its back metal sheet and foam insulation, it can be applied like standard planks cladding over the external wall insulation (fig.7.27-a-b-c). Mounting on several different wall materials like concrete, bricks or wood is possible. (Sections 7.6.1, 7.6.3, 7.6.4, 7.6.5 give a set of application examples).

7.4.3 Development into a façade system

Both developed SOLABS planks (fig 7.26-a and fig.7.27-a-b-c) are cut to length modules that require the development of specific solutions for the vertical jointing, as well as a whole set of non active elements (dummies) and interface components to provide a complete facade system. As described in the development methodology presented in chapter 6, there are two possible ways leading to this result:

1. To develop the necessary façade elements around the new multifunctional collector

2. To adapt the new multifunctional collector to an already existing facade system The first facade prototype (Demosite) was elaborated following the first method, highlighting the limits of this approach (see section 6.2.1.3.3)

139


Cladding plank collector

Fig 7.27-a-b: Solabs cladding plank collector: side and front.

Fig 7.27-c: Solabs cladding plank collectors: back .

Sandwich plank collector for wall systems

Fig. 7.26-b: Existing TKS wall system

Fig.7.26-a: Solabs wall

140


7.4.3.1 The Demosite SOLABS facade prototype (approach1).

Apart from the prototypes produced for thermal performance evaluations, it was decided to design and set-up a demonstration stand at the IEA Demosite (EPFL) [7.3], to assess and demonstrate the architectural characteristics of the new collector.

Because of its much more advanced development stage, the sandwich wall system was chosen for this demonstration facade.

Starting from the given concrete structure of a pre-existing demonstration stand (fig.7.28), a compatible portion of facade was selected among several possible options (fig.7.29) to show the newly developed facade collectors system. The designed demonstration stand underline the pre-existing concrete structure (2 concrete walls 5m. apart) and include a window opening in the facade, the outdoor situation allowing for a convincing showcase (figs.7.30 and 7.32).

A whole set of non active elements, wall connections, window interface, jointing between adjacent planks and top and bottom elements were then designed around the developed plank collector to complete the facade system (figs. 7.33 to 7.39) (see chapter 6, sections 2.3.2 and 3: Level 2 and level 3, pp.117-118).

Fig 7.29: Demosite design: choosing a peculiar façade portion compatible with the characteristics of the developed collector and the pre-existing Demosite concrete structure.

Fig 7.28: Demosite existing concrete structure at EPFL (5m x 2m x 2m).

141


Fig 7.30: Demosite design : sketch.

Fig 7.32: Demosite design: understructure.

Fig 7.31: Demosite design: study over plank dimemensions.

142


Fig 7.35: Demosite design: development sketches for the vertical jointing. One main issue was to provide a thin vertical jointing, while allowing material dilatations at the different collector working temperatures (from -20°C to +100°C)

Fig 7.34: Demosite design: studies over the profiles for the interface jointing with the window.

29 cm

MEDIUM LEVEL OF INTEGRABILITY NON ACTIVE ELEMENTS

ADVANCED LEVEL OF INTEGRABILITY INTERFACE / JOINTING ELEMENTS

Fig 7.33: Demosite design: impact of non active modules, vertical jointing, finishing elements and interface components in the overall Demosite design.

143


This process required a significant amount of work, considering the lack of expertise and tooling for facade components by the collector manufacturer.

10cm 1cm

Fig 7.36: Demosite design: vertical cross section with

details, final design (final drawing traced in

collaboration with Jorges Gomez and Olivier Godin,

Clipsol).

144


Fig 7.39: The resulting Demosite prototype.

Fig 7.37-a: Demosite design: Studies over collector colour (simulation). Fig 7.37-b: Eight samples of different grey shades paint were provided by the National Institute of Ljubljana to choose from.

Fig 7.38 a-b-c-d-e: Different mounting phases: 1- Mounting the under-structure (fig a); 2- Mounting the plank collectors (fig. b-c-d); 3- Window mounting (fig. e).

Sicomix-8027-10-6 As 0.793 et 0 359

S-4044-7 As 0.841 et 0.384

S-10430-5 As 0.783 et 0.335

S-4047-7 As 0.839 et 0.395

SIL10204-7 As 0.799 et 0.274

S-Pk-778-7 As 0.853 et 0.394

S-5056-7 As 0.829 et 0.369

S-Pk-10550 As 0.763 et 0.318

a b

c d e

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This approach left the maximum design freedom in the development of the interface/jointing components, but required to develop the whole façade concept from scratch.

7.4.3.2 Approach 2: adaptation of the Solabs collector to an existing facade system.

The complexity of a façade system (offering all necessary elements (fig.7.40)), together with the lack of appropriate facade cladding know-how and equipment by the collector manufacturer, strongly advocated for an alternate solution for the development of the final facade system. Contacts were taken with facade manufacturer TKS Hoesch Bausystem to explore the possibility to adapt the developed solar plank to their existing facade cladding systems.

Being at the very final stage of the project, only the cladding plank option was further developed in this perspective. The plank presented in fig 7.41 is derived from the availble TKS Bausystem plank cladding, and can therefore be directly interfaced with all the other components of the system.

Fig 7.40: TKS Bausystem sandwich elements system for

façade.

Fig 7.41: Unpainted SOLABS plank cladding based on TKS

Bausystem (side, front and back views).

146


7.5 Architectural integration guidelines applied to Solabs planks.

For a successful architectural integration, all the features of the solar system having an impact on building appearance have to be coherent with the global building design logic. The characteristics of the Solabs system are intended to ease this -usually difficult- integration design work.

7.5.1 System position and dimension

"The position and dimension of collector field(s) have to be coherent with the architectural composition of the whole building (not just within the related façade)." (cf. chapter 4, section 1). Thanks to the multifunctionnality of the Solabs collector and to the availability of dummies, the size and position of the collector field can be defined according to both energy and architectural needs: only the suitable surfaces (in terms of solar exposure, suitable area, energy production goals, etc) will in fact be equipped with operating solar collectors, while the remaining ones can be covered with the sole cladding (dummies) according to the specific architectural needs.

7.5.2 Collector colours and materials

"The collector visible material(s) surface texture(s) and colour(s) interact with the same characteristics of other building envelope elements; as a consequence they should be compatible with the other building skin materials, colours and textures." (cf. chapter 4 section 2). The matt steel finishing characterizing the Solabs absorber is generally well suited for the façade cladding of most building types, as confirmed by the façade metal claddings market. The large palette of colours offered within Solabs is a great tool for the architect who has the possibility to choose a colour matching the other elements of the building (new or existing). The characterisation of each painting by its specific emittance and absorption coefficients helps choosing the colour, by considering also the specific energy production goals.

7.5.3 Module size and shape; module jointing

"Module size and shape have to be compatible with the building composition grid and with the various dimensions of the other facade elements." "Jointing types must be carefully considered while choosing the product, as different jointing types differently underline the modular grid of the system in relation to the building." (cf chapter 4 section 3 and 4)

147


The plank shape of the Solabs collector is characterized by free length, small width and negative jointing. This makes perceiving the Solabs cladding more as a homogenous covering than as a modular one. In the case of a retrofit, avoiding the modular grid effect makes easier to deal with a pre-existing building composition grid.

148


7.6 Application examples

A few simulations were carried out using Photoshop to test and demonstrate the architectural integration possibilities offered by the Solabs unglazed collector in the light of the previously described integration criteria.

7.6.1 Survey examples

Decision was taken to start testing the Solabs collector integrability potential taking as base cases the examples used in the first part of the questionnaire. The aim was to see if an improvement in the integration quality was possible by changing the characteristics of the collector to integrate. The roof integration examples and the fully successful integrations were skipped for obvious reasons. Two examples were then selected among the remaining cases: one that was considered just acceptable, and another considered as the worst.

Youth hostel renovation

The first Solabs integration simulation uses as a base the youth hostel renovation presented in example 4, whose survey rating by the architects was “just acceptable" (fig 7.42-a). The glazed solar modules of the rated system cover only the blind wall of the lateral façade, differentiating it from contiguous façades. On the contrary, in the original building there was no solution of continuity at the angle between the two facades. By removing the existing solar system we can clearly see that the original building is composed of three elements, two parallel blocs lying on a basement, and that the glazed collector integration doesn’t respect this compositive structure (fig 7.42-b). A new integration following the original whole building design logic is proposed exploiting the flexibility of the new collector (fig 7.42-c).

a. b. Fig 7.42-a: Youth hostel building in Austria integrating glazed collectors. Fig 7.42-b: Building appearance without the integrated solar system (simulation).

149


A new group of 20 architects with a solar energy background was asked to rate the level of improvement of the integration quality. Two third of the interviewees thought that the new integration quality was improved, moreover 37% said that it was widely improved (Fig.11-d).

c.

-- - +/- + ++0 % 16 % 20 % 26 % 37 %

-- - +- ++ +

Fig 7.42-c Solabs plank integration in respect of the

original building composition logic (simulation).

Fig 7.42-d: Quality improvement rating.

150


Single family house.

The second building selected for a Solabs integration simulation was the single family house presented in the survey as Case 3 (7.43-a). This example was considered totally unsuccessful by the architects. The solar collectors are applied to the wall as an added “decorative” element without any construction and/or composition logic. Even though single family houses aren’t the main Solabs system target, it was interesting and challenging to test the formal flexibility of the new collector in a case considered so tough (from the formal point of view).

As in the previous case, a simulation of the “naked” building was produced by

removing the original glazed system (7.43-b).

Then a new Solabs integration was designed using the collector as a façade

cladding covering the whole wall system. The exposed surfaces are covered with

active elements while shaded or too small areas and non exposed facades are

covered with non active elements. (7.43-d and e).

Again the integration quality was judged by the group of selected architect as

widely improved (7.43-c)

-- - +/- + ++0 % 1 % 0 % 53 % 42 %

-- - +- ++ +

Fig 7.43-a: Single family house with facade integrated solar system (existing building) 7.43-b: Building appearance without the integrated solar system (simulation).

Fig 7.43-c: Quality improvement rating.

151


Fig 7.43-d Proposed Solabs plank system integration

(simulation).

Fig 7.43-e Active and non active (dummies) elements.

152


7.6.2 Commercial buildings: a new Ikea standard

The well known international furniture company IKEA has some standard features in its building design throughout the world. Part of the design are the yellow IKEA logo and the blue background of the metallic façade. Without changing the “corporate image” nor the façade structure type, it would be possible to replace the existing system by Solabs collectors (sandwich panels or cladding) in well exposed surfaces, and Solabs non active elements in the other parts.

Two complete simulations of the resulting buildings appearances are presented (Fig.7.44-a-b and 7.45-a-b), for IKEA stores in USA and China. The accompanying sketches (Fig 7.44-c and 7.45-c) are showing which parts are active Solabs collectors and those that are non active façade elements.

Fig 7.44-a: Ikea megastore in Minneapolis, USA (existing building) 7.44-b: Proposed Solabs plank system integration (simulation).

Fig 7.44-c: Active and non active (dummies) elements..

153


Ikea mega store in China

Fig 7.45-a: Ikea megastore in China (existing building).

7.45-b: Proposed Solabs plank system integration (simulation).

Fig 7.45-c: Active and non active (dummies) elements.

154


7.6.3 Office buildings: new MSI headquarters in Lausanne-Vidy.

The new MSI office building in Lausanne-Vidy (Maison du Sport International) is a typical medium size office building. The main façade is totally glazed while the lateral facades are characterized by the carrying function of the blind walls. Blind walls in lateral facades and heads of flagstone in the main façade are insulated on the outer side and covered with a profiled aluminium cladding. (Fig. 7.46-a) The Solabs integration simulation respects the building structure and uses the solar elements in replacemnt for the original aluminium cladding. (Fig. 7.46-b) Active elements are placed on the walls of the southern lateral façade, while non active ones are used to cover flagstone heads. (Fig. 7.46-c)

Fig 7.46-a: MSI office building in Lausanne (existing building).

155


Fig 7.46-b: MSI office building, proposed Solabs plank system

integration (simulation). .

Fig 7.46-c: Active and non active (dummies) elements

(simulation). .

156


7.6.4 Residential building retrofit, Préverenges.

This residential building of the seventies has been retrofitted recently, using Eternit slates and aluminium cladding (Figs. 7.47-a-b-c). Three different variants using the Solabs cladding for some parts of the facades are presented, combining this new element with white plaster over external insulation or aluminium breast walls. These variants show the high level of flexibility of the developed system, which allows to freely tailor the active collector area to the defined thermal goals, within any chosen building composition logic (Figs. 7.47-d-e-f-g-h-i).

Fig 7.47-a: Residential building retrofit in Préverenges (CH) (existing building).

Fig 7.47-b and c: details of the Eternit cladding used for the facade retrofit (existing building).

a b

c

157


Solabs system integration - variant 1

Fig 7.47-e: Active and non active (dummies) elements:

non active elements are used for the too small areas (in the

main facade).

Fig 7.47-d: proposed Solabs plank system integration

(simulation). The solar collectors occupy the

entire lateral facade area..

158



Fig 7.47-g: Non active elements are not needed in this case.

Fig 7.47-f: proposed Solabs plank system integration (simulation). The solar collectors occupy all the breast wall area of the South-west facade .

159



Fig 7.47-i: Collectors are integrated in both the south

east and the south west facade, where no dummies are needed in this case. Differently we can

imagine to use dummies fro the cladding of North West facade

(non visible in the picture).

Fig 7.47-h: proposed Solabs plank system integration

(simulation). The solar collectors occupy all

the breast wall of the main facade and part of the lateral

one.

160


7.6.5 Residential building retrofit, La-Chaux-de-Fonds

This residential building, constructed in La Chaux-de-Fonds in the seventies, has been renovated recently using Eternit cladding. Two different Solabs integration simulations are presented here in replacement of the Eternit cladding, which shows once more the flexibility of the plank system and the advantage to dispose of non active elements (dummies) (figs. 7.48-a-b-c-d-e).

Fig 7.48-c: Proposed Solabs plank system integration - detail(simulation).

Fig 7.48-a: Retrofitted residential building in La-Chaux-de-Fonds (existing building)

Fig 7.48-b: Active and non active (dummies) elements: non active elements are used in the areas too small to be covered by active elements.

161


Fig 7.47-d: Version 1: All the facades are covered by Solabs

planks. The non exposed and to small areas are covered by

non active elements (dummies)

Fig 7.47-e: Version 2: Only the exposed angular building

blocks are covered by Solabs planks. The non exposed and to small areas are covered by

non activel elements (dummies)

162


References

[7.1] MC. Munari Probst, C. Roecker, EU projects SOLABS, Deliverable 1.1: Specifications, criteria and user-wishes for architectural integration, February 2005.

[7.2] MC. Munari Probst, C. Roecker, EU projects SOLABS, Deliverable 1.2: Guidelines and examples for Architectural Design, november 2006.

[7.3] Roecker, C.; Affolter, P.; Muller, A.; Schaller, F., Demosite: The Reference for Photovoltaic Building Integrated Technologies, In 17th European Photovoltaic Solar Energy Conference - Munich (2001).

[7.4] SOLABS, Development of Unglazed Solar Absorbers (Resorting to Coloured Selective Coatings on Steel Material) for Building Facades, and Integration into Heating Systems, EU project, Contract N0 ENK6-CT-2002-00679.

[7.5] B. Orel et al., Silicone-based thickness insensitive spectrally selective (TISS) paints as selective paint coatings for coloured solar absorbers (Part I), Solar Energy Materials & Solar Cells (2006), doi:10.1016/j.solmat.2006.07.013

[7.6] B. Orel et al., Selective paint coatings for coloured solar absorbers: Polyurethane thickness insensitive spectrally selective (TISS) paints (Part II), Solar Energy Materials & Solar Cells (2006), doi:10.1016/j.solmat.2006.07.012

[7.7] B. Orel1*, H. Spreizer1, A. Šurca Vuk1, M. Fir1, D. Merlini2, M. Vodlan2, M. Köhl3, Polyurethane-based Thickness Insensitive Spectrally Selective Paints for Coloured Solar Absorbers, in Proceedings Eurosun 2006, Glasgow (UK), 2006

[7.8] R. López Ibáñez, F. Martín, J.R. Ramos-Barrado, D. Leinen, Optimization of spray pyrolysis zirconia coatings on aluminized steel, Surface & Coatings Technology 200 (2006) 6368–6372.

[7.9] R. Romero Pareja, R. López Ibáñez, F. Martín, J.R. Ramos-Barrado, D. Leinen, Corrosion behaviour of zirconia barrier coatings on galvanized steel, Surface & Coatings Technology 200 (2006) 6606–6610

[7.10] MC Munari Probst, C. Roecker, SOLABS: Development of a Novel Solar Thermal Facade Cladding System, in Proceedings Eurosun 2006, Glasgow (UK), 2006

[7.11] MC. Munari Probst, C. Roecker, A. Schueler, Impact of new developments on the integration into facades of solar thermal collectors, in Proceedings EUROSUN 2004, Freiburg im Breisgau, Germany, 2004.

[7.12] P.Bonhôte, Y.Eperon, P.Renaud, TRANSYS simulations for performance evaluation of heating systems coupled with unglazed coloured solar absorbers on facade, in Preceedings Cisbat 2005, Lausanne, Switzerland, 2005.

163


METHODOLOGY VALIDATION: GLAZED SYSTEM

164


165


METHODOLOGY VALIDATION FOR A GLAZED SOLAR THERMAL SYSTEM I 8

Abstract: A second successful development is described, presenting another application of the suggested methodology detailed in chapter 6. The project, based on a novel glass filter development, solves major problems of glazed flat plate collectors’ integration and leads to the concept of glazed active solar facade systems.

8.1 Context of study

Referring to the set of formal requirements discussed in section 6.2.3 (VENUSTAS-formal integration, page 107 to 118), we can notice that in the field of glazed collectors for building facade, the most advanced products already offer some formal flexibility, but still have major formal limitations to overcome. These advanced systems offer a wide range of module dimensions and can provide tailored elements of different shapes. They can be used as multifunctional envelope elements and offer jointing systems compatible with the facade use (mainly consisting of covering jointing profiles framing the modules). However, no system provides flexibility in surface colour and texture (6.2.3.1 Basic level of integrability, c.collector colour and d.Visible surface textures and finish, page 113 to 116), and none provide "non active elements" (dummies) to complete the facade system (6.2.3.2 Medium level of integrability, page 117). Hence, glazed collectors are still predominantly characterized by the black colour of the absorber, its surface imperfection, welding marks and piping junctions (fig.8.1). Due to the absence of non active elements (dummies), the dimensioning of the collectors field is determined by thermal needs only, and its positioning limited to the sole available sun exposed areas. This makes it particularly difficult to satisfy at the same time the constraints related to building composition.

166


8.2 The approach: working on glazing transparency. A possible way to overcome simultaneously the formal limitations due to the absorber appearance and the lack of dummies is to work on glazing transparency. Transparent collector glazing lets appear absorber surface imperfections, welding marks and black colour (hardly acceptable on facades). The glazing transparency also makes it very difficult to provide non active elements similar to the active ones (dummies): to keep the same aspect these elements would require the use, behind the cover glass, of a metal sheet similar to the absorber, and would not actually solve the main problem of absorber appearance (besides being expensive and pointless in terms of construction -and thermal- needs) (fig.8.2).

Fig 8.1: Standard glazed flat plate collectors: absorber surface imperfections, black colour and welding marks are visible through the glazing

Fig 8.2: Facade integration of glazed flat plates collector in a residential building in Austria (AKS Doma) [8.1]. This example illustrate on one hand the architect’s will of using non active element having the same appearance to complete the facade, and on the other hand the limits brought by glass transparency in this sense.

SOLAR COLLECTORS NON ACTIVE ELEMENTS

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Some collector manufacturers already use slightly structured glasses to smoothen the absorber appearance, but this is by far not enough to solve the problem (fig.8.3). One innovative Swiss manufacturer of collectors (H+S Solar) has recently produced samples in A3 format to test the possibilities of masking the absorber using silk printed glasses (fig.8.4)(see also fig 6.11, page 114). Blue and white printings in few different patterns were tested. The masking effect was convincing, but the results weren't fully satisfactory, the silk printing reducing in a very significant way the energy transmission coefficient of the covering glass. Considering the simplicity and cost effectiveness of silk printing process, and the large patterns freedom it could offer, this option should not be abandoned too quickly. It would be very interesting to explore the impact of much lighter (less dense) patterns and different colours on energy efficiency and glass visual transparency, possibly conducting the tests on up scaled glasses to get a more realistic impression.

8.3 One solution: combining selective filters and diffusing treatments.

Overcoming glass visual transparency by providing non transparent energy efficient glazing would clearly mean overcoming the main limit to the spread of facade applications in the field of glazed flat plate collectors. In the light of these considerations, researches were undertaken at LESO-PB EPFL to provide coloured, visually non transparent glazing, which would still allow most of the solar radiation passing through. Considering that the general trend in this field is to look for the most performing extra white (low iron) glass to optimize the energy transmission factor, this is a real change of approach. The idea is to accept reducing the collector efficiency by a tiny fraction to finally open the way to facade applications of glazed flat plates, allowing the implementation of thousands of squared meters of new collectors. The desired properties of such glazing have been obtained in several steps by the application of successive treatments over the same glass.

Fig 8.3: Detail of a diffusing glazing effect over the absorber (Agena solar

thermal collector [8.2]).

Fig.8.4: Silk printed glass over standard black absorber

(H+S Solar [8.3]).

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8.3.1 Thin film selective interference filters

Considering that the human eye is sensitive to only a small fraction of the solar spectrum, the LESO idea was to develop a selective filter able to reflect only a specific part of the visible range of wavelengths, while letting the rest of the solar radiation passing through. This characteristic has been obtained by depositing on the glass a specially developed selective interference filter (Fig.8.5). Depositing successive nano layers of TiO2 and SiO2 on the internal side of the glass, a coloured thin film interference filter is obtained, which characteristics are very close to the ideal filter presented below: fig.8.5 shows such a coloured filter, which reflects only a tiny part (5-10%) of the solar spectrum in the visible range and lets the rest of the solar radiation reaching the absorber. By modifying the position of the reflection peak it is possible to obtain a specific colour. (Responsible for the nanotechnology for thin film interference filters development at LESO-PB: Dr. A. Schueler, PhD student E. de Chambrier) [8.4][8.5][8.6][8.7][8.8].

The resulting glazing have a coloured mirror appearance, which yet still let partially perceive the absorber structure.

Due to the characteristics of the interference filters, the glazing colour varies slightly with the angle of vision (more or less, according to the specific colours)[8.9]. As the

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Fig 8.5: Spectral characteristics of the interference selective filters: only a very small part of the solar spectrum in the visible range is reflected back by the filter (5-10%), while the rest of the solar spectrum pass through the glass and reach the absorber.

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masking effect is based on light reflection, it is very sensitive to shadows, resulting in absence of colour and consequently glass transparency (see fig 8.6)

8.3.2 Diffusing glass treatments

To face these inconveniences and to avoid the mirror aspect (very popular in the eighties, but less seducing today) an additional diffusing treatment is needed.

Fig 8.6 Demonstration box showing the effect of sun (left)

and shadow (right) on different colour samples:

a1-a2: blue coating b1-b2: yellow coating

c1-c2: red coating

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Fig 8.7 Blue coated extra white glass (without diffusing

treatment) mounted on a standard Agena collector

laying on the ground in front of a building (reflected on the

collector), and tremendous smoothing effect of five

different A4 diffusing glasses placed on top of it.

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In order to study the effect of different possible treatments over the different glass colours, a demonstration box, called "demoboîte", has been designed and built at the LESO-PB (technical support: Pierre Loesch) (fig.8.8 and 8.9).

The demonstration box was designed to host at will one or two glass sheets in A4 format. A standard black absorber has been placed on the bottom at a distance of 5 cm from the glazing; sides have been closed to simulate the light conditions inside a standard glazed collector.

As the first selective filters had been deposited by dip coating in the LESO-PB laboratory, both sides of the glass were coated. The first tests to simulate the effect of diffusing glass treatments were then conducted by superposing an additional diffusing glass over the coated ones. Structured glasses (pyramidal), acid etched glasses, and sand blasted glasses were used in this initial testing phase. The results were very satisfactory: the diffusing treatment layer solved both problems of important angle dependency and absence of colour under shadows, providing a much more homogeneous appearance under all light conditions (fig.8.10).

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Fig 8.8: Demonstration box "Demoboîte" designed to host two A4 glass samples of 4mm thickness: base and cover dimensions.

Fig 8.9: Demonstration box "Demoboîte", 3D simulation of base and cover.

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Fig.8.10: Different colour coated glasses (left column) and effect of adding different diffusing glasses on top (structured pyramidal in the centre column and acid etched glasses in the right column).

EXTRA WHITE STANDARD GLAZING STRUCTURED GLAZING (PYRAMIDAL) ACID ETCHED GLAZING

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Such encouraging results opened the way to the next phase of the project: the application of both treatments (interference filter + diffusing treatment) over the same glass, and up scaling to real collector dimensions (see scheme in fig 8.11).

8.3.3 Full glass treatment and up scaling

To test the coating and the impact of diffusing treatments on a single glass and on larger size, it was decided to apply the coloured filters by magnetron sputtering rather than by dip coating. Magnetron sputtering allows coating of large size glasses using the equipment normally employed by glass manufacturers to produce selective glazing. At the same time it allows an easy application of the interference filters on a single side of the glass only, letting the other side free to receive a diffusing treatment. An agreement was made with glass manufacturer Glass Troesch to use its equipment; three different colours (blue, green and yellow) were applied on one side of several 2x3 meters extra white float glasses. The colours were selected considering their low angle dependency and interest for architectural applications.

For the glass to have the desired homogeneous appearance, diffusing treatments have to be applied to the external side of the glass (see scheme in fig.8.11). This makes it important to choose a treatment with a good energy transmission factor (acceptable losses around 1%) and dirt repellent. Among diffusing treatments, the acid etching seemed very promising in this respect, and clearly the most flexible in terms of surface textures/patterns. A collaboration was started with Fällander Glas in Fällanden, a company specialized in the manual acid etching treatment; a first set of A4 samples were treated. Different intensities of homogeneous etching were provided showing that very light etchings are sufficient to obtain the needed diffusing effect.

A certain number of A4 format samples were cut out of the resulting coloured coated glazing and treated using various acid etchings and sand projections, to test the impact of these diffusing treatments on the final appearance of the glass. Several sub-options were also tested, as acid etched regular patterns and even custom designed etchings (text, logo, etc.), in order to show the possibilities offered to users.

As the number of interesting samples grew rapidly, the need for a simultaneous comparison between options appeared, leading to the development of three demonstration boxes able to host 4 glasses each ("Demobandes") (Fig. 8.12 and 13).

Fig 8.12: Demobande showing blue coated glasses with different diffusing treatments patterns and resulting different levels of absorber visibility . The solar transmission factor is only reduced from 92% (white glass) to 80-85% depending on the chosen colour, reflection intensity and surface treatment.

Extra white solar glass with blue selective filter (inner side) and different diffusing treatments (outer side) in front of black absorber.

Standard extra white solar glass in front of black absorber (Energie Solaire SA).

Standard extra white solar glass with different selective filter colours (inner side) in front of black absorber.

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SCHEME 8.11: COLOURED GLAZINGS - WORKING PRINCIPLE, COLOURS, TREATMENTS

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These samples allowed selecting the treatments of the two first large scale glasses cut to the collector sizes of Schweizer (120 cm x 210 cm) and Agena SA (243 cm x 93 cm), respectively: Fällander H16 acid etching standard for Agena and Fällander H16 with small squares pattern for Schweizer (fig. 8.14, fig.8.15, fig.8.16).

The result was really convincing and two other glasses of the same size were treated and mounted on two other complimentary Schweitzer standard collectors: yellow coating with homogeneous acid etching, and green coating with text/acid etching (fig.8.17). Three exhibition supports were designed and realized to display the glasses vertically one beside the other, and get a realistic impression of the impact they would have on a building facade.

Fig 8.13 Demobandes showing green and yellow

glassed with various etching and patterns: The availability of various coloured coatings combined with the different

diffusing treatments offers an interesting palette for façade

claddings and allows implementing “incognito”

collectors.

Fig 8.14 Schweizer collector with naked absorber and the

same collector with the new blue acid etched glazing with

a small squares pattern.

Fig 8.15 Mounting the new colour glazing over the

existing Schweizer collector.

Fig 8.16: Agena collector with its standard structured glass

beside the same collector with the LESO blue coated

glass photographed in a cloudy day in front of Agena

factory in Moudon.

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Fig.8.17: Three resulting up scaled glazing mounted on Schw

eizer collectors (real picture). From left to right: Blue coating plus Fällander m

anual acid etching (H16) w

ith regular pattern resulting from non etched

small squares; green coating plus m

anual acid etching with personalized text pattern; yellow

coating plus homogeneous acid etching.

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8.4 Addressed key integration issues

As expected, the resulting glazing offers the needed flexibility on surface colour and texture, solving the integration problems related to the black and irregular surface of the absorber with only 5-10% energy transmission reduction. The new integration possibilities offered by the newly developed glazing are discussed in the light of the results of a survey over users' wishes. The pool was composed of about 30 architects with 2 to 5 years of professional experience, and was conducted within a seminar on building integrated solar technologies.

8.4.1 Glass surface colour

The selective filters technology is able to provide very good colour flexibility. The different colour shades can slightly vary with the angle of vision, red colours being the most angles dependent, blue colours the most stable, yellows and greens being in between. To help identify which colour shades should be made available it was asked to appreciate the interest for blue, red, yellow and green colour shades on a 5 point scale ( - - ; - ; +/- ; + ; ++). The most appreciated colours were green and blue shades, with red shades being the least appreciated. The colour angle dependency was considered just acceptable (fig.8.18).

In the survey conducted within the Solabs project (unglazed collectors) a clear preference for grey colours was recorded for steel absorbers (p.130, section.7.3.3).

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COLOUR APPRECIATION SURFACE FINISH APPRECIATION Fig 8.18 (left): Architects’

appreciation of the red, blue, green and yellow shades, for

collector glazing, and acceptability of colour

variations with the angle of vision

[-100 to +100 scale].

Fig 8.19 (right): Architects’ appreciation of different glass

surface finish and patterns [-100 to +100 scale].

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This was explained by the architects' well spread preference for true materials colour (steel = grey). This hypothesis is compatible with the preferences recorded for the glazing colour, green and blue shades reminding respectively the natural colour of glass and the natural sky reflection over glass surfaces. Confirmation of this tendency can be found in the predominant use of these colours in existing glass claddings (fig.8.20-a-b)(fig.26-a-b-d).

8.4.2. Glass surface texture

Users' wishes for glass finish are clear: acid etching and structured glass are both considered highly interesting. Patterns are appreciated options, and customized ones, like texts or logos, are particularly appealing (see also detailed questions in annexe 5) (fig.8.19, fig.8.21.a-b, fig.8.25-a-b-c).

Fig 8.20-a b: Green/blue coloured glazing over opaque envelope parts: - a (left): ISP building, Basel, 1998, Herzog &. De Meuron. The glass cladding is overlaid with a grid of green points. From a distance, the building appears as a homogenous green glass volume. Credit: Matière d'art, Birkhauser , 2001 - b (right): Les Ouches, school building, Genève,2003-2005, Architect A. Bassi. Credit: L. Bonvin.

Fig 8.21-a (left): Transparent glazing with regular text pattern used as facade cladding over opaque envelope parts in the Art Gallery Lentos, Linz (A), 2004, arch Bellorini, Weber and Hofer,Zurich. Credit: Profile, Architecture Magazine 04, Schuco. Fig 8.21-b (right): Art Gallery Bregenz (A), Peter Zumthor 1997. Homogeneous acid etched glass cladding (Fallender) over opaque and transparent parts of building envelope.

179


The possibility to apply the coating on a single face of the glass only, allows using on the other side any type of diffusing glass finish not relevantly affecting the transmission coefficient. The use of manual treatments like the acid etching and sand projection, offers a large freedom in both the treatment intensity (more or less smooth/transmitting/diffusing) and the possible patterns (regular, irregular, personalized texts, images, logos). The cost of such processing may be affordable for special/representative buildings, but would generally be too high for standard buildings, meaning that more industrialized options should be provided. The ideal solution would be to deposit the magnetron sputtering coating on glasses which are already diffusing on the other side (structured glasses, industrially acid etched, industrially sand blasted ...). Further research should be conducted over the types of treatment compatible with magnetron sputtering deposition on the other side of the glass. Structured glasses for instance are produced by lamination (rolled glass) (fig.8.22), which may result in surface irregularities also on the non diffusing glass side. The point will be to see if these irregularities in the glass surface still allow the magnetron sputtered coating to meet the expectations.

Industrial acid etched glasses would be on the contrary perfects for the magnetron sputtering process, since the etching can be applied on floated glass, characterized by a perfectly flat surface. Actual limitations are in the low availability of industrial treatments on extra white glass, in comparison with the almost unlimited choice proposed for standard glasses. Should the market not already offer these products, studies would then have to be conducted together with a glass manufacturer about the best ways to provide industrial etching over floated extra white glasses, on the definition of the ideal etching intensity to be provided, and on the impact of the treatment on dust and dirt deposition.

Fig 8.22: Albarino extra white patterned glass by Saint

Gobain offers several patterns resulting from

lamination (rolled glass). Credit: Saint Gobain.

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8.4.3. Non active elements (dummies)

The special properties of the developed coloured glazing makes it finally possible to provide non-active elements (dummies) having the same appearance than the solar collectors: this is a crucial step in the field of glazed flat plate collectors. What is very promising is that these non active elements (dummies) look like the standard glass panels currently used for the cladding of both new buildings and renovations. Thanks to the masking effect the same glass can be used as external glass in front of solar absorbers, but also as facade cladding (over insulation) on areas which are not equipped with thermal collectors. This option was highly welcomed by the surveyed architects: 93% of interviewed are interested in this new possibility, 75% of them being really enthusiastic (fig.8.23). All interviewees said this new level of freedom would encourage them integrating solar collectors into building facades (70% of them saying this would even be highly encouraging) (fig.8.24).

Glass is a durable and stable material, often associated with an enhanced building image. Glass claddings are a valuable option for new buildings (fig.8.25-a-b-c) and are also suitable for the renovation of many buildings from the fifties, sixties, seventies requiring today a comprehensive envelope retrofit (Fig: 8.26 a-b-c-d). The developed coloured glazing would be in all these cases an effective way to combine envelope energy performances enhancement, use of solar thermal, and aesthetic.

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Fig 8.23 (left): Distribution of architects’ appreciations for the new possibility to use the same glass in front of solar absorbers, and as facade cladding on areas not equipped with thermal collectors. Fig 8.24 (right): Distribution of architects’ answers to the question: “How much the new glazing would encourage you to integrate solar thermal into building facades?”.

Non active elements (dummies) Interest

Fig 8.25 a-b-c: New school building in Altstatten (CH), 2007, Architects Goldi+Eggenberger. Acid etched glasses with texts as facade cladding over opaque envelope parts. (credit fig.8.25-b: E.Haltiner, Fassade 4/2007, p.55) a b c

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The main advantage of the developed concept is that the active elements (i.e. the collectors) can be positioned at will on the exposed areas, and that their quantity is determined only by thermal requirements, not by architectural composition. The non recognizability of the solar system brought by the new concept is welcomed by the contacted architects: only less then 20% wish to clearly recognize the solar function (fig.8.27).

Fig 8.26-a-b-c-d-e-f-g: examples of existing buildings

retrofitted using standard glass panel as cladding over

opaque:

a-b: Philippe Morris building renovation, Lausanne,

Architects Dévanthery et Lamunière, 2007: Tinted

glass panels as facade cladding over insulation (original building 1972).

c (left): Detail of La Poste office building, Lausanne, retrofitted using structured

glazings over opaque envelope parts (architect

Roland Mosimann, Lausanne).

d (right): Primary School in Pully: building renovation (Dévanthery & Lamunière

1998-99) using coloured glass cladding:

Fig 8.27 (left): Distribution of architects’ answers to the

question: “would you recognize the solar function of

the collectors?”.

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By freeing that portion of the façade that can be clad with this glazing from the thermally needed surface for collectors, a major step towards helping architects using solar thermal is achieved. By meeting the requirements related to both functions of heat production and facade cladding, this glazing fulfils in fact the main conditions to successfully develop a multifunctional active façade system (see also integration simulation in the following section 9.6 of this chapter).

8.5 Next steps

Beside the present achievements, further developments are still needed to finalize the project:

- Optimize filter characteristics (transmission, colours) and production process.

- Identify the way to obtain industrialized diffusing white glasses compatible with the magnetron sputtering process.

- Test the effect of tempering the glasses for facade application

- Finalize compatible facade system concepts with facade and collectors manufacturers, with particular attention to the jointing and fixing issues (fig.8.28).

8.6 Integration simulations

A few integration simulations are presented to show the interest of the developed glazing and of the related active facade concept. Existing buildings using standard glass panel as cladding over opaque envelope parts are the basis for the simulations. Both new buildings and renovations are presented.

Fig 8.28: Different glass jointing and fixing options. Source: Facade construction Manual, Herzog Krippner Lang, p.191 [8.14].

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Building renovation: example 1

Fig 8.29-a (left): Primary School in Pully: building

renovation (Devanthéry & Lamunière 1998-99) using

coloured glass cladding over opaque envelope parts.

Fig. 29-b (right): The standard

glazing could be replaced by the new glazing. In the

exposed facade areas they would be used as collector

glazing and in the non exposed ones they would be

used as facade cladding over insulation.

Fig.29-c: Integration

simulation, using a blue coated acid etched glazing with small squares pattern. The building still looks very

similar to the original: the facades are homogeneous,

and the solar system is invisible.

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Building renovation: example 2

Fig 8.30-a-b-c: La Poste office building in Lausanne: building renovation using structured glass as facade cladding over opaque envelope parts (architect Roland Mosimann, Lausanne). a- South facade b- Detail of the corner between the South and East facades. c- East facade

Opposite page:Fig. 30-d-e: The standard

glazing could be replaced by the new glazing. In the

exposed facade areas they would be used as collector

glazing and in the non exposed ones they would be

used as facade cladding over insulation.

Fig.30-f-g: Integration simulation of a standard

glazed collectors system in the south facade (whole

building-left-, and detail of the South-East corner-right-).

Fig.30-h-i: Integration simulation, using a green

coated acid etched glazing the integration of the solar

thermal system is compatible with a homogeneous

appearance of the different facades (whole building -left-,

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New building example 1

Fig 8.31-a: Restaurant in Graz, Austria, using opaque light blue coloured glazings as facade cladding Fig 8.31-b: The standard glazing could be replaced by the new glazing. In the exposed facade areas (and according to the thermal needs) they would be used as collector glazing and in the non exposed ones they would be used as facade cladding over insulation. Fig 8.31-c: Integration simulation of a standard glazed flat plate collectors system in the South facade.

Opposite page: Fig 8.31-d: Integration

simulation using a green coated acid etched glazing as collector glazing in the South faced and as cladding in the

non exposed areas.

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References [8.1] AKS Doma Solartechnik -Flex. http://www.aksdoma.com

[8.2] Agena Energies - http://www.agena-energies.ch

[8.3] H+S Solar GmbH - Produkt H+S Pa. http://www.hssolar.ch www.hsserviceag.ch

[8.4] Schueler, A. ; Roecker, C. ; Scartezzini, J.-L, “Interference filters for colored glazed thermal solar collectors”, in: Proceedings ISES Solar World Congress 2003, Göteborg (SE), vol. 03, num. 16, 2003, p. 51

[8.5] Schueler, A. ; Roecker, C. ; Scartezzini, J.-L, Boudaden, J., Videnovic, I.R., Ho, R.S.-C., Oelhafen, P., "On the feasability of coloured glazed thermal solar collectors based on thin film interference filters" , in Solar Energy Materials & Solar Cells, num. 84 (2004), p. 241-254.

[8.6] Schueler, A. ; Roecker, C. ; Scartezzini, J.-L. ; Boudaden, J. et al., “Towards coloured glazed thermal solar collectors”, in: Solar Energy Materials & Solar Cells, num. 84, 2004, p. 225

[8.7] A. Schüler, J. Boudaden, P. Oelhafen, E. de Chambrier, C. Roecker, J.-L. Scartezzini, “Thin film multilayer design types for colored glazed thermal solar collectors”, Solar Energy Materials & Solar Cells 89 (2005), 219-231

[8.8] E. De Chambrier, D. Dutta, C. Roecker, M. Munari-Probst, J.-L. Scartezzini, and A. Schüler, Nanostructured Coatings on Glazing for Active Solar Facades, In CISBAT 2007, Lausanne, Switzerland, 2007.

[8.9] Schueler, A. ; De Chambier, E. ; Dutta, D. ; Roecker, C. et al. “Angle-dependent spectrophotometry of Sol-Gel deposited multilayered oxide coatings on solar collector glasses”, Presented at: CISBAT 2005, Lausanne, September 28.In: CISBAT 2005, 2005, p. 227-232.

[8.10] Munari Probst, M.-C.; Roecker, C.; Schueler, A.; Scartezzini, J.-L. , “Impact of new developments of the integration into facades of solar thermal collectors", In EUROSUN 2004 Proceedings, Freiburg in Brisgau, vol. 2 (2004), p. 351-357

[8.11] Munari Probst, M.C. ; De Chambrier, E. ; Roecker, C. ; Scartezzini, J.-L. et al. “New:coloured glazings for solar thermal facades”, Presented at: EPFL Research Day 2008, Lausanne, 15 April 2008. (Prize of Sustainable Development).

[8.12] Munari-Probst, M.C. ; Kosoric, V. ; Schueler, A. ; De Chambrier, E. et al., “Facade Integration of Solar Thermal Collectors: Present and Future” Presented at: CISBAT 2007, Lausanne, 4-5 September 2007.In: CISBAT 2007, 2007, p. 171-176, Lausanne : EPFL, 2007.

[8.13] Roecker, C. ; Munari Probst, M.C. ; De Chambrier, E. ; Schueler, A. et al, “Facade Integration of Solar Thermal Collectors:A Breakthrough?”, Presented at ISES2005, Beijing, 2007.

[8.14] T. Herzog, R. Krippner, W. Lang, Façade construction manual, Birkhauser, edition Detail, 2004.

Chapter 9 I Conclusions

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CONCLUSIONS


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CONCLUSIONS I 9

The objective of this thesis was to investigate possible ways to enhance the architectural quality of building integrated solar thermal systems (BIST). Being at the junction between architecture and technology, it dealt with both fields and brought new elements in each of them. To start from an objective ground, a large EU survey was conducted over architects' perception of the architectural quality of different existing building integrated systems. The survey results showed a clear consistency of architects' judgement, demonstrating that architectural integration quality is not just the result of a personal feeling, and can thus be described.

The integration requirements leading to architectural quality were defined, considering the different aspects of architecture: functional (utilitas), constructive (firmitas) and formal (venustas) ones. The focus of this research was then concentrated on the formal aspects, generally underestimated and/or considered as merely subjective by most professionals acting in the solar thermal field.

It has been demonstrated that all the system characteristics having an impact on building appearance, and not just some, affect the integration quality, and should consequently be coherent with the global building design logic. These key characteristics have been identified as: field size and position; collector materials, surface texture(s) and colour(s); module shape and size; module jointing.

From that base, integration guidelines focusing on the three most relevant solar thermal technologies (glazed and unglazed flat plates and evacuated tubes) have been derived to support architects’ design work and manufacturers’ product design.

The role of the architect in the integration design and the parameters of which he disposes to play/work with in order to integrate energy performing systems according to the proposed guidelines have been explored and described (energy production goals, formal integration needs, solar thermal technology choice, specific product choice within the technology, etc).

The survey on the products proposed by the market led to the recognition that existing solar systems were mainly conceived as technical elements to optimize solar energy collection, with a low awareness of building integration issues, and a very low


192


level of formal flexibility. Architects’ integration design work has consequently been recognized to be a hard task, in particular when it comes to facade integrations.

This led to identify in the lack of products conceived for building integration the main real barrier to integration quality.

In this perspective, an original methodology to help design novel collectors meeting not just energy production goals but also architectural integration requirements has been developed and described.

Three progressive steps needed to meet architectural requirements have been described on the path leading to the novel concept of active façade systems. The central role of façade manufacturers within this new vision has been stressed.

Finally two separate developments in both fields of glazed and unglazed systems have been used to check the relevance of the proposed approach:

- In the field of unglazed collectors, a novel system for façades was developed according to the new methodology within the EU project Solabs, representing the very first concept of an active thermal facade system, and raising a very high level of interest.

- In the field of glazed collectors, the potential of a novel coloured glazing to ease façade integration of solar thermal has been demonstrated. Giving a real answer to the problems related to the transparency of the glazing (identified as the main limit to facade integration for this specific technology), the new glazing can be used both for insulation cladding and collector cover, opening a new level of flexibility in the design of active glazed facades.

In both the developed systems the solar heat collection function is not openly declared, and remains an “invisible” added function among the wide and complex set of functions fulfilled by the building skin. Using invisible multifunctional systems is clearly not the sole possible approach to BIST architectural integration. Present collectors, optimized for the heat collection function, can in fact still be used within fully successful building integrations, like in the case of the School building designed by Architects Gsell und Tobler (chapter 4 - page 65); on the other hand “visible” collectors with a new aesthetic, for buildings with a new architectural language, can and will certainly also be developed to complete the market offer.

All that said, the large size of the collector field at the facade scale lets foresee in the proposed multifunctional active facade concept the most promising approach to a wider and easier architectural use of active solar thermal technologies in buildings.

Both developed systems have shown a much better integrability when compared to the best available systems in the corresponding field (ref. innovative available systems, section 5.2, p.79 and p.85) (fig.9.1), and have received enthusiastic feedbacks when presented to the architects' community (fig.7.23 p.134 and fig. 8.24 p.180), confirming the validity of the methodology.


193


The award received with the paper presenting the methodology at the PLEA Conference in 2005, and the impact of this work in the definition of the newly accepted IEA Task 41 “Solar Energy and Architecture”, are further confirmations of the relevance of the proposed approach [4.3] [Annexe1].

Glazing: finish / texture choice

+

+

+

+

+

+

Developed unglazed system

Best existing

unglazed system

+/-

-

-

+/-

+

+

Jointing options

Absorber colour choice

Absorber: finish/ texture choice

Shape & size flexibility

Availability of dummies

Multifunctional element

+ +

+ - + - + +/- + + + - + +

Developed glazed system

Best existing glazed system

Fig. 9.1: "integrability" of the two systems developed

according to the proposed methodology, in comparison

with the most innovative products available on the

market in the respective fields.


194



189


ANNEXE 1: IEA TASK 41SOLAR ENERGY AND ARCHITECTURE


190


Task XX

______________________

Solar Energy and Architecture ___________________________ Annex Plan Draft: November 5, 2008 Developed by: Maria Wall (SE), Jens Windeleff (DK), Anne G Lien (N) Contributors: Anne Grete Hestnes (N), Torben Esbensen (DK), Henrik Sørensen (DK), Urs Wolfer (CH), Tilmann E. Kuhn (D), Francesco Frontini (D), Claudio Ferrara (D), MariaCristina Munari Probst (CH), Christian Roecker (CH)

Approved as IEA SHC Task 41, at the IEA Ex-Co Meeting 19-21November 2008.

_________________________________________________________________________ IEA Solar Heating & Cooling Programme - Task XX: Solar Energy and Architecture 2

TASK XX Solar Energy and Architecture 1. Preamble

Solar energy can be utilized in buildings in several ways. Often we differentiate between two main ways to utilize solar energy. Either by letting the solar radiation transmit through windows to passively contribute to space heating and offer daylight that can reduce the electricity need for lighting. Or by using active solar systems on the building envelope to produce solar heat and electricity that can be used to reduce the building’s need for non-renewable energy supply. Passive solar utilisation is more or less always part of a building’s energy balance. Passive solar gains can result in a reduced heating demand and a reduced lighting demand but also in excessive indoor temperatures and in increased cooling demand. Windows are used in most buildings and often well integrated in the building envelope. Shading devices are in many regions also frequently used even if there are regional differences both regarding the need and the tradition of using them. Active solar systems are sometimes integrated in new buildings as well as put on existing buildings to produce hot water or electricity. The possibilities are many; solar thermal systems that contribute to domestic hot water heating and space heating and photovoltaics that produce electricity used either directly in the building or, when allowed, distributed into the common electricity grid. Also solar hybrid systems which produce both heat and electricity are available. While the technical development and energy performance improvements are always in progress, the actual use of these systems in buildings is not increasing as it could and should do. Existing buildings account for over 40% of the world’s total primary energy use and 24% of greenhouse gas emissions1. A combination of making buildings more energy-efficient and using a larger fraction of renewable energy is therefore a key issue to reduce the non-renewable energy use and greenhouse gas emissions. A large portion of the potential for energy efficiency in existing buildings and potential to utilize solar energy still remains unused. It is clear that solar energy use can be an important part of the building design and the building’s energy balance to a much higher extent than it is today. Cleverly used, active and passive solar energy can both contribute to the energy supply and to a higher quality of the architecture. Badly used, passive solar energy can increase the cooling and heating demands as well as cause

1 IEA Promoting Energy Efficiency Investments – case studies in the residential sector. ISBN 978-92-64-04214-8. Paris. 2008.


discomfort. Wrongly used, active solar energy can make the buildings less robust and uglier and can lead to a higher cost without even supplying much energy. Why are solar energy systems not more frequently used in buildings? Despite all the available solar technologies and the opportunity to reduce the energy demand, solar energy systems are in most cases not used in buildings today. This has several causes:

1. Economical factors such as investment costs and maintenance costs.

2. Technical knowledge factors such as lack of knowledge among decision makers and architects, as well as a general reluctance to “new” technologies.

3. Architectural (aesthetic) factors: solar technologies for building use have

an important impact on the building’s architecture. Due to the large size of solar systems in relation to the scale of the building envelope, the architectural quality of their integration has a major impact on the final architectural quality of the building. In this respect the limit to the spread of solar technologies lies in the generally poor architectural quality of their integration into the building envelope.

Subsequently, the architectural factor has three main components:

3 a) Active technologies, solar thermal in particular, are characterized by a general lack of products conceived for building integration, caused by a lack of architectural knowledge of manufacturers.

3 b) The architects’ knowledge in the possibilities offered by available technologies and available innovative products is generally insufficient.

3 c) A lack of simple tools that can quantify and illustrate (also architecturally) the influence of various solar applications, at an early design stage when there is still time for changes.

The present Task will focus on this third group of factors and sub factors, and is intended to support promoting the use of solar technologies as a complement to promotion policies focusing on subsidies and technical information spread. The vision – and the opportunity – is to make architectural design a driving force for the use of solar energy. Architectural quality Looking at the many solar plants installed in the last generation two facts are clear: good architectural integrations do exist; they are extremely rare. Moreover, it is also a fact that public acceptance of solar energy to a high degree depends on the quality of the architectural integration. Hence the justification for a common effort to improve the quality of architectural integration of solar technologies and the dissemination of related results.


Although subjective elements cannot be excluded in preferences on architecture styles and solutions, judgements on the quality of the architecture can certainly converge among skilled professionals and thereby constitute a valuable consensus for the future common work. It is therefore one of the main goals of this Task to deal in depth with the theme of solar architectural quality, in an international and co-operating way. As recent works have shown, criteria can be defined and guidelines proposed for all the actors in the field; architects, collector and façade/roof manufacturers, clients and public bodies (municipalities, city planners). Through various interactions with all these actors, the results of this task should largely contribute to increase the architectural quality of the products and of the integrations. Solar energy AND architecture The title of this Task indicates that focus is on both high architectural quality and high energy performance. Thus, it would be counterproductive to show the use of solar applications in buildings where the energy performance is poor or even worse than without solar applications. This title also indicates a new way of approaching the use of active solar energy in buildings that sees architects composing their architecture with solar components conceived as building elements.

2. Objectives and Scope The main goals of the Task are to help achieving high quality architecture for buildings integrating solar energy systems, as well as improving the qualifications of the architects, their communications and interactions with engineers, manufactures and clients. Increased user acceptance of solar designs and technologies will accelerate the market penetration. The overall benefit will be an increased use of solar energy in buildings, thus reducing the non-renewable energy demand and greenhouse gas emissions. To achieve these goals, work is needed in three main topics:

A. Architectural quality criteria; guidelines for architects by technology and application for new products development.

B. Tool development for early stage evaluations and balancing of various solar technologies integration.

C. Integration concepts and examples, and derived guidelines for architects. The first objective is to define general architectural quality criteria and extract recommendations for solar components/systems, to support manufacturers in developing existing products as well as new products. Specific criteria for the architectural integration of different solar energy components/systems will be developed in cooperation between architects, manufacturers and other actors.


New adapted products should result from this activity as well as appropriate ways to use them. The second objective concerns methods and tools to be used by architects at an early design stage, which need to be developed or improved. An example of such a tool can be how to visualize the solar energy concepts to show e.g. clients. Other examples can be tools needed to quantify and clearly illustrate the solar energy contribution and help balance the use of different active and passive solar technologies on the building envelope. The last objective is to provide good examples of architectural integration, in the form of both existing projects that can be analysed as well as proposals for new projects. Buildings, installations and products will be included. Case studies will be an important basis to gain experience regarding the level of successful building integration, achieved solar energy contribution and to identify barriers related to e.g. technical and economical aspects and attitudes. New demonstration buildings will be developed in connection with the Task work and followed at least for the first part of the design stage, to learn from and to test guidelines and tools. Communication tools and guidelines with facts and arguments for architects to help convince their clients to include solar energy systems will be produced. Arguments and facts related to architectural value, energy performance and life cycle costs are essential. Here, the arguments and facts need to be tailored for different building types and owner/user structures. The results will also serve as a basis for teaching material that could be used in e.g. architecture schools. To communicate the value of solar energy designs and technologies, the Task will carry out seminars, workshops and produce articles in e.g. architectural magazines. Scope The scope of the Task includes residential and non-residential buildings. Both new and existing buildings will be included, for the climatic zones represented by the participating countries. In this way the potential impact of the Task can be large. Already cost-effective systems can, with a successful architectural integration, accelerate the market penetration. But also technologies not yet fully cost-effective can benefit from the work to pave the way to successful integration and user/client acceptance, and make the coming market penetration smoother. The work will be linked to national activities and will focus on individual buildings or groups of buildings with special focus on the building envelope. The work will be based on workshops with architects, manufacturers and other key actors. The workshops may be carried out nationally or regionally based on a common format developed within the Task. In addition, special workshops and seminars may be held in connection with a Task meeting; to let Task experts and representatives from local practitioners and manufacturers come together and


discuss barriers and what can be done. Analysis of existing components, systems and buildings will help to develop innovative design solutions. Good examples will also be used to inspire and as help to convince the client. 3. Means The Task is organized in three Subtasks, derived from the above described objectives and goals. The integration problems related to the different technologies (product development, method of integration) are treated in subtask A. The balance issues between the different types of solar gains, related to energy and cost impacts, are treated in subtask B. Finally the architectural integration issue is treated as a whole in subtask C, based on case studies. The objectives shall be achieved by the Participants in the following Subtasks and activities: 1) Subtask A: Criteria for Architectural Integration

This Subtask focuses on architectural integration of active solar energy products and systems since these are the least developed products for building envelope integration. The objectives of this Subtask are:

• Improve the architectural integration quality and flexibility of active solar products and systems (integrability).

• Bring together architects and product/system developers to understand each others needs. Develop criteria for products and systems, aiming at integrating solar energy systems in high quality architecture. Give recommendations to the industry.

• Focus on products/systems that offer an important potential of increasing quality regarding architectural integration. Examples of products/systems are: solar thermal systems, PV systems and systems combining functions.

• Educate/inform architects on integration characteristics for various technologies and on state of the art of innovative products.

The Participants shall achieve this objective by:

• Identifying and differentiating between the technologies already mature or needing new developments.

• Identifying the need for product development.

• Industry workshops with architects and manufacturers presentations, as a basis for discussion. Through the workshops and interviews, identify


barriers and define key factors for successful component and system integration.

• Collaborating with architects, engineers and product developers to specify key issues and develop criteria for products and systems.

• Studying and documenting good examples of products and systems. 2) Subtask B: Methods and Tools

This Subtask is focused on methods and tools for architects to use in the early design stage. The use of the building envelope to achieve a good balance of both active and passive solar utilisation will be considered. The work includes tool development and the use of tools to produce material for the Communication Guidelines (Subtask C). The objectives are:

• Define criteria for methods and tools to support architectural integration in the early design stage.

• Focus on tools that help give an overview and evaluate the energy and cost impacts of various active and passive solar options for the building envelope.

• Initiate the development/spread of design tools showing the visual impact of various solar options (elements libraries) and their influence on the energy balance of the building.

• Provide tools for Subtask C to support communication activities.

• Together with Subtask C, produce facts, illustrations and arguments to be included in the Communication Guidelines.

The Participants shall achieve this objective by:

• Studying available methods and tools: Organize workshops with presentations of available tools and from the architect’s point of view discuss and document key features, what is already available and what could be improved. Identify if any lack of new types of tools.

• Improving methods and tools, test within the Task and if possible test in ongoing planning of demonstration buildings.

• Providing library elements (link Subtask A) to tool developers.

• Using tools to produce facts, illustrations and arguments for the Communication Guidelines.

3) Subtask C: Concepts, Case Studies and Guidelines


This Subtask is looking at concepts for architectural integration as well as case studies, with a whole building perspective. The Subtask also condenses the results into communication guidelines, with support from Subtask A and B. The objectives of this Subtask are:

• Develop concepts and principles for high quality architectural integration of solar systems, based on analyzes of existing systems as well as proposals for future systems through national and later on international architectural colloquiums and workshops.

• Develop building concepts that utilize active and passive solar energy, achieving high quality architecture, sustainable solutions and high energy performance. The developed concepts should aim at reducing the energy demand in buildings and increasing the fraction of renewable energy use such as solar energy.

• Develop knowledge and strategies to promote and implement high quality architecture using solar energy.

The Participants shall achieve these objectives by:

• Collecting good examples of buildings using solar energy and sort into a set of typologies (link to IEA SHC Task 40).

• Analyzing such example buildings and documenting architectural quality, technologies and energy performance.

• Analyzing the performance of different concepts focusing on the effects of the solar system(s).

• Studying the potential for solar energy to cover the energy needed for buildings.

• Presenting the results in international seminars.

• Participating in the development of demonstration projects.

4. Results The products of work performed in this Task are targeted to architects, manufacturers of components and systems, clients, building engineers, municipalities etc. Results of the activities specific for the three Subtasks will consist of:

Subtask A Criteria for Architectural Integration: (a) Document for product and system developers that describes important

architectural design criteria for different categories of solar systems.


(b) Developed or new products/systems initiated by the Task (link to Subtask B; element libraries).

(c) Dissemination of new knowledge to e.g. practicing architects through seminars and workshops.

(d) Documents (articles, brochures) describing good examples of products and system integration in buildings.

Subtask B Methods and Tools: (a) Improved or new methods and tools for architects for the early design

stage. Tools supporting communication activities (link Subtask C). (b) Provide element libraries that could be used in design tools showing the

visual impact of various solar options. (c) Convincing arguments and facts to be included in the Communication

Guidelines (link Subtask C). Subtask C Concepts, Case Studies and Guidelines: (a) Typical concepts for building integration of solar energy systems. (b) A study on the potential for solar energy to cover the energy needed for

buildings. This includes different potentials for roof integration and façade integration in an urban context.

(c) Presentation of exemplary buildings including architectural design, systems, technologies, energy performance and costs.

(d) Present concepts, principles, potentials and exemplary buildings (a+b+c) in communication guidelines, in an IEA SHC web page, articles, architecture magazines, and at seminars for architects, engineers, component and system developers, clients, planners etc. The communication guidelines will include convincing arguments and facts with support from Subtask A and B.

(e) Basis for teaching material. 5. Time schedule – to be determined This Task shall start on May/June, 2009 and remain in force until May/June, 2012. Within the limits of the term of the agreement this Annex may be extended by agreement of two or more participants acting in the Executive Committee and shall thereafter apply only to those participants.


6. Specific Obligations and Responsibilities of the Participants (a) A Participant must undertake and complete all agreed activities and

contribute to all or to a specific of the tasks outlined in Section 3 in a timely manner.

(b) Each Participant must actively participate in working meetings and other activities such as workshops.

(c) Attendance at Experts meetings of the Task will be mandatory. Experts meetings of the Task will be carried out at intervals of approximately six months. Experts meetings may be accompanied by national workshops dedicated to target audiences of the Task, mainly from the national industry of the host country of the Experts meeting.

(d) Each Participant shall provide timely, detailed reports on the results of their work carried out to the Subtask Leader and Operating Agent.

(e) Each Participant must contribute to one or more Task deliverables and shall participate in the editing and reviewing of draft reports and other outputs of the Task and Subtasks.

7. Specific Obligations and Responsibilities of the Operating Agent and Subtask Leaders 7.1 Operating Agent (a) In addition to the obligations enumerated in Articles 5 and 6 of this

Agreement, the Operating Agent shall: (1) Be responsible for the overall management of the Task, including

overall co-ordination and communications with the Executive Committee.

(2) Prepare the detailed Programme of Work for the Task in consultation with the Subtask Leaders and the Participants and submit the Programme of Work for approval to the Executive Committee.

(3) Provide semi-annually, periodic reports to the Executive Committee on the progress and the results of the work performed under the Programme of Work.

(4) Manage the preparation and distribution of the results described in Article 4 above.

(5) At the request of the Executive Committee organise workshops, seminars, conferences and other meetings.

(6) Provide to the Executive Committee, within six months after completion of all work under the Task, a final report for its approval and transmittal to the Agency.


(7) In co-ordination with the Participants, use its best efforts to avoid duplication with activities of other related programmes and projects implemented by or under the auspices of the Agency or by other competent bodies.

(8) Provide the Participants with the necessary guidelines for the work they carry out and report with minimum duplication.

(9) Perform such additional services and actions as may be decided by the Executive Committee, acting by unanimity.

7.2 Subtask Leaders:

(a) A Subtask Leader shall be a Participant that provides to the Subtask a high level of expertise and undertakes substantial research related to the Subtask.

(b) In addition to the obligations enumerated in Articles 6 of this Agreement,

the Subtask Leaders shall:

(1) Assist the Operating Agent in preparing the detailed Programme of Work.

(2) Actively participate in the dissemination activities. (3) Co-ordinate the work performed under that Subtask. (4) Subtask leaders may arrange, direct and provide summarizes of

Subtask meetings and workshops in between or in association with Task meeting.

(5) Provide the Operating Agent with timely written summaries of Subtask work and results.

(6) Edit technical reports resulting from the Subtask and organize their publication.

(7) Collaborate with the Operating Agent and other Subtasks and contribute to the preparation, production and distribution of the results described in Article 4 above within the framework of the Task dissemination plan.

(c) The Subtask Leaders shall be proposed by the Operating Agent and

designated by the Executive Committee, acting by unanimity of the Participants. Changes in the Subtask Leaders may be agreed to by the SHC Executive Committee upon the recommendation of the Operating Agent.

8. Funding (a) Each participant will bear the costs of their participation in the Task,

including travel costs. Task meetings will be held twice annually and hosted


in turn by Participants. The cost of organising meetings will be borne by the host country.

(b) Participation in the Task requires active participation in at least one of the

Subtasks A, B or C. (c) Level of effort The Participants agree on the following commitment:

(1) Each Participant (country) will contribute to this Task a minimum of 4 person months per year for the duration of the Task.

(2) Subtask Leaders will contribute a minimum of 4 person months per year for the duration of the Subtask.

(3) The Operating Agent will contribute a minimum of 6 person months per year to the Task.

(d) Participation may partly involve funding already allocated to a national (or international) activity which is substantially in agreement with the scope of work outlined in this Task. Aside from providing the resources required for performing the work of the Subtasks in which they are participating, all Participants are required to commit the resources necessary for activities which are specifically collaborative in nature and which would not be part of activities funded by national or international sources. Examples include the preparation for and participation in Task meetings, co-ordination with Subtask Participants, contribution to the documentation and dissemination work and Task related R&D work which exceeds the R&D work carried out in the framework of the national (or international) activity.

(e) The level of effort to be contributed by each country will be specified in a "Letter of National Participation" which is signed by both the Participant and their Executive Committee representative within 7 months from the start date of the Task.

9. Operating Agent, Subtask Leaders – to be determined (a) The Operating Agent for the Task will be Lund University, Dept of

Architecture and Built Environment, Division of Energy and Building Design, Lund, Sweden, represented by Maria Wall.

(b) Subject to securing funding for their participation, the Subtask Leaders for

the Task are:

1) The Subtask A Leader will be the EPFL-LESO, Lausanne, Switzerland, represented by Maria Cristina Munari Probst and Christian Roecker?

2) The Subtask B Leader will be the XXXX, Norway?, represented by XXXX.

Commentaire [MW1] : Not sure this is correct.


3) The Subtask C Leader will be Esbensen Consulting Engineers, Copenhagen, Denmark represented by XXXX and Torben Esbensen.

10. Information and Intellectual Property (a) Executive Committee's Powers

The publication, distribution, handling, protection and ownership of information and intellectual property arising from this Task shall be determined by the Executive Committee, acting by unanimity, in conformity with the Agreement.

(b) Right to Publish

Subject only to copyright restrictions, the Participants shall have the right to publish all information provided to or arising from this Task, except proprietary information.

(c) Proprietary Information

The Participants and the Operating Agent shall take all necessary measures in accordance with this paragraph, the laws of their respective countries and international law to protect proprietary information provided to or arising from this Task. For the purposes of this Task, proprietary information shall mean information of a confidential nature such as trade secrets and know-how (for example computer programs, design procedures and techniques, chemical composition of materials, or manufacturing methods, processes, or treatments) which is appropriately marked, provided such information:

(1) Is not generally known or publicly available from other sources. (2) Has not previously been made available by the owner to others

without obligation concerning its confidentiality. (3) Is not already in the possession of the recipient Participant without

obligation concerning its confidentiality.

It shall be the responsibility of each Participant supplying proprietary information and of the Operating Agent for appraising proprietary information, to identify the information as such and to ensure that it is appropriately marked.

(d) Arising Information

All information developed in connection with and during activities carried out under this Task (arising information) shall be provided to each Participant by the Operating Agent, subject only to the need to retain


information concerning patentable inventions in confidence until appropriate action can be taken to protect such inventions.

For arising information regarding inventions the following rules shall apply: (1) Arising information regarding inventions shall be owned in all

countries by the inventing Participant. The inventing Participant shall promptly identify and report to the Executive Committee any such information along with an indication whether and in which countries the inventing Participant intends to file patent applications.

(2) Information regarding inventions on which the inventing Participant

intends to obtain a patent protection shall not be published or publicly disclosed by the Operating Agent or the other Participants until a patent has been filed, provided, however, that this restriction on publication or disclosure shall not extend beyond twelve months from the date of reporting of the invention. It shall be the responsibility of the inventing Participants to appropriately mark Task reports which disclose inventions that have not been appropriately protected by filing a patent application.

(3) The inventing Participant shall license proprietary information arising

from the Task for non-exclusive use to participants in the Task: (a) On the most favourable terms and conditions for use by the

Participants in their own country. (b) On favourable terms and conditions for the purpose of sub-

licensing others for use in their own country. (c) Subject to sub-paragraph (1) above, to each Participant in the

Task for use in all countries, on reasonable terms and conditions.

(d) To the government of any Agency Member country and nationals designated by it, for use in such country in order to meet its energy needs.

Royalties, if any, under licenses pursuant to this paragraph shall be the property of the inventing Participant.

(e) Production of Relevant Information by Governments The Operating Agent should encourage the governments of all Agency Participating Countries to make available or to identify to the Operating Agent all published or otherwise freely available information known to them that is relevant to the Task.

(f) Production of Available Information by Participants


Each Participant agrees to provide to a Subtask Leader or to the Operating Agent all previously existing information, and information developed independently of the Task, which is needed by a Subtask Leader or by the Operating Agent to carry out its functions under this Task and which is freely at the disposal of the Participant and the transmission of which is not subject to any contractual and/or legal limitations: (1) If no substantial cost is incurred by the Participant in making such

information available, at no charge to the Task.

(2) If substantial costs must be incurred by the Participant to make such information available, at such charges to the Task as shall be agreed between the Operating Agent and the Participant with the approval of the Executive Committee.

(g) Use of Confidential Information

If a Participant has access to confidential information which would be useful to a Subtask Leader or to the Operating Agent in conducting studies, assessments, analyses, or evaluations, such information may be communicated to a Subtask Leader or to the Operating Agent but shall not become part of the reports, handbooks, or other documentation, nor be communicated to the other Participants, except as may be agreed, between the Subtask Leader or the Operating Agent and the Participant.

(h) Reports on Work Performed under the Task

The Operating Agent shall, in accordance with paragraph 7 above, provide reports of all work performed under the Task and the results thereof, including studies, assessments, analyses, evaluations and other documentation, but excluding proprietary information.

(i) Copyright

The Operating Agent may take appropriate measures to protect copyrightable material generated under this Task. Copyrights obtained shall be the property of the IEA? for the benefit of the Participants provided, however, that the Participants may reproduce and distribute such material, but if it shall be published with a view to profit, permission should be obtained from the Executive Committee.

(j) Authors

Each Participant will, without prejudice to any rights of authors under its national laws, take necessary steps to provide the co-operation from its authors required to carry out the provisions of this paragraph. Each Participant will assume the responsibility to pay awards or compensation required to be paid to its employees according to the laws of its country.


11. Participants in this Task – to be determined The Contracting Parties in this project are indicated in the following table. Others may still join and Information on participants will be provided in the detailed workplan.

Country Contracting Party Australia ?

Austria Republic of Austria?

Belgium ?

Canada Natural Resources Canada?

Denmark Danish Energy Agency

France Agence de l'Environnement et de la Maitrise de l'Energie (ADEME) ?

Germany Forschungszentrum Jülich GmbH?

Italy ?

Mexico ?

Netherlands ?

Norway Royal Norwegian Ministry of Petroleum and Energy?

Portugal I.N.E.T.I., Departamento de Energias Renováveis?

Spain ?

Sweden Swedish Energy Agency

Switzerland The Swiss Federal Office of Energy?

U.S.A The Government of the United States of America?


189


ANNEXE 2: WEB SURVEYARCHITECTURAL INTEGRATION QUALITY OF B.I.S.T.


190


Design & positionning proposals

Architectural integration quality of BIST

EU s u r v e y

M u l t i M u l t i –– f a m i l y h o u s e s ( D )f a m i l y h o u s e s ( D )

-- - +- + ++

-- - +- + ++

-- - +- + ++

ArchitecturalIntegration

Panel colour

Panel shape/size

1. Express an aesthetical appreciation(from -- to ++) on the solar thermal system beside:

Q u e s t i o n n a i r e : I . T h e e x i s t i n g

c o l l e c t o r sG l a z e d


M u l t i M u l t i –– f a m i l y h o u s e s ( D )f a m i l y h o u s e s ( D )

-- - +- + ++

-- - +- + ++

-- - +- + ++


Panel colour



G l a z e d c o l l e c t o r s

Panel shape/size

R e n o v : r e s i d e n t i a l h o u s e ( D )R e n o v : r e s i d e n t i a l h o u s e ( D )

-- - +- + ++

-- - +- + ++

-- - +- + ++


Panel colour




Panel shape/size


R e n o v a t i o n : Y o u t h h o s t e l ( A )R e n o v a t i o n : Y o u t h h o s t e l ( A )

-- - +- + ++

-- - +- + ++

-- - +- + ++


Panel colour




Panel shape/size

R e n o v a t i o nR e n o v a t i o n

-- - +- + ++

-- - +- + ++

-- - +- + ++


Panel colour




Panel shape/size


U p p e r s t a g e c e n t r eU p p e r s t a g e c e n t r e

-- - +- + ++

-- - +- + ++

-- - +- + ++


Panel colour




Panel shape/size

S o l a r w a l l g y m n a s i u m , C a n a d aS o l a r w a l l g y m n a s i u m , C a n a d a-- - +- + ++

-- - +- + ++

-- - +- + ++


Panel colour



U n g l a z e d c o l l e c t o r s

Panel shape/size


S o l a r w a l lS o l a r w a l l , C a n a d a i r , C a n a d a, C a n a d a i r , C a n a d a -- - +- + ++

-- - +- + ++

-- - +- + ++


Panel colour




Panel shape/size

E n e r g i e S o l a i r e s . a .E n e r g i e S o l a i r e s . a .-- - +- + ++

-- - +- + ++

-- - +- + ++


Panel colour




Panel shape/size


E n . S o l a i r e s . a .E n . S o l a i r e s . a . , h o u s i n g , S, h o u s i n g , S

-- - +- + ++

-- - +- + ++

-- - +- + ++


Panel colour




Panel shape/size


189


ANNEXE 3: E.U. PROJECT SOLABS


190


EU PROJECT SOLABS FP5 Project Record 604. Development of unglazed solar absorbers (resorting to coloured selective coatings on steel material) for building facades, and integration into heating systems (solabs) General Project Information FP5 Programme Acronym: EESD Project Reference: ENK6-CT-2002-00679 Contract Type: Cost-sharing contracts Start Date: 2003-01-01 End Date: 2006-06-30 Duration: 42 months Project Project Acronym: SOLABS Project Description

Objectives and problems to be solved: The goal is to develop an innovative solar system with a significant reduction of capital cost and unit cost of the delivered heat (target: 0.025-0.03 /kWh), a major improvement of the public acceptability (non-technical barrier) and a simplified implementation in large office, residential or industrial buildings for new or retrofit applications. R&D work on weather-resistant, coloured selective solar absorbers made of steel, will be operated as unglazed collectors in order to avoid the cost for glazing, and designed for integration in the building envelope (particularly facades).Description of the work:

1. Specifications for architectural integration: architectural design & integration of absorbers as facade elements, investigation of other acceptability criteria (colour, structure, shape, sizes), development of guidelines in order to facilitate better user acceptance and market penetration (see Work-packages WP1 and WP6) leading to a price reduction by mass production.

2. Research on selective coatings and characterisation of the coatings: R&D on coloured selective coatings suitable for steel material, optical characterisation and durability tests (WP2, WP3, and WP4). Cheaper and more attractive coatings help to get new market shares at lower costs.

3. Design and prototyping of the absorbers: the focus lies on the design specifications of absorbers to be used as façade elements (WP5). Several concepts and issues will be studied such as size and modularity, costs, thermal expansion, irrigation and hydraulic connections. New and approved concepts enable new applications and cheaper manufacturing by industrial mass production.

4. Integration in suitable heating systems and simulation of heating systems: identification, development or improvement of simplified concepts of heating systems suitable for the low temperature heat delivered by facade absorbers, production of guidelines for the design and sizing of the system (WP6).

5. Reporting and dissemination : activities to ensure short-term implementation Expected results and exploitation plans: The final expected result of this project is the widespread of solar heating by 1 reduction of the solar energy price 2. an increase of the architectural acceptance This result can be achieved with the development of new attractive coloured selective surfaces for less expensive steel absorbers, as a part of well-integrated building façades with low additional costs for the solar-specific features, and with the design of new hydraulic systems for improving the solar system performance.

Coordinator

Organisation Type: Research Department: INSTITUT FUER SOLARE ENERGIESYSTEME DEPARTMENT OF THERMAL AND OPTICAL SYSTEMS Organisation: FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V. Oltmannsstrasse 5 79100 FREIBURG (IN BREISGAU) GERMANY Participants 1. Organisation Type: Research Department: LABORATORY FOR SPECTROSCOPY OF MATERIALS Organisation: NATIONAL INSTITUTE OF CHEMISTRY 19 Hajdrihova 19 P.O. Box 3430 1000 LJUBLJANA SLOVENIA Contact Person: OREL, Boris (Prof) 2. Organisation Type: Education Department: LABORATOIRE D'ENERGIE SOLAIRE ET DE PHYSIQUE DU BATIMENT INSTITUT DE TECHNIQUE DU BATIMENT Organisation: SWISS FEDERAL INSTITUTE OF TECHNOLOGY LAUSANNE Batiment LESO, Ecole Polytechnique Federale de Lausanne PO Box 555 1015 LAUSANNE SWITZERLAND ROECKER, Christian

3. Organisation Type: Other Department: RESEARCH & DEVELOPMENT, QUALITY ENGINEERING AND MATERIALS TESTING Organisation: THYSSEN KRUPP STAHL A.G. Kaiser Wilhem Srasse 100 47166 DUISBURG GERMANY Contact Person: RAULF, Martin (Dr) 4. Organisation Type: Industry Department: RESEARCH AND DEVELOPMENT DEPARTMENT Organisation: CLIPSOL S.A. Parc d'Activités Les Combaruches 73100 AIX LES BAINS FRANCE Contact Person: JEAN, André (Mr) 5. Organisation Type: Research Organisation: DOC DORTMUNDER OBERFLAECHENCENTRUM GMBH Eberhardstrasse 12 44145 DORTMUND GERMANY Contact Person: SÄMANN, Nicole (Dr) 6.Organisation Type: Industry Organisation: INTERPANE SOLAR BESCHICHTUNG GMBH AND CO Sohnreystr 21 37697 LAUENFOERDE GERMANY Contact Person: PAVIC, Davorin (Mr) 7. Organisation Type: Research Department: DEPARTMENT OF THERMAL AND OPTICAL SYSTEMS INSTITUT FUER SOLARE ENERGIESYSTEME Organisation: FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E.V. Oltmannsstrasse 5 79100 FREIBURG (IN BREISGAU) GERMANY Contact Person: KÖHL, Michael (Mr) 8. Organisation Type: Education

Department: INSTITUT FUER SOLAR TECHNIK Organisation: HOCHSCHULE FUER TECHNIK HSR Oberseestrasse, 10 8640 RAPPERSWIL SWITZERLAND Contact Person: FREI, Ueli (Professor) 9. Organisation Type: Education Department: LABORATORIO DE MATERIALES Y SUPERFICIE DEPARTAMENTO DE FISICA APLICADA I - FACULTAD DE CIENCIAS Organisation: UNIVERSIDAD DE MALAGA Capmus de Teatinos 29071 ESTEPONA (MALAGA) SPAIN Contact Person: DE LA CALLE, Adelaida (Dr)


189


ANNEXE 4: WEB SURVEY:USERS WISHES FOR UNGLAZED COLLECTORS

FORMAL CHARACTERISTICS


190



Questionnaire

Q u e s t i o n n a i r e

Q u e s t i o n n a i r e

s o l a b s

Questionnaire structure:

I. Existing thermal collectors: aesthetical appreciation.

II. Project SOLABS: unglazed painted collectors for façade cladding:

1. Shape/Size.

2. Texture.

3. Colours.

III. Renovation: Surface availability & cladding choices.

IV. Final questions.


II. Project SOLABS: new unglazed coloured collectors for

façade cladding.

1. Shape.

2. Texture.

3. Colour.

s o l a b s

Q u e s t i o n n a i r e : I I. T h e p r o j e c t

s o l a b s


II.1. The Shape.

concept: The SOLABS unglazed solar thermal panel for façade cladding will be designed considering the metallic cladding elements already existing on the market:

a – Cassette modules

b – Panel-planks

c – Profiled sheet (skipped because technically hardly adaptable)


II.1.a. Cassette modules

On the metallic cladding

market,

the cassettes are elements

with folded edges on all

sides which come in a range

of geometrical proportions

from 1:1 to 1:4. They are

well-suited for cladding

large wall surfaces.

In order to achieve an

appropriate cladding the

designer have to carefully

evaluate the dimensions of

the cassette module.

s o l a b s


I I . 1 .a .

C a s s e t t e s c l a d d i n g

d.1. d.2. d.3. d.4

C a s s e t t e s C a s s e t t e s s i z es i z e

11. Minimum acceptable flexibility of the solar cassette module:

a. Made to measure modules.

b. Cut to length modules.

c. A range of standard modules.

d. A standard module.In this case, please choosethe most suitable ratio/size:

(d.5 none of those)


v

-- - +- + ++ -- - +- + ++-- - +- + ++

I I . 1 .a .

C a s s e t t e s

c l a d d i n g C a s s e t t e s C a s s e t t e s j o i n t i n gj o i n t i n g

12. Aesthetical appreciation of different joint types:

Frame jointing Profile free moduleHorizontal joint. profile

II.1.b. Tongue-and-groove panel planks:

For covering ordinary surfaces, only width of

20cm to 35cm are used on the metallic cladding market.

Maximum length of individual panels is therefore usually

4.00m.

The panels may be used in any direction, i.e. vertically,

diagonally or horizontally...

s o l a b s



The variable width of the reveals (from 0 to 30mm) makes

the standard modular element more flexible, so that the

panel-planks can be used for the cladding of the various

architectural elements.

s o l a b s


13. Suitable solar plank width:

a. 20-25 cmb. 25-30 cmc. 30-35 cmd. 35-40 cm

P a n e l P a n e l -- p l a n k sp l a n k s

I I . 1 .b .

P l a n c k s

c l a d d i n g

?


14. Importance of having a variable width* joint :

-- - +- + ++

*The variable width of the reveals (from 0 to 30mm) makes the standard modular element more flexible…

I I . 1 .b .

P l a n c k s

c l a d d i n g

P a n e l P a n e l -- p l a n k sp l a n k s

10mm

30mm

0mm

s o l a b s


II.1. Shape. Unglazed panels like metallic cladding elements:

15 . Please give an aesthetical appreciation of the different shape type for the new SOLABS solar collector:

Solar cassettes modules: Solar panel-planks:

-- - +- + ++-- - +- + ++


II.2. The texture

s o l a b s


S u r f a c e a p p r e c i a t i o na p p r e c i a t i o n

I I .2 .

P a n e l s u r f a c e

16. Which surface geometry do you think is aesthetically appropriate for the solabs solar collector?

a. Flat b. Profiled c. Embossed d. Lenticular perforated


S u r f a c e a p p r e c i a t i o na p p r e c i a t i o n

17. Finishing preference:

I I .2 .

P a n e l s u r f a c e

a. Polished surface finishing

b. Matt surface finishing

II.3. The colour.

s o l a b s



C o l o u r s a p p r e c i a t i o na p p r e c i a t i o nI I .3 .

P a n e l c o l o u r

18. Choose the most reasonable solabscolour palette:

a. Palette made of 3-5 standard colours.b. Palette made of 5-10 standard colours.c. Palette made of 10-20 standard colours.d. Palette made of 20-40 standard colours.

19. Importance of having the possibility to freely choose the colour:

-- - +- + ++

C o l o u r s a p p r e c i a t i o na p p r e c i a t i o n

I I .3 .

P a n e l c o l o u r

RAL5010

RAL5002

RAL5019

RAL5007

E

F

G

H

RAL6017

RAL6002

RAL6003

RAL6018

A

B

C

D

RAL8003

RAL8015

RAL8024

RAL8017

O

P

Q

RN

RAL3000

RAL2009

RAL3003

I

L

M

RAL3004 RAL7024

RAL7011

RAL7033

S

T

U

V

RAL7023

20. Select any 3 colours that you think should definitely appear in the solabs colour palette:

RAL1033

RAL1004

RAL1003

RAL1011

W

X

Y

Z


III. Renovation: surface availability & cladding choices.

s o l a b s

Q u e s t i o n n a i r e : I II. R e n o v a t i o n

ADMINISTRATION BUILDING, MORGES 1952

Unglazed solar panels in renovation.

21. Which solar cladding shape type will be more appropriate for the renovation of the facades of the building beside? :

a. Cassette modules.

b. Panel planks.

22. Would you cover with solar cladding all the available South (S-E, S-W) exposed surface?

a. Yes.

b. I will cover only façade A.

c. I will cover only façade B.

23. Evaluate the importance of having dummy elements for the covering of non exposed facades:

-- - +- + ++

Q u e s t i o n n a i r e : I II. R e n o v a t i o n

available South (S-E, S-W) exposed surface

A B


IV. Final questions:

24. Would you like to recognize the cladding as a solar installation?

-Yes-No

25. Would you accept to see external piping connection?

-Yes-No

26. Level of interest in the solabs project?

27. Remarks & suggestions...

s o l a b s

Q u e s t i o n n a i r e : I V. F i n a l q u e s t i o n s

-- - +- + ++


189


ANNEXE 5: SURVEY: USERS WISHES FOR GLAZED COLLECTORS FORMAL CHARACTERISTICS


190



F A Ç A D E S S O L A I R E S À V I T R A G E C O L O R É

Questionnaire

M . C . M u n a r i P r o b s t , C h r i s t i a n R o e c k e r , E P F L – L E S O , E n e r g i s s i m a 1 3 . V I . 2 0 0 7


1 - Finis de surface: intérêt...

-- - -+ +++ -- - -+ +++ -- - -+ +++ -- - -+ +++

coat

ing

colo

rése

ul

colo

ré+

traité

àl’a

cide

colo

ré+

stru

ctur

e py

ram

ides

verre transparent fini miroir fini satiné fini structuré

aucu

n tra

item

ent



-- - -+ +++ -- - -+ +++ -- - -+ +++

lignes horizontales petits carrés motif sur mesure ?


2 – Motifs (patterns): intérêt ...


-- - -+ +++ -- - -+ +++ -- - -+ +++ -- - -+ +++

tonalités rouges tonalités bleues tonalités vertes tonalités jaunes


3 – Couleurs... .....

4 – Variabilité de la couleur en fonction de l’angle de vision: acceptable ?

-- - -+ +++



a. Un seul module aux dimensions fixes.(spécifiez les dimensions)

b. Une série de modules standard.

c. Une dim. fixe, l’autre sur mesure.

d. Modules sur mesure.


5 – Quelle flexibilité dimensionnelle minimale?


a. Joints en gomme noire (EPDM)

b. Cadre en aluminium.

c. Cadre en métal thermolaqué (coloré à choix).

c. Fixation ponctuelle.

d. Fixation invisible (joint négatif).

e. Autre (spécifiez).


6 – Quels types de joints ? ..........

(SVP choisir-cocher max 3 options)




7 - Comment jugez vous la nouvelle possibilité d’utiliser un revêtement de façade homogène sur les parties équipées et non équipées de capteurs?

8 - Dans quelle mesure l’innovation présentée vous encourage-t-elle à utiliser des capteurs en façade?

9 - Souhaiteriez-vous pouvoir reconnaître les capteurs thermiques comme tels?

-- - -+ +++

-- - -+ +++

-- - -+ +++




Merci beaucoup de votre collaboration!

Nom prénom (facultatif)*:

Profession: architecte ingénieur autre (spécifier)

Expérience professionnelle: moins de 2 ans 2 à 5 ans plus de 5 ans

Avez vous déjà installé du solaire thermique ? oui non

Adresse e-mail (facultatif)*:

(* Vos coordonnées personnelles seront utilisées uniquement dans le cadre de cette enquête et dans le respect de l’anonymat. Votre adresse e-mail nous permettra de vous communiquer les résultats de cette recherche).

CURRICULUM VITAE

PROFESSIONAL EXPERIENCES

2003 - 2008 Teaching and Research Assistant, LESO-PB, section of Architecture, EPFL

Research:

PhD research project.

Participation in International Research Projects (EU project SOLABS ; OFEN Project Coloured

Glazing ; IEA Task 39; IEA New Task "Solar Energy and Architecture"- to be started).

Reviewer for the international conference PLEA 2007 (Passive and Low Energy Architecture) -

Singapore.

Member of Swissolar (Solar Construction group).

Teaching:

Teaching assistant, course of Building Physics 2nd and 3rd year students.

Lecturer MAS Master in Architecture and Sustainable Development.

Invited Speaker:

IEA Task preparation meeting "Solar energy & Architecture", Copenhagen (2008)

IEA Ex-Co Meeting in Graz (2008)

1st Swiss Renewable Energies exhibition Energissima 2007, Bulle

International conference Cisbat 2007 (selected speaker for plenary session), Lausanne.

1999 - 2008 Independent architect activity (own studio):

Zero Energy house, project, La Sarraz (Switzerland) (2007-2008)

Competitions: passive Minergie-P housing in Vaux-sur-Morges (2006); Joint urban

development for EPFL and St-Sulpice (2005).

Passive solar house with building integrated Photovoltaic, project and construction, St-Sulpice

(2000-2001).

This building has been presented to several international conferences and exhibitions on solar

energy and architecture (International seminar Photovoltaics: introduction to architectural

integration- organized by EPFL and OFEN, 2001; Forum Sviluppo Sostenibile, Trieste, Italy,

2002; Swiss newspaper Le Matin 16 sept.2003; Jornadas Construcción Sostenible / Salón

Internacional de la Construcción , Barcelona, 2007; MAS Architecture and Sustainable

Development, EPFL, 2007 and 2009.

Extension and renovation projects of a traditional house in Echichens and of a single family

house in Préverenges (Switzerland) (2001).

Multiplex Cinema, project for Metrociné Construction office, Lausanne (1999).

MARIA CRISTINA MUNARI PROBST Ch des Pâquis 6 - CH1025 St-Sulpice [email protected] June 14th 1971, Treviso (I). Italian, C permit in Switzerland. Married, 2 children.

1996 - 1997 Bar Manager during summer, Open Air Cinéma Metrociné, Lausanne.

1995 Part-time assistant at the computer laboratory of the University of Architecture of Venice.

1990 - 1994 Private lessons in technical drawing and waitress on week-ends, Castelfranco Veneto.

EDUCATION

2004 - 2008 PhD, Swiss Federal Institute of Technology, Solar Energy and Building Physics Laboratory

(EPFL/LESO-PB). Advisor: Prof. Jean-Louis Scartezzini; Co-Advisor: Christian Roecker.

1998 Architecture degree Summa cum Laude, University of Architecture of Venice (IUAV)

1995 - 1996 ERASMUS (one academic year) at the University of Architecture of Bath, England

1990 Maturità Scientifica Liceo Giorgione, Castelfranco Veneto, Scientific orientation with Latin.

ACADEMIC AWARDS

2008 Best Poster Award EPFL Research Day "Sustainable Development"

2006 Performance bonus for the activity of research assistant at EPFL / LESO-PB

2005 Best Paper Award PLEA2005 International conference (Passive & Low Energy Architecture)

EXTRA-SCHOLAR EDUCATION, SCOLARSHIPS

2000 International workshop of Architecture (3 weeks, on selection) in Monte Carasso (Switzerland)

organized by Professor Luigi Snozzi.

1998 SNALS prize for young university graduates.

International Laboratory of Architecture and Urban Design (ILAUD) (7 weeks workshop, on selection),

organized by Professor Gian Carlo De Carlo and the city of Venice. 13 Universities from

EU and US participate. Work published in The edge of the Arsenal, ILAUD, Maggioli Editore, 1999,

p.152-157.

1998 Atelier Européen de Technologie de l’Architecture, Paris-Tolbiac, (2 weeks workshop, on selection). 5

European Universities participate to this project financed by the EU program SOCRATES 98.

1991 Aci Sant’Antonio - un rilievo orientato, Sicily, (3 weeks workshop), financed by Ministero dei Beni

Culturali. Work published in Un rilievo orientato, C.Balistreri , R.Bertucci, G.D’Ambra editors,

Cartotecnica Veneziana Editrice,1992 p.199-204

LANGUAGES

Italian: mother tongue.

French: fluent, spoken and written.

English: good, spoken and written.

P U B L I C A T I O N S

Munari Probst MC., Roecker C., From thermal collectors integration to active façade systems, Proceedings PLEA 2007,

Singapore, 2007.

Munari Probst MC., Kosoric V., Schueler A., De Chambrier E., C. Roecker. Façade integration of solar thermal collectors: present

and future, Proceedings CISBAT 2007, Lausanne, Switzerland, 2007 (Plenary session).

E. De Chambrier, D. Dutta, C. Roecker, M. Munari-Probst, J.-L. Scartezzini, and A. Schüler, Nanostructured Coatings on Glazing

for Active Solar Facades, In CISBAT 2007, Lausanne, Switzerland, 2007.

Roecker C., Munari Probst MC., Schueler A., De Chambrier E., Scartezzini J.-L., Facade integration of solar thermal collectors: a

breakthrough?, ISES 2007, Peijing, China, 2007.

Munari Probst MC., Roecker C., Towards an improved architectural quality of building integrated solar thermal systems (BIST), in

Solar Energy (2007), doi :10.1016/j.solener.2007.02.009.

Munari Probst MC., Roecker C., SOLABS: Development of a Novel Solar Thermal Facade Cladding System, in Proceedings

EUROSUN 2006, Glasgow, Scotland, 2006.

Roecker C., Munari Probst MC.,Capteurs solaires colorés et intégration architecturale, Symposium Yverdon ER 2006.

Munari Probst MC., Roecker C., Integration and formal development of solar thermal collectors, in Proceedings PLEA2005, Beirut,

Lebanon, pp.497-502, 2005. Conference Best Paper Award.

Munari Probst MC., Roecker C., Schueler A., Architectural integration of solar thermal collectors: results of a European survey, in

Proceedings ISES 2005, Orlando, Florida, 2005.

Munari Probst MC., Roecker C., Schueler A., Impact of new developments on the integration into facades of solar thermal

collectors, in Proceedings EUROSUN 2004, Freiburg im Breisgau, Germany, 2004.