Ultra-Thin, Energy-Efficient Façades - a Contradiction in Terms? - Challenges and Novel Strategies. Hans-Peter Ebert

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1 ICEBO 2008 Ultra-Thin, Energy-Efficient Façades - a Contradiction in Terms? - Challenges and Novel Strategies Hans-Peter Ebert Bavarian Center for Applied Energy Research (ZAE Bayern) Division: Functional Materials for Energy Technology Würzburg, Germany

2 Energy Use in Europe Industry; 28% Building; 40% Transport; 32% com (2006) 545 final Thermally optimized façades reduces energy consumption for heating and for cooling

3 History of Ultra-Thin, Energy-Efficient Façades Wall thickness: 60 to 70 mm U-value 1.3 W/(m 2 K) Average temperature -3.2 C

4 Advantages of Ultra-Thin Façades saving of space (centre of cities) low weight more design freedom

5 Critical Aspects of Ultra-Thin Façades low heat capacity need for control, PCM high U-Value improved thermal insulations thermal bridges more planning work

6 Further Content Motivation Vacuum Insulation Panels (VIP) Vacuum Glazing Textile Architecture Conclusion - Outlook

7 Comparison of Thermal Insulation Materials W m K thermal conductivity λ AIR solid+ radiation standard thermal insulation (e.g. mineral wool) vacuum insulation panel (VIP)

8 Components of a VIP nanostructured highbarrier laminate nanoporous loadbearing filler material

9 Retrofitting a Terrace House with VIPs Architect: F. Lichtblau, Munich, 2001 U-value before = 1.0 W/(m²K) U-value after = 0.15 W/(m²K) Architekt: F. Lichtblau, München, 2001 Thermal imaging: Blue areas indicate excellent thermal insulation performance

10 Vacuum insulation glass (VIG) Windows represent thermal weak spots of buildings façade: U 0.3 W/(m 2 K) double glazing: U 1.1 W/(m²K) triple glazing: U 0.6 W/(m²K)

11 Analyses of Heat Transfer Thermal insulation glazing: U g = 1.3 W/(m 2 K) ε= 0.03 gap: 16 mm air Components of the U-value 90,2% radiative heat transfer 9,8% thermal conduction

12 VIG-Design spacers low-ε coating Thinner and lighter than triple glazing: system thickness 9 mm 2 x 4 mm float glass evacuated gap U < 0.5 W/(m²K) glass airtight seal

13 Challanges Thermal optimization Innovative edge construction Optical optimization (spacers!) Gas tightness Mechanical stability

14 VIG Prototypes U-value = 0.5 W/(m 2 K) prototypes at glasstec 2007 commercial production planned for 2009

15 Thermally Improved Window Frames TopTherm 90 ESL-IC a PU-foam kernel for thermal insulation thin polymeric layer for improved mechanics and surface texture U f = 0,7 90 mm system thickness low weight simple production and installation

16 Thermal Performance of Windows Northern Side, test reference year Würzburg, Germany ESL-IC a Effective U-value / W(m²K) 2 1,1 1,0 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 standard optimized VIG + TopTherm90 2-Iso 3-Iso VIG Passiv house 0,1 0, Bautiefe [mm] System thickness / mm

17 Textile Architecture Source: Herzog + Partner, Lang, Munic Entwurf: LangHuggerRampp GmbH Architekten Foster and Partners

18 Textile Architecture Multifunctional Membranes ESL-IC a Microtherm thermal insulation heat storage (PCM) low-ε coatings photovoltaic

19 Textile Architecture Properties of low-ε coatings ESL-IC a low emission of thermal radiation NBIA high reflection of thermal radaition glass fiber fabrics with aluminum coating low thermal emittance ε low emission of thermal radiation saving of energy

20 Textile Architecture Transparent low-ε coatings ESL-IC a TCO (transparent conductive oxide) layers on textiles TCO: e.g. ITO: Indium Tin Oxide, AZO: Aluminum Zinc Oxide coating by a sol-gel process reflectance, transmittance T vis = 0.80 ε IR = 0.19 reflectance transmittance wavelength λ / µm

21 Conclusion Ultra-thin façades could be energy efficient! Innovative materials and systems offer the potential for more energy-efficient systems (VIP, VIG, PCM, low-ε coating) Textile architecture is an challenging field with a great potential for the realization of energy efficient façades.

22 Thank you for listening! Further information: R&D work is funded by the German Federal Ministry of Economics and Technology within the framework of the research programme Energy- Optimized Building (EnOB)