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Key elements of and material performance targets for highly insulating window frames

Gustavsen, A., Grynning, S., Arasteh, D., Jelle, B. P. and Goudey, H.
2011
Energy and Buildings, 43(10): 2583-2594

Gustavsen, A., Grynning, S., Arasteh, D., Jelle, B. P. and Goudey, H., (2011), "Key elements of and material performance targets for highly insulating window frames", Energy and Buildings, 43(10): 2583-2594.
Abstract:
Arild Gustavsen, Steinar Grynning, Dariush Arasteh, Bj?rn Petter Jelle, Howdy Goudey, Key elements of and material performance targets for highly insulating window frames, Energy and Buildings, Volume 43, Issue 10, October 2011, Pages 2583-2594, ISSN 0378-7788, 10.1016/j.enbuild.2011.05.010.

(http://www.sciencedirect.com/science/article/pii/S0378778811002027)

Abstract: The thermal performance of windows is important for energy efficient buildings. Windows typically account for about 30¨C50 percent of the transmission losses though the building envelope, even if their area fraction of the envelope is far less. The reason for this can be found by comparing the thermal transmittance (U-factor) of windows to the U-factor of their opaque counterparts (wall, roof and floor constructions). In well insulated buildings the U-factor of walls, roofs and floors can be between 0.1 and 0.2 W/(m2 K). The best windows have U-factors of about 0.7¨C1.0. It is therefore obvious that the U-factor of windows needs to be reduced, even though looking at the whole energy balance for windows (i.e., solar gains minus transmission losses) makes the picture more complex.

In high performance windows the frame design and material use are of utmost importance, as the frame performance is usually the limiting factor for reducing the total window U-factor further. This paper describes simulation studies analyzing the effects on frame and edge-of-glass U-factors of different surface emissivities as well as frame material and spacer conductivities. The goal of this work is to define material research targets for window frame components that will result in better frame thermal performance than is exhibited by the best products available on the market today.

Keywords: Fenestration; Window frames; Heat transfer modeling; U-factor; Thermal transmittance; Thermal performance

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Author Information and Other Publications Notes
Gustavsen, A.
  1. Aerogel insulation for building applications: A state-of-the-art review
  2. Fenestration of today and tomorrow: A state-of-the-art review and future research opportunities
  3. Gas-filled panels for building applications: A state-of-the-art review
  4. Phase change materials for building applications: A state-of-the-art review
  5. Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review
  6. State-of-the-art highly insulating window frames -- research and market review
  7. Vacuum insulation panels for building applications: A review and beyond  
Grynning, S.
  1. Gas-filled panels for building applications: A state-of-the-art review
  2. Vacuum insulation panels for building applications: A review and beyond  
Arasteh, D.
  1. A database of window annual energy use in typical North American residences
  2. Fenestration of today and tomorrow: A state-of-the-art review and future research opportunities
  3. Future advanced windows for zero-energy homes
  4. Gas-filled panels: an update on applications in the building thermal envelope
  5. Highly insulating glazing systems using non-structural center glazing layers
  6. Issues associated with the use of infrared thermography for experimental testing of insulated systems
  7. Laboratory procedures for using infrared thermography to validate heat transfer models
  8. State-of-the-art highly insulating window frames -- research and market review
  9. Surface temperatures of insulated glazing units: infrared thermography laboratory measurements
  10. Surface temperatures of window specimens: infrared thermography laboratory measurements
  11. Window-related energy consumption in the US residential and commercial building stock
  12. Zero energy windows  
Jelle, B. P.
  1. Aerogel insulation for building applications: A state-of-the-art review
  2. Gas-filled panels for building applications: A state-of-the-art review
  3. Large-scale experimental wind-driven rain exposure investigations of building integrated photovoltaics
  4. Phase change materials for building applications: A state-of-the-art review
  5. Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review
  6. State-of-the-art highly insulating window frames -- research and market review
  7. The path to the building integrated photovoltaics of tomorrow
  8. Vacuum insulation panels for building applications: A review and beyond  
Goudey, H.
  1. Fenestration of today and tomorrow: A state-of-the-art review and future research opportunities
  2. Highly insulating glazing systems using non-structural center glazing layers
  3. Surface temperatures of window specimens: infrared thermography laboratory measurements  


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