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State-of-the-art highly insulating window frames -- research and market review

Gustavsen, A., Jelle, B. P., Arasteh, D. and Kohler, C.
2007
Project report 6, SINTEF Building and Infrastructure

Gustavsen, A., Jelle, B. P., Arasteh, D. and Kohler, C., (2007), "State-of-the-art highly insulating window frames -- research and market review", Project report 6, SINTEF Building and Infrastructure.
Abstract:
This document reports the findings of a market and research review related to state-of-the-art highly insulating window frames. The market review focuses on window frames that satisfy the Passivhaus requirements (window U-value less or equal to 0.8 W/m2K ), while other examples are also given in order to show the variety of materials and solutions that may be used for constructing window frames with a low thermal transmittance (U-value). The market search shows that several combinations of materials are used in order to obtain window frames with a low U-value. The most common insulating material seems to be Polyurethane (PUR), which is used together with most of the common structural materials such as wood, aluminum, and PVC.

The frame research review also shows examples of window frames developed in order to increase the energy efficiency of the frames and the glazings which the frames are to be used together with. The authors find that two main tracks are used in searching for better solutions. The first one is to minimize the heat losses through the frame itself. The result is that conductive materials are replaced by highly thermal insulating materials and air cavities. The other option is to reduce the window frame area to a minimum, which is done by focusing on the net energy gain by the entire window (frame, spacer and glazing). Literature shows that a window with a higher U-value may give a net energy gain to a building that is higher than a window with a smaller U-value. The net energy gain is calculated by subtracting the transmission losses through the window from the solar energy passing through the windows. The net energy gain depends on frame versus glazing area, solar factor, solar irradiance, calculation period and U-value.

The frame research review also discusses heat transfer modeling issues related to window frames. Thermal performance increasing measures, surface modeling, and frame cavity modeling are among the topics discussed. The review shows that the current knowledge gives the basis for improving the calculation procedures in the calculation standards. At the same time it is room for improvement within some areas, e.g. to fully understand the natural convection effects inside irregular vertical frame cavities (jambs) and ventilated frame cavities.

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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. Key elements of and material performance targets for highly insulating window frames
  5. Phase change materials for building applications: A state-of-the-art review
  6. Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review
  7. Vacuum insulation panels for building applications: A review and beyond  
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. Key elements of and material performance targets for highly insulating window frames
  4. Large-scale experimental wind-driven rain exposure investigations of building integrated photovoltaics
  5. Phase change materials for building applications: A state-of-the-art review
  6. Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review
  7. The path to the building integrated photovoltaics of tomorrow
  8. 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. Key elements of and material performance targets for highly insulating window frames
  8. Laboratory procedures for using infrared thermography to validate heat transfer models
  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  
Kohler, C.
  1. A database of window annual energy use in typical North American residences
  2. Highly insulating glazing systems using non-structural center glazing layers  


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