Thermal importance of windows

Thermal importance of windows

Thermal importance of windows and helpful information.

By Brittany Hanam, MASc, EIT, Graham Finch, MASc, P.Eng., and Dave Ricketts, MSc, P.Eng.


All images courtesy RDH Building Engineering


Of all the components of a building enclosure, windows can have the greatest impact on energy consumption. This can be disproportionate to the area of the enclosure the windows cover. Therefore, it is important architects and specifiers are aware of the significant impact of windows on the overall building enclosure’s thermal performance when designing, evaluating, and selecting enclosure assemblies for new buildings and retrofit projects. The examples in this article focus on residential buildings, but the discussion generally applies to most facility types.

Understanding the thermal performance of windows
There are two properties that describe the energy performance of windows: U-value (i.e.U-factor) and solar heat gain coefficient (SHGC).

Thermal importance of windows

Thermal performance of windows and other building enclosure components is typically measured in terms of either U-value or R-value. The former is a measure of the overall rate of heat transfer through the entire fenestration product (or other enclosure assembly) under standardized winter conditions. While the rate of heat transfer varies through the frame, the glass edge, and the centre of glass, the READ MORE

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