Article #111 - Why is Window Area so Important to Energy Code Compliance?
Windows typically have a higher U-factor than the rest of the building envelope so structures with high glazing areas are less likely to comply with the energy code.
Energy codes have traditionally forced buildings with high glazing areas to have higher insulation levels. In most energy codes, the glazing level is determined by the window-wall area ratio.
The window-wall ratio is the percentage that results from dividing the total glazed area of the building by the total wall area.
Window U-factors typically range from 0.2 to 1.2, while the U-factors of other building assemblies (e.g. walls, floors) typically range from 0.02 to 0.10 when insulated. Using efficient windows decreases the energy consumption of the structure and helps the project comply with the code.
