What are the U-values for steel windows and doors?
U-values vary depending on the type and thickness of glass used. The U-value for steel windows is calculated for the entire window, including frame material and the glass, and incorporates the style of window, fixed or operable. The U-value can be either physically tested or simulated with a computer program. The combination of the minimal framing profiles of steel, the low coefficient of heat transfer, and larger glass areas will produce U-values as low as 0.30 for fixed windows, while operable windows can be as low as 0.50.
