What are the R-factors for various window frames, and what is considered acceptable?
“R” stands for resistance. A measure of a product’s ability to resist the transfer of thermal energy. The higher the R-factor, the greater amount of insulation a window provides. The R-factor rating of a window frame, sash and glass is very important since it directly affects the cost of heating and cooling your home. As with any measure of energy efficiency, it’s not so much what’s considered acceptable, as what’s acceptable to you.
