What is an R-value or a U-value?
The R-value or R-factor of a window is the measure of its resistance to the transfer of heat flow. The higher its R-value, the greater its insulating ability. The U-value is actually the important variable in evaluating windows. The U-value or U-factor is the measure of the window’s ability to conduct heat. This is the amount of heat transmitted through the window. The lower a window’s U-value, the better the window is at insulating your home.
