What is U-factor?
The U-Factor is the rate of heat loss coming from your window and expresses the insulation value of your windows . You want a window with a low U-Factor because the lower the U-Factor, the greater the insulating capabilities of your windows. The National Fenestration Rating Council (NFRC) is the nationally recognized organization that provides comparisons of energy performances of windows, doors, and skylights and is the organization that designates what windows U-Factors are.
