Window U-Factor and SHGC Ratings Explained for Virginia Homeowners
What U-Factor And SHGC Actually Measure If you only compare two performance numbers on a window label, make them U-factor and SHGC. U-factor measures how well a window keeps heat from moving through the glass and frame. That is why a lower number usually means better insulation. SHGC, or solar heat gain coefficient, measures how much of the sun's heat a window allows into the home. Depending on the window's exposure, too much solar gain can make rooms feel wa