What does Solar Heat Gain Coefficient (SHGC) mean?
The number to know when selecting windows, doors, and skylights. It’s a measure of how much of the sun’s heat is transmitted through those fixtures, expressed in a number from zero to one. A window that has a SHGC of .3 will allow 30 percent of the sun’s heat to pass through. Whether you want a higher or lower number will depend on your goal: A product with a low SHGC will help to block heat and reduce cooling loads in hot weather; a product with a high SHGC will be more effective at harnessing solar heat in cold weather. Generally the lower the SHGC the lower the U-Factor.
