What is solar heat gain coefficient (SHGC)?
The Solar Heat Gain Coefficient is the fraction of the incident solar radiation admitted through a window, both directly transmitted and absorbed and subsequently released inward. SHGC is expressed as a number between 0 and 1. The lower a windows solar heat gain coefficient, the less solar heat it transmits. A SHGC of 0.40 or less is recommended in warm climates. In heating-dominant climates, a high SHGC increases passive solar gain for the heating, but reduces cooling season performance, but reduces passive solar gain for heating.
