What is SHGC (Solar Heat Gain Coefficient)?
The Solar Heat Gain Coefficient (SHGC) is the percent of solar energy incident on the glass that is transferred indoors both directly and indirectly through the glass. The direct gain portion is the solar energy transmittance, while the indirect is the fraction of solar energy incident on the glass that is absorbed and re-radiated or transmitted through convection indoors.
A lower number indicates improved solar control. With a long air-conditioning season, it is most important to reduce solar gain and therefore reduce air-conditioning loads.