Solar Heat Gain Coefficient
A number between 0 and 1 that represents the fraction of solar radiation admitted through a window, both directly transmitted and absorbed then released inward.
SHGC is a critical specification for window selection in Canada. A higher SHGC allows more solar heat in (beneficial in winter for passive heating), while a lower SHGC reduces cooling loads in summer.
In Canadian climates, the ideal SHGC depends on orientation: south-facing windows benefit from higher SHGC (0.4-0.55) for passive solar gain, while west-facing windows may need lower SHGC (0.25-0.35) to prevent overheating. ENERGY STAR Canada specifies maximum SHGC values by climate zone.