The solar heat gain coefficient indicates what?

• A. Amount of solar radiation transferred through product
• B. Thermal conductivity of wall material
• C. Reflectivity of glass surface
• D. Sound transmission through glazing

Answer: (A)

SHGC tells you how much solar energy actually becomes heat inside the building through the glazing. It includes both the energy that passes directly through and the energy absorbed by the glass and surrounding materials that is later released indoors. The value ranges from 0 to 1 (0% to 100%), so a lower SHGC means less heat from the sun gets into the space, while a higher SHGC allows more. This helps you pick windows based on climate: lower SHGC is preferable in hot climates to reduce cooling loads, while higher SHGC can be beneficial in cold climates to gain solar heat. It’s not about how well heat conducts through the wall (that’s the U-factor), nor about reflectivity or sound transmission.