Nov 15 2007
Windows are important to the efficiency of our homes and often account for a significant portion of our heating and cooling bills. New technologies are beginning to address common issues, such as solar heat gain and insulation, so that we can expect more from our windows in the future.
What is a SHGC?
Windows allow sunlight into our homes. Sunlight is composed of short and long wavelengths. The short wavelengths represent the visible light that makes our homes bright and sunny. The long wavelengths produce the heat we feel from that sunlight. This heat is also known as solar radiation.
The amount of solar radiation transmitted through a window is represented by the Solar Heat Gain Coefficient (SHGC), a number between 0 and 1. A window with a high SHGC allows a lot of solar radiation into your home. The heat provided can be welcome in colder climates, but provides unnecessary heat in warmer climates. A window with a low SHGC blocks solar radiation, which reduces the need for air-conditioning in summer but is not ideal for cold climates.