Choosing a glass structure or window system can often be confusing for someone with no knowledge of glazing terms. Solar heat gain coefficient (SHGC) is a phrase often used to describe glazed products, but the significance is often not fully explained. SHGC is the amount of solar radiation that passes through a window and is expressed as a number between 0 and 1. The higher a window’s SHGC, the more solar heat it transmits. The amount of solar heat gain increases with the intensity of the sun, therefore, the SHGC will be higher during the summer and also in warmer climates.
There are a number of ways to reduce solar heat gain. Installing awnings and canopies can shade a single window or be designed to shade an entire side of your home or business and will cut down on the amount of direct sunlight a room receives. There are several ways the window itself can decrease solar heat gain. Insulated or multi-pane glass increases a window’s thickness, which allows light to pass through, but combats heat and radiation. Tinted glass and LowE glazing can also help block UV rays without compromising visible light transmittance, further decreasing SHGC. Perhaps the simplest way to decrease SHGC is the addition of retractable shades. Shades are easy to install, inexpensive, and will not require a permanent fixture.
Glass is a versatile building material, and monitoring SHGC is an important factor to consider when planning any project involving glass. Therefore, it is crucial to understand the key terminology when working with the material in order to ensure a comfortable and enjoyable structure.