SHGC, or solar heat gain coefficient, is the measure of how much solar heat can pass through a window, and is one of the criteria that window energy efficiency ratings are based upon. Understanding some of the specifics about it can help you get the right replacement windows for your home. In today’s post, window and roofing installation contractor Advanced Roofing shares a quick guide to understanding SHGC.
Solar Heat Gain
The goal behind energy efficiency ratings is to provide information about a product’s energy efficiency performance at the point of purchase. An energy-efficient replacement window should complement the other insulated parts of the house, such as the attic and exterior walls, and help keep heat leaks to a minimum. It should help reduce the need for heating and cooling systems to compensate for the heat loss or gain, ultimately resulting in energy savings.
There are two ways heat can be transmitted through windows. The first is through radiant heat gain, or the heat radiating from the air and from surfaces heated by the sun. A roof absorbs radiant heat on its surface, which is why every roof maintenance company installs insulation in the attic. Windows have double or triple-pane glass that helps reduce radiant heat transfer. The second way heat is transmitted is through solar heat gain. As a form of light, solar heat can pass through clear glass easily regardless of the number of panes a window has.
SHGC and Energy Efficiency
SHGC is the ratio where 1 is the maximum amount of solar heat that can pass through a window, while 0 is the absolute lowest. Clear, uncoated glass would have an SHGC rating of nearly 1, while a heavily shaded window would be rated nearly 0. Therefore, the lower the SHGC value, the less hot your home would get during the day.
Replacement window manufacturers offer window glass with coatings that selectively block solar heat and UV rays without darkening the window glass. Look for replacement windows that have low SHGC and high visible transmittance (VT) values. Replacement windows with these ratings are ideal for walls that receive direct sunlight during the day.
Advanced Roofing is your leading provider of window and roofing installation services. Give us a call at (630) 521-3573. You can also fill out our contact form to schedule an appointment or if you would like to inquire about emergency roof repair cost. We serve customers in Plainfield, IL, and the surrounding communities in Illinois.