As radiative heat from the sun comes from a surface at 11,000F, different calculation techniques are needed to account for the heating effect. The solar heat gain coefficient (SHGC) is defined for this purpose. When sunlight hits a window, some of it goes right through the window, some is reflected back and some is absorbed, heating up the various parts of the window. The absorbed heat can either flow to the inside of the house or the outside. The SHGC represents the fractional amount of the solar energy that strikes the window that ends up warming the house.
A look at the NFRC website will find the explanation "The lower the SHCG, the better a product is at blocking unwanted Sun.” This is true, but it should be followed with"The lower the SHGC, the more a product blocks wanted sun.” For most area, most solar heat gain is unwanted, as it will increase electric bills for air conditioning. However, in cold area, solar heat gain is normally desired,especially in a winter. A window with a high SHGC will raise cooling bills, but it will generally reduce heating costs more.
LS182 SHGC Window Tint Meter is self-contained light sources and self -calibration. No manual adjustment is needed. The users only need plug the power supply, turn on the switch to choose 950nm, SHGC(Solar heat gain coefficient) and 1400nm,then put the solar film in the opening. The resulting performance data appear on the display.