Understanding NFRC Window Labels
Windows are certified by The National Fenestration Rating Council (NFRC), which provides energy performance labels to help you compare one window to another and make informed decisions about the windows you buy.
The NFRC is a nonprofit organization that empowers consumers who are in the market for energy efficient windows, doors, and skylights. When you see the NFRC label on these products, this is your assurance that it’s going to perform the way it’s advertised to perform.
Under the NFRC program, windows, doors, and skylights – otherwise known as fenestration products – are independently tested, certified, and labeled. Labels do not recommend which products to buy, they simply provide you with information on how the product will perform so you can decide for yourself if it’s right for you.
Below is some terminology that commonly appears on NFRC labels and what it means for you and your home:
U-Value: A measure of the rate of non-solar heat loss or gain through a material or assembly. Tests are usually performed under conditions which simulate 0˚ outside and 70˚ inside with a 15 MPH wind. The lower a U-Value, the greater a window’s resistance to heat flow, and thus the better its insulating value. Actual U-Values are based on the glass family you choose.
Visible Transmittance (VT): This is the fraction of the visible spectrum of light weighted by the sensitivity of your eyes that is transmitted through the window. Simply put, it represents the amount of daylight that the window lets in. Example; .44 = 44% of visible light comes through the window.
Solar Heat Gain Co-efficient (SHGC): The fraction of solar radiation admitted through a window including what is absorbed and subsequently released inward. The lower a window’s SHGC, the less solar heat it transmits and the greater its shading ability. Different climates require different SHGC values for maximum efficiency.
Energy Star Climate Zone Map
Vista windows are available with glazing configurations that meet or exceed EnergyStar standards in every zone. For more information, talk to your Authorized Vista Dealer. The U.S. Dept. of Energy's EnergyStar program utilizes our windows thermal performance data, as tested, measured and rated by the National Fenestration Rating Council (NFRC).
Click on the map to see the performance criteria for your region.