NFRC Numbers - What do they Mean?

National Fenestration Rating Council (NFRC) allows consumers to compare apples to apples in the window and door market.  This independant agency rates windows for thermal performance.  Comapre these numbers and you can easily see which window is a better thermal barrier.

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NFRC - What do all these numbers mean?

Looking for Top-Rated Windows?   Then look for the NFRC –certified label for accurate and reliable Energy Performance Information   National Fenestration Rating Council (NFRC) is a non-profit, public/private organization created by the window, door and skylight industry. It is comprised of manufacturers, suppliers, builders, architects and designers, code officials, utilities and government agencies. NFRC provides consistent ratings on window, door and skylight products. The National Fenestration Rating Council (NFRC) energy performance label can help you determine how well a product will keep your home cool in the summer and warm in the winter.  By using the information contained on the label, you can reliably compare one product with another and make informed decisions about the windows you buy.

U-Factor measures how well a product prevents heat from escaping. The rate of heat loss is indicated in terms of the U-factor (U-value) of a window assembly. t.  The lower the U-value, the greater a window's resistance to heat flow and the better its insulating value.  A window must have a U-Factor of .30 or lower to qualify as an Energystar produc

Solar Heat Gain Coefficient (SHGC) measures how well a product blocks heat caused by sunlight. The SHGC is the fraction of incident solar radiation admitted through a window (both directly transmitted and absorbed) and subsequently released inward. SHGC is expressed as a number between 0 and 1. The lower a window's solar heat gain coefficient, the less solar heat it transmits in the house.  A window must have a SHGC of
.40 or lower to qualify as an Energystar product.

Visible Transmittance (VT) measures how much light comes through a product. The visible transmittance is an optical property that indicates the amount of visible light transmitted. VT is expressed as a number between 0 and 1. The higher the VT, the more light is transmitted.

Air Infiltration is indicated by an air leakage rating expressed as the equivalent cubic feet of air passing through a square foot of window area (cfm/sq ft). Heat loss and gain occur by infiltration through cracks in the window assembly. The lower the AL, the less air will pass through cracks in the window assembly.

































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