NFRC is a non-profit organization that administers the only uniform, independent rating and labeling system for the energy
performance of windows, doors, skylights, and attachment products.
The National Fenestration Rating Council
(NFRC) energy performance label can help you determine how well a product will perform the functions of helping to
cool your building in the summer, warm your building in the winter, keep out wind, and resist condensation. By using the information
contained on the label, builders and consumers can reliably compare one product with another, and make informed decisions
about the windows, doors, and skylights they buy.
All
energy performance values on the label represent the rating of windows/doors as whole systems (glazing and frame).
U-Factor 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. U-Factor ratings
generally fall between 0.20 and 1.20. The insulating value is indicated by the R-value which is the inverse of the U-value.
The lower the U-value, the greater a window's resistance to heat flow and the better its insulating value.
Solar Heat Gain Coefficient 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.
Visible Transmittance
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.
