National Fenestration Rating Council is a U.S.-based nonprofit organization that sponsors an energy-efficiency certification and rating system for windows, skylights and doors. These ratings provide consumers with information pertaining to energy efficiency, performance and whether a product meets code.
NFRC ratings cover air leakage, u-factor, solar heat gain coefficient, visible transmittance and condensation resistance. These ratings also provide information pertaining to building and energy codes as well as tax credits and utility incentive programs. The comprehensive rating system used by NFRC labels provide the only reliable way for consumers to assess the energy properties of a replacement window or to compare different products.