Summary: NFRC, the National Fenestration Rating Council, maintains standards for rating the heat loss, solar heat gain, visible light transmittance, and other fenestration performance characteristics. “Fenestration” includes windows, doors, curtain walls, storefront glazing systems, skylights, and similar openings. For further information on the NFRC rating, labeling, and certification programs, see Both the commercial and residential energy codes require almost all window glazing to have an NFRC label or label certificate. For both residential and commercial construction, the code provision reads: “U-factors of fenestration products (e.g. windows, doors, and skylights) shall be determined in accordance with NFRC 100 by an accredited, independent laboratory, and labeled and certified by the manufacturer.” The Solar Heat Gain Coefficient (SHGC) must also be certified by NFRC.

Date Revised: 05/05/2021

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