The National Fenestration Rating Council (NFRC) is a United States 501(c)3 non-profit organization which sponsors an energy efficiency certification and labeling program for windows, doors, and skylights.
[1] NFRC labels provide performance ratings for such products in five categories: U-value, Solar Heat Gain Coefficient, Visible Transmittance, Air Leakage, and Condensation Resistance.
[2] In 2003, NFRC implemented one-size testing, moving away from the dual u-factor ratings that it had previously used (which were a compromise between founding manufacturers).
[2] NFRC product ratings are determined through a combination of computer modeling and physical validation testing.
For a given product line, all configurations and options are modeled using THERM and WINDOW software programs, developed by Lawrence Berkeley National Laboratory.
Consumers who purchase Energy Star rated windows and doors may be eligible for a tax credit.