Look for the NFRC Label

Beginning October 1, 2009, either a black or red label will appear on windows, door, and skylights.

The label indicates high-efficiency fenestration products that qualify as ENERGY STAR but are less stringent than the requirements that will be implemented April 1, 2010.

Windows, doors, and skylights purchased after June 1, 2009 need to have a U-factor and a Solar Heat Gain Coefficient (SHGC) of 0.30 or less, and the ratings must be certified by the National Fenestration Rating Council.