Understanding the NFRC Performance Label
The National Fenestration Rating Council (NFRC) is a nonprofit organization that developed an energy rating program based on "whole product" performance – not just the glass.
The NFRC label is found on every window. It's the most reliable way to determine a window's "whole unit" energy performance.
All reputable window manufacturers rate and certify their products according to National Fenestration Rating Council requirements.
This number tells you how well the window insulates. The lower the U-Factor, the better.
Solar Heat Gain Coefficient (SHGC)
This number tells how effective the window is at blocking the sun's radiant heat. The lower the SHGC, the less solar heat the window allows into your home.
Check that the manufacturer reports "whole product energy performance"
This is the best way to know how your window will perform – versus only reporting the "center of glass" performance.
The ENERGY STAR® logo
When you see this logo on the NFRC label, you can be assured you've purchased a high-efficiency window or door that meets ENERGY STAR® guidelines.