Measuring Performance: ENERGY STAR® Windows
The Department of Energy (DOE) and the Environmental Protection Agency (EPA) have developed an ENERGY STAR designation for products meeting certain energy performance criteria.
Windows that have the ENERGY STAR designation will be labeled showing the zones in which it is qualified.
Since energy efficient performance of windows, doors, and skylights varies by climate, product recommendations are given for four U.S. climate zones. For making comparisons among ENERGY STAR products, use the NFRC label or the NFRC Certified Products Directory.