What Is a Good U
What is a good U-factor for windows ? Learn how window ratings work and how to choose energy efficient windows that reduce heat loss and lower utility bills.
Understanding ENERGY STAR window ratings can help you save on energy bills. Learn how U-factor, SHGC, and climate zones affect window performance.
What Do Energy Star Window Ratings Mean
Energy Star windows help lower energy bills and boost efficiency. Discover what these ratings mean and where to find qualifying windows .
Know how to buy energy -efficient windows with window ratings . Find out about window ratings certifications, ENERGY STAR® program, and more.
Your 2026 Guide to ENERGY STAR Windows
Learn about the energy saving power of ENERGY STAR windows , including yearly cost savings, window ratings and requirements, and more.
The National Fenestration Rating Council (NFRC) is the trusted, independent, nonprofit certification body for the energy performance of windows , doors, and skylights. NFRC certification ensures that products are tested using precise, scientifically validated methods, resulting in ratings that are fair, accurate and credible.
PDF ENERGY STAR Product Specification Residential Windows, Doors, and ...
B. Equivalent Energy Performance: To qualify for ENERGY STAR, Windows may also have NFRC-certified U-Factor and, where applicable, SHGC ratings at levels which meet or exceed the equivalent energy performance criteria specified in Table 4.
Lower energy consumption also reduces greenhouse gas emissions from power plants and homes. Thanks to advances in technology, today's ENERGY STAR certified windows , doors, and skylights offer greater savings than ever before. Just look for the correct ENERGY STAR label for where you live.
PDF Guide to Energy
Guide to Energy -Efficient Windows Replacing your home's windows with ENERGY STAR® qualified windows will improve indoor comfort and filter out damaging ultraviolet light, while potentially saving you hundreds of dollars a year on heating and cooling costs.
Discover the most energy efficient windows for 2025. Expert-tested rankings, climate-specific recommendations, and detailed buying guide with ROI analysis.