A replacement window qualifies for ENERGY STAR certification through partner manufacturing and independent NFRC verification. With 730+ towns served across Massachusetts, New Hampshire and Maine and 7,000+ installations completed since 2011, Coastal Windows & Exteriors is an InstallationMasters-certified, woman-owned exterior remodeling company. Certification matters most before winter, when drafty windows drive up heating costs.
What Homeowners Need to Know:
- Northern zone target: ENERGY STAR certified windows for the Northern zone need a U-factor of 0.22 or lower. Get a free estimate to compare qualifying options before winter.
- Independent testing: Each certified window is tested and verified by the National Fenestration Rating Council. Its ratings must meet EPA efficiency guidelines.
- Winter sun gain: Northern zone windows also need a solar heat gain coefficient of at least 0.17. That lets winter sunlight help warm your rooms.
- Label check: Look for the ENERGY STAR label for your climate zone beside the NFRC label on the glass. Confirm your zone using the ENERGY STAR Climate Zone Finder.
- Heating season savings: Certified windows, doors, and skylights can lower heating and cooling costs by up to 13% on average. See how energy efficient windows perform in cold winters.
Choosing Certified Windows With Confidence
- Top Recommendation: ENERGY STAR certified windows rated for the Northern zone cut heating-season heat loss most effectively. Book a free estimate with Coastal Windows & Exteriors before winter.
- Best for cold-climate comfort: Low U-factor windows paired with adequate solar heat gain for the heating season.
- Smart for shoppers: Verify the label for your zone using the ENERGY STAR Climate Zone Finder before buying.
Request a free window estimate from Coastal Windows & Exteriors.
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Still have questions about what makes a replacement window qualify for ENERGY STAR certification? See the areas we serve and talk to your local replacement window contractor.
Last Updated: October 2026
Sources:
- ENERGY STAR certified windows are built by an ENERGY STAR partner, verified by the NFRC, and rated by climate zone. ENERGY STAR What Makes It ENERGY STAR?, the program’s official product criteria for windows. (Accessed September 2026)
- Northern zone windows need a U-factor of 0.22 or lower and an SHGC of 0.17 or higher. Andersen ENERGY STAR Version 7.0 Quick Guide, a manufacturer overview of the updated performance criteria. (Accessed September 2026)
- Shoppers should look for the ENERGY STAR label for their climate zone beside the NFRC label on the glass. ENERGY STAR Windows, guidance on identifying certified windows. (Accessed September 2026)
- Certified windows, doors, and skylights can lower heating and cooling costs by up to 13% on average nationwide. ENERGY STAR Windows, Doors & Skylights, program savings data versus non-certified products. (Accessed September 2026)
- A lower U-factor means less heat escapes, which matters most during the winter heating season in colder climates. Pella Performance Information, a homeowner explanation of U-factor and solar heat gain. (Accessed September 2026)
