ENERGY STAR Window Requirements by State
ENERGY STAR certification for windows is voluntary but increasingly expected by contractors and homeowners. Version 7.0 (effective 2023) tightened requirements significantly, and windows meeting ENERGY STAR standards automatically meet energy code requirements in most jurisdictions.
ENERGY STAR Version 7.0 Requirements
| Climate Zone | Max U-Factor | Max SHGC |
|---|---|---|
| Northern (Zones 5–8) | 0.22 | Any |
| North-Central (Zone 4) | 0.27 | Any |
| South-Central (Zone 3) | 0.25 | 0.25 |
| Southern (Zones 1–2) | 0.40 | 0.25 |
Note: ENERGY STAR uses its own four-region climate classification, not the IECC eight-zone system. The Northern zone corresponds roughly to IECC Zones 5–8; Southern to Zones 1–2.
ENERGY STAR vs. Code Minimum
In some jurisdictions, ENERGY STAR Version 7.0 is stricter than the local code minimum. For example, the Northern zone ENERGY STAR U-factor of 0.22 is more stringent than the IECC 2021 requirement of 0.27 for Zones 5–6. Meeting ENERGY STAR is a good target for quality but not legally required unless your jurisdiction specifically adopts it.
Tax Credit Eligibility
Under the Inflation Reduction Act, windows meeting ENERGY STAR Most Efficient criteria qualify for the Energy Efficient Home Improvement Credit (25C) — a tax credit of 30% of the cost up to a $600 annual cap for windows. Verify current eligibility with the IRS or a tax professional, as requirements may change.