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ENERGY STAR windows in Kentucky: what to ask for
Two numbers on the NFRC label tell you most of what you need: U-factor (heat loss, lower is better) and SHGC (solar heat let in).
Current ENERGY STAR criteria (Version 7, effective Oct 23, 2023)
ENERGY STAR sets limits by climate zone. Find your county's zone with the official Climate Zone Finder, then match it to the V7 specification:
| Zone | Window U-factor | Window SHGC |
|---|---|---|
| Northern | ≤ 0.22 | ≥ 0.17 |
| North-Central | ≤ 0.25 | ≤ 0.40 |
| South-Central | ≤ 0.28 | ≤ 0.23 |
| Southern | ≤ 0.32 | ≤ 0.23 |
How to use this when comparing quotes
- Ask every installer for the exact product line and its U-factor and SHGC in writing.
- Check the line is certified for your zone in the ENERGY STAR product finder.
- ENERGY STAR says certified windows cut energy bills by an average of up to 13% nationwide when replacing single-pane windows (source). Savings are smaller if you're replacing decent double-panes.
- Installation matters: ENERGY STAR advises following the maker's instructions and sealing gaps around the frame.
More: honest energy-savings guide · window types
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