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The energy code in effect
Clark County adopted the 2024 International Energy Conservation Code with the Southern Nevada amendments. According to the Clark County Building Department, all new building permit applications filed from January 11, 2026 must show compliance with the 2024 IECC. The Southern Nevada amendments were drafted by a committee that included Clark County, Henderson, Las Vegas, North Las Vegas, Boulder City, Mesquite and Pahrump, and they only become code where each jurisdiction adopts them. Check with the building department that will issue your permit.
Window requirements in the prescriptive path
| Climate zone | Where in Clark County | Max. window U-factor | Max. window SHGC |
|---|---|---|---|
| 3B | Most of the county, including the Las Vegas valley | 0.30 | 0.25 |
| 5B | Areas above 4,000 feet elevation | 0.30 (footnote applies above 4,000 ft) | No requirement |
From Table R402.1.2 of the Southern Nevada Amendments to the 2024 IECC. Clark County's amendments treat areas above 4,000 feet as Climate Zone 5B. Projects can also comply through other paths in the code, which your designer or builder will choose.
Planning tips
- Bring window choices into the design early. Window size, orientation and shading all affect whether a design meets the code and how comfortable rooms are.
- Ask for the NFRC-rated U-factor and SHGC of every window on your plans, since those are the numbers the code uses.
- If you want ENERGY STAR certified windows, note that ENERGY STAR's South-Central limits (U-factor 0.28, SHGC 0.23) are stricter than the code minimum.
- Check HOA architectural rules for window styles, frame colors and tints before ordering.
The federal 25C credit never applied to new homes. The IRS says it covers existing homes you improve or add onto, and only for improvements made through December 31, 2025.
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Sources
- Clark County Building Department: Codes and local amendments
- Southern Nevada Amendments to the 2024 International Energy Conservation Code, Clark County (PDF)
- Clark County Board of Commissioners: File 25-2618, adoption of the 2024 IECC
- U.S. Department of Energy, Building America: Guide to Determining Climate Regions by County (PDF)
- ENERGY STAR Version 7.0 Residential Windows, Doors and Skylights Specification (PDF)
- ENERGY STAR: Climate Zone Assignments by ZIP Code and County (Excel)
- IRS: Energy Efficient Home Improvement Credit
Sources checked November 15, 2026. Codes, rebates and tax rules change, so confirm details with the agency before you rely on them.