WindowConsultant.net isn't a window company and doesn't sell products. We connect homeowners with independent local window professionals who can recommend and quote specific windows.
The three numbers on a window label
| Rating | What it measures | What to look for here |
|---|---|---|
| U-factor | How much heat passes through the whole window. Lower is better. | ENERGY STAR South-Central: 0.28 or lower |
| Solar Heat Gain Coefficient (SHGC) | The share of the sun's heat that gets through the window. Lower means less solar heat. | ENERGY STAR South-Central: 0.23 or lower |
| Visible transmittance | How much daylight comes through. | A trade-off you choose: lower SHGC glass can still let in plenty of light |
ENERGY STAR Version 7.0 requirements for windows, effective October 23, 2023. Clark County ZIP codes are assigned to the South-Central zone.
Why SHGC matters so much in the desert
The Department of Energy's Building America guide on window selection explains that low-solar-gain low-e coatings, typically with an SHGC below 0.25, cut summer solar heat gain while keeping visible light, and that with these coatings a window's orientation has much less effect on cooling. The same guide notes that overhangs do much less to shade east- and west-facing windows, because the sun is lower when it hits them.
ENERGY STAR and the energy code are separate
ENERGY STAR is a certification program with its own four climate zones. Building codes use IECC climate zones. Most of the Las Vegas valley is IECC Climate Zone 3B, where the 2024 IECC as amended for Southern Nevada sets a maximum window U-factor of 0.30 and SHGC of 0.25. A window can meet one standard and not the other, so if your project needs a permit, check both. More detail is in the Las Vegas guide.
Rebates and tax credits right now
- Federal tax credit: The IRS says the Energy Efficient Home Improvement Credit (25C) can be claimed for improvements made through December 31, 2025. Windows installed in 2026 don't qualify.
- NV Energy: The 2026 Home Improvements Program rebate sheet covers duct sealing and attic, wall and floor insulation. Windows aren't on the list.
- State home energy rebates: The Nevada Governor's Office of Energy lists the launch of its federally funded home energy rebate programs as pending federal review and program guidance.
Be cautious of anyone who promises a specific rebate or a set dollar savings on window replacement. Ask them to show you the official program page.
Want a local pro to look at your windows?
Tell us about your project. An independent window professional who serves your area can follow up.
Sources
- ENERGY STAR: Residential Windows, Doors and Skylights
- ENERGY STAR Version 7.0 Residential Windows, Doors and Skylights Specification (PDF)
- ENERGY STAR: Climate Zone Assignments by ZIP Code and County (Excel)
- U.S. Department of Energy, Building America: Measure Guideline, Energy-Efficient Window Performance and Selection (PDF)
- U.S. Department of Energy, Building America: Guide to Determining Climate Regions by County (PDF)
- Southern Nevada Amendments to the 2024 International Energy Conservation Code, Clark County (PDF)
- IRS: Energy Efficient Home Improvement Credit
- NV Energy: 2026 Home Improvements Program Rebates and Requirements (PDF)
- Nevada Governor's Office of Energy: Home Efficiency Rebates Program
Sources checked November 15, 2026. Codes, rebates and tax rules change, so confirm details with the agency before you rely on them.