The 2026 Title 24 numbers for replacement windows
California's 2025 Building Energy Efficiency Standards (Title 24, Part 6) took effect January 1, 2026, so permits applied for this year fall under them. Replacement windows of the same total area must meet the prescriptive U-factor and SHGC values for the home's climate zone.
| Situation | Max U-factor | Max SHGC |
|---|---|---|
| Replacement windows, Climate Zones 11 and 12 (2025 code) | 0.27 | 0.23 |
| Replacement job of 75 sq ft or less | 0.40 | 0.35 |
| Replaced skylights | 0.40 | 0.30 |
| Jobs permitted under the 2022 code (before 2026) | 0.30 | 0.23 |
Sacramento is the reference city for Climate Zone 12, which also includes Elk Grove, Davis, West Sacramento, Carmichael and Fair Oaks. Roseville and Rocklin are listed in Climate Zone 11. Under the 2025 code both zones use the same window values. Zones are assigned by ZIP code, so if you live in Folsom, Citrus Heights, Orangevale, Rancho Cordova or Lincoln, check the California Energy Commission's climate zone map or ask the installer to confirm.
Glass-only or sash-only replacement counts as a repair, not a replacement, as long as the new glass performs at least as well as the old. See window glass replacement.
What U-factor, SHGC and low-e mean
U-factor: heat moving through the window
U-factor measures how easily heat passes through the whole window, frame included. Lower is better. It matters on winter nights when the furnace is running and on summer afternoons when the attic and walls are radiating heat back into the house.
SHGC: sunlight turning into heat
Solar heat gain coefficient is the share of the sun's heat that gets through as heat inside the room, on a scale from 0 to 1. Lower means less heat. The 0.23 cap is why a new window on a west-facing wall at 5 p.m. in July feels so different from the old one: most of the sun's heat stays outside.
Low-e coatings
Low-emissivity coatings are microscopically thin metal layers on one of the inner glass surfaces. They let visible light through while reflecting infrared heat. Different low-e recipes trade off light, color and solar control; to hit SHGC 0.23, most windows use a solar-control low-e, sometimes with a slight tint. Look at a sample in daylight if the color of the view matters to you.
Reading the NFRC label
Title 24 requires U-factor to be rated under NFRC 100 and SHGC under NFRC 200, and air leakage can be no more than 0.3 cfm per square foot. Each window carries a temporary NFRC label with these numbers, and that label must not be removed before the building inspector sees it. A permanent label stays on the unit.
- Find U-factor and confirm it is 0.27 or lower (or 0.40 or lower on a job of 75 sq ft or less).
- Find Solar Heat Gain Coefficient and confirm 0.23 or lower (or 0.35 on a small job).
- Check Visible Transmittance if you care about brightness; higher means more daylight.
- Make sure the label matches the product, size class and glass package on your quote.
- Leave the sticker on until final inspection.
Where ENERGY STAR fits
ENERGY STAR is a voluntary EPA label that certifies a window meets its efficiency criteria for a climate region. It is a useful shorthand when comparing products from different makers, but in California the binding requirement is Title 24, and the NFRC numbers on the label are what the inspector checks. ENERGY STAR Most Efficient was the bar for the old federal tax credit; with that credit gone, it no longer unlocks money on its own.
Rebates and tax credits: the honest picture
- Federal 25C credit: ended. The IRS says the Energy Efficient Home Improvement Credit is not allowed for property placed in service after December 31, 2025. Windows installed in 2026 get no federal credit.
- SMUD: SMUD's Home Performance Program page lists rebates for heat pumps, panel work and sealing and insulation, but nothing for windows right now. SMUD serves most of Sacramento County, including Elk Grove, Folsom, Rancho Cordova and Citrus Heights.
- Roseville Electric: offered a residential windows and sunscreen rebate in past years. Whether one is available now is not confirmed; check the city's rebates page before you buy.
- PG&E areas (Davis, West Sacramento, Placer County outside Roseville, El Dorado County): check PG&E's current offerings directly.
Be wary of any quote that promises a specific rebate or tax credit for windows without showing where it comes from.
Getting the most from efficient windows
Prioritize the windows that take direct afternoon sun, usually west and south, and any older single-pane units; see double-pane windows for the dual-pane basics. Ask the installer how they seal the new unit to the opening, because air leaks around the frame undo good glass. On summer evenings, operable windows still earn their keep: when the delta breeze comes in, opening the house up can flush out the day's heat.
Cost guides put the average window at about $800 installed nationally (Fixr), with a typical range of $450–$1,200. Our window replacement cost in Sacramento page breaks it down by material and style, and vinyl windows covers the most common budget option. For the full process, see window replacement in Sacramento.
Main guide: window replacement in Sacramento.