January 5, 2026 · 6 min read
Energy-Efficient Windows in California: What You Need to Know
Understanding Energy Star ratings, U-factor and SHGC can save you thousands over the life of your windows.
California's Title 24 building code sets some of the most demanding energy standards in the country. If you're replacing windows, understanding the ratings matters.
The Two Numbers That Matter
- U-factor — how well the window insulates. Lower is better. Look for 0.30 or below.
- SHGC (Solar Heat Gain Coefficient) — how much solar heat comes through. For most of California, aim for 0.25 or lower.
Available Rebates
SoCalGas, SCE and many local utilities offer rebates for Energy Star qualified window replacement. Federal Energy Efficient Home Improvement Credit may also apply (up to $600/year for qualifying windows).
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Get a written quote for your California window project — no obligation.