Title 24 Window Requirements in 2026: What San Diego Homeowners Need to Know

California's 2025 Energy Code took effect for projects permitted on or after January 1, 2026. Every replacement window you install must meet a maximum U-factor and, in most of the state, a maximum Solar Heat Gain Coefficient. In the City of San Diego — Climate Zone 7 — the prescriptive limits are a U-factor of 0.30 or lower and an area-weighted average SHGC of 0.23 or lower. San Diego did not get the tighter 0.27 U-factor that some other climate zones did.

If you have been putting off a window replacement, the code changed underneath you at the start of this year. It is not a dramatic change for San Diego specifically — and that is worth knowing, because a fair amount of what is circulating online right now describes a tightening that does not apply here.

Here is what actually changed, what applies to your address, and what to ask an installer before you sign anything.

What changed on January 1, 2026?

The California Energy Commission's 2025 Energy Code (still commonly called "Title 24," after Part 6 of Title 24 of the California Code of Regulations) replaced the 2022 edition. The trigger date is the permit application date, not the installation date. A project permitted in December 2025 is governed by the old code; one permitted in January 2026 is governed by the new one.

Two things are worth separating in your head, because they get conflated constantly:

• Mandatory requirements apply to every project, no exceptions. The mandatory minimum for fenestration is now a weighted-average U-factor of 0.40.
• Prescriptive requirements are the stricter numbers you must hit if you are complying the simple way, without an energy model. These are the numbers most window replacements are held to, and they vary by climate zone.

Which climate zone is San Diego in?

The City of San Diego and the coastal county — including Chula Vista, Coronado, Imperial Beach, Oceanside, Carlsbad and Vista — sit in California Climate Zone 7. Inland and eastern parts of the region fall into Climate Zone 10, and the desert east of the mountains is Zone 14 or 15.

This matters more than any other single fact in this article, because the 2025 code's U-factor tightening was zone-specific. The prescriptive maximum U-factor dropped from 0.30 to 0.27 in Climate Zones 1–5, 11–14 and 16. Zones 6–10 and 15 stayed at 0.30.

Zone 7 and Zone 10 are both in the group that stayed at 0.30. So for the overwhelming majority of San Diego County addresses, the U-factor bar did not move this year.

The numbers for a San Diego window replacement

Requirement	Climate Zone 7 (coastal San Diego)	Climate Zone 10 (inland)
Prescriptive max U-factor	0.30	0.30
Max area-weighted average SHGC	0.23	0.23
Mandatory min U-factor (all zones)	0.40	0.40
Changed in the 2025 code?	No U-factor change	No U-factor change

In practice, both numbers are met by a standard dual-glazed unit with a Low-E coating. This is not exotic glass. Any current-generation replacement window from a mainstream manufacturer will carry an NFRC label showing a U-factor and SHGC, and for a San Diego job you are checking that the U-factor reads 0.30 or lower and the SHGC reads 0.23 or lower.

What "area-weighted average" means for you

SHGC is assessed across the whole project, not window by window. If you are replacing eight windows and one of them is a north-facing unit you want clearer glass in, the average across all eight is what has to land at or under 0.23. That gives you some room to make different choices in different rooms — which is worth using, because a single SHGC applied blindly to a whole house is rarely the best-looking or best-performing answer.

Do I need a permit to replace windows in San Diego?

Usually yes. Most California jurisdictions require a permit for window replacement, and San Diego is not an exception you should assume your way into. The common misconception is that "like-for-like" replacement is exempt — in many jurisdictions a straight retrofit into the existing frame with no change to the opening is treated more leniently, but any change to the size of the opening, any structural work, or any new opening definitively requires one.

Two practical reasons not to skip it, beyond the obvious:

• Resale. Unpermitted work on a disclosure form is a negotiating lever handed to a buyer, and window replacement is visible.
• Insurance. Claims involving water intrusion around a window opening go differently when the work was permitted and inspected.

What is a CF2R form, and why should you care?

The CF2R-ENV-01-E is the Certificate of Installation for fenestration. It is the document that says the windows physically installed in your house match the energy performance figures submitted at permit stage. Your installer completes and registers it; the building inspector wants to see it at final sign-off.

This is the single most common place a window job stalls. The windows are in, they look right, and then final inspection cannot close because nobody registered the CF2R. Ask about it before work starts, not after.

Three questions worth asking any San Diego window installer

1. "Which climate zone is my address in, and what U-factor and SHGC are you specifying?" If the answer is vague, that is informative.
2. "Are you pulling the permit, or am I?" Get this in writing. An installer who wants you to pull your own permit is telling you something.
3. "Who registers the CF2R, and when?" The answer should be "we do, before final inspection."

Does any of this apply to doors?

Yes — glazed doors are fenestration too. A sliding glass door, a multi-slide, a bifold system or a French door with glass is assessed on the same U-factor and SHGC basis as a window, and counts in the area-weighted average. That is easy to overlook on a project where the big patio opening is the centrepiece: it is often the largest single piece of glass in the house and therefore the biggest lever on the whole-project average.

If you are planning a lift-and-slide or multi-slide door installation, get the glazing spec settled at the same time as the window spec, not afterwards.

Does replacing one broken window trigger all of this?

Replacing the glass in an existing frame is a repair, and is treated differently from replacing the window. Replacing the whole window unit — frame and all — is a replacement and is subject to the current code. If a single failed unit is the problem, glass replacement is often the faster and less disruptive route.

This distinction is genuinely useful. A homeowner with one fogged dual-pane unit and seven perfectly good windows does not need a whole-house project, a permit, and a Title 24 compliance path. They need one insulated glass unit replaced.

The short version

• The 2025 Energy Code applies to projects permitted from January 1, 2026.
• San Diego is Climate Zone 7 (coastal) or 10 (inland). Neither got the tighter 0.27 U-factor.
• Target U-factor 0.30 or lower and area-weighted SHGC 0.23 or lower.
• Assume you need a permit. Confirm who is pulling it.
• Make sure someone owns the CF2R-ENV-01-E before work starts.
• Glass doors count in the same calculation as windows.

This article is general guidance for San Diego homeowners, not a compliance document. Requirements vary by jurisdiction, by climate zone and by project scope, and the code is periodically amended. Confirm the specifics for your address with your local building department or your Title 24 consultant before making purchasing decisions.