Title 24 Energy Requirements for Replacement Windows in Orange County
Summary
Orange County spans California Climate Zones 6 and 8. Replacement fenestration must meet prescriptive maximums of U-factor 0.30 and SHGC 0.23 under the 2022 Building Energy Efficiency Standards, certified by NFRC label and documented on a CF1R form.
- Author
- Written by: OCWR Research Desk
What Title 24 actually requires
California's Building Energy Efficiency Standards — Title 24, Part 6 — apply to window replacement as an alteration, not only to new construction. Replacing an existing window with a new unit triggers the fenestration requirements for alterations.
Orange County is covered by two California building climate zones:
| Area | Climate Zone |
|---|---|
| Coastal and central OC (Newport Beach, Huntington Beach, Costa Mesa, Irvine, Laguna, Mission Viejo, San Clemente) | Zone 6 |
| Inland north and east OC (Anaheim, Brea, Yorba Linda, Orange, Placentia, Fullerton inland areas) | Zone 8 |
Prescriptive limits
Under the 2022 standards, the prescriptive path for replacement fenestration in both Zone 6 and Zone 8 sets maximums of:
- U-factor: 0.30 (rate of heat transfer — lower is better)
- SHGC: 0.23 (solar heat gain coefficient — lower admits less solar heat)
These are maximums, not targets. A unit at 0.28 / 0.21 complies; a unit at 0.32 does not, on the prescriptive path.
Where the numbers come from
Compliance values must be NFRC-certified. The temporary NFRC label on a new window states U-factor, SHGC, visible transmittance and air leakage for that specific product configuration — including the glass package and grid option. A unit with an added grid or a different low-E coating is a different rated product.
Do not accept "meets Title 24" as a specification. Ask for the NFRC-rated U-factor and SHGC for the exact configuration being ordered, and confirm they match the values written on the CF1R compliance form filed with the permit.
Performance path
A whole-building performance calculation can allow individual windows that exceed the prescriptive maximums if compensating measures are documented. In practice, residential window-only replacement in Orange County is almost always done on the prescriptive path because it is faster and cheaper to document.
What this means for your project
- Zone 6 and Zone 8 share the same numeric limits, but inland Zone 8 summers make SHGC the number that changes comfort on west and south exposures.
- Low-E coatings are how manufacturers reach 0.23 SHGC. Expect a spectrally selective coating on any compliant unit.
- The CF1R is the document the city plan checker reads. If installed values do not match it, the inspection can fail.
Sources & Citations
Citations for this reference are being catalogued.
Related research
Low-E Coatings, Argon Fill and Spacers: How Window Glass Performance Works
U-factor and SHGC are produced almost entirely by the glass package: the low-E coating, the gas fill, and the spacer. This page explains what each component does and how to read an NFRC label.
Reviewed by Technical Review Board
Orange County Window Replacement Permit Requirements
Every Orange County city requires a building permit for window replacement, including like-for-like retrofit work. Plan review verifies Title 24 fenestration values, safety glazing locations, and bedroom egress.
Technical reference
Vinyl vs. Aluminum Replacement Windows: Technical Comparison
Vinyl frames offer far better thermal performance and no corrosion path; thermally broken aluminum offers narrow sightlines, large spans and rigidity. Non-thermally-broken aluminum cannot meet current Title 24 limits in most configurations.
Reviewed by Technical Review Board
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