California Title 24 Fenestration: U-Factor & SHGC Guide

What Title 24 Part 6 requires for windows and doors in California: U-factor, SHGC and labeling, and what exporters must document.

Last updated: November 2, 2026

Windows & Fenestration · Last updated: 2 November 2026 · Jusen Doors Technical Team · Reviewed by Jusen Doors Engineering Team

California Title 24 Fenestration: U-Factor & SHGC Guide

Quick answer: California Title 24, Part 6 fenestration requirements are driven by the adopted Energy Code cycle, building type, climate zone and whether compliance is shown prescriptively or through performance modelling. U-factor and Solar Heat Gain Coefficient (SHGC) must come from an accepted rating route—normally NFRC-certified values for the actual product. Export buyers should freeze the code cycle and compliance path before asking a factory whether a window 'meets Title 24'.

Title 24 is a compliance system, not a window grade

A window does not become compliant merely because a supplier publishes a low centre-of-glass U-value. The project must satisfy the mandatory and applicable prescriptive or performance requirements for its building type and climate zone. Fenestration area, orientation, shading and trade-offs in an energy model can change the acceptable product values. That is why a door/window schedule should carry the compliance target assigned by the energy consultant, not a generic California number copied from another project.

U-factor and SHGC measure different risks

U-factor describes overall heat transfer through the complete fenestration product; lower is generally better for conductive loss/gain. SHGC describes the fraction of incident solar radiation admitted as heat; the desired value depends on climate, orientation and cooling strategy. Frame material, thermal break, glass coating, spacer and product size all affect certified values. A centre-of-glass figure from a glass supplier is useful screening data but is not the whole-window rating.

Use NFRC evidence correctly

California fenestration compliance relies on rated values through accepted procedures. The buyer should identify whether the product has an NFRC listing, a temporary label for the project, or another route allowed in the adopted code for site-built/custom products. Ratings belong to a defined operator type and configuration. Changing a fixed unit to a casement, adding a grid package or altering the frame can change the value. See how to read an NFRC label.

Climate zone and building type prevent universal limits

This article deliberately does not publish a single U-factor/SHGC table as 'the 2026 California limit'. Residential and non-residential provisions differ, alterations differ from new construction, and later Energy Code cycles change values and procedures. State the cycle, permit date, climate zone and compliance approach in every factory RFQ. A supplier that answers without asking those four questions is not ready to warrant compliance.

Procurement submittal checklist

Energy Code cycle and local reach code if applicable.
Climate zone, building type and new-build/alteration status.
Prescriptive target or performance-model allowance for each mark.
Whole-product U-factor and SHGC from the accepted rating route.
Air-leakage and product certification evidence.
Installation flashing/perimeter details assigned to the responsible party.
Labels and certificates required at inspection.

Specification checklist: what to confirm before ordering

Destination code, climate/wind exposure and compliance route fixed before product selection.
Operator type, maximum size, frame system and glass build-up matched to test evidence.
Structural, water, air, thermal and safety-glazing duties specified separately.
Labels, calculations and submittal documents required at permit/inspection.
Anchorage, flashing and perimeter sealing responsibilities assigned.

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FAQs

What U-factor do I need for California?

There is no single defensible answer. It depends on code cycle, climate zone, building type, scope and compliance path. Obtain the target from the project energy documentation.

Can centre-of-glass data prove Title 24 compliance?

Usually not by itself. The whole fenestration product must be rated through an accepted method.

Does a low SHGC always help?

It can reduce solar cooling load but may reduce useful winter solar gain and daylight quality. The energy model and orientation decide the appropriate balance.

Data note: Figures described as typical, common or planning ranges are industry budgeting ranges with the stated assumptions. Building-code duties, tested scope and final quotations depend on destination, selected construction and order schedule.