Dynamic Glass and Electrochromic Windows Under Title 24
Best-rated values count only with an NFRC label and automatic controls that modulate solar gain by daylight or solar intensity, per Exception 4 to Section 150.1(c)3A. Outside that exception the product is documented like any other window: its NFRC label, or the Table 110.6 defaults if unlabeled. Chromogenic glass also cannot be area-weighted with ordinary windows.
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What qualifies as dynamic glazing
Section 100.1 separates two families. Chromogenic glazing switches reversibly between high and low transmission and may be active, such as electrochromic, or passive, such as photochromic and thermochromic. An integrated shading system has an active layer, such as shades or louvers, built into the unit. Shades or other devices attached to a window frame do not count.
When the best-rated values apply
Exception 4 to Section 150.1(c)3A lets chromogenic glazing use its lower-rated, better-performing labeled U-factor and SHGC, but only with automatic controls that modulate solar gain in multiple steps, responding to daylight levels or solar intensity. An integrated shading system's NFRC label shows both end points with a variable arrow when the product can rest at intermediate states.
Outside that exception, the Standards set no separate rating path: the product is documented like any other window, by its NFRC label or, unlabeled, by the Table 110.6-A and Table 110.6-B defaults. Ask the energy consultant how to document a labeled product that lacks automatic controls.
Why it is averaged separately
Exception 4 to Section 150.1(c)3A says chromogenic glazing is considered on its own. It cannot be area-weighted with fenestration that is not chromatic, so the rest of the windows still make their own average. See mixing window types for that arithmetic.
What the installer verifies
For dynamic glazing, the controls are installed and verified against the maker's operating specifications, and a user manual goes to the owner. The temporary label and the installation certificate are handled as for any other window, with copies to the owner and the enforcement agency. The label path is on NFRC labels.
Replacement and added area
The manual treats replacing windows with dynamic glazing, or adding area, as a fenestration alteration like any other, so the usual U-factor, SHGC and area rules apply on top of the label test. The broader comparison of the two numbers is on U-factor versus SHGC, and the window basics are on windows and Title 24. Our residential reports model dynamic glazing as labeled.
Common Title 24 Questions
- When is Title 24 required for a home?
- Does a remodel need Title 24?
- Does a room addition need Title 24?
- What plans are needed for a residential Title 24 report?
- How much does a residential Title 24 report cost?
- How long does a residential Title 24 report take?
Frequently Asked Questions
No. Exception 4 to Section 150.1(c)3A requires automatic controls that modulate solar gain, not just a label, before the best-rated SHGC applies. Without them, the product is documented like an ordinary window, by its label or the Table 110.6 defaults.
No. The definition excludes shading devices that attach to the window framing or glazing, removable or not.
Explore U-Factor and SHGC
- Mixing Window Types: How the Area-Weighted Average Works and What to Do When One Misses
- Title 24 U-Factor vs SHGC: Which Number Matters?
- Where Window U-Factor and SHGC Appear: CF1R, Plan Set, Label and Installer Certificate
- Are Double-Pane and Low-E Windows Required in California?
View all U-Factor and SHGC guides → · Windows and Building Envelope · Title 24 guide