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Building Code Reference

Got a Title 24 150.0(q) correction?

Fenestration U-factor and SHGC

For builders in California, Greater Seattle, the Las Vegas area, the Denver area and Kansas City · CrossBeam Permits

What this code requires, how to fix it, and how cities and counties review it

What this code requires

Title 24 150.0(q) is the mandatory California Energy Code section that caps the weighted average U-factor of all windows, glazed doors, and skylights in new single-family construction and additions at 0.40. The prescriptive package (Section 150.1(c)3 and Table 150.1-A) then sets tighter U-factor and solar heat gain coefficient (SHGC) limits by climate zone. U-factor measures how fast heat escapes through glass; SHGC measures how much solar heat gets in. Every window needs NFRC-certified ratings to show it meets them. Most single-family, ADU, and addition permits get flagged on 150.0(q) when the plans show unlabeled windows or omit the NFRC ratings entirely from the energy compliance documentation.

How to fix it

  1. Identify your climate zone on the CF-1R

    Pull your energy compliance report (CF-1R) and confirm which California climate zone applies to this project address. The CF-1R header lists it directly. The 2025 Title 24 Energy Code uses 16 climate zones, and U-factor and SHGC maximums vary by zone. For example, most low-desert climate zones require a lower SHGC than coastal zones. If you do not have a CF-1R yet, your energy consultant or the CEC climate zone lookup tool at energy.ca.gov can tell you which zone applies to the parcel.

  2. Pull the U-factor and SHGC limits for your climate zone

    Once you know the climate zone, pull the prescriptive fenestration requirements from Table 150.1-A of the 2025 Title 24 Part 6 standards or your CF-1R compliance software output. In the 2025 single-family prescriptive package, the maximum U-factor is 0.27 in most climate zones and 0.30 in Climate Zones 6 through 10 and 15. The maximum SHGC is 0.23 in most zones and 0.20 in Climate Zone 15, with no prescriptive SHGC limit in Climate Zones 1, 3, 5 and 16. Do not guess the numbers. Use the exact values from the code table or your energy consultant’s CF-1R output.

  3. Verify every window and skylight carries NFRC certification

    Every window, glazed door, and skylight on the project needs an NFRC-certified U-factor and SHGC. The NFRC label is a sticker on the glass or comes in product documentation from the manufacturer. If a product is not NFRC-certified, it defaults to the worst-case default values in Title 24, which typically fail compliance in every climate zone. Contact your window supplier and ask specifically for the NFRC-labeled product datasheet. If the product is not certified, switch to one that is before you spec it on the drawings.

  4. Add U-factor and SHGC columns to the window schedule

    Update the window and door schedule on your architectural drawings to include U-factor and SHGC columns for every unit. List the NFRC U-factor and NFRC SHGC explicitly, for example: "Window Type A: U-0.28, SHGC-0.22." These values should match what appears on the NFRC product label or datasheet. Do not write "per code" or "per energy report" in these columns. The plan-checker needs to see the actual certified values on the plans, not a cross-reference to another document.

  5. Cross-check the CF-1R against your updated window schedule

    Run the energy compliance report using the products you have actually specified, then verify that the U-factor and SHGC values in the CF-1R match the values on your architectural window schedule. Discrepancies between the two documents are the second most common reason plan-checkers reject 150.0(q) even when both look correct in isolation. If your energy consultant used placeholder products to model compliance, update the CF-1R to reflect your specified products, or update your window schedule to match what the consultant modeled.

  6. Note the total fenestration area on the energy summary sheet

    Some compliance pathways under Title 24 also limit total glazing area as a percentage of conditioned floor area. On the plans, note the total window and skylight area in square feet and the conditioned floor area. Your energy consultant’s CF-1R already calculates this, so you can pull the numbers directly from there. Some plan-checkers want to see this explicitly on an energy notes sheet rather than having to calculate it themselves from the window schedule.

  7. Add a plan note about NFRC verification at rough inspection

    On your general notes or energy notes sheet, include this note: "All windows, glazed doors, and skylights shall be NFRC-certified and shall not exceed the U-factor and SHGC values shown in the fenestration schedule. NFRC labels or product documentation shall be available to the building inspector at rough framing inspection." This satisfies plan-checkers who want confirmation that NFRC documentation will actually be on-site when the inspector arrives.

  8. Resubmit the revised architectural sheets and updated CF-1R together

    Your resubmittal should include the revised architectural sheet with the updated fenestration schedule and the updated CF-1R. If your window supplier gave you a product datasheet with the NFRC values, include it as a supporting document. Cloud or highlight the changed areas on the revised sheets so the plan-checker can locate the 150.0(q) correction without reviewing the entire set from scratch. Most offices accept targeted corrections on revised sheets only. You do not need to reprint sheets that were not changed.

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Why you got flagged

Plan-checkers flag 150.0(q) most often because the fenestration schedule on the plans does not include the NFRC U-factor and SHGC values. The window schedule might list the manufacturer name, size, and frame type, but if the U-factor and SHGC columns are blank or say "per code," the reviewer has no way to verify compliance. This is the single most common trigger, and it is an easy fix if you catch it before submission.

A second scenario: the energy compliance report (CF-1R) lists specific NFRC values, but the window schedule on the architectural drawings calls out a different product or omits the rated values altogether. The plan-checker compares both documents. When the fenestration product on the plans does not match the CF-1R, they flag 150.0(q) even if the energy report itself is correct. Make sure the window specs on your architectural sheets match the products used to run your energy model.

Climate zone is another failure point. California has 16 climate zones, and the prescriptive U-factor and SHGC maximums in Table 150.1-A differ between them, even though the 150.0(q) mandatory cap of U-0.40 is the same everywhere. A window rated for Climate Zone 3 (coastal) may not meet the requirements for Climate Zone 10 (inland valley). If a plan set uses generic window specs or specs pulled from a different project in a different climate zone, the numbers may look plausible but still fail the local threshold. Check the climate zone designation on the CF-1R and confirm the NFRC ratings on your window schedule are within that zone’s limits.

Skylight additions get flagged under 150.0(q) at a higher rate than windows, because skylights often come from smaller manufacturers who may not carry NFRC certification or whose certification paperwork is hard to obtain quickly. If the plans show a skylight without an NFRC U-factor and SHGC, expect a correction even on minor remodel permits.

The official code

California Energy Code Title 24 Part 6 — Building Energy Efficiency Standards (energy.ca.gov)

Read the source →

Common questions

What U-factor and SHGC does Title 24 require for windows in California?
It depends on your climate zone. California has 16 climate zones, and the maximum U-factor and SHGC differ between them. Under the 2025 Title 24 Part 6 prescriptive path, most zones require windows no worse than U-0.27 (U-0.30 in Zones 6 through 10 and 15) and SHGC-0.23, but some coastal climate zones (like Zone 3) have no prescriptive SHGC limit because solar heat gain is less of a cooling burden there. Check your project’s CF-1R compliance report — it will list the exact limits for your parcel’s climate zone. If you do not have a CF-1R yet, your energy consultant can run the numbers, or you can look up your climate zone at energy.ca.gov.
Do skylights need NFRC ratings under Title 24 150.0(q)?
Yes. Title 24 150.0(q) covers all fenestration, which includes windows, glazed doors, and skylights. Skylights fall under the same 0.40 weighted-average cap in 150.0(q). In the single-family prescriptive package they count toward the Table 150.1-A U-factor and SHGC limits, with an exception for up to 16 square feet of skylight per dwelling unit at U-0.40 and SHGC-0.30 (no SHGC limit in Climate Zones 1, 3, 5 and 16). If the skylight product you are specifying does not carry NFRC certification, it defaults to the worst-case values under the code, which usually fail compliance. Ask your skylight supplier specifically for the NFRC-labeled product line before you spec it on the plans, because tracking down certification paperwork after the fact adds time to your correction cycle.
Can I use a window without an NFRC label if it physically meets the spec?
No. California Title 24 requires NFRC certification as the verification mechanism — not just meeting the performance spec. A window without an NFRC label defaults to the code’s worst-case default values (typically U-1.2 and SHGC-0.86 for single-pane equivalent), which fail 150.0(q) in every California climate zone. The plan-checker cannot verify the actual performance of an unlabeled product, so even a physically good window will not pass plan check without the NFRC number. Switch to an NFRC-certified equivalent from the same manufacturer or an alternate supplier.
Does 150.0(q) apply to ADU projects and window replacement permits?
Yes for ADUs: new ADUs are treated as new residential construction for energy code purposes, and the fenestration schedule must show NFRC U-factor and SHGC for every window. For window-only replacement permits (no new conditioned space added), California applies an alteration pathway that still requires replacement windows to meet current U-factor and SHGC limits for your climate zone. If you are adding a window where there was none before, the new window must meet current prescriptive limits. If you are replacing an existing window with an identical size unit, confirm the specific requirement with your local building department, as some jurisdictions apply the alteration pathway differently.
My CF-1R passed but the plan-checker still flagged 150.0(q). Why?
This almost always means the window values on your architectural drawings do not match the CF-1R. Plan-checkers compare both documents. If the CF-1R used a specific window product with U-0.28 and SHGC-0.22, but your window schedule on the drawings lists different products or does not include those NFRC values, the plan-checker cannot verify the plans match the energy model. Fix it by updating the architectural window schedule to show the exact NFRC values for the products specified in the CF-1R — or rerun the CF-1R using the products you actually intend to install.
What products count as fenestration under Title 24 150.0(q)?
Fenestration under Title 24 includes all glazed openings in the building envelope: windows, sliding glass doors, French doors, glass entry doors with more than half their area glazed, skylights, and clerestory windows. Fixed glass panels such as sidelights and transoms count as fenestration. Opaque or solid doors without significant glazing generally do not. Glass block is handled separately under its own provision. If you are unsure whether a specific product counts as fenestration for 150.0(q) purposes, check how your energy compliance software classifies it — that classification matches what the plan-checker will use.

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