The reliable way is to have the NFRC-certified values pulled for the exact units you're specifying, then checked against the Title 24 targets for your project's climate zone. Not a similar unit from the same series, and not the glass manufacturer's data sheet. What you need is the certified whole-window number for the specific configuration you intend to order.
Ask a specialist at Window Concepts and we'll locate them for you. We do this at the design stage, before drawings are final and long before anything is ordered, so your Title 24 consultant is modeling the real product from the start rather than discovering a gap at plan check.
One clarification is worth making, because the terms get used interchangeably. NFRC and Title 24 are not the same thing. The National Fenestration Rating Council is an independent body that tests and certifies window performance. It does not set requirements. Title 24 Part 6, California's energy code, sets the targets. You need both: an NFRC-certified value, and a value that satisfies Title 24 for your address.
What are U-factor and SHGC?
They are the two numbers Title 24 uses to judge a window, and they measure different things.
U-factor is the rate at which heat moves through the whole window assembly, meaning frame, glass, and spacer together. It describes how well the window resists heat flowing in or out by conduction. The bottom line is that a lower value is better. U-factor is the inverse of R-value, which is why the direction feels backwards if you're used to insulation.
SHGC, or Solar Heat Gain Coefficient, is the fraction of the sun's energy that passes through the window, on a scale of 0 to 1. An SHGC of 0.22 means 22% of the solar energy striking the glass enters the room. Lower admits less solar heat.
The distinction matters because they address different loads. U-factor governs heat conducted through the assembly. SHGC governs heat the sun delivers directly through the glazing.
In Los Angeles, SHGC is usually the harder of the two to satisfy. Winters are mild, so a mediocre U-factor carries a small heating penalty. Summers are not, and cooling load drives the energy model. A west-facing wall of glass in the Valley is a solar gain problem long before it's an insulation problem.
Why the number you find yourself may not be the number that counts
NFRC rates the whole window including the frame, while glass manufacturers publish center-of-glass values that exclude it. Frames conduct more heat than glazing does, so the whole-window figure is always the worse of the two, and it's the one Title 24 uses.
A glass package advertised at U-0.24 center-of-glass can rate U-0.32 as an installed window. A spec written off a glass data sheet describes a product that doesn't exist, and the compliance model built on it won't match what shows up on site.
This is also where frame material stops being purely aesthetic. Aluminum and steel conduct readily, which is why thermally broken systems exist. The polyamide barrier interrupting the conductive path is what lets a metal window post a competitive whole-window U-factor at all.
Do Brentwood and Beverly Hills have the same Title 24 requirement?
No, and they sit about a mile apart. California has 16 building climate zones, and the Westside straddles two of them.
| Area | ZIP | Climate Zone |
|---|---|---|
| Brentwood | 90049 | 6 |
| Pacific Palisades | 90272 | 6 |
| Santa Monica | 90402-90405 | 6 |
| West LA | 90025 | 6 |
| Mar Vista | 90066 | 6 |
| Beverly Hills | 90210, 90211, 90212 | 9 |
| Bel-Air | 90077 | 9 |
| Westwood | 90024 | 9 |
| Rancho Park | 90064 | 9 |
| West Hollywood | 90069 | 9 |
Zone 6 is the coastal band, where marine air moderates the temperature swing. Zone 9 runs inland and warmer, and its targets reflect that. Two projects that feel like the same market, a Brentwood remodel and a Beverly Hills new build, are held to different numbers.
It gets finer than neighborhood. West LA (90025) is Zone 6, while Rancho Park (90064), directly adjacent, is Zone 9.
Climate zone is assigned by ZIP code, and each ZIP sits entirely within one zone. Every address in 90049 shares Brentwood's Zone 6, but you can't infer the zone from the city, or from the neighborhood next door.
Across our showroom markets, Santa Barbara and Montecito are Zone 6, San Diego is Zone 7, Irvine is Zone 8, and the San Fernando Valley (Encino, Woodland Hills, Calabasas, Sherman Oaks) is Zone 9.
Title 24 also updates on a three-year cycle, and the cycle that governs is the one your permit application falls under, not the one current when construction starts. On a Westside project with a long entitlement or design-review timeline, that can shift the target mid-design.
How do I get the NFRC values for my project?
Ask us. Bring a plan set, an elevation, or even a preliminary window schedule, and we'll return the NFRC-certified whole-window U-factor and SHGC for each configuration you're considering.
We can do this well before anything is ordered. At the design stage that means your architect can test whether an opening works before it's committed to on the drawings, and your Title 24 consultant can run the model against real numbers rather than assumptions.
Because we carry lines across steel, aluminum, clad wood, solid wood, and composite, a schedule can usually be tuned to hit a target without redrawing the elevation. That might mean swapping a glazing package, or shifting which units carry the load, rather than shrinking the glass. Start a project or visit a showroom and bring the drawings.
Common questions
How do I know if my windows meet Title 24 requirements?
Have the NFRC-certified whole-window U-factor and SHGC pulled for the exact units you're specifying, then check them against the Title 24 targets for your project's climate zone. NFRC certifies the numbers, Title 24 sets the targets. A specialist can locate these values at the design stage, before anything is ordered.
What is the difference between U-factor and SHGC?
U-factor measures how fast heat moves through the whole window assembly. SHGC measures the fraction of solar energy that passes through, on a scale of 0 to 1. Bottom line is lower is better on both. A lower U-factor insulates better, and a lower SHGC blocks more solar heat. In Southern California, SHGC is usually the harder one to satisfy, because cooling load drives the energy model.
Why is the glass U-value different from the window U-factor?
Glass manufacturers publish center-of-glass values that exclude the frame. NFRC publishes whole-window values that include it. Because frames conduct more heat than glazing, a package rated U-0.24 center-of-glass may rate U-0.32 as an installed window. Title 24 uses the whole-window number.
Can I get NFRC values before the windows are ordered?
Yes. Certified values are published per configuration, so they can be pulled during design from a plan set or preliminary window schedule. That lets a Title 24 consultant model the real product rather than an assumption, and lets an architect test an opening before committing to it.
Do Brentwood and Beverly Hills have the same Title 24 window requirement?
No. Brentwood (90049) is in Climate Zone 6, the coastal band. Beverly Hills (90210, 90211, 90212) is in Climate Zone 9, which runs inland and warmer. They are held to different targets despite sitting about a mile apart.
What climate zone is the Westside of Los Angeles in?
It straddles two. Brentwood, Pacific Palisades, Santa Monica, West LA and Mar Vista are Climate Zone 6. Beverly Hills, Bel-Air, Westwood, Rancho Park and West Hollywood are Climate Zone 9. Climate zone is assigned by ZIP code, and each ZIP falls entirely within a single zone.