Where is the NFRC label on a window?

It's a temporary sticker on the glass before install — removed during or after inspection. The compliance record lives in your permit documents (CF1R/CF2R), not on the window.

What does LA Title 24 require for windows?

In climate zones 8 and 9 (most of LA), U-Factor ≤ 0.30 and SHGC ≤ 0.23. Zone 10 (Antelope Valley) is U-Factor ≤ 0.32, SHGC ≤ 0.25.

Does a lower SHGC always mean better performance?

Not for every window. Lower SHGC also means lower VT (less daylight). On north-facing windows in coastal LA, a slightly higher SHGC can be the better spec — you lose no meaningful heat protection and gain significantly more natural light.

Can I specify custom NFRC targets on a window order?

Yes — we put the target U-Factor, SHGC, and VT in the contract as spec requirements, then select the coating package that meets all three. The hard part is balancing low SHGC with high VT, which limits coating options.

How do I find a window's NFRC rating after installation if the sticker is gone?

Pull your permit records from the building department — the CF1R filed with your permit lists every window's NFRC specs by opening. LADBS records are searchable by address at ladbs.org. If you don't have a permit on file, the invoice from your installer should include the manufacturer model number, which you can look up in the NFRC certified product directory at nfrc.org.

Does a lower SHGC affect how the room looks?

Yes — lower SHGC means lower VT (visible transmittance), which means darker glass. A window spec'd to SHGC 0.20 may have a VT of 0.38, giving the room a slightly tinted, dimmer cast compared to a window at SHGC 0.28 and VT 0.55. This tradeoff matters most in north-facing rooms where you're not blocking meaningful solar heat but are reducing daylight.

Buying Guides

Reading the NFRC Label: U-Factor, SHGC, and VT Explained for LA Buyers

Q: What's the difference between NFRC-rated and Energy Star?

NFRC is the measurement standard; Energy Star is an EPA certification that uses NFRC numbers. Title 24 requires specific NFRC values, not Energy Star certification per se.

By Israel AquinoFebruary 14, 20267 min read

TL;DR

The NFRC label has five ratings: U-Factor (heat loss), SHGC (solar heat gain), VT (visible light), AL (air leakage), and CR (condensation resistance). California Title 24 in LA's Zone 8 and Zone 9 requires U-Factor ≤ 0.30 and SHGC ≤ 0.23. Most salespeople only mention two of the five — and they often don't tell you that a lower SHGC means darker glass. We spec all five, per elevation, per neighborhood.

The National Fenestration Rating Council (NFRC) label is the nutrition label for windows — standardized, third-party tested, and required on every window sold in California. If a contractor hands you a quote without mentioning NFRC ratings, that's your first red flag.

The label has five ratings: U-Factor, Solar Heat Gain Coefficient (SHGC), Visible Transmittance (VT), Air Leakage (AL), and Condensation Resistance (CR). California's Title 24 energy code in LA's climate zones requires a U-Factor of 0.30 or lower and an SHGC of 0.23 or lower — these are the two numbers that determine whether your permit inspection passes or fails.

Most homeowners only ever get shown U-Factor and SHGC. Here's what all five ratings actually mean, what Title 24 requires by climate zone, and why the SHGC number your salesperson quotes you might not be the right one for your specific home.

All five NFRC ratings explained

What every number on the label actually measures.

1
U-Factor (typically 0.20–0.45)
Measures how quickly heat escapes through the window — the rate of non-solar heat loss. Lower is better. A U-Factor of 0.30 means the window loses heat at 0.30 BTU/hr·ft²·°F. LA Title 24 requires ≤ 0.30 for most openings in climate zones 8 and 9. This is the number contractors lead with because it's the most intuitive — think of it like insulation R-value in reverse.
2
SHGC — Solar Heat Gain Coefficient (0.0–1.0)
Measures how much solar radiation the window lets in as heat. A 0.23 SHGC means 23% of incident solar energy passes through. Lower blocks more sun. LA Title 24 requires ≤ 0.23 in zones 8 and 9, which is aggressive — it reflects how much of LA's heating load comes from direct sun rather than ambient conduction. This is the coating spec, and it's where the real design tradeoffs live.
3
VT — Visible Transmittance (typically 0.40–0.70)
Measures the fraction of visible light the window admits. Higher means more daylight and a clearer view; lower means darker glass. A window with SHGC 0.20 and VT 0.40 will look noticeably tinted compared to one at SHGC 0.28 and VT 0.58. VT is not regulated by Title 24 — it's a comfort and livability spec. This is the number most homeowners wish they'd known about before signing.
4
AL — Air Leakage (cfm/sqft, optional on label)
Measures how much air infiltrates around the window assembly under standard test pressure. Lower is better. The label lists AL only when the manufacturer chooses to test and publish it — it's not required. For LA's climate, look for AL ≤ 0.30 cfm/sqft. A leaky window undermines your Low-E glass spec entirely; infiltration loads can exceed conduction losses on older-construction homes with large openings.
5
CR — Condensation Resistance (1–100, optional)
Measures how well the window resists condensation forming on the interior surface. Higher is better. Also optional on the label. In LA's mild climate, CR rarely matters as a pass/fail issue — condensation is a bigger concern in colder climates. We note CR on our proposals for coastal clients who leave windows cracked and want to minimize moisture on the frame, but it's not a Title 24 input.

What LA Title 24 actually requires, by climate zone

The thresholds that determine whether your permit inspection passes.

California's Title 24 energy code divides the state into 16 climate zones. Most of LA County falls into Zone 8 (coastal and westside areas — think Santa Monica, Venice, Brentwood, Malibu) or Zone 9 (inland LA and the San Fernando Valley — Burbank, Sherman Oaks, Encino, Van Nuys, Glendale). Zone 8 and Zone 9 share the same U-Factor threshold (≤ 0.30) and SHGC threshold (≤ 0.23) for vertical fenestration. The coastal/inland distinction matters more for mechanical equipment specs than for windows.

Zone 10 covers the Antelope Valley and high desert areas northeast of LA — Palmdale, Lancaster, and the Mojave-adjacent communities. Zone 10 has a slightly relaxed U-Factor (≤ 0.32) but a stricter SHGC (≤ 0.25) compared to zones 8 and 9. The logic: the high desert has more extreme summer solar loads but also significantly colder winters, so the code balances heat gain control against heating-season heat loss.

When we pull a permit, the CF1R form (the compliance certificate of record) lists every window opening by size, orientation, and NFRC spec. The inspector's CF2R form confirms the installed product matches what was filed. This per-opening documentation is what creates the compliance chain — it's what a future buyer's inspector or real estate attorney looks for when they pull your permit history. A contractor who skips the permit doesn't just leave you with an illegal install; they leave you with no compliance record, which is a problem at sale or refinancing.

What salespeople don't tell you about SHGC tradeoffs

Blocking solar heat also blocks daylight — and that tradeoff matters by elevation.

SHGC and VT are tightly coupled in real glass coatings. A lower SHGC means less solar energy gets through — but glass doesn't selectively filter heat while passing light. As you push SHGC down, VT follows. A window at SHGC 0.20 might have a VT of 0.38, giving the room a noticeably dim, slightly blue-green cast. A window at SHGC 0.28 might have a VT of 0.55, looking substantially clearer and admitting meaningfully more daylight.

In practice, this means blanket-speccing the same SHGC across every window on a job is almost always wrong. On a south- or west-facing elevation in Encino, a 0.20 or 0.22 SHGC is worth every point — you're directly blocking afternoon sun that would otherwise drive your cooling load and fade your flooring. But on a north-facing window in a coastal Santa Monica neighborhood, you're getting almost no direct solar gain regardless of SHGC — the sun doesn't shine in the north window. Speccing a 0.20 SHGC there costs you VT (daylight) without any meaningful heat-gain benefit.

We spec SHGC per elevation and per neighborhood, not with one number across the whole job. On north-facing openings in coastal zones, we'll often recommend SHGC 0.28–0.30 — which technically exceeds the Title 24 threshold for that opening, but is allowed when the overall building compliance path uses a whole-building tradeoff calculation (CEC's CBECC-Res software). We document the tradeoff calculation in the permit package. If your contractor is quoting one SHGC across every window on your house and not discussing orientation, ask them about it.

Red flags to watch for on a quote

Four signs a contractor hasn't done this work properly.

1
No NFRC ratings mentioned anywhere on the quote
Any legitimate window replacement quote should specify U-Factor and SHGC at minimum. If a contractor hands you a proposal that describes windows by brand and series only — no NFRC numbers — they're either not pulling a permit (and therefore not doing a Title 24 compliance calc) or they haven't verified the product meets code. Ask for the NFRC numbers in writing before signing.
2
Quote specifies U-Factor but omits SHGC
U-Factor is the easier number to hit. SHGC ≤ 0.23 is what most contractors get wrong — it requires a specific Low-E coating, often a more expensive one. Seeing U-Factor without SHGC usually means the quoted product hasn't been verified against the solar heat gain threshold. This is the spec where Title 24 inspections most commonly fail.
3
Quote uses 'energy efficient' without citing numbers
'Energy efficient,' 'Low-E glass,' 'double-pane,' and 'insulated' are marketing language, not compliance specs. A 2006-era double-pane window is technically double-pane and technically has Low-E, but its U-Factor might be 0.42 and SHGC might be 0.35 — both non-compliant with current Title 24. If there are no numbers, there is no spec.
4
Contractor says a permit isn't required for window replacement
It is. Every jurisdiction we work in — LADBS, Beverly Hills, Santa Monica, Burbank, Pasadena, Glendale — requires a permit for window replacement. The permit is not bureaucratic overhead; it's the mechanism that generates your Title 24 compliance record, your inspection sign-off, and your title-transfer documentation. A no-permit install saves $300–$500 up front and creates a disclosure liability of unknown size at sale.

What people ask

NFRC questions we get every week.

01Where is the NFRC label actually located on a window?

On new windows before installation, the NFRC label is a temporary sticker affixed to the glass — usually in a corner, facing the interior side. It gets removed before or during install (or after final inspection, depending on the inspector). On windows already installed, the label is gone. The compliance record lives in your permit documents and the CF1R/CF2R forms filed with your building department, not on the window itself. If you want to know what's currently in your home, pull your permit history from the city's online portal — every permitted window job since roughly 2010 will have the product specs in the file.

02Does a higher Condensation Resistance (CR) rating matter in LA?

Rarely, and it's not a Title 24 input. CR matters most in cold-climate homes where the interior glass surface drops below the dew point frequently. In LA's mild climate, you'd need to be running a very cold AC, living in a high-humidity coastal zone, and leaving windows partially open consistently to encounter condensation as a real problem. Where CR does show up as a concern for us is on large fixed windows facing the ocean in Malibu or Santa Monica, where night temperatures can drop and interior humidity stays high from proximity to the water. In those cases, we spec products with CR 60+. For everything else in the Valley or inland LA, don't pay a premium chasing CR score.

03What's the difference between NFRC-rated and Energy Star certified?

NFRC rating means the product's performance was tested and certified by an independent lab under NFRC protocols — it's the measurement standard. Energy Star is a separate EPA program that sets minimum thresholds for each climate zone and awards a certification to products that meet them. Every Energy Star-certified window has NFRC ratings (you need the ratings to certify), but not every NFRC-rated window is Energy Star. For Title 24 compliance, NFRC ratings are what matters — California doesn't require Energy Star as such, it requires specific U-Factor and SHGC values. Energy Star is a marketing designation that can be a useful shortcut but shouldn't substitute for reading the actual numbers.

04Can I request specific NFRC numbers on a custom order?

Yes, within what the glass manufacturer's coating portfolio allows. When we spec a window for a project, we start with the performance target (e.g., SHGC ≤ 0.22, U-Factor ≤ 0.28, VT ≥ 0.45) and then work with our manufacturer reps to identify glass packages that hit all three. The constraint is usually the VT floor — getting both a low SHGC and a high VT in the same coating is genuinely difficult, and there's a cost premium for coatings that do it well. Solarban 60 and 70XL from Vitro, and Guardian's ClimaGuard, are the coating lines we spec most often in LA for their SHGC/VT balance. We can put the target numbers in your contract as a specification requirement, not just a description.

05Why does the same window model have different NFRC ratings in different sizes?

Because NFRC ratings are calculated for the whole window unit, including the frame — and a larger window has more glass area relative to frame area. Glass performs differently than frame (the frame typically conducts more heat). A 24" × 36" casement has more frame relative to its total area than a 48" × 60" casement of the same series. As the window gets bigger, the glass dominates the calculation more and the U-Factor typically improves (glass U-factor is better than frame U-factor in most modern windows). This is why NFRC labels specify the exact size tested — and why oversized custom windows sometimes have better thermal numbers than their standard-size siblings.

Title 24 at a glance

LA climate zone NFRC requirements and what products clear them.

What we mean

Red Stag

Typical contractor

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How to use the NFRC label when comparing quotes

A practical checklist for reading window quotes against NFRC specs.

1
Ask for the NFRC label on the specific purchase order unit
Not the display window on the showroom floor, not the 'similar' product the salesperson describes — the unit on the actual purchase order. The model number on the PO should match a specific NFRC-certified rating in the manufacturer's certified product directory (CPD), which is searchable at nfrc.org.
2
Verify U-factor and SHGC against Title 24 for your zone
Zone 8 and 9 both require U-factor ≤ 0.30 and SHGC ≤ 0.23. Check your address on the California Energy Commission's climate zone map if you're not sure which zone you're in. Most of LA City and the Valley is Zone 9; the beach cities and areas west of the 405 are Zone 8.
3
Ask about VT on any room where natural light matters
A window that meets Title 24 SHGC requirements may have a VT of 0.38 — noticeably darker glass. If you have a north-facing room that depends on daylight, or a south-facing room where you're speccing a lower SHGC than strictly required, ask for the VT alongside the SHGC before ordering.
4
Confirm whether AL is published for the product
Not all manufacturers test and publish Air Leakage. If AL is missing from the spec sheet, ask the manufacturer's rep. For LA homes that rely on natural ventilation at night, a leaky window frame is more of a thermal concern than the glass coating.
5
Check whether the product is on the NFRC certified product directory
Any window claiming an NFRC rating should be findable at nfrc.org in their certified product directory by manufacturer name and series. If the product isn't there, the rating hasn't been independently certified — the manufacturer's stated numbers are self-reported, which has a different weight when a plan checker reviews your CF1R.