Title 24 Compliance for Custom Steel Windows and Doors
2025 California Energy Code
Studio Steel thermally broken fixed windows achieve whole-unit U-factors as low as 0.21. The 2025 code's residential prescriptive maximum is 0.27 in most California climate zones and 0.30 in Climate Zones 6-10 and 15, meaning the lowest-U Studio Steel configurations meet the maximum in every zone. Higher-U configurations within the certified range require zone-specific configuration selection.
California is PINKYS' home market, and the 2025 Energy Code is the most stringent fenestration standard in the US.
16 CLIMATE ZONES — Prescriptive Compliance, 2025 Residential
| Zone | Cities | Max U / SHGC | Compliance Path | Notes |
|---|---|---|---|---|
| 1 | Arcata, Blue Lake | 0.27 / None | Prescriptive or Performance | No SHGC limit. Triple pane SB70 (U 0.21) meets the U max. Dual pane SB70 (U 0.30) does not - use triple pane for prescriptive, or dual pane on performance. |
| 2 | Sacramento, Napa | 0.27 / 0.23 | Prescriptive or Performance | Triple pane SB70 (U 0.21, SHGC 0.15) meets both. Dual pane SB70 (U 0.30, SHGC 0.22) meets SHGC but exceeds U threshold - triple pane needed for prescriptive. |
| 3 | Oakland, San Francisco | 0.27 / None | Prescriptive or Performance | No SHGC limit. Same as Zone 1 - triple pane meets, dual pane needs performance path. |
| 4 | San Jose, Santa Rosa | 0.27 / 0.23 | Prescriptive or Performance | Same pattern as Zone 2 - triple pane SB70 meets both. |
| 5 | Santa Monica, Long Beach coast | 0.27 / None | Prescriptive or Performance | No SHGC limit. Triple pane (U 0.21) meets the U max. |
| 6 | Los Angeles, San Diego coast | 0.30 / 0.23 | Prescriptive or Performance | PINKYS home climate zone. Full certified range (0.21-0.30) qualifies - either config meets prescriptive. |
| 7 | San Diego inland, Chula Vista | 0.30 / 0.23 | Prescriptive or Performance | Full certified range qualifies. Cooling load dominant; SB70 Low-E recommended. |
| 8 | Los Angeles, Pasadena | 0.30 / 0.23 | Prescriptive or Performance | Full certified range qualifies. Significant cooling load; SB70 essential. |
| 9 | Anaheim, West Covina | 0.30 / 0.23 | Prescriptive or Performance | Full certified range qualifies. Significant cooling load; Low-E specification critical. |
| 10 | Riverside, San Bernardino | 0.30 / 0.23 | Prescriptive or Performance | Full certified range qualifies. Triple pane (SHGC 0.15) provides additional margin. |
| 11 | Redding, Marysville | 0.27 / 0.23 | Prescriptive or Performance | Triple pane SB70 meets both - needed for prescriptive; dual pane exceeds U threshold. |
| 12 | Sacramento metro | 0.27 / 0.23 | Prescriptive or Performance | Same pattern as Zone 11. |
| 13 | Fresno, Bakersfield | 0.27 / 0.23 | Prescriptive or Performance | Same pattern as Zone 11. Extreme summer heat. |
| 14 | Lancaster, Victorville | 0.27 / 0.23 | Prescriptive or Performance | Same pattern as Zone 11. Widest diurnal swings in state. |
| 15 | Palm Springs, El Centro | 0.30 / 0.20 | Prescriptive or Performance | SHGC max is 0.20 here, not 0.23. Dual pane SB70 (0.22) no longer meets SHGC. Triple pane (0.21/0.15) meets both - required for prescriptive here. |
| 16 | Big Bear, Mammoth | 0.27 / None | Prescriptive or Performance | No SHGC limit. Triple pane (U 0.21) meets the U max; heating-dominated zone benefits from triple pane regardless. |
Source: 2025 California Energy Code, Title 24 Part 6, Table 150.1-A (residential, single-family).
Every zone has a certified SB70 configuration that meets the prescriptive path. In the 10 zones capped at 0.27 (all except CZ 6-10 and 15), that means specifying the triple pane configuration specifically - dual pane still works, but only via the performance path in those zones. In CZ 6-10 and 15 (capped at 0.30), the full certified range qualifies for prescriptive, though Zone 15's tighter SHGC max (0.20) still narrows the field to triple pane there too.
Title 24 is shorthand for the California Code of Regulations, Title 24, specifically Part 6, the California Energy Code, administered by the California Energy Commission (CEC). It sets minimum energy efficiency standards for new construction and significant alterations across all building types in California. The current operative version is the 2025 Energy Code, which took effect January 1, 2026 and applies to any project with a permit application dated on or after that date.
For fenestration (windows, doors, skylights, and glazed assemblies), Title 24 Part 6 establishes mandatory minimum performance requirements for U-factor, SHGC, and air leakage. Requirements vary by climate zone, building type, and compliance path. NFRC-certified values are the required input for both compliance paths.
Steel is approximately three times stiffer than aluminum, achieving the same structural performance at a fraction of the profile depth. Narrower profiles mean more glass area per opening. The thermal break, a non-conducting polyamide isolator, closes the thermal gap with aluminum. With it, Studio Steel certified U-factors reach 0.21 on fixed windows, meeting the prescriptive maximum in every zone at the low end of the certified range.
The CEC updates Title 24 on a roughly triennial cycle. The 2025 code took effect January 1, 2026, superseding the 2022 code's flat 0.30 U-factor maximum. Documentation referencing the 2022 code's uniform 0.30 threshold is now outdated.
Prescriptive Path
Each individual fenestration product must meet the code's specified U-factor and SHGC maximums for its climate zone. No whole-building energy model required. For thermally broken fixed windows, the lowest-U configuration (0.21) meets every zone; configurations toward the top of the certified range (up to 0.30) meet only Climate Zones 6-10 and 15.
Performance Path
The entire building is evaluated using CEC-approved energy modeling software (CBECC-Res residential, EnergyPro nonresidential). Individual products don't need to meet prescriptive maximums in isolation. Studio Steel provides complete NFRC data for energy modeling input. Compliance analysis is the responsibility of the project's licensed Title 24 analyst.
U-Factor
Whole-unit rate of heat transfer through the complete assembly, BTU/hr-ft2-F. Lower is better. 2025 residential prescriptive max: 0.27 in most zones, 0.30 in Climate Zones 6-10 and 15. Studio Steel fixed windows achieve as low as 0.21.
SHGC
Fraction of solar radiation admitted as heat. Confirmed against the 2025 code (Table 150.1-A): 0.23 in most zones, not required in Zones 1, 3, 5, and 16, and a tighter 0.20 in Zone 15 - the only zone where the 2025 cycle lowered the threshold below 0.23. SB70 dual pane achieves SHGC 0.22; SB70 triple pane achieves SHGC 0.15.
VT (Visible Transmittance)
Proportion of visible light transmitted. Title 24 does not mandate a minimum VT, though it factors into daylighting credits under the performance path.
Air Leakage
Confirmed against the 2025 code (Section 110.6(a)1): flat 0.3 cfm/ft2 for windows and residential doors - no operable/fixed split. Matches Studio Steel's current NFRC chart. Nonresidential double swinging doors specifically: 1.0 cfm/ft2 (not applicable to Studio Steel's standard line).
COMPLIANCE STATUS
Thermally broken assemblies only, SB70 glazing configurations.
Prescriptive residential maximum (windows/glazed doors, per Table 150.1-A): U 0.27 (most zones) / U 0.30 (Climate Zones 6-10, 15).
SHGC 0.23 in most zones, NR in Zones 1/3/5/16, 0.20 in Zone 15.
| Product | U-factor Range (SB70) | SHGC Range (SB70) | Compliance Path |
|---|---|---|---|
| TB fixed windows | 0.21-0.30 | 0.15-0.22 | Prescriptive or Performance - triple pane meets every zone; dual pane meets CZ 6-10, 15 outright and needs performance path elsewhere |
| TB casement windows | 0.31-0.38 | 0.13-0.19 | Performance Only - best configuration (0.31) exceeds even the most permissive residential threshold (0.30) |
| TB swing doors | 0.26-0.35 | 0.13-0.20 | Prescriptive or Performance - triple pane (U 0.26) meets every zone; dual pane (U 0.35) needs performance path everywhere |
| All other TB products | Contact PINKYS | Contact PINKYS | Contact PINKYS for configuration-specific compliance path |
| Solid steel, non-TB (Fixed Window SDL/TDL, Swing Door SDL/TDL) | 0.41-0.74 | 0.20-0.48 | Performance Only - best-case configuration (0.41) still exceeds every residential prescriptive threshold |
All figures are whole-unit NFRC values for confirmed SB70 configurations.
NONRESIDENTIAL PRESCRIPTIVE — Table 140.3-B
| Product type | Max U-factor | Max RSHGC | Min VT | Compliance Path |
|---|---|---|---|---|
| Fixed window | 0.36 (Zones 1-8,10,16) / 0.34 (9,11-15) | 0.25 (1-8,10,16) / 0.22 (9,11-15) | 0.42 | Prescriptive or Performance - TB fixed window range (0.21-0.30) clears every zone with margin |
| Curtainwall / storefront | 0.38 (Zones 1,7) / 0.41 (all other) | 0.25 (1,7) / 0.26 (all other) | 0.46 | Contact Studio Steel |
| Operable window | 0.46 all zones | 0.22 all zones | 0.32 | Prescriptive or Performance - TB casement range (0.31-0.38) clears every zone |
| Glazed doors | 0.45 all zones | 0.23 all zones | 0.17 | Prescriptive or Performance for TB swing doors (0.26-0.35, both configs clear); Performance Only for non-TB swing doors (0.53-0.74) |
Source: Title 24 2025
Max WWR: 40% all climate zones, all nonresidential building types.
Confirmed against the 2025 code: for residential (single-family) prescriptive path, the cap is 20% of conditioned floor area (CFA) for total fenestration, with an additional 5% CFA cap on west-facing area in most zones (not required in Zones 1, 3, 5, and 16). For nonresidential, the WWR cap is a flat 40% across all climate zones.
A Studio Steel thermally broken frame achieves the same structural performance as a wider aluminum frame at a fraction of the profile depth, meaning more glass area within the same WWR budget. Pair that with the correct Low-E tier and glazing configuration for the zone and orientation, and the result is a large glazed design that meets Title 24 without design compromise - even under the tighter 0.27 threshold now in effect across most of the state.
Prescriptive path: NFRC Certified Label ships with each assembly - the primary compliance documentation accepted by California building departments. Additional documentation available on request: product-specific certified values, climate zone compliance confirmation, and CF1R/CF2R form support.
Performance path: Complete product performance data (U-factor, SHGC, VT, air leakage, frame area, glazing area) in CBECC-Res / EnergyPro input format. Performance path compliance analysis is the responsibility of the project's licensed Title 24 analyst.
Contact PINKYS at specification stage with project climate zone, building type, and compliance path. Lead time is 12 to 15 weeks from approved shop drawings.
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