California Title 24 — the California Building Energy Efficiency Standards — is one of the most stringent energy codes in the United States. Updated every three years by the California Energy Commission, the 2025 version (effective January 1, 2026) affects every permitted residential and commercial project in the state. For projects with steel doors and windows, understanding Title 24 compliance is not optional — it determines whether your project passes final inspection.

This guide explains what Title 24 requires for steel fenestration, how HERRERO products comply, and what documentation you need for permit approval.

What Title 24 Actually Requires for Doors and Windows

Title 24 establishes minimum energy performance requirements for all fenestration products — windows, skylights, and glazed doors — in California buildings. The two primary metrics are:

• U-factor: Measures the rate of heat transfer through the assembly. Lower is better. Required U-factor maximums vary by California climate zone but generally must not exceed 0.30–0.32 for residential fenestration under the prescriptive compliance path.
• Solar Heat Gain Coefficient (SHGC): Measures how much solar heat passes through the glazing. Lower means less solar heat gain. Required SHGC maximums in most California climate zones range from 0.23 to 0.25.

These values must be verified through NFRC (National Fenestration Rating Council) certification — not estimated, not calculated by the manufacturer, but independently tested and listed in the NFRC Certified Products Directory. The building inspector will look for NFRC labels on your doors and windows during final inspection.

The Thermal Break Requirement for Steel

Here is the most important technical fact about steel and Title 24: steel is a metal, and metals conduct heat. Without a thermal break — an insulating element that interrupts the metal frame — steel windows and doors cannot achieve the U-factor performance required by Title 24 in conditioned spaces.

This is not unique to steel. Most standard aluminum windows and patio doors on the market also fail Title 24 requirements for the same reason — aluminum is an even better conductor of heat than steel. The solution in both cases is a full thermal break integrated into the frame design during manufacturing.

A thermal break interrupts the conductive path between the exterior and interior faces of the frame. It is incorporated during fabrication — it cannot be added after the fact. This means thermal break must be specified at the time of order, not discovered as a requirement during permit review.

California’s 16 Climate Zones

California is divided into 16 climate zones, each with different Title 24 requirements for U-factor and SHGC. The specific requirements for your project depend on where in California it’s located. Key zones for HERRERO customers:

• Zone 6 (Los Angeles coastal): Mild temperatures, moderate solar gain requirements
• Zone 8 (Los Angeles inland / San Gabriel Valley): Higher solar gain requirements due to warmer temperatures
• Zone 3 (San Francisco Bay Area coastal): Heating-dominated; U-factor performance is particularly important
• Zone 10 (San Bernardino Valley / Riverside): Hot climate; strict SHGC requirements
• Zone 16 (High desert / Mountain): Extreme temperature range; demanding U-factor requirements

Confirm your project’s climate zone with your energy consultant or the California Energy Commission’s online tools before finalizing glass specifications.

How HERRERO Products Achieve Title 24 Compliance

NFRC Certification Across 12,000+ Glass Variations

HERRERO has tested more than 12,000 variations of glass types and insulated glass unit makeups within NFRC certification programs. This extensive testing library means we can match the right glass specification to your project’s specific climate zone and energy performance requirements — and provide certified performance data for your compliance documentation.

NFRC thermal ratings vary depending on glass type and configuration, including pane thickness, spacer type, gas fill, and Low-E coating specification. Not all glass types are included in NFRC certification programs, and custom glass makeups require simulated performance reports. HERRERO provides these reports — generated using Intertek Labs industry-standard certification software — for submission to code enforcement officials when custom glass specifications are required.

The Eco-Sky Line: Title 24 Engineered

HERRERO’s Eco-Sky Line is our primary specification for projects requiring Title 24 compliance. Features include:

• Full thermal break construction interrupting the conductive path through the frame
• Tested NFRC performance ratings across multiple glass configurations
• U-factor performance suitable for all California climate zones under the prescriptive compliance path when paired with appropriate glass specification
• SHGC optimization through glass selection — we help you select the right Low-E configuration for your specific zone’s solar gain requirements

The Pure Line W40 and Other Lines

Our Pure Line W40 is rated for air infiltration and carries NFRC certification for thermal performance. Depending on glass specification, Pure Line products can achieve Title 24 compliance in some climate zones. Discuss your specific zone requirements with your HERRERO representative to confirm compliance pathway before ordering.

Two Compliance Pathways

California Title 24 offers two ways to demonstrate compliance:

• Prescriptive path: Every component must individually meet minimum performance standards. Simpler to document but less flexible — if any component falls short, the entire envelope fails. Most common for straightforward residential projects.
• Performance path: The overall building energy performance is modeled. Trade-offs between components are allowed — for example, better roof insulation can compensate for slightly lower-performing windows. Required for complex projects with large glazing ratios. HERRERO can provide certified product data for energy modeling software used by your Title 24 consultant.

What Documentation You Need

For Title 24 compliance documentation with steel doors and windows, you will need:

• NFRC certified product listings for each door and window specified (HERRERO provides this)
• NFRC labels on the physical products at time of installation — inspectors will verify these labels during final inspection
• Simulated Performance reports (Intertek Labs format) for any custom glass specifications not in standard NFRC certification (HERRERO provides this)
• CF1R Energy Report generated by your Title 24 consultant using the above certified performance data

Do not lose the NFRC labels from your HERRERO units. They must remain on the product until the building inspector has verified compliance. Labels removed before final inspection may result in failed inspection and significant cost to resolve.

Air Infiltration Performance Note

Not all HERRERO products carry air infiltration ratings. Specifically:

• Pure Line products: Rated for air infiltration
• Sliding products (other lines): Do not carry an air infiltration rating
• Sliding doors with HERRERO draining tracks: Demonstrate effective resistance against water infiltration at the sill, even without a formal air infiltration certification

If air infiltration certification is required for your specific compliance pathway, confirm which HERRERO products are appropriate for that requirement before finalizing your specification.

Working with Your Title 24 Consultant

Title 24 energy compliance for projects with significant glazing — particularly those with large steel pivot doors, sliding systems, or window walls — typically requires a dedicated energy consultant to model and document compliance. HERRERO works regularly with California energy consultants and can provide all necessary certified performance data in formats compatible with compliance software.

Specify HERRERO products early in the design process — before the energy model is finalized — so that accurate certified performance data can be incorporated into your compliance documentation from the start. Last-minute product substitutions that change U-factor or SHGC values can require a complete energy model revision.

Get Title 24 Compliant Steel Door Specifications

HERRERO’s sales team can provide certified NFRC performance data, compliance documentation, and specification guidance for Title 24 projects across all California climate zones. For an instant starting-from estimate on Eco-Sky Line or other NFRC-certified products, use our AI quote agent Marco at quote.herrerodoors.com.