Steel Windows and California Title 24 Compliance — What Architects Need to Know
A common misconception in California architectural practice is that steel windows cannot meet Title 24 energy code requirements. This is not accurate — modern thermally broken steel window systems are designed and tested to comply with California’s fenestration performance requirements across all climate zones.
What Title 24 Requires for Windows
California’s Title 24 Part 6 energy code sets maximum U-factor and Solar Heat Gain Coefficient (SHGC) values for fenestration products. These requirements vary by climate zone, project type, and building orientation. U-factor measures heat transfer rate — lower is better. SHGC measures solar radiation transmitted — lower means less solar heat gain.
Can Solid Steel Windows Meet Title 24?
It depends on the climate zone and glass package. With a high-performance Low-E glass package, some solid steel windows can meet Title 24 requirements in California’s more temperate coastal climate zones. In stricter inland and desert climate zones, thermally broken steel is generally required to achieve compliance.
Herrero ECO-SKY: Title 24 Compliant Steel Windows
Herrero’s ECO-SKY thermally broken steel line meets Title 24 requirements across California’s climate zones. The integrated polyamide thermal break dramatically reduces frame U-factor, and combined with Low-E insulated glass delivers overall window performance that satisfies California energy code for virtually all project types and locations. Herrero provides complete Title 24 documentation — U-factor and SHGC values, climate zone applicability tables — for permit applications.
The Correct Specification Approach
- Identify the California climate zone for the project
- Determine applicable U-factor and SHGC limits
- Assess whether solid steel with high-performance glass can achieve compliance, or ECO-SKY is required
- Obtain compliance documentation from Herrero for the permit application
Contact Herrero’s technical team at 714.776.5555 or herrerodoors.com/contact to discuss Title 24 specifications for your California steel window project.