What Is a Thermally Broken Steel Window? A California Architect’s Guide
If you are specifying steel windows and doors for a California project, the choice between thermally broken and solid steel will have real implications for Title 24 compliance, long-term performance, and project cost. Here is what you need to know.
The Basic Problem: Steel Conducts Heat
Steel is an excellent structural material and an excellent thermal conductor. In a solid steel window, the same metal frame that carries structural loads also conducts heat directly between the interior and exterior of the building. In California’s hot inland climate zones this means summer solar heat conducted inward through the frame. In humid conditions it means condensation on cold interior frame surfaces.
The Solution: The Thermal Break
A thermally broken steel window incorporates a continuous non-conductive material — typically a high-performance polyamide — within the steel profile. This thermal break physically separates the interior and exterior steel components, interrupting the conductive heat path. The result is a window frame that dramatically reduces heat transfer while maintaining the narrow visual profile and structural performance that makes steel the preferred fenestration material for California luxury architecture.
Herrero ECO-SKY: Thermally Broken Steel for California
Herrero’s ECO-SKY line is our thermally broken steel system, available in the full range of door and window configurations. ECO-SKY maintains the same narrow sightlines and architectural character as our solid steel SLIM-LINE and PURE LINE collections — the thermal break does not constrain design flexibility or compromise the visual profile.
Title 24 and Thermally Broken Steel in California
California’s Title 24 energy code imposes U-factor and SHGC requirements on fenestration products that vary by climate zone. The ECO-SKY line meets Title 24 requirements across California’s 16 climate zones when specified with the appropriate glass package. Herrero provides full compliance documentation for ECO-SKY projects. Contact us at 714.776.5555 or herrerodoors.com/contact.