Understanding Title 24: Ensuring Compliance with Windows and Doors Regulations
When it comes to energy efficiency, windows and doors are essential, accounting for as much as 50% of energy costs in some cases. This is why Title 24 compliance is critical in California. Title 24, officially known as the California Building Energy Efficiency Standards, was established in 1978 and is updated every three years to keep pace with new energy-saving technologies. The latest update was in 2025, bringing in important changes that impact your home or business.
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But what exactly is Title 24, and how does it influence your projects? Let’s explore the Title 24 window requirements for 2025 and discover how to choose products that make your life easier and more energy-efficient.
Overview of California’s Title 24 Requirements
Title 24 is a comprehensive set of building regulations made up of 12 parts, covering everything from the California Building Code (CBC) to electrical, mechanical, and plumbing codes. However, when people talk about Title 24, they're often referring to Part 6, the California Energy Code, which sets the standards for energy efficiency across both residential and commercial buildings statewide.
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The Title 24 Energy Code establishes regulations for a variety of building components, including appliances, insulation, roofing, and fenestration products—windows and exterior doors. Before construction, remodeling, or additions can begin, a local building department will require a Title 24 Energy Report to ensure compliance. Inspections throughout the build may also take place to confirm adherence.
What Does Title 24 Mean for Windows?
Title 24 plays a crucial role in determining the energy efficiency of windows. According to the code, a window is defined as a vertical structure made of a frame and sash, containing at least one piece of glazing or glass. In California, windows must meet strict standards for both U-factor and solar heat gain coefficient (SHGC), with double-paned glass being a mandatory requirement.
What About Window Replacements?
If you’re replacing windows as part of a renovation or remodel, you’ll need to comply with Title 24 guidelines. If replacing over 75 square feet of windows, the new windows must meet the SHGC and U-factor standards discussed above. For smaller replacements (under 75 square feet), the requirements are slightly less strict, with an SHGC of 0.35 or less and a U-factor of 0.40 or less.
Solar Heat Gain Coefficient (SHGC)
SHGC is a measure between 0 and 1 that shows how much solar heat passes through a window. The lower the SHGC, the better the window is at blocking solar heat. In hotter climates, a lower SHGC can reduce the workload of air conditioning systems, saving both energy and money. For 2025, windows in certain climate zones need to meet a maximum SHGC of 0.23 or lower, helping to improve cooling efficiency during hot months.
U-Factor Requirements
The U-factor measures the rate of heat transfer through a window, including the frame, spacers, and glass. Like SHGC, a lower U-factor is preferred as it indicates better insulation. California’s Title 24 mandates that windows must have a U-factor of 0.30 or lower, ensuring that heat stays inside during cold weather and outside during warmer months.
Aluminum Windows and Title 24 Compliance
The material used in window frames significantly impacts energy efficiency. Since aluminum isn’t a great insulator, many aluminum windows fail to meet Title 24 standards unless they have special features like polyurethane thermal barriers. At Nuimage, for example, several aluminum windows meet Title 24 compliance by incorporating these technologies, helping them provide superior insulation.
Shop Nuimage's title 24 certified windows today!