If you do business in California, you need to know what’s new in the state’s updated Title 24 energy standards, which take effect January 1, 2017. Last week, the American Architectural Manufacturer’s Association (AAMA) hosted a webinar that covered this important topic that’s relevant to anyone who does business in the state, which is one of the nation’s largest construction markets.

Ken Nittler, the owner of WESTLab, said the updated standards are a refinement to those in effect since 2013. Most U-factor and solar heat gain coefficient (SHGC) performance targets are unchanged, though he called the standards “quite a bit more stringent overall. They should be about 25 percent tighter.”

Nittler said that in addition to energy efficiency, Title 24 standards also focus on greenhouse gas emissions. Legislation establishes that by 2020, emissions in the state must meet 1990 levels. By 2050, greenhouse gases must be 80 percent below 1990 levels.

To achieve that, the law says that by 2020, new residential construction must be net zero energy and by 2030 for commercial buildings. Nittler explained that net zero means the building consumes only as much energy as can be generated by on-site renewable energy systems.

In California, buildings are supposed to be life-cycle cost-effective to the building owner. The reference point is typically 30 years for residential and 15 years for non-residential. About half of the peak electrical demand in California is caused by air conditioning. The use of Time Dependent Valuation (TDV) focuses emphasis on measures. To that end, a lower SHGC would help, Nittler said.

The Title 24 standards in California are based on climate zones, he added. There are 16 in the state, and they affect the regulations. For example, there are no SHGC standards in the mild coastal zones 1, 3 and 5. To meet the Title 24 requirements, Nittler said there are mandatory measures and prescriptive measures. The third concept is the performance approach. The latter allows a builder to use software to calculate energy calculation. Nittler said California puts a big emphasis on the performance approach, because the prescriptive is sometimes too restrictive.

The performance approach allows for trade-offs, Nittler said. (For example, better windows vs. better air conditioning.) In California, 90 percent of all compliance is done via the computer performance trade-off method, Nittler said.

He added that you must know what the compliance documents say to do business in California. In the new standards, the residential U-factor for windows is 0.32 and the SHGC 0.25.

“Almost all flat glass guys have products in this category,” he said, adding that replacement windows now must meet the U-factor and SHGC requirements.

He reminded listeners that every fenestration product in California must have a label that lists U-factor, SHGC and visual transmittance (VT) and certifies compliance.

Finally, to avoid confusion, Nittler urged listeners to dig deeper into the variety of information sources available.

“Investor-owned utilities have developed a great resource for learning, interpreting and using the standards,” he said.


  1. Can I still use custom build windows that a caftsman builds in his shop for new residential in California. The glass used would comply with the requirements in regards to U-Factor, SHGC and VT and thus would have the label.
    Thank you! Eva.

  2. If I was going to be constructing a new building, I would want to see about them being energy efficient. As you said, there are standards in place to make sure the systems in the buildings last as long as the structure. Also, I’d be sure to see about getting some professional help regardless of how much that I think I know about this.

  3. If the windows are not NFRC rated, then they would need to comply with Title 24 for Center of Glass ratings, which could be more strict.

    1. Hello Steven! I am intrigued by your comment! As I am interested in importing not certified windows from Europe, I am unsure how a building inspection would go if the product is missing the NFRC label. Can you tell me where I can find more information on the Title 24 Center of glass rating? Thank you! Arian

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