California Association of Building Energy Consultants

Title 24 Energy Compliance for Additions (Alone) for the 2016 Energy Code

Energy Compliance for additions may use an exception to the Energy Code method of compliance called Prescriptive Compliance. This means that if all of the energy features can meet certain energy requirements then the project complies. This method of compliance does not consider the existing home and focuses only on the addition to the home.

For all additions this is the best method of compliance to keep in mind during the design process. For additions of 300 SF or less there is not a requirement for the new roofing product to be a "cool-roof" rated product. This allows easy matching of the color of the new exterior roof to the color of the existing exterior roof.

However if the addition is over 300 SF, then the new roofing product must meet requirements of a "cool-roof" rating of a minimum 0.20 Solar Reflectance and a minimum of 0.75 Thermal Emittance. When designing check the Cool Roof Rating Council's website for a product that will meet these requirements and match the existing home's roof color. If that can be found then it is possible to have an addition over 300 SF still meet the prescriptive method of compliance.

The exception rules change as the square footage of the addition changes. Please read carefully and if there are any questions, I am here to help.

Also note, Title 24 Energy Documentation is required and I (Beth Smithwick of CompuCalc) am ready to provide the proper energy documentation for submittal to the building department. My 25 years of experience in this industry and extra achievement of Certified Energy Analyst status since 1994 makes me an expert in this field.

Below are the Exceptions for Additions according to the Square Footage of the addition.

9.3.1 Additions Only

9.3.1.1 Prescriptive

The prescriptive requirements for new addition construction are listed in §150.2(a)1.

Unless otherwise noted, the prescriptive requirements contained in §150.1(c) also apply.

  1. Additions of ≤ 300 ft²: Does not require a cool roof to be installed;
  2. Additions ≤ 400 ft²:
    1. Total glazing area up to 75 ft² or 30 percent of the conditioned floor area, whichever is greater.
    2. Total glazing area maximum for west facing glazing is 60 ft² or 5 percent in Climate Zones 2, 4, and 6-16.
    3. Mandatory ceiling insulation of R-22.
    4. Extensions of existing wood-framed walls may retain the dimensions of the existing walls and require the following cavity insulation:
      1. In 2x4 wood-frame walls, insulation shall be R-15.
      2. In 2x6 or greater wood-frame walls, insulation shall be R-19.
  3. Additions > 400 ft2 and ≤ 700 ft²:
    1. Total glazing area up to 120 ft² or 25 percent of the conditioned floor area.
    2. Total glazing area maximum for west-facing glazing is 60 ft² or 5 percent in Climate zones 2, 4, and 6-16.
    3. Mandatory ceiling insulation of R-22.
    4. Extensions of existing wood-framed walls may retain the dimensions of the existing walls and require the following cavity insulation:
      1. In 2x4 wood-frame walls, insulation shall be R-15.
      2. In 2x6 or greater wood-frame walls, insulation shall be R-19.
  4. Additions > 700 ft²:
    1. Total glazing area up to 175 ft² or 20 percent of the conditioned floor area, whichever is greater.
    2. Total glazing area maximum for west-facing glazing is 70 ft² or 5 percent in Climate zones 2, 4, and 6-16.
    3. Extensions of existing wood-framed walls may retain the dimensions of the existing walls and require the following cavity insulation:
      1. In 2x4 wood-frame walls, insulation shall be R-15.
      2. In 2x6 or greater wood-frame walls, insulation shall be R-19.

Note: Except as noted, all applicable prescriptive requirements for additions must be met when using the prescriptive approach. Otherwise, the building must comply using the performance approach.

For prescriptive additions, a certificate of compliance (CF1R-ADD) form must be completed and submitted for permit. If any mandatory or prescriptive measures require HERS verification and/or testing, the certificate of compliance for the project must be registered online with a HERS Provider before submittal to the enforcement agency.


As always, I am available to discuss the process of meeting the California Energy Code for any building project. Contact me …