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Grass Valley, CA 95945


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Chico, CA 95926


Residential Energy Updates



In the mid 1970s, the Warren Alquist Act was passed. This created the California Energy Commission and granted the Commission authority to develop and maintain building energy efficiency standards.

The California Energy Commission states “A review of California’s 2016 Building Energy Efficiency Standards compared to international standards set in 2015, found a 29 percent annual energy savings from the state’s standards over international standards. California’s standards saved enough electricity to power 300,000 additional homes annually.”

According to the California Energy Commission, the 2019 code changes will:

  • Create 7% more efficient than 2016 Standards
  • Reduce energy consumption by an average 53% with photovoltaic (solar)
  •  Reduce greenhouse gas emissions by 700,000 metric tons over 3 years
  •  Have monthly life cycle costs of $40 with savings of $80 for “typical” homes (statewide)


In order to achieve these results, several changes will take place in the design and construction of homes.  “Solar” is the big ticket item that we have heard quite a bit about leading up to the code change, but it is not the only change that took place.  By adding solar to the list of mandatory (few exceptions) requirements, the energy consumption of homes is lowered, but to make the homes more efficient will require the introduction of different and/or modified building materials and appliances.  Some of the bigger changes include:

  • Wood framed 2×6 wall’s insulation has increased to R-20 minimum
  • Exterior doors now have a U-Factor rating
  • Exterior doors with 25% or more glazing will be treated as fenestrations (previously 50% or greater)
  • Increased efficiency with hot water systems
  • Increased lighting efficiencies


How this affects home owners and builders alike

When it comes to new construction, most of the code updates will be implemented (all the mandatory measures will be utilized).  Where this can be confusing is how these changes apply to additions and accessory dwelling units (ADUs).

The energy code provides some flexibility when the additions are less than 1000 square feet.

  1. Additions of ≤ 300 ft2 do not require a cool roof product (if required by §150.1(c)11) to be installed.
  2. Whole-house fan (or ventilation cooling) does not apply to additions of 1,000 ft2 or less (if otherwise required by §150.1(c)12).
  3. Existing space conditioning systems that are extended to provide conditioning to an addition are not required to meet the Energy Standards (§150.2(a) Exception 4).
  4. Indoor air quality (IAQ) requirements (§150.0(o)1C, D, or F) do not apply to additions of 1,000 ft2 or less that are not a new dwelling unit.
  5. Photovoltaic (PV) requirements do not apply to additions/alterations.

#5 above is a key allowance to keep in mind. Most ADUs are treated as additions when it comes to the energy code. #5 allows most ADUs to occur without adding solar to the ADUs. The exception is newly constructed detached ADUs. This also applies to any size addition you are building.

If you are interested in learning more about the recent changes to ADUs, reference our previous article here.

If you have questions about the energy code, or input on your energy code encounters, please leave us a comment!


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