California Title 24 Ordinance for Accessory Dwelling Unit (ADUs)

Updated: Feb 6


California in 2019 passed and updated Title 24 Building Energy Efficiency Standards the goal was to promote a healthy and sustainable dwelling. It ensures new and existing buildings achieve energy efficiency and preserve outdoor and indoor environmental quality standards and guidelines. These energy efficiency standards also apply to Accessory Dwelling Units or better known as ADUs.


What Title 24 Means to California residences looking to build an ADU on their property

Since January of 2020, all new construction, additions, and alterations to residential property in California are required to meet energy efficiency standard guidelines and be in compliance with the 2019 ordinance. Thus, Title 24 also impacted residential homeowners that are converting or building new accessory dwelling units (ADUs). Those items in Title 24 that Architects and Contractors adhere to in ADU construction are HVAC, Windows Glazing, Lighting, Water Heating, Insulation, Roof, and Doors.


What to Know About How California Title 24 Codes Affect your ADU Project

You will need to be in compliance with Title 24 and provide certificate of compliance through Home Energy Rating also known as HERS to obtain final Certificate of Occupancy. As the homeowner you’ll need to hire a third party HERS Rater that either your Architect, or your Contractor will provide. You can also find a HERS rater through CalCERTS. Once all Testing is Complete HERS rater will submits a report to CHEERS. A CHEERS report is available only after a project has passed verification and testing by an independent HERS Rater. Those reports will also be passed along to your local building and safety city inspector during inspection time by your contractor.


Title 24, Part 6 Compliance Quick Reference. The following chapters are the most important for home owners to know when building an ADU.


Chapter 3 - Building Envelope Requirements. This chapter covers the design of the envelope components which can significantly affect the energy demand needed to meet heating and cooling loads to maintain the desired inside comfort temperature of your ADU. Here are a few areas to look at.

  • Insulation Types

  • Windows and Glazed Doors

  • Radiant Barriers plywood

  • Roof Products

  • HERS-Verified Reduced Building Air Leakage


Chapter 4 - Building HVAC Requirements. This chapter covers the heating and cooling requirements for ADU’s and are mandatory measures. Here are a few areas to look at.

  • Gas Appliances

  • Non-ducted Systems

  • Ventilation Cooling

  • Field Verification and/or Diagnostic Testing


Chapter 5 - Water Heating. This chapter covers new requirements for residential water heating for the 2019 Energy Standards for ADU. Most tankless water heaters on the market will satisfy Title 24 but homeowners must consult with Architect or Manufacture. Here are a few areas to look at.

  • External tank insulation

  • Shower Head

  • HERS Field Verification and/or Diagnostic Testing


Chapter 6 - Residential Lighting. This chapter covers residential buildings and spaces, all the lighting requirements are mandatory. Here are a few areas to look at.

  • Indoor Luminaire Requirements LED

  • Indoor and outdoor lighting

  • Recessed Downlight Luminaires in Ceilings

  • Indoor Lighting Control Requirements.


Does Title 24 Require me to have Solar Panels on my ADU?

As of January 1, 2020 Title 24 mentions that newly built, non-manufactured units, that are detached ADUs will generally need to install solar panels if your local planning department is enforcing the prescriptive energy requirements. Furthermore, if you’re installing a manufactured ADU units, or converting an existing garage, generally you won’t be required to install solar panels.

Please refer to the California Energy Commission on Solar requirement matters. For more information, refer to www.energy.ca.gov, or contact the Energy Standards Hotline at 800-772-3300.


Sacramento is pushing additional new buildings guidelines to reach a self-sustainable net-zero waste. Before planning ahead it's important to have your ducks in a row regarding title 24, before summiting plans to local city for approval and permits.


Let us help you move forward with your ADU construction. CentrePoint Construction will discuss all options with you before plans are summited and approved.




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