Accessory Dwelling Units according to the Energy Code – Does it require solar?
As ADUs are built across the state, it’s important to know that the Energy Code/Title 24 2022 code update uses its own definition of ADUs including a new JuniorADU definition*. The definition is in the Single-Family Residential Compliance Manual, Section 9.3.5, and includes any applicable exceptions or exemptions.
The code defines compliance requirements by whether an ADU is an Addition to an existing residence or a New Construction Building.
The 2022 Energy Code update defines them like this:
- If you convert an existing unconditioned space (garage) to an ADU, it is an Addition.
- If you construct a new ADU that is attached to an existing home or existing garage, it is an Addition.
- If you build an ADU detached from an existing home or attached via breezeway/covered walkway, it is a Newly Constructed Building.
All New Construction Buildings, must have a solar array installed, and under the 2022 code be prepared to meet Battery requirements as well. Yes, even if it’s an ADU, it is required to meet all New Construction Single-Family Residential related code requirements.
If your project is an Addition, regardless of ADU status, you are exempt and do not require a new solar array. Some walls may qualify as “Existing wall with siding” which reduces some insulation requirements. An Energy Code Coach is available to help answer questions regarding these additional requirements for your specific project. Submit a question here.
There’s a new definition for a Junior ADU (JADU) with the 2022 code, too.
“A JADU is a dwelling unit that is no more than 500 square feet in size and contained entirely within an existing single-family building. A JADU includes an “efficiency kitchen”, a separate entrance from the main entrance to the building, and an interior entry to the main living area. A JADU may include separate sanitation facilities, or may share sanitation facilities with the existing single-family building”.
By definition, a JADU will always be considered an Addition, therefore, a JADU will not be required to have solar installed per the 2022 Energy Code. The JADU designation also exempts additions from meeting new dwelling unit IAQ ventilation requirements, however all additions must meet local exhaust for bathrooms and kitchens.
In summary, for compliance with the Energy Code, if the ADU is attached or converted unconditioned space, it’s an Addition, and if it’s separate or connected by a breezeway, it’s New!
New construction is required to install solar where Additions are exempt.
* The California Department of Housing and Community Development (HCD) developed the Accessory Dwelling Unit Handbook. While it’s updated regularly with the latest ADU regulations, zoning standards, bedrooms, height requirements and impact fees, you won’t find any information in there about Energy Code requirements for ADUs.