Whether a JADU needs Title 24 energy paperwork depends on what you build. A JADU inside space that is already heated or cooled is an alteration, so the Energy Code covers only what you change. A JADU that adds conditioned space is part of an addition.
What counts as a JADU?
The Energy Code (Section 100.1) defines a junior accessory dwelling unit as a unit of no more than 500 square feet that sits entirely within a new or existing single-family building. It includes:
- A kitchen.
- A separate entrance from the main entrance.
- An interior entry to the main living area.
It may have its own bathroom or share one with the house.
How does the Energy Code treat my JADU?
The CEC says JADUs "may be subject to the Energy Code requirements depending on the scope of work." Here is how that plays out:
| Your JADU | Energy Code category | What applies |
|---|---|---|
| Inside an existing bedroom or other conditioned space | Alteration | Section 150.2(b), for each part you change |
| Inside an attached garage or other unconditioned space | Addition | Section 150.2(a) |
| Built as part of a new home | New construction | New-home rules |
What triggers the rules in an alteration?
The CEC defines an alteration as a change to a building's water heating, space conditioning, lighting, electrical power distribution or envelope that is not an addition. It lists examples that trigger requirements in an ADU or JADU conversion:
- A newly installed water heater.
- A new mini-split heat pump.
- Lighting upgrades. Alterations follow Section 150.2(b)1K.
- Changes to the envelope, such as new windows or doors.
If none of these change, there may be nothing for the Energy Code to cover. Your building department makes that call, so ask it what it needs for your scope.
Which form do I need?
The CEC's compliance manual says additions and alterations generally use the prescriptive approach, with the performance approach as an option. Prescriptive alterations use a CF1R-ALT-01 form. Prescriptive additions use a CF1R-ADD form. A performance model uses a CF1R-PRF report.
If any item needs ECC (HERS) rater testing, such as a new mini-split's refrigerant charge, the forms must be registered in CHEERS.
Do JADUs need solar or ventilation?
Solar: no, unless the JADU is part of a new home. The CEC compliance manual says PV requirements do not apply to additions or alterations.
Ventilation: possibly. The CEC says ventilation for JADU additions and alterations may be required by the California Mechanical Code, which may point back to Energy Code Section 150.0(o). The CEC refers those questions to the California Department of Housing and Community Development (HCD).
What about a water heater for a JADU?
If a JADU in an addition of 500 square feet or less gets its own water heater, an electric water heater with point-of-use piping is allowed prescriptively (Section 150.2(a)1Diii).
What should I send?
- A floor plan showing the JADU and the rest of the house
- What is changing: walls, windows, heating and cooling, water heater, lighting
- Whether the space is heated or cooled today
We will tell you which forms your scope needs before you order.
Ready to start? See our flat prices.
Frequently asked questions
What is a JADU under the Energy Code?
The Energy Code (Section 100.1) defines a JADU as a dwelling unit of no more than 500 square feet, contained entirely within a new or existing single-family building. It has a kitchen, a separate entrance, and an interior entry to the main living area.
Does a JADU need a Title 24 report?
It depends on the scope. A JADU carved out of space that is already heated or cooled is an alteration, so Energy Code rules apply to the parts you change, such as a new water heater, mini-split, lighting or windows. A JADU that adds conditioned space is part of an addition.
Does a JADU need solar?
Not as an addition or alteration. The CEC compliance manual says PV requirements do not apply to additions or alterations. A JADU built as part of a new home follows the new-home rules.
Does a JADU need its own ventilation?
Possibly. The CEC says ventilation for additions and alterations, including JADUs, may be required by the California Mechanical Code, and points those questions to HCD.