Title 24 Energy Compliance Documentation & Mandatory Solar PV (Certificate of Compliance, CF1R) for ADUs

Title 24 Energy Calculations and the ADU Solar Mandate: A Plain-English Guide for LA Homeowners If you're building an ADU in Los Angeles, somewhere in your...

Written by 1-800-ADU-Pros

Last updated: July 16, 2026•8 min read

Title 24 Energy Compliance Documentation & Mandatory Solar PV (Certificate of Compliance, CF1R) for ADUs

Title 24 Energy Calculations and the ADU Solar Mandate: A Plain-English Guide for LA Homeowners

If you're building an ADU in Los Angeles, somewhere in your permit checklist is a line that reads "Title 24 Energy Sheets/Calculations." It sounds like boilerplate. It isn't. For many detached ADUs, that single requirement is what quietly triggers a mandatory rooftop solar system — one of the most common surprise costs in the whole project. Here's what it actually means, in normal language.

What Title 24 is

Title 24, Part 6 is California's Building Energy Efficiency Standards — the "Energy Code." The California Energy Commission writes it; your local building department (LADBS for the City of LA, LA County Building & Safety for unincorporated areas) enforces it.

When you add conditioned living space — anything heated or cooled — you have to prove it meets minimum standards for insulation, windows, HVAC, water heating, lighting, and air-sealing. That proof is a set of documents called the Certificate of Compliance, commonly known as the "CF1R" forms. A Title 24 energy consultant runs your plans through state-approved software and produces them. You drop the CF1R into your building-permit package alongside your architectural and structural plans.

So far, so routine. The twist is what comes attached to it.

The solar surprise

Under Section 150.1(c)14 of the Energy Code, a newly constructed detached ADU is treated as a brand-new single-family home — which means it generally must include a solar photovoltaic (PV) system. The required size is calculated from your conditioned floor area and your climate zone. The CF1R is where that calculation lives, which is why "energy calcs" and "solar mandate" are really the same conversation.

This catches people off guard because nobody framed their backyard cottage as a power plant. But if it's detached and newly built, plan for it.

When you can skip solar

Good news: not every ADU owes solar.

Small-ADU exemption: If the calculated minimum PV size comes out below 1.8 kWdc, no solar is required. In practice this often covers detached units under roughly 600–700 sq ft, depending on climate zone. Always have your consultant check this before you budget for panels.
Limited solar-access exemption: If your roof doesn't have enough usable, unshaded area, the requirement can be waived.
Attached ADUs and conversions: An ADU attached to your house, or a garage/interior conversion, is generally treated as an addition — it needs Title 24 energy calcs but usually does not trigger a new PV system.

One catch even the exempt should know: a new dwelling unit of any size must still meet "energy storage system (ESS) ready" rules under Section 150.0(s) — essentially battery-ready electrical wiring (think a 225-amp busbar and reserved backup circuits). You don't have to install a battery, but the panel has to be ready for one.

Which code applies to you

California updates the Energy Code on a three-year cycle. The 2025 Energy Code took effect January 1, 2026 — so any permit application submitted on or after that date must comply with the 2025 standards (applications in 2025 used the 2022 code). The 2025 update leans hard into heat pumps for both space heating and water heating, so a gas-appliance-heavy design can make compliance harder. If your designer hands you a 2022-cycle report for a 2026 submittal, send it back.

How to file it

Confirm your ADU type — detached (likely solar) or attached/conversion (calcs only).
Give your plans to a Title 24 energy consultant (or have your architect prepare the set).
Have them run the calcs and check the PV result — claim the small-ADU or solar-access exemption if it applies.
Add the signed CF1R (and any HERS-rater verification) to your building-permit package.
Submit to LADBS or LA County and clear any plan-check corrections.

What it costs and how long it takes

There's no separate government fee for the form itself — review is bundled into your ADU plan check. Your real costs are the energy consultant (commonly $150–$500 for a simple ADU), possible HERS field verification (a few hundred dollars), and — if solar is required — the PV system itself, which typically runs several thousand dollars and up. Preparing the CF1R takes a few days to a week; it then moves with your overall permit review, which can range from over-the-counter for standardized plans to a couple of months for custom designs.

The mistakes to avoid

The classic one is assuming every ADU needs solar (only detached new builds generally do) — or assuming yours does without checking the 1.8 kW exemption first. The other big one is mismatched paperwork: the window, insulation, and PV specs on your drawings have to match the CF1R exactly, or you'll bounce in plan check. Get the energy consultant involved early, design around heat pumps, and treat the roof as part of the plan from day one — not a problem you discover at final inspection.

Reference card

Official number: CF1R Certificate of Compliance (e.g., CF1R-PRF-01 performance method); California Energy Code = Title 24, Part 6. Solar PV mandate = Section 150.1(c)14. ESS-ready = Section 150.0(s).
Issuing body: Standard set by the California Energy Commission (CEC); enforced and submitted to the local building department — LADBS for City of Los Angeles, LA County Building & Safety (Public Works) for unincorporated areas.
What it is: Title 24, Part 6 is California's Building Energy Efficiency Standards (the "Energy Code"). When you build an ADU, your building permit package must include a Title 24 energy-compliance set — a Certificate of Compliance (the "CF1R" forms) that proves the conditioned living space meets state requirements for insulation, windows, HVAC, water heating, lighting, ventilation, and air-sealing. For most newly built DETACHED ADUs, that same compliance package also triggers a mandatory rooftop solar photovoltaic (PV) system under Section 150.1(c)14, plus "energy storage system (ESS) ready" electrical provisions (battery-ready wiring) under Section 150.0(s). It is not a permit you file separately — it is a required document set inside your ADU building permit, but homeowners are routinely surprised by the solar mandate and its cost, which is why it deserves its own explainer.
Who needs it: Required for: any new ADU that creates conditioned (heated/cooled) living space — you always need the Title 24 energy calcs. The SOLAR PV mandate specifically hits NEWLY CONSTRUCTED DETACHED ADUs, which the Energy Code treats as new single-family dwellings. You can often SKIP the solar requirement when: (1) the calculated minimum PV size comes out below 1.8 kWdc — the small-ADU exemption under Exception 2 to 150.1(c)14, which in practice covers many ADUs roughly under ~600–700 sq ft depending on climate zone; or (2) the usable solar roof area is too small/shaded (the limited solar-access exception). ATTACHED ADUs and garage/interior conversions are generally treated as additions/alterations to the existing home and typically do NOT trigger a new PV system — but they still need Title 24 energy calcs. Note: even when solar itself is exempt, the ESS-ready (battery-ready) electrical requirement applies to a new dwelling unit of any size.
Fees: "There is no separate government 'Title 24 form fee' — the energy documentation is part of your building-permit plan check, and its review is bundled into standard ADU plan-check/permit fees. Your real out-of-pocket costs are: (1) the energy consultant who prepares the CF1R, commonly about $150–$500 for a simple ADU; (2) HERS-rater field verification if triggered, often a few hundred dollars; and (3) the big one — if solar PV is required, the installed system itself typically runs several thousand dollars (often ~$3,000–$10,000+ depending on size and climate zone). Always confirm current LADBS/LA County plan-check and permit fee schedules for your specific project size."
Timeline: "Preparing the CF1R energy calcs usually takes an energy consultant a few business days to about a week once they have your plans. It does not get reviewed on its own — it moves with your overall ADU building-permit plan check, which can range from a few weeks (or same-week/over-the-counter for standardized/pre-approved ADU plans in some LA jurisdictions) to a couple of months for a full custom review. Solar and any HERS-verified items are inspected during construction, so they affect your final inspection timeline, not the initial submittal."

Requirements

Architectural plans for the ADU (site plan, floor plan, roof plan, elevations) — the energy consultant needs these to run the calcs
A completed Title 24 Certificate of Compliance set (CF1R forms) prepared by a Title 24 energy consultant, signed by the responsible person/designer
Specified building-envelope details: insulation R-values (walls, roof, floor), window U-factor and SHGC, air-sealing
Mechanical/water-heating details — 2025 code strongly favors heat-pump space heating and heat-pump water heating
Lighting and ventilation (IAQ) compliance details
For detached ADUs not exempt: a solar PV system sized per Section 150.1(c)14 (Equation 150.1-C, based on conditioned floor area and climate zone), shown on plans and reflected in the CF1R
ESS-ready (battery-ready) electrical provisions per Section 150.0(s): e.g., 225-amp minimum busbar, dedicated backup capacity, and reserved circuits
HERS-rater verification line items where the design includes features that require third-party field testing/verification (registered through a CEC-approved HERS provider)

How to file

Confirm which code cycle applies: permit applications submitted on/after January 1, 2026 fall under the 2025 Energy Code; applications in 2025 used the 2022 Energy Code
Determine ADU type: detached (likely solar-triggering) vs. attached/conversion (energy calcs only). This decides whether you budget for PV
Hire a Title 24 energy consultant (or have your architect/designer do it) and give them your ADU plans so they can model the building
Have the consultant run the compliance software and check the PV calc — if the required PV is under 1.8 kWdc, claim the small-ADU exemption; if 80-plus sq ft of usable solar roof isn't available, document the solar-access exception
Receive the signed/registered CF1R Certificate of Compliance set (and any HERS registration) and add it to your building permit submittal package alongside architectural and structural plans
Submit the full ADU building permit application to LADBS (City of LA) or LA County Building & Safety (unincorporated areas) — Title 24 Energy Sheets/Calculations are listed as a minimum submittal item
Respond to any plan-check corrections on the energy set (mismatches between plans and the CF1R are the most common correction)
If solar is required, the PV system is permitted and inspected as part of the project; final sign-off requires the installed system (and any HERS-verified items) to match the approved CF1R

Common pitfalls

Assuming all ADUs need solar — only newly built DETACHED units generally do; attached ADUs and conversions usually don't trigger a new PV system
Missing the small-ADU exemption — if the calc lands under 1.8 kWdc you may owe no solar at all, so always have the consultant check before you budget for panels
Forgetting ESS-ready (battery-ready) wiring — even solar-exempt new units must meet Section 150.0(s); skipping it is a common plan-check correction
Plan/CF1R mismatches — the window specs, insulation, or PV size on your drawings must match the energy report exactly, or you'll get corrections
Designing around gas appliances — the 2025 code pushes heat-pump HVAC and heat-pump water heaters; a gas-heavy design can fail compliance or force costly trade-offs
Filing under the wrong code cycle — a 2026 application must use the 2025 Energy Code; using an outdated 2022 report gets rejected
Treating solar as an afterthought — roof orientation, shading, and structural load for panels should be considered in design, not discovered at inspection

Sources

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