Guide
Title 24, permits and field verification on a California changeout
Updated
Homeowners in other states never think about this part of a California HVAC quote. Dishonest bids leave it out until the job is half done.
The Energy Code applies to replacements, not just new builds
California's Building Energy Efficiency Standards live in Title 24, Part 6 of the California Code of Regulations, updated on a three-year cycle. The current edition is the 2025 Energy Code. The California Energy Commission states plainly that "buildings whose permit applications are applied for on or after January 1, 2026, must comply with the 2025 Energy Code" (energy.ca.gov).
Replacing a system is an alteration, and alterations are covered.
Field verification and diagnostic testing
California does not simply take a contractor's word that the install performs. The Energy Code carries field verification and diagnostic testing provisions, historically delivered through the Home Energy Rating System (HERS) program. On residential changeouts, the ones that come up are:
- duct leakage testing
- refrigerant charge verification
- airflow verification
Whether a given test applies depends on your climate zone and on what you are replacing. That is a question for your contractor and your building department, not for a website.
The delivery mechanism changed recently. The Energy Commission states that "effective on January 1, 2026, the HERS Program no longer supports an Energy Code compliance demonstration program". The field verification and diagnostic testing provisions now appear in the Energy Code itself: Title 24 Part 6 and the associated administrative regulations in Part 1 (energy.ca.gov).
The testing has not gone away. Ask your contractor which verifications your job triggers, and confirm it with your local building department before you sign.
What to put in the contract
- Who pulls the permit. It should be the licensed contractor. A contractor asking you to pull an owner-builder permit for their work is a warning sign, not a favor.
- The permit fee, as its own line, not folded into a round number.
- Which field verifications apply in your climate zone, who performs them, and whether the price includes the test and any re-test after a failure.
- What happens if the system fails a test. Corrective work should be the contractor's cost, and the contract should say so.
- Final sign-off. You want the permit finaled. An unfinaled permit surfaces years later when you sell.
Climate zones are not intuitive
California's 16 Energy Code climate zones are drawn from building energy performance, not county lines or how hot a place feels. Neighboring ZIP codes can sit in different zones. Prescriptive requirements, including which verifications apply, differ between them. If a contractor cannot tell you your climate zone number, they have not looked at your job properly.
Who is allowed to do the work
CSLB's advice to consumers on HVAC upgrades is direct. "Before starting, be sure your contractor holds an active C-20 Warm-Air Heating, Ventilating, and Air-Conditioning license that is issued by and in good standing with CSLB" (cslb.ca.gov).
The C-20 classification covers (CSLB classification detail):
- warm-air heating systems and water heating heat pumps
- ventilating systems
- air-conditioning systems
- the ducts, registers, flues, humidity and thermostatic controls and air filters connected to them
Separately, anyone opening a refrigerant circuit must hold EPA Section 608 technician certification (epa.gov).