Building climate zone
Climate Zone 10
Utilities
Electric: SDG&E · Gas: SDG&E
Permits
City of El Cajon Building Division
El Cajon is in California building Climate Zone 10, and its valley location makes it one of the hotter parts of San Diego County in late summer. That raises the stakes on sizing, duct sealing and attic insulation.
The city provides a simplified energy compliance form (CF1R-ALT-02-E) for HVAC change-outs that lays out the testing a replacement triggers.
What El Cajon's change-out form requires
The city's simplified form is labeled for Climate Zone 10 and walks through HERS requirements by scope. An entirely new or complete replacement system, including mini-splits, requires HERS verification of duct sealing, refrigerant charge, fan efficacy and airflow, along with MERV 13 filters. An altered system, where the condenser, coil or compressor is replaced, requires HERS duct testing to 15% leakage or less, with exceptions for very short duct runs and systems with asbestos.
Note that the form on the city's site was written for the 2019 Energy Code. Efficiency minimums have since been updated nationally (see below), so ask your contractor to confirm current requirements with the Building Division.
Equipment minimums today
Since January 1, 2023, new split-system central ACs sold in California must meet at least 14.3 SEER2 under 45,000 Btu/h (13.8 SEER2 at 45,000 and above), plus an EER2 minimum. Split heat pumps must meet 14.3 SEER2 and 7.5 HSPF2. Since 2025, new systems use A2L refrigerants such as R-454B or R-32.
- Ask for the AHRI certificate number for the matched system.
- In East County heat, compare EER2 as well as SEER2.
Before you sign a quote in El Cajon
- Confirm the contractor's CSLB license is active and carries the C-20 (HVAC) classification.
- Ask who pulls the permit and whether the HERS test fee is in the price.
- Ask for a written load calculation instead of a like-for-like tonnage match.
- Ask for the AHRI certificate number for the matched indoor and outdoor units.
More detail: HVAC permits and HERS testing in California, how to check a contractor's license, and what a replacement costs in Southern California.
El Cajon HVAC questions
What climate zone is El Cajon?
El Cajon is in California building Climate Zone 10, according to the city's own simplified HVAC compliance form.
Does a mini-split in El Cajon need HERS testing?
The city's form lists entirely new or complete replacement systems, including mini-splits, as requiring HERS verification. Confirm with your contractor and the Building Division for your specific scope.
Nearby city guides
Sources
Last checked October 2026. Rules change; confirm with your city before work starts.