# §110.2: HVAC equipment efficiency
What it requires
Every piece of residential heating or cooling equipment installed in California must meet a minimum efficiency rating for its category:
- Split-system air conditioners — SEER2 14.3 federal minimum (effective 2023); §110.2 references the federal floor for unitary equipment.
- Split-system heat pumps — SEER2 14.3 cooling, HSPF2 7.5 heating minimum.
- Gas furnaces — AFUE 80% minimum for split systems, AFUE 81% for weatherized.
- Mini-split / VRF systems — efficiency floors per the AHRI category they certify to.
- Packaged equipment — its own SEER2 / HSPF2 / EER2 floors, slightly lower than split because of the package geometry penalty.
- Heat-pump water heaters — covered separately in §110.3, but the same mandatory-floor logic applies.
The §110.2 floor is the absolute minimum. The §150.1(c) prescriptive package sets a higher target (HSPF2 9.0, SEER2 18.5 or 22 depending on climate zone — see §150.1(c)) that becomes the "standard design" for performance comparison.
When it applies
- Newly constructed residential, on every installed unit.
- Replacements under alteration scope — the new equipment must clear §110.2, the existing equipment is grandfathered to whatever was code-compliant at install.
- Additions adding new HVAC capacity.
How we use it
We model HVAC efficiency at the §150.1(c) prescriptive level by default — which already clears §110.2 by a comfortable margin. The High-Performance Envelope and Hybrid options vary the equipment tier in opposite directions (HP-Envelope drops slightly to balance the better envelope; Hybrid bumps up to buy back the missing wall CI). All three clear §110.2.
The mandatory floor binds in alteration scope when a homeowner asks for a "like-for-like" replacement of an old, lower-SEER unit — §110.2 doesn't allow it, the new unit has to clear the current minimum.
Common gotchas
- AHRI ratings that look high on the sticker but are matched-pair ratings, not coil-only — the installed mixed-pair efficiency can drop below §110.2.
- Old equipment swapped in at the customer's request — the AHJ rejects the permit if the listed SEER2 is below the current federal minimum.
- "SEER" (the old metric) vs "SEER2" (the new metric, 2023+) — SEER2 numbers are about 4–7% lower than the equivalent SEER number, so a unit listed at SEER 14.0 doesn't equal SEER2 14.3.