EPA Exempts California Heat Pumps From ENERGY STAR Sizing Limits

Here's the thing: California didn't change its heat pump sizing rule. The federal ENERGY STAR program changed to stop fighting it.

If you design or rate single-family HVAC in California, you may have run into this wall. A heat pump sized to carry the home's heating load can end up with more cooling capacity than ENERGY STAR allows. The 2025 Energy Code points you one way; the ENERGY STAR checklist pointed you another. For a production builder chasing certification, that is a real bind — satisfy the code or satisfy the checklist, pick one.

The U.S. EPA picked California's code.

The two rules that collided

ENERGY STAR caps cooling oversizing. The federal program limits a single-family heat pump's cooling capacity to no more than 115 percent of the calculated cooling load, figured per ACCA Manual S, Second Edition.

The 2025 California Energy Code pushes the other way for heat pumps. It makes the heat pump meet the home's heating requirement on its own compressor — not counting electric-resistance or gas backup. When the heating load runs well above the cooling load — a cold climate zone, say — the compressor you need to hit that heating number can push the cooling capacity right past ENERGY STAR's 115 percent cap.

Same equipment, two sizing masters.

What the code actually says

The sizing rules live in Section 150.0(h)5. Systems are sized to ACCA Manual S-2023, and the heat-pump heating-capacity subsection is where it bites. The CEC writes the citation as 150.0(h)5Biiia — formally §150.0(h)5.B.iii.a:

• Minimum (150.0(h)5.B.iii.a): "Heating systems are required to have a heating capacity meeting the minimum requirements of the CBC, not including any supplementary heating."
• Maximum (150.0(h)5.B.iii.b): "There is no limit on the maximum heating capacity."

Verified against the 2025 Energy Code, Part 6 text for Section 150.0(h)5: the heat-pump minimum reads exactly as quoted, and the maximum subsection places no ceiling on heating capacity.

Read those two together and the conflict is structural, not accidental. California makes the compressor carry the heating requirement and sets no cap on how big that makes the equipment. ENERGY STAR still caps the cooling side. In a heating-dominated climate, you cannot always satisfy both.

What the EPA did

To resolve it, the EPA exempted heat pumps in single-family homes built to the 2025 California Energy Code from the ENERGY STAR cooling sizing limit — and the exemption holds until the program's sizing limits are reevaluated.

Two things worth underlining.

First, this is not a Title 24 change. California amended nothing. The code provision is the fixed point; the federal program moved to accommodate it. If you are briefing a plan checker, frame it that way — nothing in 150.0(h) changed.

Second, it is documented. The exemption is recorded in ENERGY STAR's Single-Family New Homes Policy Record (last revised October 7, 2025), which adds a footnote to the affected design and rater documents stating that, in California jurisdictions requiring the 2025 Building Energy Efficiency Standards, heat pumps are exempt from the program's cooling sizing limit.

Which boxes to mark exempt

This is the part raters and designers actually need. Per the CEC's reporting of the EPA action:

• HVAC designers are exempted from Item 4.10 of the National HVAC Design Supplement to Standard 310, and Item 4.16 of the National HVAC Design Report, for heat pumps.
• Raters are exempted from Items 3a.3 and 3b.2.8 of the National Rater Design Review Checklist, for heat pumps.

So a designer sizing a heat pump to 150.0(h)5.B.iii.a knows the Manual S cooling-oversizing line will not fail certification. And a rater reviewing that design knows exactly which checklist items are off the table for the heat pump: mark them exempt, note the California 2025-code basis, and move on.

One caveat to keep. The exemption is explicitly temporary — it lasts only until ENERGY STAR reevaluates its sizing limits — and it is scoped to single-family homes built to the 2025 California code. If your project sits on an edge — a jurisdiction still enforcing the 2022 code, a multifamily building, a certification-version question — confirm the current policy with your ENERGY STAR provider before you lean on it.

What CrossBeam does with it

CrossBeam reads the code your project is actually built to and flags where a state requirement and an outside program pull against each other — like this heat-pump sizing conflict — so you catch it before plan check does. When a federal program carves out an exemption for California, it shows up in the same place, citation in hand, ready for a reviewer.