How Does HVAC Efficiency Affect Title 24 Calculations?
The calculation assumes minimum-efficiency heating and cooling equipment, so a premium unit earns credit only when the rating above the minimum is modeled and then proven in the field by an ECC-Rater. A higher number on the nameplate that nobody verifies counts for nothing.
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What the reference house assumes
The standard design uses minimum-efficiency heating and cooling equipment, Option B duct insulation, ducts sealed as Section 150.0(m) requires, and correct refrigerant charge. Anything weaker is charged against the margin, and anything better is a credit only if it can be proven. All space conditioning equipment must also meet the Appliance Efficiency Regulations before any credit is considered.
Ratings that can earn credit
When compliance depends on a rating above the minimum, the installed system is field verified. The list covers SEER2, EER2, CEER and HSPF2, the variable-capacity heat pump option, a low-leakage air handler, and rated heating capacity at 47F and 17F. Each verification is a visit by an ECC-Rater (HERS raters became ECC-Raters on 1 January 2026), recorded on a certificate of verification.
The silent assumptions
The model also assumes you meet requirements it does not reward. Refrigerant charge verification applies to heat pumps in all climate zones, with airflow of at least 350 cfm per ton, or 250 for small duct high velocity systems. Fault indicator displays are no longer an option for that check. A unit that cannot reach the airflow target fails the test whatever its efficiency.
No air conditioner, still in the budget
If no cooling system is installed, the software simulates a hypothetical one with the characteristics Table 150.1-A requires, as if it were there. Leaving air conditioning out of the plans therefore does not remove its energy from the comparison.
Ducts change the same unit
For fan-forced systems the model needs the location and amount of duct insulation, so one unit can score differently with a different layout. See how ducts change the calculation.
Is a premium unit worth chasing?
Compare the cost of the unit plus its test against cheaper envelope credit before buying. The SEER2 minimums page gives the floor, HVAC requirements covers permits, and the heat pump page covers heating. Our residential report shows how much margin each choice leaves.
Common Title 24 Questions
- When is Title 24 required for a home?
- Does a remodel need Title 24?
- Does a room addition need Title 24?
- What plans are needed for a residential Title 24 report?
- How much does a residential Title 24 report cost?
- How long does a residential Title 24 report take?
Frequently Asked Questions
Only if the higher rating is modeled and an ECC-Rater verifies it. Otherwise the model treats it as minimum efficiency.
A certified ECC-Rater, working through an approved ECC-Provider, separate from the building inspector.
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View all Energy Calculations guides → · Reports and Calculations · Title 24 guide