IECC C403 — HVAC Systems (Commercial)

Updated Mar 25, 2026

Commercial HVAC efficiency: equipment minimums, economizers, energy recovery, controls, duct insulation.

IECC 2024: C403.3 equipment per ASHRAE 90.1. Unitary AC >=14 SEER2. Heat pumps >=15 SEER2. Furnaces >=80% AFUE. Economizers required >=54,000 Btu/h CZ2-8. Energy recovery when OA>70% or >5,000 CFM. Duct insulation R-6 supply, R-4 return. Commissioning required >25,000 sf.

TAGS

IECC HVAC efficiency economizer commissioning

DETAILS

code year

2024

code section

C403

SOURCES

🔗https://codes.iccsafe.org/content/IECC2021P1

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