U.S. Code of Federal Regulations
Regulations most recently checked for updates: Aug 27, 2025
(a) Whole-house mechanical ventilation system fans must meet the minimum efficacy requirements set forth in table 1 to 460.204(a), except as provided in paragraph (b) of this section. The mechanical ventilation fan efficacy requirements are adapted from section R403 of the 2021 IECC.
Table 1 to § 460.204
| Fan type description | Airflow rate
minimum (cfm) | Minimum
efficacy (cfm/watt) |
|---|---|---|
| Heat recovery ventilator or energy recovery ventilator | Any | 1.2 |
| In-line supply or exhaust fans | Any | 3.8 |
| Other exhaust fan | <90 | 2.8 |
| Other exhaust fan | ≥90 | 3.5 |
(b) Mechanical ventilation fans that are integral to heating, ventilating, and air conditioning equipment, including furnace fans as defined in § 430.2 of this subchapter, are not subject to the efficiency requirements in paragraph (a) of this section.
