Whole-House Ventilation

New homes are built tight, so fresh air has to be brought in mechanically. A whole-house ventilation fan runs continuously to exchange stale indoor air for outdoor air. We measure its airflow and confirm it meets the rate on your CF1R.

Energy recovery ventilator installed in a mechanical space

Balanced ventilation with an ERV.

Requirements

Your CF1R lists the required CFM and system type.

System	What’s verified	Requirement	Code
Exhaust-only (most common)	Exhaust airflow	≥ CF1R CFM	§150.0(o)2
Balanced / ERV / HRV	Supply and exhaust airflow — the average counts	≥ CF1R CFM	RA3.7.4.1
ERV / HRV	Fan efficacy (W/CFM)	≤ 1.0 W/CFM	§150.0(o)2
NEW FOR 2025 ERV / HRV	Fault indicator display (FID) — alerts the occupant when the system isn’t operating properly	Required — HERS/ECC verified	§150.1(c)15 · JA17

Choosing a ventilation fan or ERV/HRV? Our IAQ Product Lookup checks the model against the HVI listing — sound rating at your CF1R airflow for fans, and fan efficacy (W/CFM) per RA3.7.4.4 for ERV/HRVs.

Check a Fan Check an ERV/HRV

*NEW FOR 2025* Service access for ERV / HRV. Filters and heat/energy recovery cores must be accessible from occupiable space, a basement, garage, balcony or mechanical closet — behind a panel or grille no more than 10 ft above the floor. Systems serviced from inside the attic need an FID, an attic access door in a wall (or a ceiling hatch with an integrated ladder), and a walkway to the unit. §150.0(o)1Civ

How the required rate is set: Q_tot = 0.03 × floor area + 7.5 × (bedrooms + 1). A 2,000 sq ft, 3-bedroom home needs 90 CFM before any infiltration credit. §150.0(o)1C

What to expect

How we verify ventilation when you hire us.

Airflow

Measured with the fan running

We measure the ventilation airflow with a calibrated flow hood — exhaust only, or both supply and exhaust on balanced systems — with every fan that’s part of the system running. On ERV/HRV systems we also measure watt draw for fan efficacy, the same way as the air handler.

RA3.7.4.1 · RA3.7.4.4

HVI certification label on a ventilation fan — HVI-certified fan label.

The code

Click a section to read the actual code language, or open it in the official CEC document.

§150.0(o)1CRequired ventilation rate

i. Total Required Ventilation Rate [ASHRAE 62.2:4.1.1]. The total required ventilation rate shall be calculated using Equation 150.0-B.
Q_tot = 0.03A_floor + 7.5(N_br + 1)
where Q_tot = total required ventilation rate, cfm; A_floor = dwelling-unit floor area, ft²; N_br = number of bedrooms (not to be less than 1).

Read §150.0(o)1C in the official 2022 Standards (CEC PDF, p. 335) ↗

§150.0(o)2Field verification

A. Whole-dwelling unit ventilation airflow performance. The whole-dwelling unit ventilation airflow required by Section 150.0(o)1C shall be confirmed through field verification and diagnostic testing in accordance with the applicable procedures specified in Reference Residential Appendix RA3.7. Balanced mechanical ventilation system airflow shall be the average of the supply fan and exhaust fan flows. Ventilation airflow of systems with multiple operating modes shall be tested in all modes designed to comply with the required ventilation airflows.
…
C. Heat recovery ventilation (HRV) and energy recovery ventilation (ERV) system fan efficacy. Systems with heat or energy recovery serving a single dwelling unit shall have a fan efficacy of ≤1.0 W/cfm as confirmed by [HERS/ECC] field verification in accordance with Reference Appendix RA3.7.4.4.

Read §150.0(o)2 in the official 2022 Standards (CEC PDF, p. 338) ↗

RA3.7.4.1Airflow measurement

If multiple fans are specified to operate simultaneously to provide the total required ventilation airflow, the measurements shall be made with all applicable fans operating simultaneously.
Supply and exhaust systems: (c) If the measured total airflow is greater than or equal to the ventilation airflow rate required by the Standards or the Certificate of Compliance, the mechanical ventilation system complies.
Balanced systems: …(g) If the exhaust and supply airflow rates are within 20% of each other…

Read RA3.7.4.1 in the official 2022 Reference Appendices (CEC PDF, p. 379) ↗

Schedule ventilation testing.

Tested once the system is installed and operating.

Book a Test Check a Fan Check an ERV/HRV