Three kinds of equipment get called whole house fans. One cools your home with outdoor air. The others keep fresh air coming in when the windows are shut.
When people say whole house exhaust fan, they usually mean a whole house fan: a large ceiling fan that exhausts indoor air into the attic while open windows pull in cooler outdoor air. CentricAir models move 1,263 to 4,146 CFM. Mechanical ventilation systems, including exhaust ventilation and ERVs, are different. They run continuously at low airflow with the windows closed. ASHRAE Standard 62.2 works out to about 90 CFM for a 2,000 square foot, 3 bedroom home.
Search terms for home fans overlap in confusing ways. Whole house fan, whole house exhaust fan, whole house ventilation and ERV all show up on the same results page, and they are not the same thing. The quickest way to sort them out is to ask what each one is for: cooling, or fresh air.
What is a whole house exhaust fan?
In most searches, it is another name for a whole house fan.
A whole house fan mounts in the ceiling between the top floor and the attic. It exhausts warm indoor air up into the attic, and that air leaves through the attic vents. Open windows let cooler outdoor air flow in to replace it. Because it exhausts so much air, some people call it a whole house exhaust fan. Its purpose is cooling, and it runs when it is cooler outside than in.
How is that different from exhaust ventilation?
Exhaust ventilation is about fresh air, at a small fraction of the airflow.
The Home Ventilating Institute describes exhaust ventilation as a system that depressurizes the house by pulling air out, often from bathrooms and kitchens, while make up air leaks in through the building shell and passive vents. HVI notes it is most appropriate for colder climates. These systems are sized to a home’s fresh air needs. ASHRAE Standard 62.2 sets the continuous rate at 0.03 CFM per square foot plus 7.5 CFM per bedroom plus one, which comes to 90 CFM for a 2,000 square foot, 3 bedroom home.
What does an ERV do?
It brings in fresh air and sends out stale air while saving most of the energy you spent heating or cooling it.
An energy recovery ventilator is a balanced system: one fan brings outdoor air in and another sends indoor air out in roughly equal amounts. The air streams pass through a heat exchanger. HVI says an ERV transfers both heat and water vapor and recovers about 70 to 80 percent of the energy in the exhaust air. A heat recovery ventilator, or HRV, transfers heat only.
| Whole house fan | Exhaust ventilation | ERV or HRV | Attic fan | |
|---|---|---|---|---|
| Main job | Cooling the home | Fresh air | Fresh air with energy recovery | Venting the attic |
| Windows | Open | Closed | Closed | Closed |
| Typical airflow | Thousands of CFM | Tens of CFM, continuous | Tens of CFM, continuous | Varies (CentricAir: 1,580 CFM) |
| When it runs | When outside is cooler | All year | All year | When the attic is hot |
| Where it mounts | Top floor ceiling | Bath, kitchen or central | Mechanical room or attic, with ducts | Gable or roof |
Whole house fan and attic fan figures from centricair.com, September 2026. Ventilation descriptions from HVI. Continuous airflow from ASHRAE Standard 62.2.
Which one do you need?
If you want a cooler house with lower AC bills, a whole house fan. If you want steady fresh air in a tight home, mechanical ventilation.
These are not competitors. A whole house fan is a cooling tool that works best on cool evenings and nights. The Department of Energy’s Building America program says it performs best where summer nights drop below about 67°F. Mechanical ventilation keeps a small, steady supply of outdoor air coming in whether or not the windows are open. Many homes can use both.
Choose a whole house fan if
- You want to cool the house on summer evenings
- Your nights often drop below about 67°F
- Your AC runs most summer nights
Look at ventilation or an ERV if
- You want fresh air with windows closed
- Your home is tightly sealed
- You are building or renovating to a code that requires it
Is a whole house fan the same as a bathroom exhaust fan?
No. They share the word exhaust, and not much else.
A bathroom fan removes moisture and odors from one room through a duct to the outside. A whole house fan moves thousands of CFM through the entire house and into the attic. A whole house fan does not replace your bath or kitchen fans.
Find the CentricAir whole house fan sized for your home.
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Frequently asked questions
Is a whole house exhaust fan the same as a whole house fan?
Usually, yes. Most people searching for a whole house exhaust fan mean a whole house fan: a large ceiling fan that exhausts indoor air into the attic while open windows pull cooler outdoor air in.
What is the difference between a whole house fan and an ERV?
A whole house fan cools the house by moving thousands of CFM with the windows open. An ERV runs continuously at low airflow with the windows closed, trading stale indoor air for fresh outdoor air while recovering much of the heating or cooling energy.
Do I need mechanical ventilation if I have a whole house fan?
They do different jobs. A whole house fan runs only when it is cooler outside. Mechanical ventilation supplies a steady, small amount of fresh air all year, including when windows are closed.
How much air does a home ventilation system move?
Far less than a whole house fan. ASHRAE Standard 62.2 works out to about 90 CFM of continuous ventilation for a 2,000 square foot, 3 bedroom home.
Keep reading
Sources
- Home Ventilating Institute, Mechanical Ventilation Types: Exhaust, Supply, Balanced and Energy Recovery, accessed Sept. 2026.
- ASHRAE, Addendum m to Standard 62.2 2013, Ventilation and Acceptable Indoor Air Quality in Residential Buildings, November 2015.
- U.S. Department of Energy, Building America Solution Center (PNNL), Whole-House Fans, updated Sept. 29, 2022.
- CentricAir product specifications and prices, centricair.com, accessed Sept. 2026.
- CentricAir Gable Mounted Attic Fan product page, centricair.com, accessed Sept. 2026.