Quick answer
Ventilation rate is the amount of outdoor air a ventilation system brings into a home, or stale air it exhausts, usually measured in cubic feet per minute (cfm).
For homes, ASHRAE Standard 62.2 sets a minimum whole-dwelling rate from floor area and bedroom count. Codes in many states adopt it.
Quick facts
The key facts about Ventilation Rate, with sources:
- Unit
- Cubic feet per minute (cfm) or liters per second (L/s)
- Governing standard
- ANSI/ASHRAE 62.2; 62.2-2025 is the current edition 2
- Whole-dwelling formula (62.2-2022)
- Qtot = 0.15 × floor area (m²) + 3.5 × (bedrooms + 1), in L/s 1
- Same formula in cfm
- About 0.03 × floor area (ft²) + 7.5 × (bedrooms + 1) 1
- Fan noise limit
- Under 1 sone for whole-dwelling fans (62.2-2022) 1
- Intake rule
- More than 3 m (about 10 ft) from known contaminant sources 1
- Adoption
- Referenced in 19 state codes 3
Key takeaways
- Ventilation rate is how much fresh outdoor air a home gets on purpose.
- ASHRAE 62.2 sets the minimum from floor area and bedrooms 1.
- A 2,000 sq ft, 3-bedroom home needs about 90 cfm of continuous whole-house ventilation (see the example).
- Tight, efficient homes need planned ventilation; leaky homes get some by accident 5.
- More ventilation costs energy; ERVs and HRVs reduce that cost 4.
What ventilation rate means
Every home makes indoor pollution: moisture from showers and cooking, gases from furniture and cleaners, carbon dioxide from people. Ventilation dilutes it with outdoor air. EPA says too little ventilation raises indoor pollutant levels by not bringing in enough outdoor air and not carrying pollutants out 5.
The ventilation rate is how much air that is, usually in cfm. It is not the same as how much air your furnace blower moves. The blower recirculates indoor air; ventilation exchanges it with outdoor air.
ASHRAE 62.2 sets the minimum for homes. Its whole-dwelling rate has two parts, as summarized by Lawrence Berkeley National Laboratory (LBNL): one tied to floor area and one tied to the number of occupants, estimated as bedrooms plus one 1.
How the 62.2 rate is built
Worked example: the ASHRAE 62.2 rate for a typical house
Using the 62.2-2022 whole-dwelling formula as published by LBNL: Qtot (L/s) = 0.15 × Afloor (m²) + 3.5 × (Nbr + 1) 1. Converted to US units this is about 0.03 cfm per sq ft plus 7.5 cfm per occupant. House: 2,000 sq ft, 3 bedrooms, detached.
| Step | Math | Result |
|---|---|---|
| Floor area in m² | 2,000 ft² ÷ 10.764 | 185.8 m² |
| Area term | 0.15 × 185.8 | 27.9 L/s |
| Occupant term | 3.5 × (3 + 1) | 14.0 L/s |
| Qtot | 27.9 + 14.0 | 41.9 L/s |
| In cfm | 41.9 × 2.119 | About 89 cfm |
| Check with the US form | 0.03 × 2,000 + 7.5 × 4 = 60 + 30 | 90 cfm |
| If the fan runs 50% of the time | About 90 ÷ 0.5 | About 180 cfm while on, if the standard's averaging rules are met |
The two forms agree within rounding. A detached home with measured air leakage can reduce the fan size with the infiltration credit, Qfan = Qtot − Φ × (Qinf × Aext), where Φ is 1 for balanced systems and Aext is 1 for detached homes 1.
The last row shows the idea behind intermittent operation; 62.2 sets the averaging limits, so a designer checks them. Edition note: ASHRAE lists 62.2-2025 as current 2.
The formula above is the 2022 edition as LBNL published it; confirm the 2025 text, or your state's adopted code, before design.
How a designer sets a home's ventilation
- Calculate Qtot from floor area and bedrooms 1.
- Decide on continuous or intermittent operation within 62.2's averaging rules 1.
- Take an infiltration credit only if the home's leakage has been measured with a blower door 1.
- Pick a system type: exhaust, supply, balanced, or ERV/HRV 4.
- Size ducts and place the intake away from contaminant sources 1.
- Measure the installed airflow; 62.2-2022 requires airflows to be measured or verified 1.
Types of whole-house ventilation
| Type | How it works | Fit (per DOE) |
|---|---|---|
| Exhaust | Fans push air out; outdoor air leaks in | Cold climates; not for hot, humid ones 4 |
| Supply | Fan pushes outdoor air in; air leaks out | Hot or mixed climates; can cause moisture problems in cold ones 4 |
| Balanced | Equal supply and exhaust | All climates; costs more |
| ERV / HRV | Balanced, with heat (and for ERV, moisture) exchange | Extreme winters or summers and high fuel costs 4 |
Where you will see the term
- On new-home energy code checklists and inspections.
- On ERV and HRV quotes, as rated and set airflow.
- In blower door test reports for weatherization programs.
- On fan labels, as cfm and sones.
Benefits and trade-offs
Benefits
- Dilutes moisture, odors and indoor pollutants 5.
- Makes tight, efficient homes healthy to live in.
- Planned intake location and filtering instead of random leaks.
What the formula does not cover
The whole-dwelling rate is a minimum for general dilution. It does not replace kitchen and bath exhaust, which 62.2 treats separately as local exhaust 1. It also cannot fix a strong pollution source; EPA ranks source control first 6.
The rate assumes typical occupancy. A home with more people than bedrooms plus one, or with heavy indoor activities, may need more.
Cost drivers
HyreHVAC lists no prices without enough dated quotes. Costs depend on system type (simple exhaust fan up to a ducted ERV or HRV), ductwork, controls, airflow testing and access. Running costs depend on the rate, your climate and whether heat is recovered.
DOE notes ERVs and HRVs can cost more to install but reduce heating and cooling costs, and may not be cost-effective in mild climates 4. See the ERV and HRV services page.
How ventilation is installed and checked
Contractor work, usually under a mechanical permit.
- Calculate the required rate and pick the system.
- Locate the outdoor intake more than about 3 m (10 ft) from vents, flues and car exhaust 1.
- Install the fan or ventilator, ducts and controls.
- Seal ducts; 62.2-2022 sets a duct leakage limit under 6% of fan flow at 25 Pa 1.
- Measure delivered airflow and set controls.
- Show the homeowner how to run and maintain it.
Upkeep
- Clean or replace ventilator filters on the maker's schedule 4.
- Clear leaves and snow from outdoor intake and exhaust hoods.
- Clean ERV or HRV cores as directed.
- Do not switch the system off for the winter; it is part of the home's air quality plan.
- Have airflow rechecked after duct changes.
Signs ventilation is too low
Codes and standards
ANSI/ASHRAE 62.2 is the consensus ventilation and IAQ standard for dwelling units. ASHRAE lists 62.2-2025 as the current edition 2. Its fact sheet on the 2022 edition says it is referenced in 19 state codes and that the 2022 update tightened rules for attached dwelling units 3.
LBNL's summary of 62.2-2022 lists other requirements: measured airflows, fan sound limits, MERV 11 minimum filtration for supply air, duct leakage limits, intake setbacks, a ban on unvented combustion and CO alarms 1. The International Residential Code has its own whole-house ventilation section. Which applies depends on your state's adopted codes.
Ventilation rate vs related terms
| Term | What it measures |
|---|---|
| Ventilation rate | Outdoor air brought in, in cfm |
| Air changes per hour | How many times the home's air volume is replaced each hour |
| Infiltration | Unplanned air leaking through the shell |
| CFM | The unit used for airflow |
| Demand-controlled ventilation | Varies ventilation with occupancy or CO₂ |
Common misconceptions
- Myth Homes need to "breathe" through leaks.
- Reality Leaks are random and unfiltered. Planned ventilation is controlled.
- Myth My furnace fan ventilates the house.
- Reality It recirculates indoor air unless a fresh-air duct is connected.
- Myth More ventilation is always better.
- Reality It costs energy and can bring in humid or polluted air 6.
- Myth Bath fans cover whole-house ventilation.
- Reality Local exhaust is separate unless designed and run for that purpose 1.
Climate decides the system
DOE's guidance is climate-specific: exhaust systems suit cold climates, supply systems suit hot or mixed ones, and ERVs and HRVs pay off where winters or summers are extreme 4. California's energy code builds 62.2 into its residential rules. Check your state page for code notes.
When it matters to you
It matters if you are building, doing deep air sealing, or noticing stuffiness and window condensation. Ask the contractor for the calculated 62.2 rate, the system type and a measured airflow at startup.
Next step: use the formula above for a quick check, and compare ventilation options on the indoor air quality services page.
Questions about Ventilation Rate
How much ventilation does a house need?
ASHRAE 62.2 sets the minimum from floor area and bedrooms: about 0.03 cfm per square foot plus 7.5 cfm per occupant, with occupants counted as bedrooms plus one. A 2,000 square foot, 3-bedroom home needs about 90 cfm of continuous whole-house ventilation.
What is ASHRAE 62.2?
It is the consensus ventilation and indoor air quality standard for dwelling units in the US. It sets whole-house ventilation, local kitchen and bath exhaust, and related requirements. ASHRAE lists the 2025 edition as current, and many state codes reference it.
Can I run the ventilation fan part of the time?
Yes, 62.2 allows intermittent operation if the average over a short period meets the continuous rate. A fan that runs half the time must move roughly twice the continuous rate while on. A designer checks the averaging rules.
Do older homes need mechanical ventilation?
Many leaky older homes get some outdoor air through cracks. If the home is air sealed or measured as tight, mechanical ventilation is usually needed. 62.2 lets measured leakage count as a credit that reduces the required fan size.
What is the difference between an ERV and an HRV?
Both are balanced ventilators that recover energy from outgoing air. An HRV transfers heat. An ERV transfers heat and some moisture. DOE notes they are most cost-effective in climates with extreme winters or summers and high fuel costs.
Where should the fresh air intake go?
Away from contamination. LBNL's summary of 62.2-2022 says intakes must be more than 3 meters, about 10 feet, from known sources such as a stack, vent, exhaust hood or vehicle exhaust. Keep it clear of snow and leaves.
How loud can a ventilation fan be?
LBNL's summary of 62.2-2022 lists under 1 sone for whole-dwelling ventilation fans and under 3 sones for local exhaust. Quiet fans matter because noisy ones get switched off.
Is a bathroom fan enough ventilation?
Not usually on its own. Bath fans handle local moisture. Whole-house ventilation is a separate requirement, though a quiet, continuously running bath fan can serve as an exhaust ventilation system if designed and controlled for that purpose.
Should I turn off ventilation during wildfire smoke?
During heavy smoke, many health agencies advise reducing outdoor air and filtering indoor air. Ask your installer how to set your system's smoke or recirculate mode, keep windows closed, and use a MERV 13 filter or a portable HEPA cleaner. Return to normal ventilation once outdoor air clears.
Sources
- I. Walker (LBNL), Ventilation Standards in the US: ASHRAE 62.2-2022 (AIVC presentation), retrieved .
- ASHRAE, Standards 62.1 & 62.2 (bookstore listing, 2025 editions), retrieved .
- ASHRAE Government Affairs, Standard 62.2 fact sheet (December 2025), retrieved .
- U.S. DOE Energy Saver, Whole-House Ventilation (archived copy, 2025), retrieved .
- U.S. EPA, Introduction to Indoor Air Quality, retrieved .
- U.S. EPA, Improving Indoor Air Quality, retrieved .
- U.S. CPSC, Carbon Monoxide Information Center, retrieved .
Expert review
Written by the HyreHVAC Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: The formula, credit and other requirements are LBNL's published summary of ASHRAE 62.2-2022; ASHRAE's own listing confirms 62.2-2025 is now current, and the page says so beside the example. The worked example applies the SI formula and checks it against the US-unit form.
Suggest a correction. We fix errors and say what changed.