ASHRAE 62.2 Ventilation Calculator | Fresh Air CFM for Homes
ASHRAE 62.2 Ventilation Calculator – an interactive tool that computes the required fresh air CFM for a home using the standard formula: (Bedrooms+1) × 7.5 CFM + (Floor Area × 0.01 CFM)
🏠 ASHRAE 62.2 Ventilation Calculator
This is the minimum continuous mechanical ventilation rate per ASHRAE 62.2‑2022.
Why Use This ASHRAE 62.2 Ventilation Calculator?
Modern homes are built tighter to save energy, which can trap indoor pollutants, moisture, and carbon dioxide. The ASHRAE 62.2 standard specifies the minimum continuous mechanical ventilation rate needed to maintain healthy indoor air quality. Our tool uses the official formula: CFM = (Number of Bedrooms + 1) × 7.5 + (Floor Area × 0.01). It’s the go‑to reference for builders, HVAC pros, and homeowners.
Key Features
- Instant calculation – slide bedrooms and floor area, see required CFM live.
- Formula breakdown – shows each part of the calculation for transparency.
- Air Freshness Score – rates your home’s ventilation relative to recommended levels.
- Rotating tips – learn about ventilation best practices, HRVs/ERVs, and IAQ.
- Dark/light mode toggle – comfortable viewing day or night.
Frequently Asked Questions (FAQ)
What is ASHRAE 62.2?
ASHRAE Standard 62.2 – “Ventilation and Acceptable Indoor Air Quality in Residential Buildings” – is the US benchmark for mechanical ventilation in homes. It ensures adequate fresh air to dilute pollutants and control humidity.
Do I need to meet this CFM number exactly?
The calculated CFM is the minimum continuous ventilation rate. Many local building codes adopt ASHRAE 62.2. You can meet it with a continuously running exhaust fan, a dedicated supply fan, or a balanced system (HRV/ERV).
What if my home has a crawlspace or attic?
ASHRAE 62.2 applies to the conditioned living area. Crawlspaces and attics have separate ventilation requirements (usually based on square footage or passive vents).
Can I rely on opening windows instead?
Windows are intermittent and weather‑dependent. For year‑round IAQ, mechanical ventilation is recommended. You can still open windows for extra fresh air, but the code requires a mechanical system in most new homes.
How do I measure my current ventilation CFM?
Use a calibrated flow hood or an anemometer at exhaust grilles. Many bath fans have their CFM printed on the label – add up all continuously running fans to see if you meet the target.
Disclaimer: This tool provides an estimate based on ASHRAE 62.2‑2022. Always verify with local codes and a licensed HVAC professional for your specific project.
