Fresh Air CFM per Person Calculator
Outdoor air rate for occupied spaces.
Enter your values
ⓘ Live results
Results
- Outdoor air required
- 190 CFM
- Per person
- 9.5 CFM
- Per square foot
- 0.127
- In L/s
- 90
Working
- 15 x 20 + 0.06 x 1,500 = 190 CFM
Quick answer
Outdoor air is the sum of a per-person rate and a per-square-foot rate for the space type.
Vbz = Rp x people + Ra x area
How to use the Fresh Air CFM per Person Calculator
- 1Count design occupancy, not the number of desks.
- 2Enter the floor area served by the same air handler.
- 3Divide by the ventilation efficiency if you use a single-zone economiser.
Worked example
Using the values the calculator loads with:
Inputs
- Occupants20
- Floor area1500 sq ft
- Space typeOffice (5 + 0.06)
Results
- Outdoor air required190 CFM
- Per person9.5 CFM
- Per square foot0.127
- In L/s90
- 5 x 20 + 0.06 x 1,500 = 190 CFM
Frequently asked questions
Does CO2 control replace this?
Demand control can modulate down to the area component, but the design value still governs equipment size.
Why per area too?
Building materials and furnishings off-gas regardless of occupancy.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.