Ventilation Rate Calculator Formula
Understand the math behind the ventilation rate calculator. Each variable explained with a worked example.
Formulas Used
People Component
people_cfm = occupants * cfm_per_personArea Component
area_cfm = floor_area * cfm_per_sqftTotal Outdoor Air
total_cfm = occupants * cfm_per_person + floor_area * cfm_per_sqftVariables
| Variable | Description | Default |
|---|---|---|
floor_area | Floor Area(sq ft) | 1000 |
occupants | Number of Occupants(people) | 10 |
cfm_per_person | CFM per Person(CFM) | 5 |
cfm_per_sqft | CFM per Sq Ft(CFM) | 0.06 |
How It Works
ASHRAE 62.1 Ventilation
Outdoor Air = (People x CFM/person) + (Area x CFM/sqft)
ASHRAE 62.1 uses a two-part calculation: a per-person rate for bioeffluents and a per-area rate for building emissions. Office spaces typically use 5 CFM/person and 0.06 CFM/sqft.
Worked Example
1,000 sq ft office with 10 occupants.
floor_area = 1000occupants = 10cfm_per_person = 5cfm_per_sqft = 0.06
- 01People = 10 x 5 = 50 CFM
- 02Area = 1000 x 0.06 = 60 CFM
- 03Total = 50 + 60 = 110 CFM outdoor air
Ready to run the numbers?
Open Ventilation Rate Calculator