Ventilation Rate Calculator
Calculate required outdoor air ventilation rates per ASHRAE Standard 62.1 based on occupancy and space type.
Inputs
Office: 5 CFM/person; Classroom: 10 CFM/person; Restaurant: 7.5 CFM/person per ASHRAE 62.1
ASHRAE 62.1 area rate: Office = 0.06 CFM/ft²; Classroom = 0.12 CFM/ft²
ASHRAE 62.1: Office 5 CFM/person; Classroom 10 CFM/person; Gym 20 CFM/person
Results
Required Outdoor Air
220 CFM
Total Ventilation
220 CFM
How to Use This Calculator
- Enter Number of Occupants, Floor Area, and Space Type.
- Review Required Outdoor Air (CFM) and Total Ventilation (CFM).
- Use People Component (CFM) and Area Component (CFM) to inform your decision.
How the result changes with Floor Area
| Floor Area | Required Outdoor Air | Total Ventilation |
|---|---|---|
| 100,045 | 6,103 CFM | 6,103 CFM |
| 350,033 | 21,102 CFM | 21,102 CFM |
| 650,018 | 39,101 CFM | 39,101 CFM |
| 900,005 | 54,100 CFM | 54,100 CFM |
What each input means
- Number of Occupants
- Expected number of occupants in the zone at design conditions. ASHRAE 62.1 Table 6.2.2.1 provides per-person outdoor air rates by occupancy category.
- Floor Area
- Net occupiable floor area of the ventilation zone. ASHRAE 62.1 Table 6.2.2.1 provides per-area outdoor air rates (Ra) that supplement the per-person rates.
- Space Type
- Occupancy category per ASHRAE 62.1 Table 6.2.2.1. 1 = Office (5 CFM/person + 0.06 CFM/ft²), 2 = Retail (7.5 CFM/person), 3 = Classroom (10 CFM/person + 0.12 CFM/ft²), 4 = Restaurant dining (7.5 CFM/person).
How this is calculated
Worked example, using the default values
- Identify Input ParametersNumber of Occupants = 20, Floor Area = 2000, Space Type = 1 = 3 input(s) provided
- Calculate Required Outdoor AirRequired Outdoor Air220 = 220
- Calculate Total VentilationTotal Ventilation220 = 220
- Calculate People ComponentPeople Component100 = 100
- Calculate Area ComponentArea Component120 = 120
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.
Related Calculators
The questions that sit next to this one — chosen by subject, including calculators filed under a different category.
Air Balance Calculator
Calculate building air balance, pressurization status, and required adjustments from supply, return, exhaust, and outside air flows.
HVACManual J Heat Load Calculator
Estimate heating and cooling loads using a simplified Manual J method based on building envelope, windows, and occupancy.
Air QualityIndoor Air Quality Score Calculator
IAQ assessment from CO2, VOC, humidity, and particulates.
Green BuildingIndoor Air Quality Score Calculator
Calculate a composite IAQ score (0-100) based on ASHRAE 62.1 ventilation, MERV filtration, CO2, VOC levels, and humidity.
Occupational HealthWorkplace Air Quality Calculator
CO2, humidity, and temperature assessment for IAQ.
More in Construction & Building Trades.