How to Calculate Ventilation Rate
What is Ventilation Rate?
Ventilation Rate Calculator helps contractors and tradespeople accurately size, spec, and estimate materials and systems.
Formula
Ventilation = Outdoor Air per Person × Occupants + Area × Outdoor Air per sf
Step-by-Step Guide
- 1Apply ASHRAE 62.1: 5-15 CFM/person + 0.06 CFM/sf
- 2Apply the formula using your project measurements
- 3Add required safety factors or waste allowances per code
Worked Examples
Input
10 people, 1000 sf, office zone (5 CFM/person + 0.06 CFM/sf)
Result
Ventilation = 10×5 + 1000×0.06 = 110 CFM
Common Mistakes to Avoid
- ✕Not applying code-required safety factors or derating
- ✕Forgetting to account for waste and cut losses in material estimates
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