Air Exchange & Fan Calculator
Calculate the extraction fan size needed for your grow room
Recommended ACH by Setup
| Scenario | Suggested ACH | Air change interval |
|---|---|---|
| CO₂-enriched room (sealed) | 15 - 30 | 2 - 4 min |
| Standard grow room (temperate) | 40 - 60 | 1 - 1.5 min |
| High-intensity / high-wattage lighting | 60 - 90 | 40 - 60 sec |
| Hot climate or poor insulation | 90 - 120 | 30 - 40 sec |
Formulas: Volume (m³) = L × W × H | Extraction (m³/h) = Volume × ACH | CFM = m³/h × 0.5886
Tip: Size the intake fan 15 - 20% smaller than the extraction fan to maintain slight negative pressure, which prevents odour escaping and improves air distribution. Add 20 - 25% to fan ratings to account for duct resistance, bends, and carbon filters.
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