Find the right size exhaust fan for your greenhouse.
To determine which fan you need, you must calculate the volume of your
greenhouse.
For a simple estimation (this will slightly overestimate your volume)
multiply the length x the width x the height of your greenhouse.
For example, the 8’ x 12’ x 8’ Garden Oasis would need 768 CFM (8 x 12 x
8=760 CFM).
The 12” standard exhaust fan would be sufficient at 760 CFM.
The general rule is that your intake CFM should be less than the exhaust.
Ventilation Calculator
All greenhouses will need ventilation to successfully grow plants and cuttings.
Exhaust and Ventilation fans are rated in CFM (Cubic Feet per Minute). This rating refers to how much air is moved over time.
What size fan do you need for your greenhouse? See our example Greenhouse Ventilation CFM below. Follow the example to calculate what size of fan your greenhouse needs to promote healthy growth.
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Example
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Measure the height of your greenhouse.
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You measured a floor to ceiling height of 8 feet.
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Determine the width of your greenhouse.
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You measured the width at 8 feet.
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Find out the length.
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You enjoy a medium sized greenhouse, measuring 16 feet long.
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Multiple the height by the width by the length.
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Your greenhouse measurements were 8'h, 8'w, and 16'l.
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This is the recommended minimum ventilation fan cfm rating to keep your greenhouse healthy year round.
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8' H x 8' W x 16' L = 1024 cfm
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This is the recommended optimum ventilation fan cfm rating many growers use.
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8' H x 8' W x 16' L x 1.5 = 1536 cfm
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Ventilation fan size information:
12" Fan Kit provides 760 CFM.
16" fan is rated at 1,250 CFM
20" fan is rated at 3,000 CFM
