Greenhouse Ventilation
Size ventilation fans for a greenhouse by air changes.
About Greenhouse Ventilation
A greenhouse exchanges its whole air volume at a chosen rate, so the fan flow is the interior volume times air changes per minute. Proper ventilation pulls out the heat and humidity that otherwise stall growth and invite disease in a closed structure.
Formula
Greenhouse Ventilation
CFM = volume x air changes per minute; fans = CFM ÷ fan capacity
- air changes
- How many greenhouse volumes to exchange per minute
Worked example
With the default values below, Greenhouse Ventilation returns Ventilation Needed of 1,440. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Greenhouse lengthminimum 0 ft
- 24 ft
- Greenhouse widthminimum 0 ft
- 12 ft
- Average heightminimum 1 ft
- 10 ft
- Air changes per minuteminimum 0 per min
- 0.5 per min
- Fan capacityminimum 0 CFM
- 1,000 CFM
Results
- Ventilation Needed
- 1,440 CFM
- Fans Required
- 2 fans
- Greenhouse Volume
- 2,880 cu ft
Step by step
- 1Values used
- 2Greenhouse Ventilation
- 3Ventilation Needed= 1,440 CFM
- 4Fans Required= 2 fans
- 5Greenhouse Volume= 2,880 cu ft
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Greenhouse Ventilation calculated?
CFM = volume x air changes per minute; fans = CFM ÷ fan capacity A greenhouse exchanges its whole air volume at a chosen rate, so the fan flow is the interior volume times air changes per minute.
Why does Greenhouse Ventilation matter?
Proper ventilation pulls out the heat and humidity that otherwise stall growth and invite disease in a closed structure.
What values do I need to enter?
This calculator takes 5 inputs: Greenhouse length, Greenhouse width, Average height, Air changes per minute, Fan capacity. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.