Greenhouse Evaporative Cooling Calculator
Fan CFM for a pad-and-fan greenhouse cooling system.
Enter your values
ⓘ Live results
Results
- Required fan airflow
- 28,800 CFM
- Greenhouse volume
- 36,000 cu ft
- Fans at 15,000 CFM each
- 2
Quick answer
Greenhouses using pad-and-fan cooling typically need one full air exchange every 60-90 seconds during peak summer heat.
CFM = volume x 60 / exchange time (sec)
How to use the Greenhouse Evaporative Cooling Calculator
- 1Calculate the greenhouse volume from its footprint and average height.
- 2Use a 60-90 second full-exchange target for hot climates, longer for mild ones.
- 3Match exhaust fan capacity and pad area to that airflow together.
Worked example
Using the values the calculator loads with:
Inputs
- Greenhouse length100 ft
- Greenhouse width30 ft
- Average height12 ft
- Air exchange time75 sec
Results
- Required fan airflow28,800 CFM
- Greenhouse volume36,000 cu ft
- Fans at 15,000 CFM each2
Frequently asked questions
Why so fast an exchange?
Solar heat gain through glazing is intense, so air must be replaced quickly to hold setpoint.
Winter ventilation?
Winter minimum ventilation runs far lower, just enough for humidity and CO2 control.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.