Greenhouse Evaporative Cooling Calculator
Fan CFM for a pad-and-fan greenhouse cooling system.
Enter your values
Enter the greenhouse length in ft.
Enter the greenhouse width in ft.
Enter the average height in ft.
Enter the air exchange time in sec.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- 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)
At a glance
| What it does | Fan CFM for a pad-and-fan greenhouse cooling system. |
|---|---|
| Category | HVAC & Airflow |
| Inputs needed | Greenhouse length, Greenhouse width, Average height, Air exchange time |
| Main output | Required fan airflow |
| Formula | CFM = volume x 60 / exchange time (sec) |
| Cost | Free — no sign-up, no download |
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.
Inputs explained
- Greenhouse length(ft)
- Enter the greenhouse length in ft.
- Greenhouse width(ft)
- Enter the greenhouse width in ft.
- Average height(ft)
- Enter the average height in ft.
- Air exchange time(sec)
- Enter the air exchange time in sec.
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.
What do I need to enter into the Greenhouse Evaporative Cooling Calculator?
Just 4 values: greenhouse length, greenhouse width, average height, air exchange time. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Greenhouse Evaporative Cooling Calculator work out the answer?
Greenhouses using pad-and-fan cooling typically need one full air exchange every 60-90 seconds during peak summer heat. It applies the formula CFM = volume x 60 / exchange time (sec) and shows the working so you can check each step by hand.
Is the Greenhouse Evaporative Cooling Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.