Greenhouse Cooling Calculator

Size exhaust fans and evaporative cooling pads for greenhouse ventilation based on volume and heat load.

Inputs

Length

Width

Sidewall Height

Outside Temperature

°F

Desired Inside Temp

°F

Light Intensity

Fan Capacity

CFM

Tab to move between fields

Results

Required Airflow

473,143 CFM

Fans Needed

Greenhouse Volume28,800 cu ft

Solar Temp Rise100 °F

Cooling Pad Area1,892.6 sq ft

Pad Width315.4 ft

Water Usage4,731.4 GPM

Floor Area2,880

How to Use This Calculator

Enter your greenhouse dimensions (length, width, sidewall height in feet) to calculate the total air volume.
Enter the peak outside temperature (°F) and your desired inside growing temperature.
Enter the light intensity in foot-candles and the CFM rating of each exhaust fan you plan to install.
Review Required Airflow (CFM), Fans Needed, and Cooling Pad Area (sq ft) for evaporative cooling design.
Use Water Usage (GPM) to size your pad water supply line and recirculating pump.

How the result changes with Length

Length	Required Airflow	Fans Needed
57	280,929 CFM	29
180	887,143 CFM	89
328	1,616,571 CFM	162
451	2,222,786 CFM	223

What each input means

Length: Greenhouse length.
Width: Greenhouse width.
Sidewall Height: Eave height.
Outside Temperature: Peak outdoor temperature.
Desired Inside Temp: Target growing temperature.
Light Intensity: Foot-candles of sunlight reaching the greenhouse.
Fan Capacity: CFM rating of each exhaust fan.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Length = 96, Width = 30, Sidewall Height = 10, Outside Temperature = 95 = 7 input(s) provided
Calculate Required Airflow
Required Airflow
473143 = 473143
Calculate Fans Needed
Fans Needed
48 = 48
Calculate Greenhouse Volume
Greenhouse Volume
28800 = 28800
Calculate Solar Temp Rise
Solar Temp Rise
100 = 100

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