Evaporative Cooling

Last Updated: September 21, 2017

Definition - What does Evaporative Cooling mean?

Evaporative cooling is a common method used to reduce heat in a greenhouse or grow room. The process of evaporative cooling depends on the humidity and elevated heat in the room.

When water evaporates, it cools, which naturally helps the air temperature drop. The process of evaporative cooling utilizes the heat and humidity in the air.

The humid moisture on the plant’s leaves and the other wet surfaces in the room start to naturally evaporate rapidly once an evaporative cooling system is triggered.

The evaporated cooling process will normally cool a greenhouse or grow room by 10 to 20 degrees Fahrenheit. Evaporative cooling is most effective in drier climates, but it can provide cooling in other conditions as well.

MaximumYield explains Evaporative Cooling

There are two ways to achieve evaporative cooling in a greenhouse or grow room. One way uses a cabinet cooler, which is often referred to as a swamp cooler, and the other way uses a fan-and-pad system.

A cabinet cooler relies on a thermostat to monitor the temperature. When the temperature reaches the pre-set high, the thermostat triggers the cabinet cooler to turn on and immediately start the evaporative cooling process in the greenhouse. Once the temperature dips to the desired level, the thermostat tells the cabinet cooler to turn off. A cabinet cooler can also be controlled manually by the grower and turned on or off as desired.

The fan-and-pad system, which has been the standard method for decades, also commonly relies on a thermostat to start the evaporative cooling process. If a high-tech thermostat is not available, then the grower can control the system by turning it on and off manually when needed. With this system, aspen or cellulose pads are mounted on a sidewall of the greenhouse. The pads are fed water from attached pipes so they are constantly kept wet. Air is then drawn through the wet pads by fans on the opposite wall of the greenhouse, and the process creates a cooling vapor.

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