Greenhouses and evaporative cooling cell pads

Summer heat can cause indoor conditions to become much hotter than desired. An evaporative cooling pad (TABREED) is the way to reduce temperatures inside green houses. As water evaporates, it absorbs energy from the surrounding environment. A well-maintained ventilation system with evaporative cooling pads (TABREED) can reduce incoming air 10 to 20°C. Cooler indoor temperatures can improve the environment for plants.

Evaporative cooling systems lower air temperature using wetted pads. Introducing water into ventilation air increases relative humidity while lowering the air temperature.

Greenhouse designs usually specify 0.75 to 1 air change per minute as a maximum ventilation rate for buildings 30m to 45m long. The volume of air in a room represents an air change.

A pad-and-fan cooling system typically consists of axial-flow exhaust fans installed in one wall and correctly sized wetted pads placed along the opposing wall. The fans exhaust air from the building and draw in fresh air through the pads. Fans should be located in the side of the building that is downwind of the summertime prevailing winds. To function properly, the fans must be able to develop a slight vacuum inside the building. This requires that the remainder of the building be reasonably airtight. For example, all doors must be kept closed.