The operation, as the name suggests, is based on water evaporation. Cellulose pads are wetted with water, and as the water evaporates from the pads, the air temperature decreases. This cooled air is then circulated into the environment by fans. Evaporative cooling is a process where warm air comes into contact with evaporating water, transferring heat and resulting in cooler air. The warmer and drier the incoming air, the greater the temperature reduction. Passing warm air through the wetted cellulose pads can reduce the temperature by 10 to 20 degrees Celsius.