Dry air has an enormous natural ability to cool itself by exchanging heat with water. Water absorbs a large amount of heat from the air to evaporate. As a result of this exchange between air and water, the temperature of the air decreases. This air cooling process uses much less energy than the traditional cooling processes used by typical air conditioning systems.
A wet media cooler basically uses this principle to cool hot air by forcing it through a large surface area of inorganic panel that is moistened with water (works like a sponge). In this type of cooling, no energy is consumed to evaporate the water. The media itself has an air pressure drop that will represent a small increase in the power consumption of the fans, and a small circulation pump is used to distribute the water through the panels. The total energy consumption resulting from the additional air pressure drop and the water recirculation pump is not significant in the total energy consumption of the data center cooling system.