 She says evaporative coolers are more energy efficient than air conditioning systems and have no coils or chemicals. Water is poured into a reservoir or you can hook the unit up to a hose and let it self-regulate. A pump in the bottom of the reservoir pumps the water up and over the top of evaporative media. So we have a high velocity fan on the other side of the media and the fan actually pulls air through the evaporative media that's wet with water and the water and the air interact with one another