Evaporative coolers, or swamp coolers, are another method of cooling a house and are typically used in dry climates. They simply blow outside air over and through a wet material. The evaporating water cools the air, much like what happens when you sweat. They use about 25% less energy than an air conditioner.

An air conditioner cools a room when heat from the room is absorbed by the refrigeration fluid inside the evaporator coil. This turns the liquid into a gas. The gas is then pumped by the compressor to the condenser coil where the moving outside air cools the gas, turning it back into a liquid and releasing the heat. The fluid is cycled back to the evaporator coil to start the process again.