Swamp cooler
Swamp coolers are simple type of air conditioning device that can cool a room of a house or a car by using the cooling effect of the evaporation of water. This is known as evaporative cooling. Swamp coolers can cool the air temperature in a small space by drawing the air through wet pads (some are made of aspen wood) using an electric fan. Swamp coolers work best in dry climates such as the American Southwest and the American South. They are usually much cheaper to buy and operate than refrigerated air-conditioning devices. This type of air conditioner was first used thousands of years ago in ancient Iran.