Evaporative cooling provides a low-tech, low-cost alternative to air conditioning. It cools by combining water evaporation with the simple movement of air. A blower circulates fresh outdoor air after it has been pulled through wet material, cooling the air by evaporation. Also known as a swamp cooler air conditioner, this type of cooling can lower temperatures as much as thirty degrees. They work best in dry areas rather than in humid regions.
A small evaporative air cooler can be installed in a window to blow cool air into a room. Larger evaporative cooling units can be used with duct work to blow cool air throughout a building. While air conditioners are rated in terms of BTU (British Thermal Units), swamp coolers are rated by CFM (cubit feet per minute), which measures how may cubic feet of air are blown through a space per minute. Select a cooler by dividing the square footage of the space you want to cool by two (sq. feet/2). This number will give the CFM rating your space requires.
One striking advantage of evaporative cooling over central air conditioning is the fresh, unrecycled outdoor air used in the cooling process. Swamp coolers work best during the hottest time of the day. As temperatures climb, humidity will drop, making the process more efficient. Evaporative cooling technology is simple, and it costs 75 percent less than A/C. Most units can operate on 120 volts, as opposed to the higher amperage needs of A/C.