A swamp cooler is an alternative to a traditional air conditioner. A traditional air conditioner uses compressed Freon gas to cool the air. This system works very well in most climates where the humidity is above 30 percent. In drier climates (below 30 percent humidity) a swamp cooler is very effective. Also called an evaporative cooler, a swamp cooler works sort of like a wet bulb thermometer. Pads inside the cooler absorb water, and a fan then blows on the pads, cooling the air and making it more humid. Swamp coolers are more energy efficient that regular air conditioners because the only electricity needed is what is used for the fan; no compressor is required.