Evaporative Cooler - Cool Off Efficiently

For people who live in a dry climate, an evaporative cooler is an effective, energy efficient alternative to an air conditioner. An evaporative cooler, sometimes called a "swamp cooler," works on a simple principle.

A small motor pumps water from the bottom to the top of the cooler. The water then runs down the insides, and is absorbed by filter pads. Another small motor works a fan. This fan brings air into the evaporative cooler for the outside, then through the device, and then out into the warm room. What causes the cooling is the evaporation of water as the hot dry air goes through it.

Ventilation Required

If you are using an evaporative cooler, you should be sure the house is well ventilated. Humidity can build up inside and cause problems. This is in direct contrast to the use of an air conditioner. With an air conditioner, it works more efficiently if the house is sealed up tight.

An evaporative cooler, on the other hand, needs airflow and works better even with a window open. If the outside air is humid, an evaporative cooler won't work, because water can't evaporate as well into humid air. Unlike an air conditioner, it is not necessary to have a larger evaporative cooler for a larger area.

A small portable evaporative cooler requires normal electricity. An evaporative cooler will need to have its water reservoir filled periodically and can use up to a gallon per hour. While they do not come equipped with a thermostat, you can choose an evaporative cooler with a variable speed fan.


A portable evaporative cooler looks something like a large fan that can be placed in front of a window. They can cost from $125 to $275. A larger model can be built into a wall, roof, or permanently fitted into a window. This type of evaporative cooler can be attached to your water supply which means you don't have to keep track of refilling the water container.

Unfortunately, an evaporative cooler will only work where the humidity is quite low. For instance, much of the western part of the United States is dry enough, but the Eastern half can just forget it. However, there are other things homeowners can do to maximize the passive cooling design of their home.

For instance, they can plant trees for shade and install window blinds that deflect sunlight and insulate the windows from hot air. While many of us are unable to benefit from an evaporative cooler, we don't have to rely only on an energy gulping air conditioner.