Cooling units known as “swamp coolers” chill the air using much less energy than conventional air conditioning. Swamp coolers have been around for decades, but older designs — also known as “direct evaporative coolers” — add a lot of moisture to indoor air, so they’ve been viable only for dry, low-humidity climates, such as the Southwest.
Now, newer designs called “indirect evaporative coolers” are on the market. They take advantage of evaporative cooling effects, but chill the air without raising indoor humidity, meaning homes in more regions can tap this technology to stay cool and comfortable for less money and energy.
An indirect evaporative cooler runs on up to 80 percent less energy than a conventional air conditioning unit. That’s because, like your refrigerator, standard AC uses electricity to power a compressor that pressurizes a refrigerant.
Evaporative cooling, on the other hand, relies instead on the inherent quality of water to absorb heat when it evaporates (changes from a liquid to a gas). In indirect evaporative cooling, two opposing airstreams contact different sides of a heat exchanger. The evaporation of water cools one side of the heat exchanger, while the other side provides a cool, dry airstream without picking up humidity the way an older swamp cooler would.
Note that evaporative coolers are challenged by salty or mineral-rich water. The ideal source for a unit is rainwater, such as filtered rainwater from a cistern.
Unit size, performance and availability vary, but key manufacturers of indirect evaporative coolers include Climate Wizard (based in Australia but has a U.S. office and dealers) and Coolerado (only for commercial installations at this time). Your local building supplier or HVAC specialist may already partner with an indirect evaporative cooler supplier, but if not, ask them to work with you on sourcing a unit. Installation is easy, and the units are quiet and durable.