Splash some water on your face on a hot day in the summer and you will immediately feel cool. That’s evaporative cooling working. An evaporative air cooler works on the same principle, evaporating water provides cooling, but they combine water evaporation with air movement to cool our homes.

Evaporative air coolers are sometimes called swamp air coolers, probably because they add humidity to the air, making it more swamp like. The concept of evaporative cooling has been around for years, when people living in arid climates used to hang damp clothes in their windows at night, knowing the breeze blowing through the window would help cool the room.

While evaporative air coolers have moved beyond the hang a cloth in the window stage, the principle remains the same. Nowadays an evaporative air cooler usually consists of a large box containing a box fan surrounded by a wet pad, mounted on the roof or side of a house. A pump circulates water to keep the pad wet and the fan blows air through the pad. The damp air is blown into the house driving the hotter inside air out through open windows or vents.

While both evaporative air coolers and air conditioners aim to do the same thing, evaporative air coolers are definitely low tech and unlike air conditioners in many ways. To start with, evaporative air coolers add humidity to the air, while air conditioners remove humidity. They don’t use any refrigerants so they aren’t potentially damaging to the atmosphere.

Evaporative air coolers provide a constant supply of fresh air, while an air conditioner operates best in a closed environment and re-circulates the same air over and over. Air stand fan conditioners also cost substantially more to install and maintain than evaporative air coolers, and use three to four more times electricity to operate.

In spite of the fact that evaporative air coolers may not be a cooling option for all of us, there is no doubt that they do provide energy savings and reduce the risk of damage to the environment. So even if we all can’t use an evaporative air cooler, we all do benefit from the energy conservation and environmental protection they provide.