Evaporative Cooling Calculator

Evaporative cooling is an energy-efficient cooling method that lowers air temperature by evaporating water into the airstream. As water evaporates, it absorbs heat from the surrounding air, reducing the dry bulb temperature while increasing humidity. The effectiveness of evaporative cooling depends on the wet bulb depression—the difference between the entering dry bulb and wet bulb temperatures. In direct evaporative coolers, the theoretical maximum cooling approaches the entering wet bulb temperature. Effectiveness ratings of 85–95% are typical for well-designed media. Evaporative cooling is most effective in hot, dry climates where the wet bulb depression is large. In arid regions such as the American Southwest, direct evaporative coolers can reduce air temperature by 15–25°F while using 60–80% less energy than mechanical refrigeration. Indirect evaporative systems provide cooling without adding moisture to the supply air.