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During the recent heat wave, a friend was raving about swamp coolers. I'd never heard of them. All she could tell me was, it's a box that appears to make your room less hot. How do they work? Do I want one?
—Chief Chirpa
Back in the day—before Facebook made it possible to embarrass yourself even when drinking alone—I worked at the Clinton Street Theater. It was there I encountered my first evaporative (aka swamp) cooler.
I'm sure the Clinton's current HVAC system is a gleaming paragon of efficiency, but at the time its swamp cooler was a sputtering, Cthulhu-like array of repulsively moist hoses hanging from the backstage ceiling, like tentacles ready to penetrate the unwary.
A swamp cooler cools your house using the same principle that you use to cool your body. When water (or sweat) evaporates, the phase change from liquid to gas absorbs energy, making the air in the immediate vicinity cooler.
Thus, your swamp cooler sucks the hot, dry air from outside through a wet wick, wet fiber pads, or wet, cloth-covered hoses. As this wetness evaporates, it cools your air. It's like living in a house that can sweat!
Water doesn't evaporate well when the ambient air is already saturated with humidity, which is why swamp coolers may be news to those of us who grew up in the muggy East. In Portland's dry summers, however, they work fine. They also draw about one-fourth the power of conventional AC units, with no toxic refrigerants.
Swamp coolers do humidify your air whether you like it or not. Still, endure a little dampness for the sake of the planet—it's just the sort of meaningless sacrifice we Portlanders love to congratulate ourselves for.
WWeek 2015