As summer winds down, let’s all be thankful for the small blessing of the air conditioner, which makes your room livable even on the hottest day of the year. Or, if you live in some part of the world where ACs aren’t that common (like Great Britain), you can just dream about air conditioners, which must seem like magic.
ACs work by pumping a refrigerant, transferring heat from inside your house to outside. One side effect of this is that the humidity inside condenses on the AC’s inner workings and gets pumped outside as liquid water. This can add up to several gallons of water removed from the air around you every day, which is another way ACs keep you comfortable. In fact, ACs were first designed for just that: to remove humidity, not to lower the temperature.
Now, the basic tech of the heat pump was invented to lower temperatures. People were building refrigerators and freezers, for the crucial job of keeping food from going bad and killing us. But they used that tech to lower temperatures in confined spaces to sub-freezing levels, not to lower whole rooms to merely comfortable levels. That sort of impractical luxury wouldn’t look reasonable for another half century or so.
The first person to use a heat pump to bring an entire room down to what we call room temperature was American engineer Willis Carrier. In 1902, a New York printing company was having summer problems, with the humidity making their paper go all wonky, and they called in Carrier to help. He designed a device whose heat pipes pulled humidity out of the air.
That device happened to fill the room with blessed coolness at the same time. Carrier realized that was a pretty big plus, and as he adapted his new “air conditioner,” he focused more on the cooling.
Today, you can also get air conditioners that don’t reduce humidity. They’re called evaporative coolers, or swamp coolers, and they actually increase humidity. They’re fine enough if you live somewhere dry, but if you live somewhere that’s already swampy, you’ll wish you had a legit AC instead.
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For more on the history of invention:
That Time Tesla Casually Invented The Cattle Prod
5 Awesome Things Invented by the Last People You’d Expect
When First Invented, Everyone Hated Shopping Carts
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