6 Jul 2018

Do Fans Actually Make You Hotter?

By Adrienne Montgomerie

Open the fridge on a sweltering hot day and that blessed blast of cold air can make you want to stand there all day.
“Close the fridge door!” your parent says.
Ugh. No relief. So how can you cool off? Fans, air conditioners, and a shower can all help, but which one is best?
Some people say fans actually add more heat to a room. The important part about a fan is that it moves the air, which speeds up evaporative cooling on your skin as it dries up sweat. A fan doesn’t drop the temperature in the room, it drops the temperature of your skin. The air passing over our sweaty skin evaporates the water. That change of state, from liquid to gas, requires heat, and that pulls the heat away from our bodies. Besides, some people have crunched the numbers on the heat output from a fan motor and it’s just not very much.
What about fanning yourself instead of using a motor? Motors create heat. So does exercise. Fanning yourself can create more heat than cooling. The trick is to find how little fanning you can do to get just enough of a breeze. Or, be like those ancient royalty in movies and have someone else fan you. Just don’t let them work too hard or the heat they generate will make you even hotter!
Air conditioners have motors. Touch the side of an air conditioner and you can feel that its motor is putting out heat. Do they make the room hotter? The air conditioner is actually cooling the air, not just moving air around so that you feel cooler. Like your fridge, it moves that heat from inside to outside. A fridge makes a room hotter but makes the air inside of it much cooler. The difference is that an air conditioner moves the heat outside of the room and a fridge just moves it outside the fridge, into the room. Though most of the heat an air conditioner removes is sent outside the house, the part of the unit inside the house does give off some heat. So yes, an air conditioner does add heat to a room. The reason it still cools a room is that it removes a lot more than it adds. The net result is a temperature drop.

What about eating ice cream, can that cool you off? Eating and drinking cold stuff when you’re overheating is a really good idea. But even if you’re sitting still, digestion will create heat as the calories are converted by your body. The reason eating cold food lowers your temperature is that the cold has more effect than the conversion of calories does.
If you want to cool off even more, get away from other hot bodies, close the curtains so the sun isn’t heating things up, wet yourself down with a cool cloth, and close down the electronics. A computer can generate 100 watts of heat with light use, and even that smart phone is heating things up.
Want to get maximum cool with minimum heating? Plant a tree and get some shade.

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