5 ms·
I have seen these and pondered if it is rude to wear them. While it is actively cooling your body, you are aggressively blowing your heat to those around you. I
by SapporoChris 5y ago
I have seen these and pondered if it is rude to wear them. While it is actively cooling your body, you are aggressively blowing your heat to those around you. In a crowded subway train I would not want to be next to someone wearing this. However, perhaps I overestimate their effects.
- teruakohatu 5y agoThey appear to just circulate air around the body, which makes sweat evaporate cooling the body. If they were actual air conditioners they would be indeed moving heat from the body into the surrounding air. Edit: to be clear I am not suggesting heat/energy disappears. In this case they are cooling the air and the body using evaporation. The system appears to suck in hot air on one side and ejects cooler humid air on the other. More or less human swamp coolers. https://en.m.wikipedia.org/wiki/Evaporative_cooler#Physical_principles https://en.m.wikipedia.org/wiki/Evaporative_cooler#Physical_...
- noctune 5y agoIt's the same dilemma though. Now you are raising the humidity around you, making other peoples' sweat less effective at cooling them. Although lowering humidity can be more easily done with just ventilation.
- usrusr 5y agoNot really, because the body self-regulates temperature by pushing out as much sweat as it needs to reach target temperature. A tool that facilitates evaporation allows the body to get by with less sweating. The amount evaporated will be the same, but the carrier won't be drenched. (PS: roughly the same, additional heat transfered from air to dry skin will need to be shed by sweating, but I doubt that this would make much difference compared to all the watts resulting from metabolistic base load, even in absence of physical activity) Mandatory slightly related anecdote: on a summer drive through Morocco back when car air conditioners where a thing exclusive to America and the one percent I never felt sweaty as long as the car was moving.
- bin_bash 5y agoYeah I rarely ever feel sweat on my body when I run. It’s when I stop running that I get drenched and need to put a headband on. (I live in a dry climate and generally don’t sweat much anyways, YMMV)
- treeman79 5y agoA few years ago I stopped sweating, almost completely. Trying to cool off is nearly impossible now. I have an ice vest if I really want to go outside for then a few minutes. Mirror clothing sounds like a dream.
- rini17 5y agoOnly in poorly ventilated enclosed spaces. But the sweat usually gets evaporated anyway only slower. And when they are used outside, the added humidity is negligible compared to volume of surrounding air.
- rwmj 5y agoIsn't that just the same thing, but using a natural process (sweating) rather than phase change in a refrigerant?
- louthy 5y agoEvaporated sweat only cools the body if it leaves the area where the body is. So presumably they would be radiating warm air away from them.
- contravariant 5y agoNot necessarily, they might just be radiating humid air. It's the evaporation itself that leads to the cooling.
- Razengan 5y agoHey as long as I feel cool and look cool I don’t care what it does.
- gruez 5y agoBut the humid air makes it harder for people around you to cool evaporatively (eg. sweating)
- contravariant 5y agoWell yes, you must (irreversibly) increase entropy somehow. The air itself won't be warmer though.
- StrictDabbler 5y agoThis is why we have wet and dry bulb temperatures. Your intuition about temperature is focused on the dry-bulb temperature that a simple probe gives you. A wet-bulb is literally a probe with a wet cloth or tissue around it. As the humidity in the air increases the wet-bulb temperature approaches the dry bulb temperature. This is absolutely “warming”. The latent heat of the air increases. The sensible heat remains the same.
- Retric 5y agoWithout the jacket the person will emit the same heat. The jacket fans do generate a trivial amount of heat, but it’s likely less than a desktop fan.
- faeyanpiraat 5y agoSo heat goes poof?
- easygenes 5y agoEvaporative cooling also moves heat from the body into the surrounding air, just encapsulated in water droplets.
- fpoling 5y agoWhile it does not actively cool your body, it transfers the heat to any surface that absorbs MIR. So in a crowded space the wearer will indeed dump the heat on other people.
- kalleboo 5y agoI've only seen these in use by construction workers and parcel delivery/mail people
- ezconnect 5y agoThey are usually worn by workers with long sleeve jacket uniforms. They need to cool down during summer when it gets really hot and they need to wear their uniforms. Ordinary people do wear them and remove the sleeves and they are not that loud. You wont even notice them unless you see the fan. The DIY jackets with fan are the loud one, I've seen a couple them.
- manwe150 5y agoI wonder if that would be true at steady-state (e.g. when the train is effectively empty), but for a train at rush hour, whether much of the capacity of the AC system is already being used to remove heat generated from the humans, and if that means the temperature difference to the outside is actually mostly unimportant. That is to say, the person next to you is generating and dissipating a fixed rate of heating onto you (equal to their basal metabolic rate consumption), so all that the jacket can have changed is their steady-state perception of the local temperature.