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New ‘mirror’ fabric can cool wearers by nearly 5°C
- irjustin 5y agoOkay heat map is cool, but what does it look like? any different? Also how does it breath? Natural cotton shirts still feel the best to me. I hate Rayon. I'm interested in this because I currently live in Singapore where it's sunny, annoyingly hot and humid all year round. I'd welcome something like this when I'm outdoors. Just too light on the details.
- TaylorAlexander 5y agoYeah the lack of even a regular color photo is weird.
- rob74 5y agoUnfortunately this new fabric only helps with the "sunny" part (it keeps you cooler when you are exposed to direct sunlight), but not with the "hot" and "humid" part...
- gattilorenz 5y agoLooking at the pictures in the scientific article it doesn't look particularly weird, just a white cloth: https://science.sciencemag.org/content/early/2021/07/07/science.abi5484 https://science.sciencemag.org/content/early/2021/07/07/scie...
- bruce343434 5y agoYou link to what I assumed to be a picture, got a paywall instead.
- gattilorenz 5y agoSorry, being under the IP address of a university removes a lot of paywalls :) Here's the images from that article https://ibb.co/1fBT3RZ https://ibb.co/1fBT3RZ https://ibb.co/tQRVqS2 https://ibb.co/tQRVqS2
- bruce343434 5y agothanks!
- a_f 5y agoCool. I wonder if you could turn it inside out, such that it dumps heat inwards to have the opposite effect and warm you?
- ars 5y agoIt probably reflects sunlight, not heat. So unless you shine very brightly it won't work in reverse :)
- afterburner 5y agoOne thing I noticed is that their control was a cotton shirt "about the same thickness" as the new one. But the new shirt is "550 micrometers" thick, which is about twice as thick as a regular T-shirt. So maybe they're tilting the scales a bit to make the cooling effect seem a little better?
- cptskippy 5y agoWhat constitutes a "regular T-shirt"? I have t-shirts that are quite thin, but I also have t-shirts that are quite thick. Both I would consider regular t-shirts. At least for me, undershirts and blended material t-shirts tend to be on the thinner side while graphic t-shirts are usually heavier. I also have some t-shirts that are ridiculously thin that I think are mostly synthetics but there's no tag so I'm unsure.
- deleted 5y ago[deleted]
- ricardobeat 5y agoI wonder why they haven’t tested a full model? They say the cost is low and production is easy, so why not do that to prove it works before going to manufacturers?
- yosito 5y agoIANAS, but I'm puzzled by the use of the word "cooling". This fabric doesn't actively cool the wearer, or reduce the temperature, it simply prevents temperature from rising, keeping things up to 5 degrees cooler, if they were already cool to begin with.
- reissbaker 5y agoIt sounds like it cools the wearer by absorbing body heat and emitting it as mid-infrared radiation. It also prevents temperature from rising by being reflective against UV, visible, and near-infrared radiation.
- deleted 5y ago[deleted]
- roywiggins 5y agoI think if you started with a regular shirt, and then put this one on instead, you would eventually start cooling down. The article says that human skin radiates in MIR but that's blocked by normal fabric. So if you take off your shirt, you will radiate more, and possibly cool down a bit. This fancy shirt is similar to not wearing any shirt, except it can also reflect visible light a bit better because it's whiter. It might even be more efficient at radiating MIR than skin? I'm not sure, but if it's better than normal fabric it should help. Obviously the physiology here complicates things, but it really could cool you down- your body is always attempting to radiate way heat, and this is supposed to make that process faster. It's like carrying around your own shade.
- poorjohnmacafee 5y agoThey are talking about the atmospheric window - the band of EM/heat that can be freely radiated out to space unblocked by our atmosphere. This is an important concept in global warming/ghg that you almost never see discussed. The band that CO2 absorbs (15 microns mainly) is not in the atmospheric window. The 15 microns band is already absorbed by water vapor, and is almost 99% saturated as is. (This is where some particle physics students stop talking so they don't upset people)
- deleted 5y ago[deleted]
- goodcanadian 5y agoIf you are a particle physics student, you will understand the concept of mean free path. Adding more greenhouse gases (including water vapour) decreases the distance a photon can travel before being absorbed again, and thus increases the amount of time it takes IR radiation to escape the atmosphere. The fact that basically no photons manage it in one go is sort of irrelevant.
- poorjohnmacafee 5y agoThere is nil escape to space from that band with today's water vapor level which is why it's not considered part of the atmospheric window. Do you have any research you can link to about your opinions on the 15 micron band? An ivy league physics professor was the one who insisted in discussion adding CO2 will only increase warming by some minuscule overall amount due to the band saturation. This was over 15 years ago when the academic climate was a little different.
- goodcanadian 5y agoYou are correct that 15um radiation will not escape directly to space from the ground. It will be absorbed by by the atmosphere. The atmosphere heats up and re-radiates the energy. Some of that energy ultimately escapes to space. The atmosphere warms up until the energy escaping to space equals the energy input by the sun. By adding more greenhouse gases, you are decreasing the distance a photon in the 15um band can travel before it is reabsorbed. This causes the atmosphere to heat up more than it would otherwise. Sure, water dominates the greenhouse effect. If it weren't there, the Earth would be frozen. That doesn't meant that adding more greenhouse gas has no effect. It most certainly does. It sounds like your professor was simply wrong. This is not a bad article, but I am mainly linking it for the graph which shows that the Earth does indeed radiate at 15um: https://www.giss.nasa.gov/research/briefs/2010_schmidt_05/ https://www.giss.nasa.gov/research/briefs/2010_schmidt_05/ Though, again, that is a little irrelevant. What matters is at what temperature the total energy escaping balances the incoming energy regardless of the wavelength.
- franferri 5y agoBootStrap website really needs this in the documentation for its components
- rwmj 5y agoIn Japan they have these portable AC jackets. I believe they are mainly used by people working on building sites where it gets very hot in summer. While these are actively cooled rather than passively (as in the article), they seem like a better idea than air conditioning whole rooms. https://wonderfulengineering.com/japanese-invent-a-jacket-with-air-conditioner/ https://wonderfulengineering.com/japanese-invent-a-jacket-wi... https://www.dailymail.co.uk/sciencetech/article-2016513/Japanese-company-creates-air-conditioned-jacket-Kuchofukus-cool-look.html https://www.dailymail.co.uk/sciencetech/article-2016513/Japa... (Sorry can't find any good links - the jackets aren't a fad and seem to be popular with builders) Edit: The company website (Japanese) https://kuchoufuku.com https://kuchoufuku.com
- fy20 5y agoIt looks like it's more of an air "cooler" than an air conditioner. It probably works somewhat depending on the climate, but air conditioning actively cools the air (it produces colder air than the exterior air temperature) and reduces humidity.
- rwmj 5y agoThis page explains (not very clearly) how it works: https://kuchoufuku.com/?mode=f1 https://kuchoufuku.com/?mode=f1
- Aachen 5y ago(In Japanese)
- fy20 5y ago> The wind that runs around the clothes by the fans takes heat away from the heat of vaporization. Yeah so as I expected. It would work well in a lot of climates today, but it's basically just a very well directed fan. If the wet-bulb temperature is high, it's not going to help.
- SapporoChris 5y agoI 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.
- enjikaka 5y agoOr just use linnen...
- bamboozled 5y agoHow does linnen compare to this at all?
- elric 5y agoI love linen in summer, it's nice and breezy, but sunlight gets through and will actively heat you up all the same. This seems to be about reflecting the sunlight away from your body, so I don't think the two compare all that favourably in terms of cooling capacity.
- dkdbejwi383 5y agoI wonder if it would be useful for things like curtains or overhead canopies, adding some passive cooling to spaces to reduce the need for mechanical cooling
- fpoling 5y agoThis only works if MIR radiation can escape, like happens outdoors unless the air is very humid. As the glass and walls reflects/absorbs MIR, curtains that emit that type of infrared will do nothing unless you hang them outside the window.
- roywiggins 5y agoYeah, they've looked into using this tech for roofs and things: https://www.sciencemag.org/news/2014/11/new-way-cool https://www.sciencemag.org/news/2014/11/new-way-cool
- TuringNYC 5y agoI see how this would be useful in always-warm/hot environments. But I'm curious -- would this be useful at locations with major seasonal changes? For example, in northeastern USA, the temperature varies from 100F to 0F through the year. So this would be great in the summer, but do I just "pay" for it in the winter via more heating? I imagine it depends on the cost of heating vs cost of cooling depending on the location.
- peteradio 5y agoWhere it gets cold, a single family home would tend to have snow cover anyway.
- mrfusion 5y agoI think the idea is that the attic tries to maintain ambient outdoor temperature and the house is then insulated from the attic. So you may not get much heating from your roof in the winter anyway. Someone correct me if I’m wrong.
- Tepix 5y agoThe headline is somewhat inaccurate, the fabric reduces the heating by the sun by 5°C, which is still useful of course.
- tmvphil 5y agoI'm not sure about this particular fabric, but there are materials which will reduce temperature below ambient (i.e. below air temperature), not just reduce radiative heating from the sun. You do this by exploiting the "cold resource" of space! See https://advances.sciencemag.org/content/5/10/eaat9480?intcmp=trendmd-adv https://advances.sciencemag.org/content/5/10/eaat9480?intcmp...
- amelius 5y agoCan I put this around my CPU?
- ivan_gammel 5y agoThe interesting part is how big are the environmental costs of the production?
- giantg2 5y agoI can honestly say this is the most exciting article I've read in a long time. Can't wait for this to be commercially available.
- rcarmo 5y agoGreat to see the academic tradition of roasting graduate students as an experiment is being carried on. :) Seriously now, as someone who occasionally spends a good while walking about in direct sunlight, I'm really interested in this, especially since I have noticed a marked increase in temperatures over the last few years and my Summer walks have become quite arduous...
- chrisweekly 5y agoTry Patagonia "Capilene cool daily" t-shirts.
- chrisweekly 5y agoPSA: Patagonia makes these fantastic lightweight "Capilene cool daily" short- and long-sleeved t-shirts that feel like they must have some magical active cooling built in along with their SPF 50 protection. I don't know how they did it, but I own half a dozen and will continue to gift and recommend them as the greatest t-shirts ever made.
- iAm25626 5y agoOlder Patagonia "Capilene" material have undesirable "odor retention" feature. Patagonia claim the updated version does much better. Do you have any experience between the new vs old (circa ~2000-2005 version)?
- chrisweekly 5y agoOnly w the new ones which def do not have this (or any other) problem. Note "Capilene cool *daily*" in particular. I tried one "capilene cool runner" which was... ok I guess, but much heavier fabric, not as soft, etc.
- fouc 5y agoNo idea if it will help, but I've found regularly adding a capful of bleach to my laundry of polyester shirts eliminates all odors for me.
- AntiqueFig 5y agoMerinos ftw though.
- culopatin 5y agoWhat’s the difference? I’m looking at some now. I hate heat but I like working in my non conditioned garage, so I’ll take anything that may help
- cowmoo728 5y agoI like the feel of polyester shirts better in hot weather. But I don't buy polyester or polyester blends anymore because they stink after just an hour or two of sweating in the sun. Merino doesn't have the same "cooling" feel but is good at wicking away and evaporating sweat, which helps your body keep a consistent temperature as long as you're hydrated. And merino doesn't reek like polyester clothing.
- dwighttk 5y agoWonder how it holds up to laundering/drying. Remember those shirts that changed color based on temperature but couldn’t be put in the dryer?
- jeffkeen 5y agoHypercolor! God yeah I remember those. I wanted one so badly when I was a kid but it never happened.
- dwighttk 5y agoI listened to a podcast about their history... didn't realize the fad didn't last more than a year: https://www.omnibusproject.com/42 https://www.omnibusproject.com/42
- elric 5y agoOr those coats coated in water-repellant stuff .. which washes off and is apparently rather toxic.
- thebean11 5y agoCan't you just spray that stuff on anything? I've seen it sold for hats and shoes
- lurtbancaster 5y agoHonestly, you shouldn't have to wonder. The article is of poor quality. Given the concerns regarding microplastics release from the fabrics we wear causing environmental pollution in recent years, it would behoove any respectable science journalist/publication to press for answers to these "common sense" questions. Especially when they also seem so eager to mention >"Ma and Tao are now reaching out to textile manufacturers and clothing companies to try to get their fabric on shelves. They say the nanomaterial-infused fabric should add only about 10% to typical clothing manufacturing costs. “We can make it with mass production, which means everybody can get a T-shirt … and the cost is basically the same as their old stuff,” Ma says. “It can benefit everybody.”" Sure...and that's why stuff like PVC - one of the worst offenders of releasing microplastics into the water when washed - which was previously only used sparingly by professionals because human life depended on their using it but has sadly now come to be worn by a lot more people as a "fashion piece" way more frequently. The full paper appears to be paywalled? https://science.sciencemag.org/content/early/2021/07/07/science.abi5484 https://science.sciencemag.org/content/early/2021/07/07/scie... . Here's the Abstract - "Incorporating passive radiative cooling structures into personal thermal management technologies could effectively defend human against the intensifying global climate change. We show that large scale woven metafabrics can provide high emissivity (94.5%) in the atmospheric window and reflectivity (92.4%) in the solar spectrum because the hierarchical-morphology design of the randomly dispersed scatterers throughout the metafabric. Through scalable industrial textile manufacturing routes, our metafabrics exhibit excellent mechanical strength, waterproofness, and breathability for commercial clothing while maintaining efficient radiative cooling ability. Practical application tests demonstrated the human body covered by our metafabric could be cooled down ~4.8°C lower than that covered by commercial cotton fabric. The cost-effectiveness and high-performance of our metafabrics present great advantages for intelligent garments, smart textiles, and passive radiative cooling applications." Again, no mention of environmental impact. Also I don't know if this common is material sciences or not, so bear that in mind; but that Abstract reads like a pitch to VC firms to fund their startup. Am I wrong?
- deleted 5y ago[deleted]
- jschwartzi 5y agoThe need for the material to be tight fitting isn’t actually a problem for athletic wear. If you’re wearing a wicking shirt you would also want it to be tight fitting. And a lot of rash guards will be tight because they wick in addition to providing uv protection. So I’m skeptical that the researchers really understand the applications for their material. There’s also no discussion of how it performs when it gets wet.
- DiffEq 5y agoIf it is like a mirror then what about people around you getting all that light reflected back into their eye - light which they can't really "see"? Seems like if you are around something like that all day where multiple people are wearing such clothes that it could possibly be damaging?
- drak0n1c 5y agoIf it is a cloth with a cloth's texture it wouldn't be bad since it would be reflected in such a diffuse pattern. Besides getting it directly from the sun anyways, you're already getting harsher glare reflections off of water, glass buildings, and metallic surfaces (cars) all around you.
- smusamashah 5y agoCan it be used in reverse to keep the body heat in instead? If the body is producing the radiation, it should be usable in reverse.
- Kichererbsen 5y agoyou mean like a woolen jumper?
- mark-r 5y agoI think you just described a space blanket. In fact based on the title, I expected this to be one of those used backwards.
- leke 5y agoI need a pair of boxers made from this stuff.
- mrfusion 5y agoIf this sends the heat into space, what happens if you’re indoors? Would it still cool you?
- pjerem 5y agoIt reflects radiant heat, that is, the form of heat that is sent by the sun rays. There is no radiant heat indoors, only convective (the form of heat that is transferred through matter). So it would not cool you inside, no.
- mark-r 5y agoNot true, anything above 0 degrees K will radiate. The problem is that indoors it will get absorbed and re-radiated right back at you. The only way to lose the heat entirely is to have it radiate all the way to space.
- ur-whale 5y agoAll that's needed now is to produce enough of it wrap it around the earth.
- beebeepka 5y agoI've been waiting for something like this my entire life. I hope that fabric is good enough for producing underwear. Not even remotely overweight but I produce a considerable amount of extra heat. Seriously, whoever starts selling panties that cool my junk is going to be rewarded handsomely
- at_a_remove 5y agoI wonder how they do against UVA and UVB.
- chris_va 5y agoThe paper: https://advances.sciencemag.org/content/3/11/e1700895 https://advances.sciencemag.org/content/3/11/e1700895 And the paper for nanoPE: https://science.sciencemag.org/content/353/6303/1019 https://science.sciencemag.org/content/353/6303/1019 ... TLDR, they sandwiched a reflective and emissive surface inside of a thermally transparent material. Body heat convects to the surface (so it needs to be tight fitting), and the surface is radiatively coupled to the environment (emissive surface), but not to the body (reflective surface). You lose out on directly radiating body heat through the nanoPE, but that doesn't work well anyway. Anyway... it probably wouldn't work very well if the ambient temperature was high since it is absorbing LWIR from the environment. The article does mention MIR (MWIR) a few times, though. There isn't anything MWIR specific with this fabric, but the atmosphere is generally very cold in that band, so maybe LWIR can be reradiated in the MWIR by the fabric even when the ground temperature is at/above body temperature. The blackbody power in the MWIR at 98.6F is pretty poor, so it can't be much. They used an ambient temperature of 22.0C in the paper, which is kind of cheating (why bother with a cooling shirt at that temperature?). The LWIR coupling will help a lot at that temperature. Once the ambient gets close to human body temp, though, it'll not work nearly as well. One could run the numbers to see, the thermal model is pretty simple.
- bostonsre 5y agoThe military will love that stuff. Could you drape it over vehicles as well to hide from infrared optics?
- spockz 5y agoWouldn’t these shirts be extra easy to spot as they are essentially reflectors? It not really be helpful for hiding.
- bostonsre 5y agoInfrared optics work because humans and vehicles are warmer than their surroundings. Not sure if you would appear cooler than your surroundings at night and if so, if you would stand out more or less than a warmer object. Would expect the detectors to be tuned to look for warmer objects, but just a guess.
- moomin 5y agoJust to point out the obvious: this ain’t gonna make a blind bit of difference if wet bulb temperatures enter the kill zone, so do not rely on this to protect you from the effects of climate change.