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Making infrared cooling paint from grocery store items [video]
- ggm 3y ago[flagged]
- zeroping 3y agoWhile your comment is interesting discussion, I'm not sure the posted video is arguing for geohacking. I watched it last night and got more of a "here's a cool physics trick that seems like it has some real-world applications outside of a lab, and I did a lot of work to make it achievable outside of a research lab."
- Turskarama 3y agoI don't think anyone is talking about painting the desert with this stuff, so it isn't geohacking in any real sense. What you CAN do with this stuff is paint your roof and external walls with it, which will reduce the need for active cooling in your building. This both saves money for the purchaser (making it commercially viable) and reduces energy usage, which in turn reduces fossil fuel usage.
- hinkley 3y agoAll of which reduce the Heat Island Effect.
- blacksmith_tb 3y agoSeems like it would be a lot quicker / easier to pick up a few large sunshades? Coolaroo makes roller shades up to 10ft / 3m wide which are easy to mount under eaves (no association, except I installed one on a west-facing balcony and it works nicely), if your structure has a roof with those. Then you can block solar heat in the summer, but let it do what it can for you in the winter.
- Turskarama 3y agoPutting a shade under the eaves is great for shading a wall, but putting one over your roof is going to be an absolute pain to clean. Not to mention that your roof and walls may need paint _anyway_ depending on the material, so for new builds using it this is no added messing around.
- refulgentis 3y agoI think you may have skipped the article and assumed it was about e.g. sun-shading
- warning26 3y agoJust like in Snowpiercer!
- a1371 3y agoSince the last video I have been seriously thinking about making these powders as a hobby. The problem is that I want to mix them with some paint or resin to get a more permanent application. I know this needs some research but any ideas about where to start?
- analog31 3y agoA challenge is finding a resin that doesn't re-absorb the IR, which most materials do, even fairly thin layers.
- retrocryptid 3y agoWatch the video.
- fbdab103 3y agoEven if they work, I would question long-term stability. Would the panel still be productive after a year in the sun/rain/snow?
- KennyBlanken 3y agoWatch the video? He makes just such a thing.
- hcknwscommenter 3y agoHe makes something like that with acetone dissolved acrylic. It would be interesting to see what happens if you dispersed the microsphere material in a commercial paint. I think it would work?
- waysa 3y agoHe specifically engineered his particles to be as densely packed as possible. I assume the pigments in commercial paint would limit the cooling capacity. Probably that's why he went with a clear acrylic base (with bubbles to make it reflective).
- asimpletune 3y ago
- asd4 3y agoI wasn't familiar with the underlying effect. This paper seems relevant and is very readable. https://www.sciencedirect.com/science/article/abs/pii/S2352492822008443 https://www.sciencedirect.com/science/article/abs/pii/S23524...
- mjan22640 3y ago- absorption and radiation are correlated (a black surface would radiate more than a white surface when heated to 6000K (assuming they survive the temperature unchanged)) - a solid polished surface reflects better than a powder surface (thats imho a flaw in the article) - basically you want a surface that is white in solar and black in atmospheric
- trilbyglens 3y agoExactly. The trick here is that you're exploiting overlaps in emission and absorption spectra in the atmosphere.
- culopatin 3y agoOne of my high school professors touched on this when talking about heatsink design and I thought I remembered it wrong, glad to see it come up here.
- wessorh 3y agoSeems like a lot of work. Greenhouses sometime need shade so we coat them in 50lb bags of Hydrated lime (Calcium Hydroxide) which can be purchases for really cheap. While I enjoyed the video when I have thousands of squarefeet that need coverage hydrated lime works great.
- retrocryptid 3y agoHydrated lime doesn't cool the reflecting surface below ambient.
- 01100011 3y agoBut it turns into CaCO3 after absorbing CO2 from the air, no?
- OlympusMonds 3y agoYeah, but making lime is very energy intensive.
- mrob 3y agoIf the lifetime energy savings are greater than this energy cost then it's still a good idea. You only need a thin coating so it sounds plausible to me.
- retrocryptid 3y agoDid you read the paper?
- littlestymaar 3y agoWrong thread? (because there's no paper being discussed in this one…)
- retrocryptid 3y ago
- 0x53 3y agoI really like this guys videos. I have been thinking about this passive cooling concept for the last few years ever since I learned about skycool which is an attempt to commercialize a similar concept (radiative cooling). The main issue for most of the US is that you only want to cool for part of the year. one idea I had would be to paint blinds for windows or the louvered roof of a pergola with this type of paint so that you could open it and let the sun shine through when it is cold, but reject heat when it is hot. I’ve also tried to do some calculations for building a panel with blinds that could flip between black and cooling paint that could be hooked up to a heat pump. Both of these ideas exist on their own (see skycool panels and solar heat panels), but would be cool if you could combine them by having blinds that flip inside the panel. One of the main difficulties is that if it is cloudy outside the amount of heat the panels can reject or absorb is greatly diminished. So it may be that you need some way to store heat or cool. I think there has been some progress on this front using phase changing materials and there are now a few products that are commercially available. In any case, I think radiative cooling is an extremely cool concept and I’m excited to see what ways people come up with to harness it. Here is a video showing radiative cooling being used for interior cooling: https://youtu.be/CVginpnALL8 https://youtu.be/CVginpnALL8
- londons_explore 3y agoI am dubious of that interior radiant cooling design... I suspect the panels could easily end up below the dew point, especially in a room with lots of people in, and end up dripping water all over your kids birthday party.
- tgsovlerkhgsel 3y agoIt's used in commercial buildings, combined with a dew point monitoring system and some actual A/C to cool and dehumidify supply air. The downside is that if the dew point (and thus wet bulb temperature) gets too high, the panels shut down, so when you need them most they don't work and the building becomes a sauna.
- trilbyglens 3y agoThese don't work at all IN a room. They need to have a direct live of sight to the sky, or else you're just radiating the IR back into the room and you achieve no net cooling.
- acyou 3y agoI would like to see a comparison using a thermocouple. I'm not convinced with the measurements taken with a thermal camera. Further, the use of an insulator doesn't make for a great comparison. Is this any better than regular white paint?
- Azrael3000 3y agoYou can check out Tech Ingredients video [0] on the same topic, which will give an answer to your question. It is: Yes, it is better than regular white paint [0] https://www.youtube.com/watch?v=dNs_kNilSjk https://www.youtube.com/watch?v=dNs_kNilSjk
- londons_explore 3y agoUnfortunately that video is real science presented like quack science... which is in a way the worst of both worlds!
- justinsaything 3y agoAahh the appeal to be contrarian at all costs just to look smarter.
- acyou 3y agoThanks for the link. In my personal experience (and in the FLIR application guides) the main factor affecting paint emissivity is the glossiness (matte paint is much more emissive). I would have liked to see that test done with matte white paint, or at least have them mention that factor. From the video it was hard to tell, he said super bright Rustoleum, which isn't the same as matte. I would imagine emissivity to be more important that reflectivity given the result with aluminum (super reflective but still got super hot due to the extremely low emissivity). I like the use of the thermocouples, but unfortunately it didn't go quite far enough...
- icoder 3y agoThe fact that he measures the back of the plywood controls for quite a bit I think. At 3m27s into the vid you see the plywood that has the 'paint' on the _other_ side is even cooler than the square that had been in the shade all along. The insulator is just to prevent the plywood side that is measured to be heated by the ambient temp.
- londons_explore 3y agoI'm disappointed that governments haven't more aggressively forced this tech to be deployed commercially. Plenty of governments make building energy efficiency laws, because they realise that the commercial incentives of house-builders and house-owners and the national economy aren't well aligned. Yet these laws tend to disallow 'clever paint design' as a technique to reduce building energy consumption, despite plenty of academic papers demonstrating effectiveness.
- alhirzel 3y agoDoes anyone know what the reflectance (or emission) spectra are of this material?
- theresistor 3y agoI'm sitting in a sailboat in the boiling heat of Baja. I look forward to a day when I can paint the topsides with this.
- CGamesPlay 3y agoSailboats are an interesting use case. What percentage of the deck do you think you could apply it to? Assuming you want to keep your non-skid, and a bunch of the deck space is shaded by lines and sails. Apparently one of the problems here is that the paint has to be "very white", which I assume means that any dirt reduces the effectiveness. So that would be another challenge on the boat.
- trilbyglens 3y agoIn the vid he explains that this paint needs to be covered with a plastic layer to protect it and keep it bright white.
- CGamesPlay 3y agoYes but the plastic layer also needs to be kept very transparent. I assume the vid was talking about a cheap replaceable plastic coating, although plastic itself is probably also just more washable. Still, the top of boats gets dirty and most cruisers don’t keep it boat-show clean year-round!
- theresistor 3y agoMy boat's decks are entirely white, with non-skid molded into the gelcoat. If there were a way to suspend this pigment in gelcoat in a way that preserved its properties, this would be killer for boats.
- jansan 3y agoHas anybody ever applied this to a passive cooling box (that only uses insulation)? It would be interesting to see what temperatures can be achieved inside the box using the described effect.
- simonjgreen 3y agoThere is a detailed example of this uploaded a few months ago here https://youtu.be/5zW9_ztTiw8 https://youtu.be/5zW9_ztTiw8 [In fact, I just noticed the author of the OP video posted on this one]
- mozman 3y agoTech Ingredients has a better video on this https://youtu.be/dNs_kNilSjk https://youtu.be/dNs_kNilSjk