12 mo. ago • 99%

Ultra-white ceramic cools buildings with record-high 99.6% reflectivity

newatlas.com Ultra-white ceramic cools buildings with record-high 99.6% reflectivity

Scientists in Hong Kong have demonstrated a new ultra-white ceramic material that can drastically cool buildings by reflecting sunlight and heat at record highs. The beetle-inspired material gets its ability from its nanostructure, stays tough to the elements and should be relatively easy to scale…

Ultra-white ceramic cools buildings with record-high 99.6% reflectivity::undefined

Hacker News @derp.foo Ultra-white ceramic cools buildings with record-high 99.6% reflectivity

85 comments

You know what also cools houses down super efficiently?

Trees

106
- Excellent - how many trees can I grow on my roof? Can they be retrofitted?
  
  /s
  
  42
  
  Is your roof flat? Many. /s
  
  18
  
  Trees? Not many. Grasses, herbs, wildflowers, and shrubs? Tons of them. And you can pretty easily retrofit over an existing sloped roof. And the weight is no more than a tiled roof.
  
  6
  
  Kind of
  
  There are eco apartments (planning idk about practice); grass on the roof and trees growing up the side
  
  Lakehead University Orillia was going to do this for a new building but I don’t know what happened
  
  2
- You know what cools roofs and generates electricity? Magic!
  
  Another trick: bifacial panels oriented to pick up the reflected light from highly reflective roofs
  
  13
- What about Ultra white ceramic trees?
  
  8
- True though this is still practical for folks who live in deserts and other treeless places
  
  4
- They also dampen noise
  
  1
- but trees look gross
  
  -2
NightAHawkinLight on youtube has been working on something similar. same kind of snow-like nanostructure to reflect light away, but with the added benefit of a paint that emits light in a wavelength that travels through the atmosphere without interacting with any of it.

so if you point a painted tile at the sky it will actually cool below ambient temperature, it's pretty wild https://www.youtube.com/watch?v=N3bJnKmeNJY

103
- Tech Ingredients did a video about it as well. https://www.youtube.com/watch?v=dNs_kNilSjk
  
  The biggest problem with making stuff white and using fancy materials is the amount of crap they get exposed to.
  
  Moisture is one issue, both in the form of water vapor / condensation as well as rain. But there's also smallish animals, like birds and cats that crawl around on roofs. Not to mention all the insects. Then there is the normal sand and dust in the air, plus all the pollution. Depending on where you live, white stuff gets really dirty within weeks or months.
  
  I work in a white office building and they have it cleaned with pressure washers twice a year, it takes a whole climbing team a good two weeks to clean the whole thing and it looks dirty again after a few months. And that's just a white form of plastic (HPL) you can blast away on, without causing damage. With these fancy meta materials often they are really fragile and any damage undoes the special properties.
  
  69
  
  Here is an alternative Piped link(s):
  
  https://www.piped.video/watch?v=dNs_kNilSjk
  
  Piped is a privacy-respecting open-source alternative frontend to YouTube.
  
  I'm open-source; check me out at GitHub.
  
  8
  
  They could just put a layer of something like Teflon over it. That's why crosswalk stripes feel so slick.
  
  5
- Here is an alternative Piped link(s):
  
  https://www.piped.video/watch?v=N3bJnKmeNJY
  
  Piped is a privacy-respecting open-source alternative frontend to YouTube.
  
  I'm open-source; check me out at GitHub.
  
  8
- So blue high reflective?
  
  0
In other news, snow blindness is on the rise in suburbia.

57
- Wait, so suburbians aren't able to see white people? This'll be hilarious. 🤣🤪🍿
  
  -32
Super awesome. Not only is it white and shiny aluminum oxide, it uses a nanostructure, as observed on beetles, to maximize reflection, minimizing heat retained.

39
- What's the gains in contrast to regular white bathroom tiles? (Not a joke question)
  
  19
  
  The reflectivity of "normal" ceramic is only around 60%
  
  28
But what about it getting dirty and how well does it resist having its nano structure getting damaged? Like, there's that spray that can make sneakers or clothes virtually stainproof....until you wear them several hours or rub your hand against them.

37
Probably illegal here because of the high reflective value. Depending on the sun's position, it could dazzle and blind people, e.g. people driving cars or riding bikes. I know that for this reason, shiny metal roofs are not allowed.

34
- There is a difference between mirror like reflection and diffuse reflection. Mirror reflection is what you get with metal roofs which beam the sun directly to a target resulting in one spot being blinded. Diffuse reflection will spread it around, resulting in more light all around which is what we can handle as humans.
  
  38
  
  Can mostly handle. Snow blindness is a thing, and that's all diffuse reflection too, not specular. But it's unlikely a roof would be such a problem.
  
  31
- It's not visibly reflective. Yes, it's white, but it's cool to the touch because the majority of the energy is radiated out into space via non-visible wavelengths. Someone has already posted a great YouTube video from Night Hawk In Light in a comment where he explains how this tech works and makes his own paint!
  
  19
  
  Yeah, it's good to read the article before commenting.
  
  Here's a link to the Night Hawk video. Good stuff. https://invidious.fdn.fr/watch?v=KDRnEm-B3AI This guy just gives away a formula he developed for the pigment. OG shit.
  
  12
- I have aluminium foil covering my windows in summer and that doesn't blind anyone by far, even in full sunlight.
  
  Not everything reflecting is a mirror.
  
  2
Scotland here. Does this come in black?

24
Would we ever be able to use a material like this to reflect a significant enough portion of the light falling on Earth to reduce the total heat imparted by sunlight in a meaningful way? Could we use this as defacto ice caps to perhaps reduce global temperatures in any real way?

18
- Probably yeah, but more likely it would have to be atmospheric and not surface based. When Mount Pinatubo erupted in 1991 it was estimated that the global temp dropped about 0.5 degrees C over the ensuing year due to the ash cloud blocking the sun
  
  https://pubs.usgs.gov/fs/1997/fs113-97/
  
  11
  
  So the actual solution to climate change is to light everything on fire so the smoke cover cools down earth
  
  10
- The only feasible plan we have for increasing the albedo of the planet overall is atmospheric engineering. Basically you can make a reflective cloud that’s millions of square miles in area, many orders of magnitude more cheaply than any other kind of structure.
  
  7
- Covering our roofs with it would certainly make a difference. BUT, it works in the winter too, cooling the house when we want it warm. So, that might increase the need for heating in the winter.
  
  Personally, I'm waiting for a commercial product, because my NM house has a large, south-facing stucco wall that is currently white, but not ultra cool white. Given my experience with the house, which is well insulated, I expect I could paint the house with such paint and not need any other cooling, even when it hits 100+F here. That wall is my bedroom wall, and I can feel the heat pushing through it in the late afternoon after a full day of exposure to the sun.
  
  4
  
  In winter my roof is covered with snow. White roofing would absorb less heat from the snow but that may be a good thing, reduce melting.
  
  3
  
  Could throw some tarps over it, but that'd be difficult and expensive
  
  1
Is this what they meant about a "bright future ahead of us"?

15
Imperial March begins to play

10
- My thoughts exactly at first glance! At least, now we know why some people think storm troopers are so cool.
  
  5
Next trick: make it into a paint or spray-on treatment.

8
- Better yet, make a giant sheet of it and float it in the ocean to fix the earth's albedo and stop climate change.
  
  3
  
  Wernstrom!
  
  2
  
  The copepods and algaes also need the light to draw down assloads of carbon though. Those tiny creatures suck up staggering amounts.
  
  2
- Oh, great idea! A nanoparticle ceramic aluminum oxide aerosol? What could possibly go wrong? 🤣
  
  -2
  
  lol, it doesn’t have to be aerosolized in order for it to be sprayed. It can come out of a spray hose nozzle and be appropriately viscous. Workers can wear PPD.
  
  6
  
  Maybe a paint that you put on with a hairy stick brush would be better?
  
  1
"And if white is too boring for some houses, the material can apparently be produced in other colors and patterns by adding extra layers."

This is nice. I mean not that it should matter, but I guess it will be important to some people. Unfortunately the article ends there, it would be interesting to know if another layer changes the cooling effecitivity.

5
- I would bet there are reasons other than aesthetics at play. That's the kind of paint you would want to use on your house in the Arizona desert, but I imagine driving by a bunch of houses with 99.9% reflectivity at the wrong time of day would be blinding.
  
  Optimistically, this may be the discovery that leads to our future when everything looks like an iPhone.
  
  9
So there’s gotta be a downside to reflecting all this heat though?

I know windows sometimes can focus and reflect the sun setting your neighbours house on fire, birds aren’t going to affected, bugs?

4
- It looks like this reflects and scatters the light, rather than reflects and focuses it. Otherwise it would look like a mirror, not a ceramic.
  
  13
  
  That would only matter for something that it can focus on, it’s still reflecting. All the heat and at scale it’s not tested.
  
  Adding more heat and heat currents into the atmosphere, cannot be a good thing long term.
  
  -4
- Not if it's reflected back into space.
  
  2
- If the top of my head
  
  it cools your house in the winter, too
  
  It's probably annoyingly bright if you can see the roof from ground level
  
  likely to degrade over time necessitating replacing tiles to maintain the effect
  
  Doesn't work as well if you've got solar panels or trees obstructing it
  
  other stuff, probably
  
  0
Why ceramic and not just paint?

4
- The article addresses that. It is because ceramics are durable while paints and coatings are not.
  
  14
  
  Seems like the effort involved in putting down paint would outweigh the durability. Perhaps they’re thinking about robots to place the tiles though, like on Starship?
  
  2
- Most coatings like paint that have this effect include ceramics to do most of the reflection, but the other paint stuff the ceramic substrate is emulsified in does not have near the reflectivity, so you're impairing yourself if reflectivity/heat rejection is the only goal.
  
  5
- Maybe ceramics were considered more sustainable?
  
  2
Ceramic is brittle. Ever heard of hail?

3
Just a video on how to make high-reflective paint.

1
- Here is an alternative Piped link(s):
  
  how to make high-reflective paint
  
  Piped is a privacy-respecting open-source alternative frontend to YouTube.
  
  I'm open-source; check me out at GitHub.
  
  1
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