Cool and clear: New window coating blocks heat-generating UV rays without sacrificing clarity

[Shawn Knight]

In brief: Researchers from the University of Notre Dame have developed a new window coating that promises to block heat-generating infrared and ultraviolet light while allowing visible light to pass unimpeded. The coating could reduce air-conditioning costs in warm climates by more than a third, all without compromising the view.

Sun blocking window film and coatings have been around for decades, but they are not all created equal. Many are designed to work best when light enters at a 90-degree angle but in the real world where the angle is constantly changing due to the position of the Sun in the sky, effectiveness can vary.

Professor Tengfei Luo and his postdoctoral associate Seongmin Kim previously developed an ultra-thin window coating by stacking layers of silica, alumina, and titanium oxide onto a glass base. A silicon polymer, like what is used on contact lenses, was also added to enhance its cooling abilities.

The order of the layers played a key role in the coating's capabilities. To find the optimal configuration, Luo and Kim needed to test every possible arrangement. This wasn't practical in the real world due to the sheer number of possible combinations, so they turned to tech - quantum annealing, to be exact.

The end result was a 1.2 micron-thick coating that is said to outperform all other heat-reducing glass coatings on the market. In testing, their solution was able to reduce room temperature by 5.4 – 7.2 degrees Celsius.

Luo likened the coating to polarized sunglasses in that they lessen the intensity of incoming light. Unlike sunglasses, however, Luo said their coating remains clear and effective even when you tilt it at different angles. Best yet, the coating can be applied retroactively to existing windows and even be used on automobile glass. The quantum annealing test approach, meanwhile, can be adapted to help design other materials with complex properties.

The team's research has been published in Cell Reports Physical Science. No word yet on commercial availability.

Image credit: Scott Webb

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Cool and clear: New window coating blocks heat-generating UV rays without sacrificing clarity

 

[Lew Zealand]

"No word yet on commercial availability."

commercial viability > commercial availability

 

[Uncle Al]

In any case, this one will be a BIG winner ......

 

[The Talking Tech]

What about windows that could actually take advantage of that much solar rays, sort of like transparent solar panels?

I know there will be a day in which we will say "why didn't we work of that idea decades ago?"

 

[daffy duck]

What about windows that could actually take advantage of that much solar rays, sort of like transparent solar panels?

I know there will be a day in which we will say "why didn't we work of that idea decades ago?"

Being worked on as we type.

As for the thin film tech, the maths is very cool, used to do a lot of this stuff many years ago. I'm surprised the research team didn't use AI to test the millions of permutations of layers thickness, material and order to reduce the number of candidates to test. AI is performing miracles in material science and drug design.

 

[Theinsanegamer]

What about windows that could actually take advantage of that much solar rays, sort of like transparent solar panels?

I know there will be a day in which we will say "why didn't we work of that idea decades ago?"

Because making transparent solar panels is actually REALLY HARD, doubly so when you need them to have the strength of windows and be affordable all at once.

Shocking, I know.

 

[The Talking Tech]

Because making transparent solar panels is actually REALLY HARD, doubly so when you need them to have the strength of windows and be affordable all at once.

Shocking, I know.

Funny how we figured how to get to the moon and back in the 1960's but we can't figure how to make solar panels that can work as windows in 2024.

Shocking, I know.

 

[Lew Zealand]

Funny how we figured how to get to the moon and back in the 1960's but we can't figure how to make solar panels that can work as windows in 2024.

Shocking, I know.

With a 1% efficiency, transparent solar panels are pretty meh and that's before the problem that they receive low angle or zero sunlight for the majority of the day.

 

[The Talking Tech]

With a 1% efficiency, transparent solar panels are pretty meh and that's before the problem that they receive low angle or zero sunlight for the majority of the day.

My point still stands...how is it that it seems far more difficult in 2024 to make windows work as solar panels than going to the moon and back in 1969 with technology no greater than a kids calculator.

The thing is that back in the 1960s we were actually motivated to break ground, and we accomplished what it seemed impossible, nowadays any breakthrough depends on someone's bottom line no matter how insignificant the effort might be.

 

[Lew Zealand]

My point still stands...how is it that it seems far more difficult in 2024 to make windows work as solar panels than going to the moon and back in 1969 with technology no greater than a kids calculator.

The thing is that back in the 1960s we were actually motivated to break ground, and we accomplished what it seemed impossible, nowadays any breakthrough depends on someone's bottom line no matter how insignificant the effort might be.

Yes we were and that motivation was the Cold War. Military motivation and MONEY by proxy. And when one side won the race to the moon, the motivation and money quickly dried up because been-there-done-that. And look at NASA now, it's done to a budget with keeping some projects in-house like unmanned solar system exploration and farming out big parts of the new moon landing projects to SpaceX and others.

Without military backing and budgets all other projects like transparent solar, new battery tech, thousands of others need to progress at a pace which is continuously financially feasible so comparing to the 1969 moon landings is apples and oranges.

 

[The Talking Tech]

Yes we were and that motivation was the Cold War. Military motivation and MONEY by proxy. And when one side won the race to the moon, the motivation and money quickly dried up because been-there-done-that. And look at NASA now, it's done to a budget with keeping some projects in-house like unmanned solar system exploration and farming out big parts of the new moon landing projects to SpaceX and others.

Without military backing and budgets all other projects like transparent solar, new battery tech, thousands of others need to progress at a pace which is continuously financially feasible so comparing to the 1969 moon landings is apples and oranges

Yes we were and that motivation was the Cold War. Military motivation and MONEY by proxy. And when one side won the race to the moon, the motivation and money quickly dried up because been-there-done-that. And look at NASA now, it's done to a budget with keeping some projects in-house like unmanned solar system exploration and farming out big parts of the new moon landing projects to SpaceX and others.

Without military backing and budgets all other projects like transparent solar, new battery tech, thousands of others need to progress at a pace which is continuously financially feasible so comparing to the 1969 moon landings is apples and oranges.

So you are saying I'm right...

It's not about how difficult it might be to accomplish such windows, but the fact that we don't want to do it.

 

[Lew Zealand]

So you are saying I'm right...

It's not about how difficult it might be to accomplish such windows, but the fact that we don't want to do it.

Wrong "want." Many people want to do it but almost all people don't want to pay the big bucks up front to develop the tech quickly.

Specifically the biggest-bucks government isn't interested in funding it other than tossing out a small innovation incentive once in a while, because it offers few immediately tangible advantages. This leaves it mostly to businesses/entrepreneurs to fund development which still need to make a profit (or look like they're going to soon) during the research and design stage, otherwise they go out of business. Small amounts of money spent over a longer time saddle us with annoyingly small incremental advances. Bleah.

 

[Endymio]

So you are saying I'm right...

It's not about how difficult it might be to accomplish such windows, but the fact that we don't want to do it.

Err, no. The vast majority of the sun's light is either in the visible spectrum or infrared. To generate power from light, you have to absorb it; if you absorb visible light, your window clarity vanishes, and most IR photons are below the minimum energy required to activate the photoelectric effect.

That only leaves the 4% or so that's ultraviolet: not nearly enough to be commercially viable.

 

[The Talking Tech]

Wrong "want." Many people want to do it but almost all people don't want to pay the big bucks up front to develop the tech quickly.

Specifically the biggest-bucks government isn't interested in funding it other than tossing out a small innovation incentive once in a while, because it offers few immediately tangible advantages. This leaves it mostly to businesses/entrepreneurs to fund development which still need to make a profit (or look like they're going to soon) during the research and design stage, otherwise they go out of business. Small amounts of money spent over a longer time saddle us with annoyingly small incremental advances. Bleah.

You keep going in circles just to say that such technology is not difficulty to accomplish but held back by money to make it possible.

So we agree.

 

[Lew Zealand]

You keep going in circles just to say that such technology is not difficulty to accomplish but held back by money to make it possible.

So we agree.

Not talking in circles and I do agree. I'm explaining why instead of just making a random claim.

 

[Lew Zealand]

Err, no. The vast majority of the sun's light is either in the visible spectrum or infrared. To generate power from light, you have to absorb it; if you absorb visible light, your window clarity vanishes, and most IR photons are below the minimum energy required to activate the photoelectric effect.

That only leaves the 4% or so that's ultraviolet: not nearly enough to be commercially viable.

It may be more nuanced than that, depending on what people want. In many places with lots of hot sunny days most of the year, darkening/reflecting the sunlight from outside or rejecting IR (which leaks over into the visible making these a little darker) is common already. So if these solar windows cut the incoming sunlight by a modest amount, say 20%, more than enough sunlight still makes it inside and the rest can be used for energy generation.

 

[Endymio]

So if these solar windows cut the incoming sunlight by a modest amount, say 20%, more than enough sunlight still makes it inside and the rest can be used for energy generation.

Absolutely; and there is some research being done on just such films. But passing 80% of the light obviously severely limits efficiency, in addition to the problem of transparency itself.