Smart Glass Blocks Infrared - But Only When It's Hot

klevin writes "New Scientist has an article about a new way of making sheets of glass so they block infrared energy at temperatures above 29C (84.2F). Just so long as it doesn't have to get that hot on both sides of the glass. My AC comes on way before 84F. I suppose that with double or triple paned glass, you'd only treat the exterior pane."

Comments

window tinting?

[natron 2.0]

Sounds very similar to Ceramic window tinting film that is found on cars

Temperature of Glass

[Crazy Man on Fire]

My AC comes on way before 84F.

Looking at the article, it seems that it is the temperature of the glass that must reach 84F, not the temperature of the air inside the room. I would imagine that the glass reaches 84 much faster than the air inside, so your AC shouldn't be much of a factor unless it is cold enough to have a larger impact on the glass temp than the outside air and the solar energy.

Why Block When you can consume

[grunt107]

While the lowering of heat-causing agents is noble, the better scientific path (IMO) is to grab this energy and use it to power the home (solar).
Spend time and effort developing more efficient, resilient, and less-expensive tech on solar energy and every new house could be roofed with 100% solar tiles. These homes could even GENERATE enough exess energy to sell back to the grid, which would help every income level.
'Zero' dependence on energy businesses could be a very real thing for homes (oh the humanity)...

Re:84 degrees is okay for some things.

[value_added]

That said, I recall that while a significant percentage of heat comes from solar energy through windows... when the house is sitting in a 110 degree plain, it may not be quite as good as first thought.

What amazes me to this day is that a less hi-tech approach would be to plant a frigging tree. Cities here in Southern California still insist on cutting them down (ostensibly to save money from the city maintenance budgets). Without the shade, you get roofs and attic spaces that easily heat up to over 100 degrees and don't cool until 6-7 hours after nightfall.

Trouble

[dr_dank]

Won't this interfere with the thermal imaging cameras fire departments use to find people in fires?

Re:Trouble

[Anonymous Coward]

Won't this interfere with the thermal imaging cameras fire departments use to find people in fires?

Enter the next technological miracle: the axe.

something to be said....

[zogger]

... for the old ways of construction. 3 foot thick earth-type walls, low deep overhangs for shade. Maybe those old original settlers in the southwest weren't as backwards as we think, just because they didn't have cheap electricity.......

Re:can be used in cars

[misleb]

Ever notice how the inside of a car gets HOTTER than the outside air? That is from the sun's radiation, not conduction through the metal (or glass). If you could block the heat from the sun, cars would be much easier to cool and they might not get so damn hot when parked.

Re:Safe? Lifespan?

[mforbes]

Great idea-- but since both the layer and the glass filter the color, you end up with subtractive colors, not additive. With your solution (assuming the tone and density of the vanadium & dye layers match), no light at all gets through.

Re:Safe? Lifespan?

[Anonymous Coward]

You've never been in a building with double/triple pane glass? Where the fuck do you live, Kyrgyzstan? These windows are extremely common anywhere where heating and cooling costs are extreme. (the same places where heat-resistent glass would be useful

Re:84 degrees is okay for some things.

[Feanturi]

What amazes me to this day is that a less hi-tech approach would be to plant a frigging tree.

Given that they seemed most interested in using this glass on skyscrapers, those would need be some mighty tall trees! That, and I don't think I'd want to hang a smaller tree in front of my car either. :)

I thought visible light was the problem

[clone22]

Visible light comes through the window and is absorbed by materials which start radiating that energy as IR. Auto glass is better at transmission of visible light than IR, so inside of car gets hotter. If true, it would help to have better IR transmission than to limit IR transmission.

Bad in cars. Good in greenhouses

[Charles Dodgeson]

I haven't RTFA yet, so maybe they discuss this. But my (limited) understanding of why cars get so hot is because sunlight comes in in the visible range (to which the glass is fully transparent). It gets absorbed by stuff in the car and then re-emitted mostly in the IR range. Because the glass is already more transparent to visible light than to IR the heat gets trapped in the car.

If I am right about this, then cars would be exactly where you don't want this stuff.

Re:Roof gardens.

[valkraider]

Here in Portland, OR - they try and implement things like this, but then people just complain about the extra cost up-front.

When will Americans learn - if we build stuff cheap up front it is more expensive long term. If we spend more money up front, we save LOTS of money in the long term...

Oh, wait. That would be smart...

Grow Houses...

[okimsrazor]

Good for your neighbourhood grow house. Police Choppers with infared cameras fly overhead in search of heat blooms from grow houses. If it blocks it coming in, should block it going out too.

No sig... For shame.

MOD PARENT UP

[dcmeserve]

The amount of scientific illiteracy I'm seeing in this discussion is very disappointing -- I thought this was Slashdot!

Nature says you can't

[Engineer-Poet]

But why can't the consumptive tech be improved so solar collectors/transformers DO use ALL the heat (or the amount above xx Celsius)? Is this some law of nature where thermal can be blocked but not utilized?

Yes. It's called the second law of thermodynamics. You can't convert heat to more-useful forms without a heat "sink" at a lower temperature, and when your house is the thing at the lowest temperature and you want to cool it this is problematic. Just keeping the heat out is the easiest and most economical thing to do; heat that doesn't get in doesn't have to be pumped out again.