Good Thinking

Liquid-filled window absorbs solar heat by day, releases it at night

Liquid-filled window absorbs s...
The liquid within one of the smart windows begins to turn opaque as it's warmed by the sun
The liquid within one of the smart windows begins to turn opaque as it's warmed by the sun
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Before and after photos of one of the smart windows, the bottom half of which incorporates the new technology
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Before and after photos of one of the smart windows, the bottom half of which incorporates the new technology
The liquid within one of the smart windows begins to turn opaque as it's warmed by the sun
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The liquid within one of the smart windows begins to turn opaque as it's warmed by the sun

While double-glazed windows do help save energy, Singaporean scientists have tweaked the concept to make it even more effective. Instead of leaving an air gap between the two panes of glass, the researchers have inserted a heat-absorbing, light-blocking liquid.

Developed at Nanyang Technological University, the experimental new "smart window" consists of two panes of ordinary glass, the space between which is filled with a solution consisting of a proprietary hydrogel, water, and a stabilizing compound.

During the day, as sunlight passes through the window, the liquid absorbs and stores that light's thermal energy. This keeps the room from heating up, reducing the need to run the air conditioning.

Additionally, as the liquid warms up, the hydrogel within it changes from a transparent to an opaque state. Although this ruins the view out of the window, it also reduces the amount of visible light that passes through from outside, further helping to keep the room cool.

Before and after photos of one of the smart windows, the bottom half of which incorporates the new technology
Before and after photos of one of the smart windows, the bottom half of which incorporates the new technology

When the sun goes down at night, the gel cools and becomes clear again, releasing the stored thermal energy. Some of that energy passes through the glass and into the room, reducing demands on the building's heating system.

And as an added bonus, the smart window reportedly absorbs exterior noise 15 percent more effectively than traditional double-glazed windows.

Based on simulations and real-world testing, it has been determined that use of the windows could reduce energy consumption in office buildings by up to 45 percent. The university is now looking for industry partners to help commercialize the technology, which is described in a paper that was recently published in the journal Joule.

Scientists at Britain's Loughborough University have been working on a similar system, although theirs utilizes plain water. Once that water has been heated by the sun, it's pumped out of the window and stored in a tank. At night, the warm water is then pumped out of the tank and into pipes in the walls, heating the interior of the building.

Source: Nanyang Technological University

11 comments
clay
Such a no-brainer! Very cool.

This looks like a DIY project for the brave "it's only a small leak" Maker!
cafezinh062
On a hot night in summer the last thing you want is extra heat coming from your windows.
Username
And 5 years down the line you get to deal with water damage.
Nelson Hyde Chick
It isn't a window anymore if you can't see out of it.
michael_dowling
The British concept is more attractive.You don't lose the view,and warm water is stored for evening heating,good in winter.
Don Duncan
We all want a view, but quickly ignore it. How many people think: "I love my job because of my office windows," How often do you stand and gaze out the window, admiring the view? The same applies to homes. I know because I had a spectacular view for three years from wrap around windows on Lake Tahoe. One reason I chose the house was because of the view. Every time new people walked in the first impression was the view, which they mentioned. I was reminded by this that I seldom noticed it after the first few weeks. It was like have a million dollar masterpiece on the wall. Soon it goes unappreciated.
I was advised by an observant successful realtor that the view makes a great first impression but it quickly losses its appeal. I verified that from experience.
Therefore, if light is needed, get it from skylights without compromise of insulation integrity.
Pablo
Great, I won’t need to wait that pesky 10-15 years for my new windows to go cloudy... as a bonus, they’ll clear just when I want privacy!
Signguy
Yup, as in the Sign bizz, the mistakes or problems that can "glare" at a customer disappear after a few weeks; human nature.
stevendkaplan
This invention is stupid. Nobody wants a window that’s going to fog up when it gets hot.
The deerhunter
It would be nice if the solar gel was stabilized so as not to easily leak through small apertures.