​NTU Singapore Scientists Develop Energy-Saving 'Liquid Window'

The NTU scientists say their 'liquid window' reduces energy consumption by up to 45 percent.
Chris Young

Scientists at the Nanyang Technological University (NTU) in Singapore have developed a "smart window" that consists of a liquid solution, kept between two glass panels, that can block out the sun.

In doing so, the solution traps thermal heat, which is later released at night once the windows have cooled down. The result? Less need for air conditioning during the day and less reliance on heating by night.

The heat-absorbing, light-blocking liquid is housed in between two glass panels, where a double-glazed window would leave an air gap.


Smart windows for lower energy consumption

The NTU Singapore researchers' experimental "smart window" is made of ordinary glass and uses a liquid mixture of micro-hydrogel, water, and a stabilizing compound.

During the day, as sunlight passes through the window, the liquid absorbs and stores the sunlight's thermal energy, preventing it from heating up the room and reducing the need to use air conditioning.

What's more, as the liquid warms up, the hydrogel in the solution changes to an opaque state, which further helps to block out the light and keep the room cool.

In the evening, the gel cools down and becomes clear once again, releasing part of the stored thermal energy into the room, reducing the need for heating at night. 

Aside from presenting a handy way to reduce a user's utility bills — with the rather large caveat that any nice views out of the window are obscured during the day — the researchers say their window also presents the added benefit of absorbing exterior noise 15 percent more efficiently than traditional double-glazed windows.

A difficult trade-off?

As per New Atlas, the researchers are now looking for industry partners to develop their technology with commercialization in mind.

"Our innovation combines the unique properties of both types of materials – hydrogel and water. By using a hydrogel-based liquid we simplify the fabrication process to pouring the mixture between two glass panels. This gives the window a unique advantage of high uniformity, which means the window can be created in any shape and size," Dr. Long Yi, lead author of the research study which is published in the journal Joule, explained in an NTU Singapore press release.

Based on simulations and real-world tests, the NTU Singapore researchers say their windows could reduce energy consumption in office buildings by up to 45 percent. One of the big questions they face, however, is will potential consumers for these smart windows be willing to trade visibility for lower energy consumption?

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