Engineers open door to smart windows

Engineering research at RMIT has led to the development of an ultra-thin coating that reacts to heat and cold, letting in more warmth when the weather is cool and blocking the sun’s rays as the mercury rises.
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Engineers open door to smart windows

Engineering research at RMIT has led to the development of an ultra-thin coating that reacts to heat and cold, letting in more warmth when the weather is cool and blocking the sun’s rays as the mercury rises.

The self-modifying coating is only 50-150 nanometres thick, but has the potential to lead to major environmental benefits and significant financial savings, according to Associate Professor Madhu Bhaskaran.

New York’s Empire State Building is known for installing smart glass windows with reported energy savings of US$2.4 million and cutting carbon emissions by 4000 metric tonnes - and this was with a less effective form of the technology.

“The Empire State Building used glass that still required some energy to operate,” A/Prof Bhaskaran said. “Our coating doesn’t require energy and responds directly to changes in temperature.”

The coating was created using vanadium dioxide. At 67 degrees Celsius, vanadium dioxide transforms from being an insulator into a metal, allowing the coating to turn into a versatile optoelectronic material controlled by and sensitive to light. It stays transparent/clear to the human eye, but goes opaque to infra-red solar radiation, which humans cannot see and this causes sun-induced heating.

Up until now, it has been impossible to use vanadium dioxide on surfaces of various sizes because the placement of the coating requires the creation of specialised layers. The RMIT engineers have developed a way to create and deposit the ultra-thin coating without the need for these layers so it can be directly applied to surfaces like glass windows.

The technology can also be used to control non-harmful radiation that can penetrate plastics and fabrics and could be applied to medical imaging and security scans, the team said.

A/Prof Bhaskaran called the RMIT’s research a breakthrough that will create temperature-responsive buildings.

“We lose most of our energy in buildings through windows. This makes maintaining buildings at a certain temperature a very wasteful and unavoidable process,” she said. “Solutions to our energy crisis do not come only from using renewables; smarter technology that eliminates energy waste is absolutely vital.”

The materials and technology are readily scalable to large area surfaces, and the underlying technology has already been filed as a patent in Australia and the US and is ready to roll out, according to A/Prof Bhaskaran.

The research findings have been published in Scientific Reports – Nature.

 

Image: The Empire State Building in the US has smart windows, but RMIT engineers have gone one step better. Image source: RMIT.