| Posted: Feb 26, 2018 |
Clever nanocoating opens door to smart windows
(Nanowerk News) Researchers from RMIT University in Melbourne Australia have developed a new ultra-thin coating that responds to heat and cold, opening the door to "smart windows".
|
|
The self-modifying coating, which is a thousand times thinner than a human hair, works by automatically letting in more heat when it's cold and blocking the sun's rays when it's hot.
|
|
Smart windows have the ability to naturally regulate temperatures inside a building, leading to major environmental benefits and significant financial savings.
|
|
Lead investigator Associate Professor Madhu Bhaskaran said the breakthrough will help meet future energy needs and create temperature-responsive buildings.
|
 |
| Mohammad Taha shows off the ultra-thin coating developed at RMIT University. (Image: RMIT University)
|
|
"We are making it possible to manufacture smart windows that block heat during summer and retain heat inside when the weather cools," Bhaskaran said.
|
|
"We lose most of our energy in buildings through windows. This makes maintaining buildings at a certain temperature a very wasteful and unavoidable process.
|
|
"Our technology will potentially cut the rising costs of air-conditioning and heating, as well as dramatically reduce the carbon footprint of buildings of all sizes.
|
|
"Solutions to our energy crisis do not come only from using renewables; smarter technology that eliminates energy waste is absolutely vital."
|
|
Smart glass windows are about 70 per cent more energy efficient during summer and 45 per cent more efficient in the winter compared to standard dual-pane glass.
|
|
New York's Empire State Building reported energy savings of US$2.4 million and cut carbon emissions by 4,000 metric tonnes after installing smart glass windows. This was using a less effective form of technology.
|
|
"The Empire State Building used glass that still required some energy to operate," Bhaskaran said. "Our coating doesn't require energy and responds directly to changes in temperature."
|
|
Co-researcher and PhD student Mohammad Taha said that while the coating reacts to temperature it can also be overridden with a simple switch.
|
|
"This switch is similar to a dimmer and can be used to control the level of transparency on the window and therefore the intensity of lighting in a room," Taha said. "This means users have total freedom to operate the smart windows on-demand."
|
|
Windows aren't the only clear winners when it comes to the new coating. The technology can also be used to control non-harmful radiation that can penetrate plastics and fabrics. This could be applied to medical imaging and security scans.
|
|
Bhaskaran said that the team was looking to roll the technology out as soon as possible.
|
|
"The materials and technology are readily scalable to large area surfaces, with the underlying technology filed as a patent in Australia and the US," she said.
|
|
The research has been carried out at RMIT University's state-of-the-art Micro Nano Research Facility with colleagues at the University of Adelaide and supported by the Australian Research Council.
|
|
Their findings have been published in Scientific Reports ("Insulator–metal transition in substrate-independent VO2 thin film for phase-change devices").
|
How the coating works
|
|
The self-regulating coating is created using a material called vanadium dioxide. The coating is 50-150 nanometres in thickness.
|
|
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.
|
|
The coating stays transparent and clear to the human eye but goes opaque to infra-red solar radiation, which humans cannot see and is what causes sun-induced heating.
|
|
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, or platforms.
|
|
The RMIT researchers have developed a way to create and deposit the ultra-thin coating without the need for these special platforms - meaning it can be directly applied to surfaces like glass windows.
|
