| 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". |
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| 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. | |
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| 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 |
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| 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. |
| Source: RMIT University | |
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