These days the energy cost per hour required to regulate interior building temperature is considerable. The depletion of our natural resources makes it more important than ever to find new ways of saving energy. Now it’s no secret that windows are one of the principal sources of heat loss in winter, and that sunshine hitting your window pane in summer can rapidly transform your abode into a furnace.
With this in mind, the work carried out by Sarbajit Banerjee, Researcher at the University of Buffalo, is of crucial importance, since he may have developed, by using vanadium, a type of glass whose properties change according to the temperature.
Windows that reflect heat
Banerjee is certainly not the first to have considered windows as a way to limit energy loss from buildings, but the various systems that exist have inconvenient side effects. Apartments fitted with insulating windows sometimes transform into baking ovens, often with the added concern of mould and bacteria.
Better developed systems can regulate the inside temperature by “deciding” what quantity of heat should be expelled outside. But the use of such systems can be complicated, requiring sophisticated electronic equipment, which itself consumes energy. In other words, they can be counter-productive.
Sarbajit Banerjee’s Intelligent Windows
To get around these problems and to find a way to regulate interior temperatures without requiring electronics the American researcher had the idea of covering glass with a layer of vanadium oxide.
Vanadium is a curious material: when heated it changes state, but remains solid. As Banerjee explains, /“it doesn’t melt, but radically changes its properties, from a solid which transmits sunlight to another solid which blocks it completely, without losing any luminosity.”/
The main problem is that the temperature of transition for vanadium is 57°C, which is a little high to offer any benefit to households. There exists, however, materials with similar synthesis properties and with a transitional temperature much lower than that of vanadium, but they are more difficult to produce and would make the price of intelligent windows skyrocket. So the American Researcher and his team had the idea of shrinking the vanadium oxide into a nano-material and, by combining it with tungsten, they have succeeded in bringing down the transitional temperature to 29°C. Still a little too hot, obviously, but Sarbajit Banerjee insists he is capable of bringing it down further to something more usable, closer to 20°C which would be suitable for home use.
That said, there remains another problem to resolve: vanadium oxide is not transparent, it has a greenish-yellow tint. One imagines that people are not going to fall over themselves to buy windows that make their living space look like a morgue. However the scientists insist that this obstacle will be overcome soon.
Future developments
So the technique is not yet finalised, but the National Renewable Energy Laboratory (NREL), attached to the American Ministry of Energy is already interested. It will be about developing windows to fit buildings habitually cooled by air-con, notably in places known for incessant heat, like Las Vegas.
According to the Researcher, he needs to find a way to mass produce these windows. A challenge which he imagines doable within five years. /“The material is relatively abundant”/ he declares /“and not too expensive”/. With this in mind he envisages other possible uses for vanadium oxide, such as computer components, night vision instruments or even in missile guidance...
Sources
RCSA, Cottrell Scholar Awards.
Raphaelle OBrien - A translator of English and Russian into French, Raphaelle O'Brien also writes articles on cinema as well as literary columns for various ...
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