The thermal management of buildings is extremely energy-intensive and therefore problematic in terms of climate protection. This is particularly true in regions with large climate fluctuations. This is because some rooms have to be heated in winter and cooled in summer. The roof also plays a special role in this context. A large part of the heat arrives here in the form of sunbeams. At the same time, a lot of heat escapes through the large roof area. For some time now, there have been various roof constructions that cool down buildings in summer without external energy supply. The problem, however, is that the functionality cannot be switched off even in winter. This results in unnecessarily high heating costs on cold days. Researchers at the Berkeley Lab in the United States have now found a possible solution to this problem: a material that changes its properties above a certain temperature.
The desired effect was achieved by adding tungsten
The new discovery is called temperature-adaptive radiative coating – TARC for short. A material called vanadium dioxide serves as the basis. The researchers discovered an interesting property here a few years ago: the material is permeable to thermal radiation up to a temperature of 67 degrees Celsius. However, as soon as this temperature is exceeded, the heat rays are reflected. The researchers were then able to achieve decisive improvements in the laboratory. They replaced 1.5 percent of the vanadium with tungsten. This lowered the temperature threshold at which the material properties change to just 22 degrees Celsius. The material was then coated with a layer of barium fluoride and silver. This enabled the researchers to achieve the desired effect: if the temperature rises above thirty degrees, ninety percent of the thermal radiation is reflected. At less than 15 degrees, however, it is only twenty percent.
Smartphone batteries could also benefit from the technology
Through various tests, the researchers found that such a roof coating would result in significant energy savings in twelve out of fifteen climate zones. The effect is particularly strong in regions with large temperature fluctuations between summer and winter. According to the researchers’ calculations, an average US household could save around ten percent of its electricity consumption. With the current sharp rise in energy prices, this could be very attractive for many homeowners. The same also applies to the smart windows recently presented by researchers, which can also heat and cool as needed. Theoretically, the TARC coating can also be used in many other areas. For example, it is conceivable to coat smartphones with it on the outside. This could help extend battery life. Useful use would also be conceivable for cars and satellites.
Via: Inceptive Mind