Some window coatings reflect heat. Unfortunately, they also keep out the sun's warmth when outside temperatures are chilly. Now, chemists in England have created a window coating that automatically transforms into a heat mirror only when warmed above room temperature. The material is made of vanadium dioxide imbued with traces of tungsten.
Compared with clear glass, the film in its heat-reflecting state could reduce by up to half the amount of room heating due to infrared radiation, estimates Ivan P. Parkin of the University College London. He and Troy D. Manning of Liverpool University in England describe their new coating in the Aug.