<p>A new, high-tech material, developed by engineers from Stanford University in Cali-<br />fornia, United States, cools buildings by reflecting sunlight and radiating internal heat, directing both out into space. <br /><br />Led by electrical engineer Professor Shanhui Fan and research associate Aaswath Raman, the team of engineers produced the ‘double hit’ method, which they refer to as ‘photonic radiative cooling’. <br /><br />The material is just 1.8 microns thick – thinner than the thinnest aluminium foil – and is made up of seven layers of silicon dioxide and hafnium oxide on top of a thin layer of silver. <br /><br />The layers are of different thicknesses, engineered to radiate infrared rays at a frequency that lets them pass out of the building and into the atmosphere without warming the surrounding air. <br /><br />The coating also acts as a highly efficient mirror, reflecting 97 per cent of the sun’s rays from its surface. It provides a highly efficient means of helping cool a building passively, reducing the need for air-conditioning.<br /><br />The researchers are now working out how to turn the material into a product that can be sprayed onto building surfaces and roof-tops for cost-efficient, large-scale deployment. </p>.<p>Achal Narayanan </p>
<p>A new, high-tech material, developed by engineers from Stanford University in Cali-<br />fornia, United States, cools buildings by reflecting sunlight and radiating internal heat, directing both out into space. <br /><br />Led by electrical engineer Professor Shanhui Fan and research associate Aaswath Raman, the team of engineers produced the ‘double hit’ method, which they refer to as ‘photonic radiative cooling’. <br /><br />The material is just 1.8 microns thick – thinner than the thinnest aluminium foil – and is made up of seven layers of silicon dioxide and hafnium oxide on top of a thin layer of silver. <br /><br />The layers are of different thicknesses, engineered to radiate infrared rays at a frequency that lets them pass out of the building and into the atmosphere without warming the surrounding air. <br /><br />The coating also acts as a highly efficient mirror, reflecting 97 per cent of the sun’s rays from its surface. It provides a highly efficient means of helping cool a building passively, reducing the need for air-conditioning.<br /><br />The researchers are now working out how to turn the material into a product that can be sprayed onto building surfaces and roof-tops for cost-efficient, large-scale deployment. </p>.<p>Achal Narayanan </p>
