Sounds a bit far-fetched, but researchers at Stanford University have invented a strategy to do just this.
It is well established that electricity usage peaks during the summer months when air conditioning units are running practically non-stop. In fact, the existence of air conditioning has made it possible to live in even the most unbearably hot climates in the world, but the cost is significant both financially and to the environment. In the United States, 15% of energy costs are associated with air conditioning.
Aaswath Raman, lead researcher at Stanford, was looking for a passive way to cool buildings, without the use of electricity. He and his colleagues have developed a technology for buildings that will lower their cooling costs by projecting the heat into outer space. Dr. Raman notes that outer space is huge and very cold, making it an ideal sink for the tremendous amount of radiated heat that reaches the surface of buildings.
Dr. Raman and the research team invented a material, basically a reflecting skin that can radiate 97% of the sunlight that hits the building surface. The material consists of seven alternating layers of materials: four layers of silicon dioxide, with three layers of hafnium dioxide placed in between. The skin’s backing is made from a 220 nanometers layer of silver, which serves as a mirror. The final result is a covering that is less than two microns, functioning similar to a semiconductor, manipulating levels of energy.
There is still a bit of work to do. For one, Dr. Raman notes that the hafnium dioxide is very expensive. He wants to replace it with the much more affordable titanium dioxide. Also, the material can only be used where there is a direct vista to the sky so that the heat can be reflected straight to outer space. This means that only rooftops can be covered with the material. Buildings will still need some air conditioning units, but to reduce electricity while maintaining cooling comfort is already a great leap forward.