With summer set to officially begin in a few short days, many are preparing their homes and bank accounts for air conditioning to be on almost all day.
On a much larger scale, it is expected that, worldwide, we will use 30 times more energy for air conditioning by the end of this century because of global warming. It's a vicious cycle, with air conditioning also contributing to global warming, yet global warming causing us to need to use air conditioning more.
That's precisely why we need to find new ways to cool our homes. A target for improvement? The roof. A typical roof essentially absorbs the heat from sunlight, heating up the home or building that it covers and releasing heat into surrounding areas at night when it is cooler. There is a new material, however, that is designed to stay cooler than the air around it.
"What we set out to do was maximize the solar reflectance to see how far it could be pushed ... to see the extent of further improvements that are possible with open roofing technologies," said Angus Gentle, a researcher from the University of Technology Sydney.
The roof is essentially made by adding a number of layers of plastic on top of silver. Combined, these materials bounce sunlight back into the air, leaving the roof as much as nine degrees cooler than a standard roof. Almost all of the solar radiation is reflected back, which is very significant considering the fact that standard roofs absorb up to 90 percent of light, and even the best roofs designed to keep things cooler only reflect between 70 percent and 85 percent of sunlight.
"The coating keeps the roof cool by reflecting almost all of the incoming solar radiation," Gentle says. "A vast majority of this emitted radiation goes directly into space without being absorbed by the atmosphere."
This is also a major factor in the "urban heat island" effect in which cities are significantly warmer than nonurban areas. If a neighborhood were to take advantage of this new material, not only would individual buildings be more comfortable to be inside, but urban areas in general would be much cooler. This should significantly reduce how much people rely on air conditioners, being both cheaper for the individual and better for the environment.
During the testing phase of the new material, it even stayed significantly cooler when it was covered in dust and grime. Gentle developed the material along with physics professor Geoff Smith, a process they described in an article in Advanced Science.
While the material is still being tested for roofs, it uses common and affordable materials, making it easy to implement, especially when it starts becoming available for consumers to put on their roofs.