Finding building materials that are appropriate for hot desert conditions is one of the biggest challenges facing the Middle East and North Africa region’s construction industry. While earth used in architecture found in Egypt, Libya, Yemen and elsewhere is typically considered the most effective material for keeping interior temperatures low while the sun acts like a giant blowtorch outside, it isn’t popular among contemporary designers.
Instead, we see a lot of new buildings – particularly in urban environments – constructed with steel and glass, which exacts an enormous cooling load and requires water, another scarce resource, for cleaning. But the future holds promise; researchers from Stanford University have created a nanophotic panel that reflects sunlight off of buildings (or cars and other structures), and beams heat out right of the earth’s atmosphere.
Scientists have long sought a way to prevent buildings from absorbing heat from sunlight during the day and radiating it back into space, and now a team from Stanford University have done that. They published their findings in the journal Nano Letters.
The trick is to produce a material that can not only reflect sunlight, to prevent absorption of heat, but also to radiate that thermal energy beyond the earth’s atmosphere at a very specific wavelength to ensure that the heat isn’t simply radiated back to earth.
Known as the greenhouse effect, this trapping of heat is one of the mechanisms behind global warming and climate change.
“We’ve developed a new type of structure that reflects the vast majority of sunlight, while at the same time it sends heat into that coldness, which cools manmade structures even in the day time,” Shanhui Fan, professor of electrical engineering and the paper’s senior author, told Physorg.
They have been able to incorporate both the reflective and radiative cooling effects into one material, which is made of quartz and silicon carbide. While it is unclear how readily available these materials are for mass production, or whether they can be harvested from existing materials, they don’t absorb sunlight well, which allows the building or car on which they are placed to stay cool even during the heat of the day.
Replacing just 10 percent of a roof’s surface with this material can theoretically mitigate 35 percent of that building’s cooling load, according to Physorg, – an exciting prospect for governments that are serious about slashing their energy consumption in the face of growing energy scarcity.
Even better, this passive technology mitigates carbon emissions given that air-conditioning units would be obsolete in a building clad in such engineered panels.
As our informed followers point out, the Stanford team’s breakthrough is still conceptual, but at the very least scientists are starting to think more creatively about how to reduce the building industry’s detrimental environmental impact.
