When you’ve got more recycleables than you can fit in the your blue bin, you send them to the recycling center. So where do you send heat when you’ve got too much of that? Why, into space, of course!
Getting it there isn’t all that tricky, either. You just need a nice, reflective surface. Painting things that normally absorb heat like crazy — say, dark surfaces like roads and rooftops — white can make a huge difference in ambient temperatures. It’s a strategy that’s working pretty well in California.
A team of researchers from Stanford has used a similar approach to increase the efficiency of rooftop air conditioners. They’ve cooked up a passive system that utilizes highly-reflective panels to deflect the warming rays of the sun and reduce the workload for a building’s environmental controls.
The panels aren’t very large, only measuring about two square feet each. They are, however, around 97% reflective thanks to a special multi-layer optical coating. An array of four was placed on a rooftop and water was circulated through a series of pipes underneath. The temperature of the water was reduced between 3 and 5° F, and it all happened without using any electricity.
After proving their system worked, the team wanted to figure out how much of a difference it could make. It was off to the simulator, where they covered an entire Las Vegas rooftop with panels and used them to cool the condensor unit of a vapor-compression AC unit.
The result: the passive panels reduced power consumption by as much as 21% over the course of a typically blistering-hot Vegas summer. On some of the simulated days it was actually cut in half.