United States. SRI researchers develop a self-cooling, water-based paint that provides the ultimate in energy efficiency to meet the growing need for affordable, energy-efficient ways to stay cool. It does not require electricity or power to operate.
"The active cooling solutions we have today are not sustainable and will not be suitable in the future," said Anish Thukral, a research scientist and materials engineer at SRI, who is leading the development of this paint.
"A passive cooling solution like this is especially valuable because it's cheaper and more accessible than air conditioning," he added.
Although it looks like a standard white paint for houses, SRI's paint contains carefully designed pigments that achieve cooling in two ways. First, it reflects 96 percent of the sunlight that reaches it, according to reflectance data measured by SRI researchers. This means that the painted surface absorbs very little heat from the sun, similar to the effect of wearing a white t-shirt on a sunny day.
The second cooling mechanism is a bit more complicated. The paint materials radiate heat into the transparent atmospheric window, a specific band of infrared wavelengths that are known to easily pass through the planet's atmosphere.
Because these wavelengths don't interact with anything in the atmosphere, researchers can use the temperature difference between the paint and the cold outer space to dissipate heat. This has shown that the paint cools a surface up to 10°F below ambient air temperature and 23°F below its uncoated counterpart, according to an internal test conducted on a rooftop in Palo Alto, California.