|
The idea that a simple paint could could
compete with modern air-conditioning sounds crazy, but
researchers at Purdue University say it could become a reality
thanks to a cool new “radiative cooling paint” they developed.
Engineers at Purdue University recently unveiled a revolutionary
white paint that they claim can keep surfaces up to 18 degrees
Fahrenheit (7.8 degrees Celsius) cooler than their ambient
temperature, by absorbing almost no solar energy and actually
sending heat away from the surface it is covering. Think of it
as a way of turning basically any space into a refrigerator,
only without the energy cost.
|
 |
|
“It’s very counterintuitive for a surface in direct sunlight to be
cooler than the temperature your local weather station reports for that
area, but we’ve shown this to be possible,” Xiulin Ruan, a professor at
Purdue, said.
According to researchers, commercially available white paint can reflect
just 80%-90% of sunlight and cannot achieve temperatures below their
surroundings, while this new reflective white paint reflects 95.5%
sunlight and radiates infrared heat much more efficiently.
An article on the Purdue University website reveals that attempts to
create a reflective paint as a feasible alternative to traditional air
conditioners can be traced back to the 1970s, which speaks to how
difficult finding the right formula actually was. It took Purdue’s
engineers six years of hard work and lots of trial and error to come up
with a white paint based on calcium carbonate, an earth-abundant
compound, that actually worked.
|
 |
|
“Your air conditioning kicks on mainly due to sunlight heating up the
roof and walls and making the inside of your house feel warmer. This
paint is basically creating free air conditioning by reflecting that
sunlight and offsetting those heat gains from inside your house,” Joseph
Peoples, a Purdue Ph.D. student in mechanical engineering and a
co-author of the research, said.
But what happens to that heat that gets reflected off the surface
covered in reflective white paint? Does it go into the atmosphere?
Apparently not, as the paint is reflected from Earth into deep space,
where heat travels indefinitely at the speed of light.
“We’re not moving heat from the surface to the atmosphere. We’re just
dumping it all out into the universe, which is an infinite heat sink,”
said Xiangyu Li, a postdoctoral researcher at MIT who worked on the new
paint. That means that should the paint be used on large surfaces around
the world, like roads, rooftops and cars, it could actually help prevent
global warming.
|
|
|
|
Purdue researchers estimate that the reflective white paint would be
both cheaper to produce than commercial white paint, and also save
people about a dollar a day on air-conditioning use for a one-story
house of approximately 1,076 square feet.
Engineers are now working on other paint colors that could have cooling
benefits, although white will probably remains the most efficient, due
to its natural light reflecting properties. It’s basically the opposite
of Vantablack, the world’s blackest black, capable of absorbing 99.96
percent of light that hits it.
|