Purdue University engineers have created white paint that can keep surfaces up to 18 degrees Fahrenheit cooler than their ambient surroundings – almost like a refrigerator does, but without consuming energy. Commercial “heat rejecting paints” currently on the market reflect only 80%-90% of sunlight and cannot achieve temperatures below their surroundings. The white paint that Purdue researchers created reflects 95.5% sunlight and efficiently radiates infrared heat.
Earth’s surface would actually get cooler with this technology if the paint were applied to a variety of surfaces including roads, rooftops and cars all over the world. The paint would not only send heat away from a surface, but also away from Earth into deep space.
In a paper published Wednesday (Oct. 21) in the journal Cell Reports Physical Science, the researchers show that compared with commercial white paint, the paint that they developed can maintain a lower temperature under direct sunlight and reflect more ultraviolet rays.
This paint would be both cheaper to produce than its commercial alternative and could save about a dollar per day that would have been spent on air conditioning for a one-story house of approximately 1,076 square feet. It would take about ten gallons to paint a 1,076 square foot house.
The world makes about ten billion gallons (55 million tons of paint a year). Saving a dollar a day would mean a payback for ten gallons of paint in 6-12 months.
If paint production was doubled and the new production was used for this superwhite paint then 100,000 square kilometers could be painted every year.
Cell Reports Physical Science- Full Daytime Sub-ambient Radiative Cooling in Commercial-like Paints with High Figure of Merit
Highlights
Paint using CaCO3 fillers with high concentration and broad particle size
The paint shows a high solar reflectance of 95.5% and sky window emissivity of 0.94
Field test shows over 37 W/m2 cooling power and over 1.7°C below ambient at noon
Commercial-like paint offers a high standard figure of merit of 0.49
The new paint is compatible with regular commercial paint fabrication processes.
SOURCES Purdue University, Cell Reports Physical Science
Written By Brian Wang, Nextbigfuture.com
