High-tech paint can efficiently replace air conditioners and cool cities around the world

It comes as no surprise that common cooling methods such as air conditioners are expensive, require high amounts of energy and electricity, and often require additives that damage the ozone layer.

A team of researchers at Columbia University (Engineering Faculty) are inching towards creating an alternative for energy intensive cooling methods. 

“Now is a critical time to develop promising solutions for sustainable humanity.”

“This year, we witnessed heat waves and record-breaking temperatures in North America, Europe, Asia, and Australia. It is essential that we find solutions to this climate challenge, and we are very excited to be working on this new technology that addresses it,” says assistant professor of materials science and engineering Yuan Yang.

Building on earlier work, the team created a spreadable substance made of a polymer coating similar to paint that can reflect sunlight and heat radiations into the atmosphere.

In technical terms, an alternative to common cooling methods is called passive daytime radiative cooling (PDRC) which provides cooler temperatures while using little to no energy.

The issue is a little more complicated because developing practical PDRC designs has come with challenges. Recent design proposals have either been expensive or too complex and cannot be disseminated or applied on rooftops and buildings that vary in shapes and structures. 

A cheaper and more efficient solution used by PDRC is white paint.White paint absorbs heat energy which makes the new polymer coating a better PDRC.

The coating is capable of giving a cooling effect because researchers replaced paint pigment (which absorbs UV light) with little holes (air voids) which reflect all heat radiations coming from the sun.

“We have now demonstrated that white is in fact the most achievable color. It can be made using nothing more than properly sized air voids embedded in a transparent medium. Air voids are what make snow white and Saharan silver ants silvery.”

“This simple but fundamental modification yields exceptional reflectance and emittance that equal or surpass those of state-of-the-art PDRC designs, but with a convenience that is almost paint-like,” says Jyotirmoy Mandal, lead author of the study and a doctoral student in Yang’s group.