How much cheaper your air-conditioning bills could be if your roof never heated up in the sun?

Glass-paint keeps structures cool in heat

A novel glass-based paint could protect roofs and ship decks exposed to extreme solar radiation from damage and keep them cool even on the hottest day.

Unlike conventional polymer-based paints, the new environmentally friendly coating developed by American researchers doesn’t degrade in the sun and can survive even high doses of ultraviolet radiation.

The paint works by reflecting solar rays just like a mirror, keeping the structures cool at all times.

“Any type of damage, whether it’s corrosion or ageing or any other type of deterioration gets accelerated at high temperatures,” explained Jason J. Benkoski, a researcher from the Applied Physics Lab of Johns Hopkins University. “So as much effort as you can put into adding corrosion inhibitors into your paint you can just as well lower the temperature and get the same exact effect.”

The coating is made of silica, which - being an inorganic material - doesn’t degrade like organic polymers. It also doesn’t produce any volatile and possibly harmful compounds while degrading.

However, to create the actual paint, Benkoski had to overcome a major drawback of silica – its brittleness. Benkoski modified one version of silica, the water soluble potassium silicate and alternated the compound’s structure so that it can be sprayed onto surfaces. The new material, once it dries, becomes water resistant. Moreover, the paint can also expand and contract with metal surfaces exposed to changing temperatures. As a result, the paint does not crack.

The silicate-based paint doesn’t only reflect sunlight but also radiates heat. Any object or surface covered with the paint thus maintains the temperature of the surrounding air or can be even slightly cooler.

Benkovski sees a huge potential for his invention – it could be used anywhere from cars, industrial machinery, roofs, ship decks and anything that one can barely touch without getting blisters in hot sunny weather.

"It's not uncommon for aluminium in direct sunlight to heat 70 degrees Fahrenheit above ambient temperature,” Benkovski explained.

"You might want to paint something like this on your roof to keep heat out and lower your air conditioning bill in the summer."

As silica is abundant and inexpensive, the researcher says there are virtually no obstacles for wider commercialisation. He hopes his lab will start field testing the material in about two years.


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