Cooling Film Gets Warm Response

Mar 20, 2017

A team of University of Colorado Boulder engineers has developed a revolutionary process that cools buildings without the use of refrigerants or electricity.

The material, described in the journal Science, is a glass polymer hybrid and even under direct sunlight can cool objects.

Here's how it works:

  • Cools the object underneath by reflecting solar energy back into space.
  • Allows the surface to shed its own heat in the form of infrared thermal radiation (radiative cooling).

To make it, researchers embedded infrared-radiant glass microspheres into a polymer film. Then they added a thin silver coating underneath.

"Just 10 to 20 square meters of this material on the rooftop could nicely cool down a single-family house in summer," said Gang Tan, an associate professor in the University of Wyoming and a co-author of the paper.

The material could also make solar panels more efficient.

"Just by applying this material to the surface of a solar panel, we can cool the panel and recover an additional one to two percent of solar efficiency," said Xiaobo Yin of the University of Colorado, Boulder. "That makes a big difference at scale."

It's cheap and that's important to places like Brazil, China and India. The film costs about 50 cents a square meter. It is 50 micrometers thick (just thicker than aluminum foil) and can be manufactured economically on rolls.

"We're excited about the opportunity to explore potential uses in the power industry, aerospace, agriculture and more," according to Ronggui Yang of the University of Colorado in Boulder.

The Energy Department awarded a $3 million grant to Yang and Yin. They've applied for a patent and are working with CU Boulder's Technology Transfer Office for potential commercial applications.