Berkeley Lab scientists in process of developing low-cost paint for energy-efficient windows

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A team of UC Berkeley scientists is going hard in the paint, developing a cheap heat-reflective coating that aims to make windows more energy-efficient.

Although commercial coating similar to this already exists on the market, the team hopes to reduce the cost of what is currently available by a factor of 10.

“The motivation of this work is to drastically improve the energy efficiency of buildings,” said Raymond Weitekamp, one of the scientists on this project.

According to the Center for Climate and Energy Solutions, optimum window design and glazing specification in residential buildings can reduce energy consumption from 10 to 50 percent, with energy lost through window performance estimated to cost building owners up to $50 billion each year.  

The project is a collaboration between Lawrence Berkeley National Laboratory, the University of Colorado and several California Institute of Technology team members.

The coating uses the unique geometry of bottlebrush polymers to reflect infrared light back into the sky while allowing visible light to pass through painted windows. The process reduces the amount of both heat trapped in buildings and the carbon dioxide emitted through less air conditioning use, allowing buildings in warmer climates to save more energy.

The project began about six years ago, when Weitekamp and his colleagues ran tests on synthesized polymers as doctoral students at Caltech. They noticed changes in wavelengths when the size of polymers were manipulated.

“(My) job was to run computer simulations to understand what was happening better,” Weitekamp said. “The original idea came out of doing these simulations, seeing that if we could get the (polymer) size right, it can make them reflect infrared light.”

Bottlebrush polymers are named for their likeness to pipe cleaners, with polymers hanging on the main polymer chains. Their rigidity makes them more difficult to become entangled, creating a lower energetic barrier that can reorganize light spectrums.

With this discovery, the team has figured out a way to make these polymers reliably and in high quality.

The U.S. Department of Energy’s Advanced Research Projects Agency-Energy awarded a portion of $3.95 million in funding for the project a few months ago, according to Steve Selkowitz, another project member and Berkeley Lab senior adviser for building science.

Contract terms are currently being finalized, with the team still in the early stages of research and development.   

A project of this kind at this scale and size has never been done before, Selkowitz said.

Although the project has no official name yet, the team is focusing on developing this technology into a commercial product, according to Weitekamp. One aspect of the project the scientists are working on is exploring ways for the paint to consistently dry when coated on a window.

Campus professor of environmental science, policy and management Dennis Baldocchi said he thinks the research is a good idea.

“The campus is not efficient, (with) older buildings (needing) more improvement,” Baldocchi said.

Adapting this technology on campus, Baldocchi said, can raise students’ consciousness about being energy-efficient, especially as students will be buying homes in the future.

According to Selkowitz, the team hopes to create a viable prototype within the next three years.

Contact Jennifer Wong at [email protected] and follow her on Twitter at @jenniferwong_dc