Cool roof coating: Mechanism kept under wraps

Janet Raloff reports from the meeting of the American Chemical Society held in San Francisco.

SAN FRANCISCO — The American Chemical Society held a news briefing March 21 to feature a new energy-saving technology. It’s an ostensibly “smart” coating for roofing materials that knows when to reflect heat, like in summer time, and when to instead let the sun’s rays help heat a structure.

Roofing materials already exist that can reflect the sun’s rays. But they always reflect, says Kyle Ungvarsky, an engineer with United Environment & Energy of Horseheads, N.Y. In contrast, his company’s new material can be tuned to stop reflecting when it’s advantageous to do so.

He reported that bench-scale testing found that compared to conventional “cool roof” technologies, UEE’s climate-responsive material should be able to reduce rooftop temps “by 50 to 80 percent” in warm weather, and actually increase roofing temperatures by “up to 80 percent” during cold seasons.

“The coating is mainly made of recycled waste cooking oils” and can be sprayed onto existing asphalt shingles or some other roofing material. Depending on how it’s been chemically “tuned” for the local climate, Ungvarsky said, the novel coating can effectively “read a thermometer.” When the outdoor temperature reaches some set point, he said, the coating undergoes a phase change that switches its optical properties from reflecting to transmitting solar ultraviolet and infrared radiation onto the roofing material below.

Cool concept, but how does it do that? The patent-pending technology is “proprietary,” Ungvarsky says, so he couldn’t divulge details.

A colleague at the briefing asked what makes this new material conceptually different from commercially available window coatings that can reflect — or not. He wouldn’t say, except to reaffirm that this technology was for roofs. Which we already knew. Any chance that his company had published anything on the phase-change optical coating, that reporter asked? Nope.

As I’m puzzling over how this oil might alter its transmissivity it occurs to me: Is there something embedded in the oily polymer that does the thermostat reading and optical presto-change-o trick? Yes, Ungvarsky admits. The oil isn’t tunable by itself, but instead depends on some proprietary additive.

At which point the briefing was called to an end. The entire event lasted 8.5 minutes.

I see our job as science journalists to help demystify science by reporting on new concepts, new developments and how things work. We can’t hope to do that when all we’re offered is black-box science. And I don’t blame Ungvarsky, a young engineer with his company. He was undoubtedly instructed to offer a superficial description of the new technology. One that might invite nibbles from companies interested in partnering with UEE on a new line of commercial products. Indeed, Ungvarsky said as much.

But I am disappointed that the ACS wasted one of its few preset opportunities for reporters to meet with presenters over a project so short on details.

I visited the company’s poster, this evening, when it went up. It didn’t say much more than Ungvarsky shared at the briefing. But I did pick up a potential clue as to the tuner. The poster was part of the ACS’ cellulose division, which would suggest that the mystery additive contains, was fashioned from, or in some way resembles cellulose.

If that technology truly performs as UEE claims, that could be great. Cooling down roofs all over a warm metro area, Ungvarsky points out, could do a lot to diminish the heat-island effect associated with today’s urban areas.

On a smaller scale, the new coating could also make working conditions better for roofers. My dad and I replaced the shingles on my house many years back. And I can attest that even in early April, when the backyard was about 65°F, the temperature two stories up atop that dark asphalt was scorching and the roofing shingles gooey. Which makes it easy to damage them, not to mention get tarry deposits all over your clothes and hands.

I happened to mention this to a commercial roofer in our area, a few years back, and he agreed that his crews can easily encounter blistering working conditions that exceed 130°F in summer. I bet they would love to see cool roof technologies transform the rooftop landscape. And if UEE has its way, smart coatings for roofing could debut within three years.

Janet Raloff

Janet Raloff is the editor of Science News for Students, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer.

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