Berkeley Lab researchers find ancient pigment can improve energy efficiency

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Researchers at the Lawrence Berkeley National Laboratory found that an ancient pigment, Egyptian blue, can enhance energy efficiency by cooling rooftops and walls and could potentially be applied to the generation of solar energy.

Egyptian blue is derived from calcium copper silicate and was used in ancient Egyptian depictions of gods and royalty. According to lead researcher Paul Berdahl, it is possible that it is the first pigment ever to be intentionally produced. The pigment had previously been shown to emit near-infrared light, which holds half the energy of sunlight when it absorbs visible light — a process known as fluorescence. This research confirmed that the fluorescence, which serves to cool the surface that is absorbing the light, can be 10 times stronger than was previously thought.

“Making roofs white is an energy efficiency strategy that works in hot climates. It reduces the need for air conditioning and, believe it or not, helps a little bit towards global warming because solar energy is reflected back to the atmosphere,” Berdahl said. “But as a practical matter, white roofing is only used on large industrial buildings; most buildings need a color of some sort.”

Berdahl said he had been working on this idea for a few years and that the research presents a way to increase the efficiency of roofing. The research began with work on ruby red pigments, which Berdahl says do work but have more limitations than Egyptian blue, before focusing on what was originally three different blue pigments.

Work on Egyptian blue began after its fluorescent quality was discovered by museum workers, and Berdahl said he was surprised by the efficiency of the pigment’s fluorescence once their research began. He said that this efficiency “opens up” more applications for the pigment.

Berdahl also discussed the pigment’s versatility when combined with other colors, saying that it can be mixed with yellow to make green, or mixed with orange to make black, while still fluorescing and staying relatively cool compared to other pigments of similar colors. He said this will permit the construction of roofs that will stay cool while producing colors that are desirable for consumers.

Campus freshman Michael Huang found it “cool” that the researchers were able to find new uses for historical technologies. Huang said he was pleased that research presents a new way for us to be energy-efficient.

Campus freshman Jackie O’Hara echoed Huang’s sentiment, saying the researchers’ findings do not surprise her, but they are “definitely interesting.”

“I (once spoke to) an archaeologist who basically said that we didn’t discover anything; it’s old techniques that we’re able to modify and improve,” O’Hara said.

Contact Alex Teodorescu at [email protected] and follow him on Twitter at @AlexTeodorescu8.