Vitro Architectural Glass (formerly PPG glass) is celebrating the 10th anniversary of Solarban 70XL glass, a solar control low-emissivity (low-e) glass product that enables architects to meet stringent energy codes without sacrificing daylighting. It was introduced at the GreenBuild International Conference and Expo in 2006, reportedly as the first architectural glass to successfully integrate a third layer of silver into the coating.

Paul A. Medwick, Ph.D., senior group leader of the glass coatings group at the Vitro Glass Research and Technology Center near Pittsburgh, Pa., led the technical team that formulated Solarban 70XL glass. He said the need to develop a triple-silver-coated, low-e coating first became apparent in the late 1990s.

“Energy codes began to demand better solar control performance,” said Medwick. “At that time, the only way to meet tougher performance standards was with double-silver [coating] on a tint, but the market was shifting away from tinted glass and toward clear [glass]. We tried to bridge that gap with Solarban 80 glass, a double-silver [glass] with thicker silver layers to enhance solar control, but its highly reflective aesthetic was not as broadly appealing to the market as we had hoped.

“There was some reluctance initially to consider commercializing a triple-silver product because coaters were optimally configured for double-silver coatings. We weren’t sure how triple-silver-coated glass would be received by the industry. One concern was that the production costs for triple-silver coatings would be higher than those for double-silver due to the higher complexity of the coating design and manufacturing process. We thought that might make it difficult for customers to justify investing in a more expensive product.”

Over the next several years, product developers reportedly worked internally, then closely with architects and fabricators, to develop a triple-silver coating that could be produced economically with high levels of quality and consistency while meeting customer demands for aesthetics and performance. One of the most difficult challenges was to develop proprietary manufacturing processes and technologies that would consistently produce the same coating, one with uniform aesthetics and performance over the entire surface of large panes of glass.

Andrew Wagner, Ph.D., a scientist with the glass coatings group, was a key member of the Solarban 70XL glass development team. “As the number of silver layers increases, the optics of silver-based coatings become increasingly sensitive to small, but unavoidable, manufacturing process variations,” he said. “Eventually, we were able to find the right balance of manufacturing processes, controls and materials to produce Solarban 70XL glass within extremely tight tolerances for color and solar-control performance. Other glass manufacturers eventually came out with triple-silver glasses; yet, to date, none have been able to achieve the consistent color uniformity and quality control of Solarban 70XL.”

For more information, visit www.vitroglazings.com.