Modernization and Energy Efficiency Upgrades for Wall Systems

Wagdy Anis, BETEC chairman, and principal, Wiss, Janney, Elstner Associates, Cambridge, Mass., and Paul Totten, PE, Simpson Gumpertz and Heger Inc., Rockville, Md., discussed Modernization and Energy Efficiency Upgrades for Wall Systems at the BETEC Symposium, Dec. 10, at the Washington Convention Center. Anis spoke on retrofitting existing buildings, focusing on opaque envelopes more than fenestration. He discussed how to insulate masonry buildings, precast buildings, and buildings with exo-skeleton; and types of insulation that are appropriate, such as medium density spray polyurethane foam.“Present glass technology commonly available is not energy efficient,” Anis said. “Present frame technology is not energy efficient, either. Per my theoretical calculation, if you put 50 percent glazing in a wall, you quadruple the energy consumption.”

As far as windows are concerned, the glass industry should be looking into quad glazing, Anis said. “With quad glazing, you can increase personal comfort to the point where the air temperature delivery can be kept at a reasonable level, and perimeter heating can be eliminated.” With triple glazing, the air delivery temperature needs to be increased and so does the fan size, which increases energy consumption. Quad glazing consists of two lites of glass with two heat mirror foils and Xenon gas suspended in the middle, with multiple low-E layers. Serious Materials, Sunnyvale, Calif.,and Visionwall Corp.,Edmonton, AB,among others, produce quad glazed windows, Anis said.

For curtain walls, framing is a huge problem, Anis said. “The industry has to move toward coming up with composites such as fiberglass and carbon fiber enforcing,” he said. Quad glazing can be used on curtain walls too.

Quad glazing is not cheap. It costs $60 per square foot for windows, Anis said, but for energy efficiency that’s the way to go. “The technology’s there, the expenses have to be brought down.”