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By Nancy B. Solomon, AIA

Common concerns

Ochsendorf points out that both preservation and sustainable design share some similar challenges, as well. In regard to materials, for example, all standards address new materials. To reuse a building component, such as a salvaged beam or old flooring, an engineer must undertake a custom calculation. This is an added burden for historic renovations and sustainable design alike. Even worse, existing structures are sometimes torn down simply because standards don’t exist and the average engineer doesn’t know how to calculate the bearing capacity for the older structure. According to Ochsendorf, this was the fate of some Guastavano tile vaultings, despite the fact that they had plenty of extra capacity. “This is a catastrophe from the viewpoint of both the preservationists and the environmentalists,” says Ochsendorf. He cites a group in Cambridge, England, called the Bridge Research Center that is working on educating engineers on new methods of structural assessment designed to evaluate older structures.

Inherent conflicts

Despite the many shared values and concerns between preservation and sustainable design, occasionally conflicts do arise and trade-offs have to be made. Energy efficiency is probably the most problematic area, with windows generating the most controversy.

 

In a recent renovation of the S.T. Dana Building at the University of Michigan, built in 1903, a fourth floor was inserted on top, beyond the sight lines (below). The railing in the new atrium was made from recycled glass (top). Photography: © Christopher Campbell

Photography: Courtesy the architect

Another pet peeve of preservationists is the practice, required in some jurisdictions, of insulating the interior of thick masonry walls and installing a vapor retarder. In cold climates, this technique can reduce heat loss but can also reduce the ability of the wall to dry out when wet, thereby creating freeze/thaw cycles within the wall that can cause deterioration in the load-bearing masonry, explains engineer Matthew Bronski of Simpson Gumpertz & Heger in Waltham, Massachusetts.

Lighting requirements and preference can also generate conflicts. In the Metzenbaum project, for example, the architects chose to retain the original incandescent luminaires in the courtrooms and judge’s chambers and provide higher light levels by specifying additional, replicated incandescent fixtures to maintain the historic character of these ceremonial spaces. Says Paul Westlake, Jr., FAIA, managing principal of vDWRL, “We had to clear it with GSA, because we do have some clients who say they will not have any incandescent.”