Architects—and some owners—often love truly innovative designs. Although fascinating to look at, they may be difficult to construct. But whether a building is new and creative or tried and true, it may not adequately take into consideration the optimum building-envelope design.

“Architects receive a great background in how to design a building, but not as much in how the building envelope must come together as a system,” says Robert Corapi, building envelope consultant and principal of TBS Services, Inc., in Glenside, PA. “Every architect needs to know this.”

Why? “Owners should have all the buildings systems they are paying for actually work,” Corapi says. “Seventy percent of our business is fixing buildings that were not put together correctly from a building-envelope standpoint.”

What Is the Envelope?
According to the U.S. Department of Energy, the building envelope is everything that separates the interior of a building from the outdoor environment, including the windows, walls, foundation, basement slab, ceiling, roof, and insulation.

Although each component may be a quality product, problems with interfacing the components can lead to failures. In addition, deciding to address the building envelope late in the design process adds additional cost.

“The best time to start including the building envelope in the design process is when the project is first conceived,” Corapi says. However, completing a study and producing a design that addresses the building-envelope issues is sometimes considered an unnecessary extra cost. That’s a short-sighted mistake.

“It’s a total systems engineering and integration issue, not a prescriptive add-on.” confirms Daniel J. Desmond, deputy secretary for energy and technology deployment in Pennsylvania’s Department of Environmental Protection.

Applicable to Retrofit as Well as New

Although owners reap the greatest financial return in new construction, retrofit building-envelope projects give multiple opportunities for improvement.

For example, many experts believe a building’s most inefficient areas—those that allow air leakage or water infiltration—are the windows and curtain wall. Second on the list would probably be the roof-to-building termination. Air leakage in any building results in a facility difficult to condition, and water infiltration leads to multiple problems related to sick building syndrome, including mold.

However, a well-designed building envelope protects the building and its occupants, while allowing for proper air exchange.

Wagdy Anis, principal of the Boston architectural firm of Shepley, Bullfinch, Richardson and Abbott and board chair of the Building Enclosure Technology and Environment Council, has a memorable guideline: “Build tight and ventilate right.”