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Off the Wall: Trombe walls at a visitor’s center bask in the sunshine
Although the idea predated them, engineer Felix Trombe and architect Jacques Michel popularized the Trombe wall—ostensibly defined as a thermal collector insulated by air and covered by glazing—in the 1960s. Perhaps this pair made the idea too successful, too quickly. Trombe walls were quickly embraced by the passive-solar housing movement of the era, and now, “When you think Trombe you think early hippie houses,” says Vikram Sami, a senior building performance analyst with Atlanta’s Lord, Aeck & Sargent. “We are reinventing it in a modern context.”
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Sami is referring to the 13 two-story Trombe walls positioned on the zigzagging south elevation of the Blue Ridge Parkway Regional Destination Center, a National Park Service facility that officially opened in April. Located near Asheville, North Carolina, the 12,000-square-foot building houses exhibitions that inform visitors of the region’s background and attractions—and dispenses a number of object lessons in sustainable design. An energy-recovery unit and radiant-heated floor in the main exhibition space and lobby supplement the performance of the Trombe walls, for example, and the building’s other green features include a 10,000-square-foot extensive green roof as well as bioswales and rainwater cisterns.
The Trombe walls themselves, which the design team optimized using computational-fluid dynamics, accomplish multiple tasks. The 8-inch-thick poured-concrete walls absorb and retain the sun’s heat: In wintertime cool air from the building interior enters the walls’ lower vents, heats up inside their hollow cores, and then returns to the interior via upper vents; an additional set of exterior vents may open in summer to allow excess heat to escape from the building. Sami also points out that the walls serve as structural columns and laterally brace the building, and exhibition designers use the walls for mounting their presentations. Meanwhile, Lord, Aeck & Sargent principal John Starr, AIA, notes that the walls fulfill an aesthetic ambition. “We wanted the building’s systems to be expressed as beauty and poetry,” he says.
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