In Phoenix, temperatures can hover above 100 F for six months of the year. It seems natural then that for its project with the Arizona Board of Regents, Los Angeles–based CO Architects found inspiration for its design and cooling strategies in the surrounding desert and canyons. Located on the Phoenix Biomedical Campus, the six-story, 268,000-square-foot Health Sciences Education Building (HSEB) looks like an urban mesa, incised with self-shading fissures and a slot canyon courtyard topped by a polytetrafluoroethylene fabric roof, which blocks rain and diffuses sunlight, reducing courtyard temperatures by as much as 20 degrees on hot days.
The building’s faceted copper skin likewise serves a dual purpose, giving the HSEB its distinctive color and texture while improving energy efficiency. During field trips to canyon country to study different desert microclimates, the designers were struck by the slot canyons’ aesthetics and noticeably cooler temperatures, says Arnold Swanborn, AIA, an associate principal at CO Architects and the project’s senior design architect.
CO Architects thus designed a skin of custom-fabricated panels to reflect the colors and arrhythmic striations of the region’s canyons. Arizona is copper country, which made the metal a natural choice, though the team used recycled copper from Rome, N.Y., rather than local virgin copper. Horizontal pleats in the copper panels resemble the sedimentary striations seen in the canyon walls, but they also reduce direct sunlight much like the self-shading vertical ridges of the saguaro cactus.
Early in the design and development phase, CO Architects brought on Chandler, Ariz.–based fabricator Kovach Building Enclosures. “We wanted to use them as a resource,” Swanborn says. The collaboration allowed the team to optimize a skin design that uses 16-gauge copper coil in standard widths. Laid in a running bond pattern, the 11-foot-wide panels have 26 unique designs and vary in pleat size and heights of either 12, 18, or 30 inches tall. Thanks to modularity and a stroke of planning luck—the early purchase of 250,000 pounds of copper at a rock-bottom price—the team slashed 48 percent off the façade’s original estimate.
The nearly 6,000 panels took nine months to fabricate and seven months to install. Each panel was bent in a press brake, a punch-and-die machine tool. “The only part of the skin that wasn’t custom made was the screws,” Swanborn says. The cladding doubles as a solar chimney, reducing the building’s cooling loads by wicking hot air up and out of the envelope through a 4-inch air cavity behind the panels. Half-inch vertical joints between panels allow thermal movement in the vast field of copper.