Text by John Morris Dixon, FAIA
The Environment + Natural Resources Building II (ENRII) at the University of Arizona opened in September. The site is strictly bounded by streets to the north and south, an earlier Environment + Natural Resources building to the west, and a parking garage to the east. Rather than leave open space on any of these sides, the project team decided to fill the whole rectangle to the edges with a boxlike volume.
As a result, none of the structure’s four faces was suitable for a grand entrance, but the garage does incorporate a two-story-high recess, originally intended as a bus drop-off. So the principal entrance to the new building faces the garage and shares that found space. Alternative entries are located on the other three sides. Principal James Richärd, AIA, takes some satisfaction in “deconstructing the usual entrance sequence.”
After ruling out a prominent entrance, the architects and clients considered a central atrium, but a large volume of enclosed conditioned space would have violated the program’s mission to provide research that leads to the sustainable management of natural resources and energy conservation. The design team instead decided to organize the building around a full-height open-air space with the constricted proportions of a local geographical feature: the slot canyon.
Rather than mimicking a natural canyon’s qualities, the architects abstracted its salient characteristics: Irregular boundaries, defined by cantilevered upper-floor walkways, cast the range of light and shadow found in a canyon. Planting beds at every level bring scattered greenery, and paved paths and concrete benches reinterpret the contours of eroded stone. Swooping stairs encourage walking between floors.
The manmade origin of this canyon’s forms is evident in its compositions of straight lines and circular arcs. “There is always a challenge in developing a conceptual response to a natural setting,” Richärd says. “It requires interpretation and abstraction; we developed a geometry that recalled the experience of an [actual] canyon without being slavish to it.”
Vertical steel angles screen the balconies, playing down their horizontal edges and recalling the precipitation that forms streambeds. The building’s north and south faces are clad in the same vertical members, which help moderate the desert sun in the spaces within. The carbon steel will change color as the mill scale falls away, from near black to a dark reddish brown—relating to the campus’s characteristic terra-cotta-colored masonry but with a richer, more neutral tone. The curtainwalls behind the screens contain limited windows among glass-faced insulated panels.
Above the ground-floor auditorium, café-commons, and lecture hall, the upper floors primarily house office spaces with regular layouts that reflect the rectangular geometry of the exterior walls and support the building’s program, which involves mainly computational analysis. A roof-level conference room boasts expansive views, and paved decks and gardens allow for some open-air research.
Ovoid rooms, which house functions such as teaching labs and seminar/conference rooms, punctuate the orderly office layouts, and are placed irregularly along the open corridors that ring the central canyon. The swerves of the canyon in plan expand upon the curves of these gathering spaces.
Given the client’s environmental mission, every aspect of the structure’s energy performance was considered; it is currently seeking LEED Platinum certification. Office spaces are concentrated along the north and south façades, where they can benefit from the shading. East and west elevations house elevators and utilities, which serve as thermal buffers. A post-tensioned flat-slab concrete structural frame acts as the building’s principal thermal mass, damping diurnal temperature variations, and displacement ventilation from the raised floors distributes conditioned air. The extra ceiling-to-floor depth aligns with that of the balcony planting beds, so there is one continuous level of “terra firma” (as Richärd puts it) inside and out.
Laying out the structural columns presented a challenge because of the building’s irregular floor plans. So the design team placed all columns along consistent north–south lines, then adjusted their locations along those lines in response to the demands of the ovoid rooms and the varying balcony cantilevers.
Interiors are sleek with predominantly white surfaces, designed to maximize light dispersal and enable occupants to personalize their spaces. While the canyon’s geometries reappear in the auditorium and other shared spaces, any further visual references to the surrounding natural world have been left outside.
All told, the architecture of ENRII is derived from a demanding program, not imposed upon it. And having designed two other structures for the university, Richärd can attest to the school’s understanding of design’s appeal for students and instructors. Across the campus, and as seen here, “there’s a focused effort to create distinctive environments,” he says.