For an interior courtyard surrounded by the double-height, floor-to-ceiling glazing of the General Services Administration Office Building in Albuquerque, N.M., Page (formerly Page Southerland Page) senior principal Larry Speck, FAIA, and his team designed a suspended system of transverse wooden slats that serves the building’s site-specific shading needs, while allowing natural light inside.
Speck variably spaced his 2x6 western red cedar slats, which come in lengths of 5, 10, and 15 feet. In order to place the boards in the most effective and economical layout, the designers superimposed sun-tracking data onto its 3D building models in Autodesk Revit. By looping simulations of the sun’s movement throughout the day and year, the designers added slats accordingly and omitted them in locations where the building self-shades the courtyard. The resulting pattern is intended to look randomized for aesthetic reasons, but is in fact quite purposeful.
Eleven 61-foot-long, ¼-inch-diameter stainless-steel cables support the slats. Supplied by Landmann Wire Rope Products, the cables hang in shallow catenary arches across the center of the 59-foot-long span. “We didn’t want the cables so taut that they didn’t have a little gracefulness,” Speck says.
Credit: Patrick Coulie
The slats align on a north–south axis (the building faces the south) to provide sun-shading only where necessary—along the east, west, and north courtyard façades. In the summer, the slats block the afternoon glare as the high sun swings over and sets to the west. In winter, the lower sun follows a more southerly transect, casting its energy between the slats.
The unfinished, knot-free, grade A-and-better western red cedar slats provide warmth while its FSC certification contributed toward the project’s LEED Silver rating. “If this were humid Austin, we might have chosen a tropical hardwood, like Ipe,” Speck says. “But Albuquerque is dry, and wood does fantastic there. It weathers beautifully and lasts forever.” The slats are 5-, 10-, or 15-feet long. They attach to the cables with #4, ¼-inch, rubber-lined, stainless cushion clamps ordered from the Suncor Stainless catalog.
Most of the catenary structure was design/build. The designers assembled drawings but gave the contractor, Albuquerque’s Enterprise Builders Corp., leeway in how to install the shading system. Near the top of the east and west walls, the contractors used off-the-shelf hardware to attach 11 splice-welded eyebolts to ½-inch-diameter threaded rods. The rods are anchored with bolts and washers into grout in the concrete masonry unit back-up wall. After hanging the 11 cables, the contractors stabilized them with north-south lateral support cables, tying into each cable via a ¼” stainless steel cross-wire clamp.
Credit: Patrick Coulie
Shadows cast by the variably spaced slats dance on surfaces inside and outside the courtyard. Speck takes pride in the design’s simple elegance. “Doing an expensive, extraordinary thing is not that hard,” he says. “Doing an extraordinary thing inexpensively—that’s hard.”
Note: This article has been modified since first publication to reflect the architecture and engineering firm's updated brand name, Page.