The University of Houston Health and Biomedical Sciences Building was originally envisioned as a simple two-story building for the College of Optometry. But over time, the university gained Carnegie tier 1 research status, and the vision for the building grew to accommodate an interdisciplinary research environment. The building's physical plan also expanded, adding four more stories to accommodate research labs, classrooms, and surgical suites.
That added a lot of complexity to the design, says project designer Luke Voiland, an architect with Shepley Bulfinch. In the final design of the building, they had to consider light sensitivity to protect delicate research studies; the need to sustain the weight of heavy lab equipment on upper floors; and the desire to offer multiple types of room styles, heights, and floor designs in a single unified structure. At the same time, they also had to meet the budget, schedule, and quality requirements that come with every project.
"Precast concrete quickly became the material of choice," Voiland says.
Both the mechanical systems and research programs housed in the building needed windowless spaces to protect the equipment and projects. Typically, that would be accomplished by placing those rooms below ground, but because of the site's topography and high water table, they had to be placed on the upper floors to be protected from potential catastrophic weather.
That meant the upper half of the building required a large, prominent, windowless facade made up of large precast concrete panels. "Because the precast concrete panels could be made so large, we were able to cover a lot of that space very economically," Voiland says.
To lessen the bulk of those windowless spaces, Voiland's team took advantage of the plasticity and flexibility of precast concrete to create a beveled facade that reflects light and shadow as the sun plays across the building's surface. The design uses simple rectangular concrete panels that are triangularly faceted, creating 6 in. (150 mm) deep peaks and valleys in the facade's surface.
"The carefully detailed system of triangularly beveled concrete panels creates a distinctive visual display," says Nick Faerber, the project manager for Coreslab Structures, precaster on the project. "The bevels add a whole different dimension of light to the monochrome surface and give it the illusion of many shades of color."
Voiland's team worked closely with Coreslab to model the design and test how deep the relief needed to be. They were surprised to discover that a mere 6 in. (150 mm) delivered the contrasts and changing light that the design called for.
Working together, they also made sure that all of the panels would line up evenly to create a tight envelope. The panels spanned column to column, allowing the floor slabs to move independently from the exterior shell and for the windows to be anchored within the precast concrete. The panels were then sprayed with foam insulation to create a continuous vapor barrier that spans the precast concrete joints, reducing air infiltration and leakage.
This design choice reduced the incidence of air loss, a major concern for laboratory buildings, which have stringent ventilation requirements, Voiland says. "From a building enclosure perspective, precast concrete allowed for a much tighter building envelope."