The building leverages the thermal mass of its concrete structure to reduce heating and cooling loads. Slow to heat in the summer and cool in the winter, the concrete mass creates a stable indoor climate.
The primary heating and cooling for the building occurs through the ceiling surface of poured-in-place, thermo-active concrete slabs.
Plastic tubing in the slabs circulate cold or hot water depending on the cooling and heating needs. Engineer simulations showed a high level of indoor comfort throughout the building with 43% energy savings over ASHRAE's 90.1-2004 standard.
The concrete had to remain exposed for this system to function properly and maintain comfort in the occupied spaces. With concrete serving as the predominate finish, its appearance was critical to the success of the project. Quality standards were established through construction of a two-story mockup. The appearance of columns, slabs, embedded devices and key interfaces were resolved through the mockup. The quality standards from the mockup were then applied to the 15,500 yd of concrete that were installed.
Matt Noblett, partner at Behnisch Architekten, says coordinating the radiant slab proved to be one of the project's most challenging aspects, requiring significant teamwork.
"Before pouring the concrete, we had to have the tubing and slab elements fully coordinated and laid out," he says. "That was a huge effort with hundreds of hours of meetings that went on for more than a year."
Research into recycled content in concrete, coupled with information from Schuster Concrete, Baltimore, about what was poured at the construction site, helped to improve sustainability. By using fly ash for a portion of the cementing agent instead of Portland cement, the team estimates that approximately 1.7 million lb of carbon dioxide emissions were avoided.
Additional sustainable elements include a green roof that helps to reduce stormwater runoff and creates a habitat for native species. The lighting system utilizes LEDs and photocell technology to adjust automatically to daylight levels.
Although the building's considerable sustainability efforts factored into its overall look, Noblett says the team keenly balance aesthetics as well.
"There's clearly an architectural approach that's informed by the technology but not driven by it," he says.