This year’s Harry H. Edwards Industry Advancement Award winner proves that precast concrete enables the most innovative architectural designs while providing a highly energy-efficient and durable envelope.
The four-story office building at 1200 Intrepid Avenue in the Navy Yard in Philadelphia, Pa., was designed by Bjarke Ingels Group (BIG), a Danish architectural firm that has long relied on precast to achieve form and function in their designs. “We came very quickly to the idea that precast concrete would be a great way to achieve our goals on this project,” says Kai-Uwe Bergmann, principal at Bjarke Ingels Group (BIG), the architect on the project.
One of the most prominent features of the building is the white precast concrete façade, which dips dramatically away from the walkway along the eastern edge, then tips back out again, much like the buildings in a Dr. Seuss story.
“One of the key design challenges was to create that curved façade from precast panels,” says David Bosch, design team leader for High Concrete Group, the precaster on the project. The curved load-bearing design was achieved by assembling flat, traditional precast concrete panels to form a complex faceted geometry. An interlocking structural system was embedded within the panels to eliminate the need for traditional precast concrete spandrel panels. “The resulting façade creates an aesthetic versatility that is unique to the project,” Bosch says.
The design breaks away from traditional architecture to better engage with the local surroundings, says Bergmann. “In many cases, architects design big, boxy buildings that could be placed anywhere and don’t connect directly to the site.” He argues that the curved white façade, and deeply reflective windows in this design were inspired by the city’s rectangular city blocks and the adjacent circular park that sits just in front of the building. It also echoes the geometries of maritime architecture and nearby waterway. “You would really be hard-pressed to place this building anywhere else other than where it is, due to how it connects,” Bergmann says. “We like to think about a building beyond its borders and look at how it interacts with its neighbors and the open spaces around.”
Along with being visually inviting, the owners wanted the building to achieve LEED Gold certification, which led to several sustainability measures enabled by the use of precast concrete. The thermal benefits of the precast façade lowered projected heating and cooling costs, contributing 7 of the 60 total LEED points for overall energy performance. The panels were also created using local raw materials and recycled content less than 60 miles from the project site, minimizing the greenhouse gas emissions related to transport and adding more LEED points to the total. “While the concrete production requires a larger carbon footprint initially, it is a material that will have a long life span and can be recycled if needed,” Bosch adds.
Finally, the precast concrete façade solved the fact that the building’s steel structure was designed to carry only lateral loads, which meant the precast concrete façade had to transfer the gravity loads directly through the precast concrete panels to the foundations. To achieve this the engineers designed a structural steel system embedded into the precast concrete panels. Pockets were formed into alternating panels at the spandrel level to allow the interlocking of each panel during installation. “All the gravity loads are transferred from any given panel to the adjacent panel on either side until they reach the foundation,” Bosch explains. “In order to prevent a progressive collapse in the event that one connection should happen to fail, each panel also has a safety backup connection.”