One South First in Brooklyn, N.Y., is a new mixed-use building that promises to redefine waterfront living. Overlooking the East River, the 42-story residential tower and 22-story commercial tower have transformed the property, which was once home to an old sugar factory. The new owners saw the potential for luxury living on the site, and they wanted a façade that would maximize the waterfront views.
The architect envisioned a contemporary façade that was inspired by sugar’s crystalline structure as a way to connect the new building with the industrial history of the site.
“That brought us to the idea of dealing with sugar,” says Pam Campbell, partner at CookFox and designer of the project. “We were interested in creating a façade that would really be animated, but reminiscent of the reflection and form of sugar crystals.”
They used precast concrete to bring that idea to life.
The precast concrete façade features repetition of angled white precast concrete using interlocking panels with deep facets to create a play of light and shadow that animates the rigorous forms. Designed to self-shade, each elevation is formed to respond to its specific solar orientation and optimized to reduce energy use for cooling. “It offers a unique opportunity to prioritize energy efficiency through the complementary energy profiles of different uses,” says Steve Schweitzer, vice president of operations for Gate Precast Company.
The window openings were deep-set and the sides were faceted back at different angles to catch the light and show the sparkle of the glitter sand used in the acid-etched white concrete. The front faces of the panels were polished to give a smooth reflective surface to complement the acid-washed surface. The layout of the molds in the panel were varied throughout the building to give an appearance of randomness.
Two hundred Pours per Mold
Along with helping designers achieve their aesthetic goals, using precast concrete for this façade delivered considerable time and cost savings.
To create the façade, the precast concrete producer used 3-D printed molds in a process known as additive manufacturing. The 3-D printed forms made it possible to rapidly produce a large number of panels with window openings.
Traditionally, a mold for this type of project would require between 40 and 60 man-hours, notes Schweitzer. But with the automated 3-D printing, that time was cut to just 14 hours. Each mold could support more than 200 pours, whereas traditional wood molds typically require reconditioning after 16 to 18 uses. This allowed the production teams to run consecutive days without downtime during the fabrication of the façade.
Throughout the project, the design-assist team worked collectively using Revit software to plan and track various stages in the building's lifecycle. They created “intelligent families” within the software to enable rapid advancement and collaboration between the teams.
The Revit model served as the cornerstone for the advance production workflow, Schweitzer says. “Without the ability to make real-time modifications in the architect’s office and then share those changes with the fabrication team instantly, the process of design and detailing would have taken several more months to complete, thus delaying production and delivery on-site.”
To further expedite erection, nearly 2500 windows were installed at the precast concrete plant, which saved at least eight months on the schedule and allowed the interiors program to start sooner. “The inclusion of the window system installation at the precast concrete producer’s production facilities proved to be invaluable to the owner and construction team,” Schweitzer says.
Special considerations for the attachment methods during the design stage enabled a rapid installation time of around 30 minutes per window. “As the precast panels were erected on-site, the building envelope was virtually complete,” he adds. “This not only saved significant time on the construction schedule, but also provided a clean, weather-protected, and safe work area for the other trades that followed.”