Gehry’s starting point for the facade’s design was the residential bay window, which lets “you step outside the [flat] facade, as if you were walking on air,” he says.

Gehry wanted a sense of movement—enter the folds, creases and curves connecting the pointed bay windows. “I’ve been playing with this issue of folds for years,” he says. He finds fabric folds primitive and comforting. “They humanize the building,” he says. For the Beekman facade, “I told my guys I wanted Bernini folds,” which have a harder edge, “not Michelangelo folds,” which are softer.

Gehry Architects New York PC started conceptual design in late 2003. From 2004-05, the architect explored 50 or so schemes, applying the geometry to the wall surface using 1⁄16-in.-scale physical models. In late 2005, when the scheme had been honed to stainless steel with punched windows, Gehry started building 1⁄8-in. models. The architect also digitized the surface to create a BIM.

Also in 2005, FCRC issued a request for proposals to three curtain-wall suppliers for a design-assist contract based on Gehry’s scope and parameters. “We liked [PNA’s unitized] design and engineering, and they met our budget,” says Rechichi. Also, PNA was the only bidder familiar with CATIA—the sophisticated 3D model Gehry had used on Bilbao, Disney, EMP and other projects.

During the design-assist phase, PNA, with Gehry, developed a set of rules to turn the wall’s free-form shapes into something that could be mass-produced. The goal was to minimize the expense of a double curvature and maximize more economic, “rule-able” surfaces.

The phase, which included developing the entire panelization scheme and keeping the curvature within the budget, took more than two years. “You can’t do a job like this without design-assist,” says Michael Budd, executive vice president in PNA’s Mendota, Minn., office. Strong collaboration is needed to get to the required level of definition, he adds.

PNA used finite-element analysis to reduce the free-form shapes to single curves. Gehry refined the shapes, based on PNA rules, so that more than 90% of the surface has a single curvature. This was accomplished by slight segmentation at the panel joints, says Budd.

“We did the work zone by zone and face by face,” says Budd. “It was an iterative process,” adds Bowers.

The contract-document phase began in January 2007. Gehry developed the surfaces and the wire frame for the curtain-wall units in collaboration with PNA. The performance mock-up was completed and tested in early 2008.

PNA signed its $90-million contract and began detailed engineering in March 2008. Fabrication of the assemblies...