Sky Reflector-Net at the Fulton Center

In George Tooker’s famous 1950 painting The Subway, a woman navigates a claustrophobic, disorienting space filled with shadowy figures. The artwork perfectly represents “perceptions of compression, anxiety, [and] unease that accompany being underground,” says Vincent Chang, a partner at Grimshaw’s New York office. And until recently, this is exactly how it felt to trudge through a certain maze of dark underground passages that linked nine subway lines in Lower Manhattan just east of the World Trade Center site.

This site is Fulton Center, where a new transportation and retail hub opened this past November after more than a decade of work, and the new project reflects an altogether different vision of public transportation—a vision inspired, Chang says, by the soaring vault of Grand Central Terminal, which is pierced by oblique rays of sunlight. Among the many improvements to the Fulton complex, the most visible is the new “headhouse” building designed by Grimshaw with Arup, who oversaw work on the entire complex. For starters, there is a generous skylight, 53 feet in diameter and positioned 120 feet above street level, that allows daylight to reach all the way to the subway platforms underground.

But the space does more than just transmit natural light through an opening; it collects a larger view of the sky’s changing conditions. This is thanks to Sky Reflector-Net, a 79-foot-tall tensile structure suspended inside the conical atrium. The combination sculpture–daylighting device was conceived by artist James Carpenter, who then collaborated with Grimshaw and Arup to fine-tune it and integrate it with the architecture and engineering. Composed of a steel cable net and 952 perforated, folded aluminum panels, it drives light deep into the cavernous space. At the same time, it draws the eye up to a luminous field of blue-gray tones. And for good measure, it conceals the hulking mechanical infrastructure. Carpenter likens the perceptual effect of the net to “folding the sky down into the station.”

The artist has built his career on meticulously detailed installations that enrich the play of light and environmental phenomena in architecture. The work of his office, James Carpenter Design Associates (JCDA), frequently makes it difficult to separate art from architecture, engineering, and lighting. Sky Reflector-Net is no exception.

In 2004, JCDA won a competition sponsored by the Metropolitan Transit Authority’s Arts and Design program to design a large-scale, light-harnessing installation for the future Fulton Center. At the time, the transit hub was supposed to have been topped with a glass dome. Historically, domes have been decorated with artistic representations of the sky and its associated mythology. Even the ceiling of Grand Central Terminal’s Great Hall (while not a dome, it is an important precedent) is modeled with gold constellations and zodiac signs against a deep blue-green background, like a summer twilight sky. Carpenter thought of the Fulton Center commission as an opportunity to connect urban dwellers with the sky in a different way: not through pictorial representation, but through the play of daylight on a reflective surface, providing “a heightened experience of the sky and the mutable presence of light,” he says.

Even when daylight is monochromatic—say, on a cloudy winter’s day—Sky Reflector-Net creates a gradient of luminosity and tone. Each constituent panel is CNC-cut to a slightly different shape and size, and each has a different angle of exposure to the oculus and a different degree of opacity, which is a factor of each panel’s perforation. The panels nearest the bottom of the sculpture are the most perforated—48 percent open overall—and the size of the perforations grows smaller with each subsequent row of panels, so that the uppermost panels are only 20 percent open overall. The top of the sculpture thus appears brighter because its panels face the sky more directly so that it reflects more light, and it is nearest the skylight. Viewed from below, all that punched metal looks positively gauzy, holding the sky in a kind of embrace, more like a cloud than a building.

The perforations came about in response to a functional requirement. Sky Reflector-Net had to be designed so as not to obstruct the building’s smoke evacuation system, says Arup associate and lighting designer Matt Franks, who worked on the project from its beginning in 2003. Air passes through the reflectors as through a screen or a vent. “It’s not a hermetic shell, so it doesn’t hamper operations,” Franks says. Enormous air extract ducts—“almost large enough to stand up in,” Chang adds—are hidden conveniently behind the net. It’s a perfect example of technical performance overlaid with aesthetic intent.

The view from behind the cable structure matters too, or at least it does to the retail tenants who will occupy the glass storefronts on the mezzanine that overlook the atrium. This, Chang points out, is another reason why Sky Reflector-Net is most porous and translucent toward the bottom, so that it screens—but does not block—the light and the view of the skylit atrium. The retail spaces also enjoy a glazed exposure to the exterior.

The optical performance of the suspended array stems in part from the panels’ reflective finish. The aluminum panels have an anodized surface whose coating was originally developed for use as a material for reflectors in light fixtures. This material is approximately 95 percent light reflective and provides just the right balance of specular and diffuse reflection, says Star Davis, a lighting designer with the Arup team who worked on the project. It provides a soft reflection that spreads widely and evenly underground—and creates that ethereal field of brightness around the oculus.

As for the double-curved, hourglass form of Sky Reflector-Net, the design evolved with the changing architectural design of the Fulton Center. Between 2006–08, due to rising project costs, the originally planned dome was reduced in size and then eliminated, so JCDA had to sideline their original design for a special glass skin composed of clear, diffuse glass and metal mirrors. Grimshaw and Arup designed a smaller, more economical atrium with a conical rotunda and glazed oculus skylight at the top. (Despite the change in scale, the atrium is still roughly as large as the rotunda at the Solomon R. Guggenheim Museum farther uptown, according to JCDA.) To maximize the solar exposure, the oculus is tilted 23 degrees to the south and positioned slightly off center to evade the shadows of adjacent buildings, a move that was based on earlier light simulation models.

None of the design team members regretted the loss of the dome, at least in retrospect. On the contrary, Carpenter said, the change turned out to be “a much better opportunity to harness light.” Franks believes that it simplified the daylighting concept, replacing the omnidirectional light condition of the glass dome with a single, overhead light source. JCDA reconsidered their approach and began developing an optical liner, or sheath, to be inserted beneath the skylight. Working with engineers Schlaich Bergermann und Partner (SBP), they developed a parametric model of a two-way cable net.

This led to a series of structural form-finding exercises and ray tracings to determine optimum tensile and optical performance. “Light was the predominant thing, versus formmaking,” says Richard Kress, senior designer on the project for JCDA. The hourglass-like form of the cable net makes the sky more visible than would be possible with a conventional dome. As Davidson Norris, an architect who specializes in daylighting solutions and collaborates with James Carpenter through an affiliated practice, Carpenter Norris Consulting, explains, “The curve opens up toward the oculus. And that opening-up gives you a better view of the sky.” The view tends to be most dynamic at times of day when light comes in obliquely.

Mindful of the tensile loads of the 4,000-pound structure, SBP proposed attaching the net to the atrium structure only at the top and bottom—to the oculus compression ring and the second-level floor plate. Ultimately, with refinements by Arup, the design evolved into a stainless steel, paired-cable net supporting the 952 uniquely dimensioned panels, each one assigned to a specific place in the net’s layout. Oversize slotted holes in the connector hardware allow for thermal- or pressure-induced movement of the net even after being tensioned. It took only two weeks to install the pre-assembled lattice, and four weeks to install the panels. To further reflect and refract daylight and create a dappled effect, Grimshaw designed an array of 88 glass fins that are suspended directly beneath the oculus. The architects used parametric modeling techniques to mount the panels at various angles, scattering points of sunlight to different parts of the transit center according to the time of day and year. Measuring 6 feet long by 9 inches tall, each panel is laminated for safety and clamped to the steel frame of the oculus. While not technically part of Sky Reflector-Net, this element revisits one of Carpenter’s early ideas to have “target mirrors” embedded in the oculus dome to bounce specular reflections into the subterranean spaces.

At night, Sky Reflector-Net functions as a kind of reverse daylighting vehicle. Rather than bringing natural light into the space, it serves as a reflector for concealed electric downlights, Franks says. Metal halide lamps, grouped in fours and 400W each, are mounted around the oculus ring, mostly invisible from below. At night, these luminaires shine on the suspended net, which in turn disperses the light evenly. Compact fluorescent fixtures line the lower levels of the transit hub, and linear fluorescents in an X pattern light the underground mezzanines and passageways. Much of this lighting specification was done a decade ago, Franks says, before LEDs became readily available and suitable for general lighting. Perhaps inevitably, LED advertising screens wrap the atrium at street level, adding a significant source of brightness and a competing optical draw.

Still, Sky Reflector-Net offers a meditative moment of celestial reverie. The idea that commuters would end up resting their eyes in the sky, or in a reflection of the sky, seems almost utopian. The installation transforms commuters, however momentarily, into viewers. For this reason, architectural theorist and historian Sarah Whiting suggests in an essay from Beyond Surface Appeal: Literalism, Sensibilities, and Constituencies in the Work of James Carpenter that Carpenter’s work produces what might be called a suspended public—“a collection of individuals who share the experience of being suspended between memory and dream, suspended from everyday life … if only while they experience the project.” Revealing the natural environment with augmented clarity, Sky Reflector-Net operates in a space between empirical experience and optical imagination. It succeeds in bringing together the usually separate worlds of the street, the subway, and the sky.

   VIDEO: Artist James Carpenter of James Carpenter Design Associates, architect Vincent Chang, partner, Grimshaw, and Sandra Bloodworth, director, MTA Arts & Design discuss the collaborative process behind the Sky Reflector-Net at the Fulton Center in Lower Manhattan. Courtesy MTA.

VIDEO: Installing the Sky Reflector-Net at the Fulton Center in Lower Manhattan. Courtesy MTA.

Details Project Sky Reflector-Net at Fulton Center, New York
Client MTA Arts and Design and MTA Capital Construction Company (MTACC), New York
Artist James Carpenter Design Associates, New York
Lead Design Firm Arup, New York 
Architect Grimshaw, New York
Lighting Designer Arup 
Daylighting Consultants Carpenter Norris Consulting, New York, and Arup 
Cable-Net Structural Concept and Initial Form-Finding Schlaich Bergermann und Partner, New York office 
Cable-Net Hardware Manufacture, Engineering, and Installation TriPyramid Structures, Westford, Mass. 
Light Reflector Panel Manufacturer Durlum, Schopfheim, Germany 
Cable-Net Engineering and Installation Enclos, New York 
Total Square Footage Approximately 8,524 square feet (inner liner surface area) 
Artwork Cost $2.1 million

Project Fulton Center, New York
Client Metropolitan Transportation Authority (MTA), New York
Lead Design Firm Arup, New York
Architect Grimshaw, New York (primary headhouse building at the corner of Broadway and Fulton) Note: additional work was done by HDR (new entries and platforms) and Page Cowley (the Corbin Building)
Lighting Designer Arup
Engineer Arup
Construction Manager PB-Bovis Lend Lease
Project Size 190,000 square feet
Project Cost $1.4 billion (includes the cost for all station renovations and upgrades for Dey Street Passageway, Corbin Building refurbishment, and new entrances to the complex including the new headhouse building at Broadway and Fulton)
Lighting Manufacturers Apogee Translite, Beta Lighting, Eaton’s Cooper Lighting/io Lighting, Edison Price Lighting, Erco, Gammalux
Related Building Materials and Finishes Skylights: Oculus glazing by Viracon IGU assemblies by United Skys; oculus frame by STS Steel and TriPyramid Structures; reflective glass “parasols” by Saint Gobain; 
suspended metal ceiling systems Gordon Interior Specialties Division; reflective panels Alanod Miro 20 finish on anodized aluminum by Durlam