Practicing ArchitecturePracticing Architecture
Rays of Hope: Three New World Trade Center Buildings Celebrate Daylight
The sun will orient visitors to a new post-9/11 cityscape
By Nalina Moses
As 1 World Trade Center rises floor by floor above Lower Manhattan, three other major buildings under construction at the World Trade Center site are content to lie low and let the sun come down to them. The World Trade Center Transportation Hub by AIA Gold Medalist Santiago Calatrava, Fulton Center by Grimshaw Architects, and the National September 11 Museum by Snøhetta all incorporate daylight as an active, integral element of their interiors. It's a strategy that goes far beyond the pragmatics of wayfinding and energy conservation. Each structure is harnessing the sun to orient visitors more deeply towards the city and the sky, and to bring a degree of dignity, comfort, and lightness to a place that, more than a decade after the attacks, still arouses fierce emotions and memories of trauma.
World Trade Center Transportation Hub
Perhaps the most arresting new architectural presence at the WTC site will be Santiago Calatrava's new World Trade Center Transportation Hub, which provides an entrance to three city subway lines and Port Authority Trans-Hudson (PATH) trains to New Jersey. The station, with a projected cost of over $3 billion, is expected to open in 2015. The entrance is housed in one of the architect's signature soaring symmetrical biomorphic shells, this one constructed from sinuous white steel ribs that cross at a spine and spread into broad wing-like forms. Along the center, a retractable skylight will pull daylight and fresh air inside. The building is oriented so that each year on the morning of September 11, sunlight will fall directly onto the floor inside. While the architectural packaging is new, the structure shapes a generous, orderly, well-lit hall that's reminiscent of 19th-century American train stations, like Grand Central.
While sunlight warms the experience of commuters and visitors moving through the station, it also animates the extraordinary skeletal forms of the architecture so that they're more than a magnificent sculpture. In video animations and renderings of the design, one senses that light sliding inside through the narrow spine skylight, and in between the closely spaced ribs will shift dramatically with the movements of the sun. As Iain Rowe, lead structural engineer at Calatrava’s firm, says, “[Lighting] does not only create a more pleasant space, but can bestow a space with other attributes, such as the drama of the complex play of shadows and the changing atmosphere throughout the seasons.”
When Grimshaw Architects received the commission to refurbish Fulton Center, a subway station two blocks east of the WTC site, it was a tangle of narrow walkways, stairs and ramps that led passengers from a handful of small street-level entrances to platforms for eight different subway lines. As part of a Lower Manhattan revitalization project spurred by all the construction and redevelopment going on at Ground Zero, Grimshaw is looking to open the station to the neighborhood, which has become increasingly vibrant with the influx of visitors to the National 9/11 Memorial. To do so, the New York Metropolitan Transportation Authority decided to raze some older buildings on the block and create a large unified station with an above-ground shopping and dining concourse, all at the cost of $1.4 billion. The new glass-walled structure (to be completed in 2014) is perched at a prominent corner along Broadway, and will facilitate movement through the station by offering new, better-organized public space.
To begin modernizing the station, Grimshaw looked back to the original New York City subway stations and found that many incorporated daylight indirectly through lightwells. Grimshaw’s Vincent Chang, who led the project, describes how the New York subway system—unlike those in cities like London—is unusually shallow, which facilitates opening the stations to natural light. “In [some] places [it’s] not much greater than 20 feet beneath the street surface,” he says. “Historic photographs show that ‘sidewalk lights’—embedded glass lenses—were often used to bring natural light onto the platform.”
To bring light down through the three-story shopping concourse, the architects and their structural engineer Arup fashioned a giant oculus, 90 feet across at its base. This dramatic cone-shaped opening lets in a wash of strong bright light. To refine its effects, Grimshaw collaborated with light artist James Carpenter to fashion a porous mesh of light-bending faceted metal panels to line the opening. The architects used computer modeling to study the quantity and quality of daylight that would fall inside, as well as the movement of the sun through the day and the year. And, for inspiration, Chang and his teammates studied time-lapse photography of the main hall at Grand Central Station, observing the dynamic effects of daylight inside. Chang admits that the architects had access to great raw material: “New York is blessed with an amazing daylight signature,” he says. “It shares a latitude comparable with Madrid. The light is often crisp, providing sharp contrasts and real color warmth.”
Chang recalls one image that served as reverse inspiration: a 1950 painting by George Tooker called The Subway that shows a herd of commuters shuffling, zombie-like, through a claustrophobic underground station. It's this brand of urban dread that the new station seeks to alleviate, and it seems as if it will, by connecting visitors to the outside. After visiting the station (which is now fully enclosed), Chang says, “The oculus, oriented towards the southern sky, allows a tremendous amount of light to enter the building, even on overcast days. Every level, from the lowest concourse through to the elevated galleries that ring the site, is bathed in light. Not only does this dramatically reduce the need for artificial lighting, but it also creates a strong sense of connection between subway system and the outside world above.”
National September 11 Museum
While the National September 11 Memorial uses water to sculpt a dramatic space, the accompanying museum pavilion by the architecture firm Snohetta uses sunlight in much the same way. The entire project, including the memorial and museum, has a reported to cost of approximately $700 million, while the above-ground entrance structure will cost about $90 million. Its opening, originally slated for September 11, 2011, will happen in early 2014. The low asymmetrical museum entrance structure located at the southwest corner of the site is composed of gracefully tilting planes of metal and glass. It's oriented along an east-west axis, with a large atrium at the west entrance that carries light down to the main level of the museum below, where visitors can pass behind the base of the waterfalls that mark the footprints of the original towers.
The building's exterior is configured to admit light highly selectively, funneling much of it to the museum's atrium. Snøhetta’s Anne Lewison, AIA, says that approximately 22 percent of the building's exterior surface is atrium glazing, and both the atrium and the storefront have a low-E coating, which allowed the architects to meet LEED requirements. The exterior metal panels have a partially brushed finish, and the glass panels have a ceramic coating on the underside, so that the entire exterior will reflect light indirectly. Light that enters the building through the atrium glass will be more diffuse than direct sunlight. On the inside, sunlight will be further modulated with blackout shades, solar shades, and gauze-like curtains. The finishes and treatments soften the sunlight and the experience of entering the underground museum.
After spending time in the building, which is entirely framed and clad, Lewison is pleased that the effects of natural light inside are even more complex and ephemeral than she and her team had imagined. “Our favorite light is when the sky is a bit gray or overcast, when the building appears to be a delicate pearly color and responds visually to the adjacent trees and buildings with a soft, dreamy set of reflections,” she says. “We have also found that glazing on the adjacent towers going up around the site sends light into the middle of the memorial that gets bounced into the atrium at various times of day. Borrowed daylight is having a wonderful effect on the memorial.”
Lewison says that bringing daylight into the pavilion and then down into the museum below grade was very important from the beginning of the design process. “Both physically and emotionally, visual access to the sky has been a recurring theme of hope in this memorial project,” she says. In winter months, daylight highlights the well-known cross-shaped steel column formation that was salvaged from the original Twin Towers, now installed at the base of the museum's atrium.
While the design of the exterior cladding is rather pragmatic, to modulate sunlight that entered the building, the actual effects of daylight promise to be more emotional. The architects intend the building to be enveloped by trees that have been planted at the memorial, which have not yet reached their full spread, and for the museum to reorient visitors powerfully towards the community and the world right around them, rather than wrench them from the present back to the past. Lewison explains, “As the memorial is Reflecting Absence, the pavilion reflects the present—the weather, the seasons, and the visitors and their families who are present together in the moment.”