The 16 acres in lower Manhattan known as ground zero is arguably the most emotionally charged site of our time. It is the location of the Sept. 11, 2001, and Feb. 26, 1993, terrorist attacks, where 2,983 people lost their lives. Creating an appropriate commemoration that recognizes all the victims at the World Trade Center site, the Pentagon, and Shanksville, Pa., where flight 93 crashed, has been an important part of the rebuilding efforts. But how to proceed with the process of healing and renewal, while also addressing New York City's need to repair its public and private infrastructure, has been a complex, and at times, highly political process.

A number of forums took place in the immediate weeks and months after 9/11, and hundreds of ideas were gathered from the public and the design and construction communities. Then New York City, along with private developers and a number of public agencies—including the Port Authority of New York and New Jersey, the owner of the site where the World Trade Center had once stood—mapped out a strategic plan for rebuilding. In 2003, a design competition was then held for the memorial component of the site. Architect Michael Arad and landscape architect Peter Walker won with their entry, "Reflecting Absence," which called for a landscape of trees surrounding two reflecting pools that would echo the void of the Twin Tower's footprints.

As the design for the memorial and a museum (to be built separately on the site by architecture firm Snøhetta) proceeded along, Paul Marantz and his firm Fisher Marantz Stone (FMS) were asked to join the team in 2005. Marantz was an easy fit, as he had worked extensively with Peter Walker in the past, and had also worked with Davis Brody Bond, the firm serving as project architect for the memorial and the museum.

He was also already well versed in the language of Sept. 11 tributes. Along with fellow firm principals Jules Fisher and Charles Stone, Marantz was part of the team behind the Tribute in Light commemoration that has been held each year since 2002. His firm also designed the lighting for the Staten Island and the New Jersey September 11th Memorials.

From the start, the competition-winning design required a lighting component, as the site was intended to be accessible to the public by night, as well as by day. "The issues were one of aesthetics and appropriateness," Marantz says, "and the second issue was security."

Marantz and his team didn't want to overlight the space, but city officials mandated a significant amount of light across the plaza—5 footcandles per square foot. FMS worked closely with Robert Ducibella of DVS Security and Consulting & Engineering, which was in charge of security for the project. FMS visited a number of New York City parks to take light-level readings, and, based on the data collected, were able to convince officials that an average of 0.5 footcandles would provide enough illumination. As Marantz explains: "It became clear that the entire plaza would be supervised by video for which light intensity is no longer a challenge because the cameras are so good. But we needed the vertical footcandles." To achieve the light levels, Marantz decided to use prismatic refractors around a 4-foot linear fluorescent light source.

But Arad and Walker's design for the plaza, which used orthogonal lines, required that the luminaire be done in a square format. Previously, the technology had only ever been used in a cylindrical form. Marantz approached lighting manufacturer Selux, who had been instrumental in developing this technology, and asked if they could adapt it to the form factor required. "Selux was extremely cooperative," Marantz says, and FMS detailed the pole luminaire for the plaza in collaboration with Peter Walker. The luminaire functions as more than just a light source; it also houses cameras and radio antennas for the security system.

Although the lighting design for the plaza and the memorial employs a mere three fixtures, each of them responds to challenging design, maintenance, and public-safety criteria, while technologically breaking new ground.

One of these technical achievements occurs at the central feature of the memorial's design, the two reflecting pools, each measuring 200 by 200 feet, which sit in the voided footprints of the World Trade Center towers. "We knew from the beginning that we would uplight the fountain," Marantz says. But the new technical challenge here was how to create something that would be bright enough and withstand the constant volume of water from the 30-foot cascading waterfall. The relevant National Electric Code (NEC) dictated that such a submersible fixture run on 25V or less. And New York City's code was even more stringent; it required that the fixture run on 12V or less. No such luminaire existed to achieve these requirements, so the team received an exemption to work to NEC standards.

And then came the issue of the light source. In 2005, the only source available for an application such as this was a low-voltage incandescent or halogen. "It was unimaginable to us that we were going to have 1,600 feet of individual lamps of short life. The maintenance picture was just horrendous," Marantz says. LEDs, still in their infancy, seemed to provide a possible solution. "They held the promise of a long-life light source that would be operated if the voltage is under 25," he says. But LEDs were still new and unproven. Nevertheless, FMS decided to take the gamble.

Fountain consultant Dan Euser worked closely with the team, and he built a full-scale mock-up in his Toronto backyard of an LED system that would sit in a stationary waterproof box. Once the team saw that their concept would work, the project was sent out to bid. Winona Lighting, an Acuity Brand, designed a new luminaire that achieved the designers' desire for a singular steady line of light that traces the perimeter of the waterfall and pool edge. This fixture also was able to use the water to its technical advantage. LEDs, by nature, run very hot, and this heat has to be dissipated. Ron Schimmelpfenning, director of new product engineering at Winona, and his team designed the luminaire to incorporate water cooling. The fixture's wiring is also designed so that the entire luminaire can be disconnected and replaced from an access space adjacent to the pool and out of public view.

A third luminaire type is located at the parapet of names that ring each reflecting pool, where victim names are stencil cut through bronze plates. This makes the underside, where the fixture sits, susceptible to rain, snow, and debris. So FMS designed a light strip (three rows of 3500K LEDs) tucked out of sight and covered with a plastic reflector, which directs the light upward to backlight the names. For maintenance purposes, the reflectors also can be easily be removed and cleaned.

Despite the commotion of the city as a backdrop and the active construction that surrounds the memorial, there is a transformative, hushed reverence from the moment you enter the World Trade Center site. It is an awareness that you are stepping on hallowed ground. Lighting plays a key role in realizing the memorial design and creating a place for solace and contemplation. To get to this point, the design requirements pushed lighting technology to new bounds.