Nearly 20 years after the original 7 World Trade Center (WTC) was built, the last tower to fall on September 11, 2001, is the first to rise again, and the newly completed building is home to one of the largest interactive LED walls in the world.

Officially opened in May, 7 WTC stands 52 stories tall (the original structure was 47 stories) and is slightly narrower than its predecessor, but both share a common tenant: the 10-story Con Edison substation which holds transformers that occupy the bottom four floors. Because of the substation, construction on 7 WTC began in May 2002, and the transformers themselves were restored by May 2004. To accommodate the sensitive but critically important pieces of equipment that supply electricity to the Battery Park area of Lower Manhattan, the building's bottom floors are made from both screens and solid concrete that had to be showcased in a visually pleasing yet practical way, and it took a complex collaboration of architects, artists, lighting designers, software programmers, and LED manufacturers to do it.

The Podium Light Wall, as it is known, was the perfect solution. Located on the north and south façades of the building, the wall allows airflow to the transformers while incorporating an architectural system that catches daylight during the day on a span of glass with built-in reflectors and becomes an artistic expression of interactive light at night via colored LEDs. The LEDs first reflect dusk as a violet, then transit into a light blue, and finally turn a darker blue before shutting off completely around midnight. Seven stories tall and visible from nearby Freedom Park, the patterns the LEDs cast on 7 WTC are unique to the individuals walking by at any given time.

The building owner, Silverstein Properties, and principal architects Skidmore, Owings & Merrill LLP (also principal architects for the main World Trade Center site) brought in Cline Bettridge Bernstein Lighting Design (CBBLD) to develop and control this LED lighting concept and James Carpenter Design Associates Inc. to manage the wall's artistic design. The interactive aspect of the system, developed by Kinecity, uses several cameras that identify pedestrians walking on the sidewalk. The cameras then illuminate the LEDs in a column opposite the pedestrian, and this column of light follows either single or multiple pedestrians as they walk next to the building. CBBLD turned to Barbizon Lighting to help develop this complex control system.

It is, needless to say, a very delicate design. Francesca Bettridge, president and principal of CBBLD, notes, “Four or five years ago, LEDs were not being used like this. There were not any examples of LEDs in this type of architectural application that weren't signage and really integrated into the architecture, especially on a grand scale.”

This meant working with the LED manufacturer LED Effects to design a custom piece that would be able to withstand the intense heat coming out of the transformer vault, the building itself, and a pretty harsh climate.

Michael Hennes, senior associate at CBBLD, explains the major challenge of dealing with the wall: “Because parts are open and parts are concrete, what you would end up with is heat at certain concentrated places, and we were concerned about pieces of the wall turning off due to excessive heat that would create a sort of patchwork quilt effect. We switched the control to a system that was created by LED Effects called Stream, and the difference between that and DMX is that Stream allows bilateral communication. [See “The Pros and Cons of a Video-Based Control System,” opposite page.] There are thermal reading devices in the fixtures that can send information back to the computer processor telling the system whether the LEDs are too hot or not, and then the central computer running all the LEDs will determine if some areas of the wall are too hot, in which case it will turn off the entire system.”

Hennes explains that there are actually three different systems controlling the lights at 7 WTC, and they all work together, taking command of the wall at different times: an ETC DMX control processor as the overall control system; the LED Effects Stream protocol as the LED screen wall system; and the Kinecity motion camera system.

Watching the deep blues reflect during the winter evening rush hour, it looks like Lower Manhattan's newest rebuilding effort is off to a pretty bright start.


Building Owner: Silverstein Properties

Architects: Skidmore, Owings & Merrill LLP

Artist: James Carpenter Design Associates, Inc.

Lighting Design: Cline Bettridge Bernstein Lighting Design

Systems Integrator: Barbizon Lighting Co. Inc.

Interactive System: Kinecity

LED System: LED Effects

Construction Manager: Tishman Construction

Installing Electrical Contractor: Zwicker Electric Co. Inc.

Lighting Distributor: JDC Lighting

Façade Fabricator: Permasteelisa Group


Systems Integrator: John Gebbie

Project Managers: Brian Dunn, Thomas Fowlkes, Brian Fassett

Field Service Technicians: Grant Haase, Chris Reising, Roni Sia, Brian Dunn


592 LED Effects Custom “Type-H” LED Fixture

116 Designplan Lighting Inc. Custom LED Up Light

1 ETC Unison ER-4 Architectural Control Processor

3 ETC Unison LCD Control Station

5 Pathway Connectivity 8897 Opto Splitter

1 Watt Stopper 48 Circuit Relay Panel

1 LED Effects Streaming Animations Control Software

2 Kinecity PC

16 EverFocus Electronics Corp. EZ300 Color CCD Camera

10 LED Effects 16-Channel RS485 Terminator Panels

4 Middle Atlantic MRK-4431 Equipment Rack

1 Dell Pression 470 PC

1 Microsoft Office XP Software

1 Adobe After Effects Software Version 6.5

2 D-Link 16-Port Ethernet Switch

10 Control Device Master RTS6-16 Edge Server

1 Linksys 557414 10/100 8-Port VPN Router With Wireless Access Points

6 APC Smart 750VA UPS