7 World Trade Center Project Cover
Ph.: © Chuck Choi Architectural Photography

7 World Trade Center

New York, NY | USA
Business Area
Exteriors, Interiors
architectSkidmore, Owings & Merrill LLP (SOM)
COLLABORATING ARTISTJames Carpenter Design Associates (JCDA)
Ph.: © SOM
The Concept

Today the ‘new’ 7 WTC marks the entrance to the renewed World Trade Center, reconfirming the vitality and business leadership of Lower Manhattan. This 52-story tower rising some 226.5 m (743 ft) comprises three main elements: a sharply angled main body whose transparent glass envelope gives it an evanescent lightness that seems to dissolve in the light of dawn and dusk; a podium clad in stainless steel panels reflecting natural or artificial light in myriad ways and creating ever-changing surfaces; and a radiant blue volume or ‘locking block’ that visually and conceptually links the stainless steel podium and glass tower into one extruded form.


226 m / 741 ft

52 stories tall

Given its geographical location, Lower Manhattan enjoys an extraordinary quality of light, which, however, often does not reach into the narrow streets coursing between the high-rises. So, out of an aesthetic choice and from sheer necessity, the 7 WTC literally collects light and, thanks to its reflective surface, amply diffuses it to the surrounds. The main vision behind the architectural program was to maximize the efficiency of the available light with a transparent crystalline building able to orientate and re-direct the sun’s rays off its inclined reflective surfaces. From the start, it was meant as a construction whose spectacular but functional skin would stand out from the traditional skyscrapers all around.

Ph.: © Chuck Choi Architectural Photography
Ph.: © Chuck Choi Architectural Photography
Ph.: © Chuck Choi Architectural Photography
The Spirit

Working with Permasteelisa we developed a linear-lap curtain wall, setting up a blue daylighting reflector in the spandrel sill that picks up the sky’s brightness and projects the color of the sky up into the spandrel. Each floor’s vision panel overlaps the spandrel below, which is open to the outside. The highly transparent, lightly reflective, low-e insulated glass units and linear lapping system simultaneously capture qualities of light behind the outer skin, giving the building a much more responsive ability or capability within its context to always embody multiple properties of light in a richly layered way.


James Carpenter, James Carpenter Design Associates (JCDA)

The Project
Scope of Work

Design & engineering, manufacturing and installation of 51,600 sqm (555,400 sq ft) of curtain wall with additional 5,200 sqm (56,000 sq ft) of stainless steel cladding for the podium area, 420 sqm (4,500 sq ft) cable-net glass wall and interior lobby’s significant elements.

Ph.: © JCDA

Diagrams illustrating the spandrel’s redirection of the sun’s rays in the summer and the winter. 

Ph.: Permasteelisa Group

Main façade partial elevation and vertical section.

A light-reflecting prism

The 42 stories making up the main tower volume are entirely clad in a 51,600 sqm (555,400 sq ft) curtain wall made up of floating vision panels and concave stainless steel spandrels. The glass vision panel is glued to an aluminum frame so as to partly overlap the recessed spandrel panel in a façade design especially developed for the 7 WTC. The resultant modular system is made up of transparent glass panels and slightly undulating light-refracting opaque panels.

The panels of extra-clear glass are placed over the spandrel panels flush with the edge of the floor plates. The effect is to make these front panels seem to float in the air, giving the façade a luminous depth. The stainless steel spandrel panels are slightly concave in shape - with a curvature of approximately 9 m (29.5 ft). This, together with their pressed specular texture, makes the light reflect and refract off the surface in infinite ways, an effect enhanced by two surface treatments: embossing with a light pattern to stimulate abrasive blasting and then corrugation to obtain a horizontal corrugated pattern. The sill in front of the spandrel is clad in a blue plate that reflects the sun’s rays onto the curved spandrel surface so that the whole building façade mirrors the color of the sky.

Standing 25 m (82 ft) high, the podium is made up of two layers of stainless steel slabs separated by an 18 cm (7”) cavity allowing the airflow needed to ventilate the transformers. The panels comprise a series of different-shaped cold-formed triangular-section prismatic profiles placed vertically side by side and oriented at a special angle to create different patterns. The profiles are welded onto a 1.52 x 4.27 m x 25.4 cm (5 x 14 x 0.8 ft) subframe. The front screen prismatic wires all have 12 mm (1/2”) cross section faces and are highly polished, while the back screen prismatic wires have 6.35 mm (1/4”) cross section faces and are glass bead blasted to diffuse and scatter light. The two wire sizes produce complementary light-reflecting properties and reduce the moiré (bifurcating) effect generally created by two layers of parallel lines. The millimeter-precision placing of the triangular profiles set at a series of different angles produces a kaleidoscopic interplay of light and colors, giving the observer a luminous sense of depth. By day, the outer layer of the steel prisms reflects the light depending on their particular orientation while any light penetrating the outer layer is bounced off the surface behind. At night, this porosity is highlighted by LEDs backlighting the outer surface. In addition, an infrared light circuit trips in with the movement of passers-by on the street.

Ph.: © SOM

Context plan.

Technical Details
Ph.: © Chuck Choi Architectural Photography
Ph.: © Chuck Choi Architectural Photography
7 World Trade Center podium detail
Ph.: © Chuck Choi Architectural Photography
7 World Trade Center cable-net wall detail
Ph.: Scott McDonald © Hedrich Blessing
7 World Trade Center lobby internal view
Ph: SOM © David Sundberg/Esto
Ph.: SOM © Ruggero Vanni
Facts & Figures

2006 Completion

The first Ground Zero edifice to be rebuilt after 9/11

A skyscraper built over a power substation

9,000 customized, unitized façade glass units

‘Linear-lap’ curtain wall units overlapping the floor plates

A stunning prismatic podium giving a volumetric sense of light

A 32 m (105 ft) long transparent structural glass wall

Lobby interior with artistic lighting elements

NYC’s first LEED Gold® Office Building

OWNER & DEVELOPER: Silverstein Properties, Inc.

LANDOWNER: Port Authority of New York and New Jersey

ARCHITECT: Skidmore, Owings & Merrill LLP (SOM)

COLLABORATING ARTISTS: James Carpenter Design Associates, JCDA (podium and curtain wall ‘linear lap’ glazing detail); Jenny Holzer (art installation in lobby)


More Information

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