The office tower of the Union Bank of Switzerland, known as One North Wacker, rises 50 floors into the skyline of Chicago.
Uniting the interior
with the exterior
The UBS Tower in Chicago is a distinct addition to the skyline of the famous “Windy City” in the Midwest of the United States.
At a height of 199 meters and with 50 floors over ground, the UBS Tower, often referred to as One North Wacker, is one of the most impressive architectural achievements in the city. Architect Steve Nilles of Lohan Associates, Inc. designed a state-of-the-art high-rise building that features a staggered east facade with two setbacks and a number of other elegant architectural details.
Transparence as a philosophy
In line with UBS’s corporate philosophy to strive for the greatest possible transparence, an exterior wall of anti-reflective “Amiran” glass frames the 13-meter high atrium lobby. This SCHOTT glass, which was dip- coated on both sides with ultrathin interference layers, reduces reflections by eightfold. The remaining surface reflectivity of just one percent makes the glass wall practically invisible, thus creating an inviting atmosphere. The entrance area remains light and friendly even when the sky is overcast. The idea is for the lobby to be open to the numerous pedestrians passing through the plaza in front of the Tower. The advantage is that customers enter the building without any feeling of restraint.
A web of cables supports the facade
A wall of anti-reflective glass encloses the 13-meter-high lobby.
The main idea behind this design was to create the appearance of a uniform glass facade without the interference of supporting structures. It thus gives the impression of a transparent suspended glass curtain. Architect Steve Nilles compared this kind of construction to the principle of a tennis racket. When a tennis ball hits the racket, the tightly interlaced network of strings changes shape, but then immediately springs back to its original position as defined by the frame. The stress on the glass facade, caused for example by wind pressure, is distributed evenly throughout the network of internal cables.
Birthplace of skyscrapers
The round metal medallions attached to the corners of the glass panes are the joints for the network of steel cables and also stabilize the glass facade.