lgn2204

Helmut Jahn and Werner Sobek:
"Working towards the elimination of the inessential in architecture using laminated glass"

Helmut Jahn of Murphy/Jahn (Chicago, Illinois, USA) and Werner Sobek of Werner Sobek Ingenieure (Stuttgart, Germany) have collaborated on a large number of award-winning projects worldwide since the early 1990s.

Helmut Jahn, president and CEO of Murphy Jahn

Helmut Jahn was born in 1940 in Nürnberg, Germany and pursued graduate studies in architecture at the Illinois Institute of Technology in the 1960s. He joined CF Murphy Associates of Chicago in 1967 and became principal of Murphy Jahn in 1981. Since 1983, he has been president and CEO of Murphy Jahn and has also held professorships at Harvard, Yale and IIT.

Jahn said in a keynote paper entitled 'Archi-neering' (1999): "Buildings in the year 2000 and beyond cannot be made of brick and steel. They will be built with new available technologies, using elements with changing properties. The skin of the building will integrate energy through the use of photosynthetic, photovoltaic or photochromatic processes. This will become possible through a change in the traditional architect-engineer relationship.

"The ultimate purpose of architecture in say, a thousand years from now, will be to construct shells for community life made of thin, transparent, elastic membranes that are actually designed to protect people from unpredictable natural events happening outside. 'Weight' will lose any inherent sense and opacity alone will meet the need to obscure views and light.

"Glass is one of the few building materials with room for development. The material's ecological and aesthetic opportunities include transparency, reflection, opacity and refraction.

"We are very interested in dealing with light and transparency. Light is traditionally directed towards the material fabric of a building, illuminating the solid. In our most recent projects, we are moving into a direction where light is the essence of the design, where buildings are luminous, not illuminated. The facades start acting as fabrics that moderate the natural and artificial light, so the glass façade is acting more like a screen.

"There is still a lot of room for innovation with architectural glass. Creativity has more to do with the elimination of the inessential than with inventing something new. Perfection is achieved not when nothing is to be added, but when nothing can be taken away."

Werner Sobek, founder of Werner Sobek Ingenieure (WSI) of Stuttgart, a structural engineering and design consultancy

Werner Sobek was born in Aalen, Germany in 1953. He studied structural engineering and architecture at the University of Stuttgart, achieving his Ph.D. in 1987. Since 1995 he has been Professor of Engineering at Stuttgart University, where he is also director of the Institute for Lightweight Structures and of the Central Laboratory for Structural Engineering. In 1992 he founded Werner Sobek Ingenieure (WSI) of Stuttgart, a structural engineering and design consultancy operating on a global basis.

Sobek says: "WSI buildings are characterized by their load-bearing structures which have been reduced to the absolute minimum by their innovative facades and by ingeniously-designed load distribution - seen in the lines of the buildings. Of particular note are the large glass areas, which render these structures transparent and well lit. By applying the principles of lightweight construction to every detail and using new jointing and assembly techniques in an innovative manner, it is possible to build roofs of large spans, which visually have a filigree-like lightness, often due to an ingenious handling of glass, steel and fabrics.

"We are using laminated glass to achieve minimal weight and maximum size: the result we want is maximum transparency. An engineering firm is always facing two problems: how to resist internal load and how will the glass behave in a post-breakage environment (for example as a result of impact from blast or vandalism). Laminated glass provides us with an excellent solution to these two problems because of its structural strength and post-breakage behaviour.

"SentryGlas® Plus provides architectural engineers an extra safeguard; it's a very stiff interlayer. If we expand it outside of the glass panes, we are able to use the ionoplast as a distributed strength, load-bearing interlayer to the substructure, with the advantage of complete transparency."

Cologne-Bonn Airport, Terminal 2 (1992-2000)
Jahn: "The objective was to create a bright, easily accessible and friendly building which by its generous proportions and filigree-like structure induces in the traveller a feeling of pleasant expectation regarding the impending flight. The intention was to 'import' the activities on the apron and taxiways into the terminal and turn them into an experience for all visitors.

"The glazed terminal façade designed by WSI plays a key role in this. The 800 m long façade is divided into sections 40 to 70 m long and varies in height between 10 and 20 metres. The special feature of this façade is that it consists of thermal glazing panels fixed in point-like mountings. This subjects the load bearing structure to extreme deformation stresses. All sections of the façade are designed on a tensioned cable net structure.

"The façade glazing consists of white laminated glass thermal glazing units fixed stress-free in point-like mountings. The cross-shaped cast stainless steel mountings are fixed to the cable structure. This method of fixation represents a technically and architecturally innovative step compared with the conventional method of drilling the glass."

Sobek: "This was the first major project where we used tiny (60 mm wide) pads of opaque, sandblasted stainless steel instead of point fixings and so we did not have to drill the insulating laminated glass, which was quite cost effective. The overall effect is of overwhelming transparency. The project would not have been possible with out laminated glass, which is used throughout for safety reasons and because we wanted to minimize glass thickness and obtain a light substrate in our quest for immateriality."

Sony Centre, Berlin (completed: 1993-2000)
The Sony Centre on Berlin's historic Potsdamer Platz consists of a complex of buildings grouped around a central atrium. Eight individual buildings are used for offices, apartments, large cinemas and a museum of fine art.

Jahn: "In the reconstruction of Berlin, the Sony Centre stands for a new technical vision and order. Light, both natural and artificial, is the essence of the design. The Sony Centre is luminous, not illuminated. The glass facades and roof act as a fabric that moderates the natural and artificial light. With its characteristics of transparency of permeability to light, reflection and refraction, there is a constant change of images and effect during day and night, affecting not only the appearance but also maximizing the comfort and minimizing the use of energy resources.

"The Sony Centre is a 'Kulturform' (a new form of culture) for the millennium where the serious business of entertainment is portrayed as the real challenge to the high arts of classical music, theatre and painting.

Sobek: "For me, this is a glass masterpiece of the last millennium. Among the special structures are a large number of facades consisting only of laminated glass up to 20 m in height. These are supported by vertical glazed cable structures and cable nets, large winter gardens or protected historic building fragments enveloped by laminated glass cubes. All these structures designed by WSI share the extreme lightness and transparency of the building envelopes. Laminated glass was used for its safety benefits. At this stage, we were still using point fixed system with drilled holes to secure 5 m high panels of laminated glass.

"Of particular interest are the glass walls in front of the Esplanade, a former hotel where the German Kaiser used to take breakfast, later concreted over by the communist regime and now restored as an historic monument. A 60 m long x 20 m high laminated glass wall shows off the restored and exposed walls, supported by a cable net structure.

Like a three-dimensioned trussed beam, the Flying Truss spans the air space between the southern section of the building and the Bilka wing. The Flying Truss carries a laminated glass façade consisting of standard floor-to-ceiling glass elements.

Sobek: "The Flying Truss is a 40 m wide structure where laminated glass is used as a structural element. It's kind of fun because the 'façade' flies around in front of the building. We used laminated glass for safety; the façade is about five stories high and underneath is a very public space. Laminated glass was the only safety option.

Jahn: "The building is like a simple and clear diagram. Its components are placed in a logical, rational and constructed way. The interest is in engineering and performance, rather than design and style. The result is a building of maximum transparency.

"Transparency deals with light. Traditionally, light has been directed at the material fabric of a building, illuminating the solid. At the HA-LO headquarters, we are moved into a realm where light is the essence of the design. The building is luminous not illuminated. The façade acts as a fabric, which moderates the natural and artificial light; it becomes a screen. The functions are within an acceptable envelope which responds to the exterior environmental conditions and creates the desired interior environment. Newness is achieved through the elimination of the non-essential."

Sobek: "This is a cutting edge building for the USA, where building owners typically prefer a much more conservative, 'retrospective' style! Seriously, we are always trying to achieve transparency in architecture. I believe that if we were to live in glass houses our brains would be stretched, metaphorically speaking, because visually we would be constantly 'breathing in' air and lights. Our intellectual focus would widen. If you're stuck in an office with no windows, your intellectual vision is impaired accordingly, I believe. That's very important.

"Laminated glass is used throughout this project for safety reasons, because of its excellent post-breakage behaviour. We have played with various levels of opaqueness and transparency, from the perforated steel screen (which seems almost transparent when viewed from a distance) to the laminated glass fins that support the façade."

Exhibition Centre, Shanghai-Pudong (completed 2001)
The new Shanghi-Pudong exhibition centre strikes the observer by the clarity of its architectural and structural design concept.

Jahn: "The uncompromising realization of the principles of lightweight construction results in large, light-flooded spaces which provide very large, unobstructed floor areas."

Sobek: "The front facades are all of laminated glass for safety reasons, due to heavy traffic and potential damage from vandals.

MAX Tower, Frankfurt (completion: 2005)

This prize-winning design for an office tower in the Frankfurt banking quarter is a building of 63 stories, at a height of 228 metres. The plan dimensions are 55 m in length and 38 m in width. In plan view, the long axis terminates in two semi-circles, which are linked by a slightly concave central section.

Jahn: "The shape of an incised ellipse responds to its central location in the high-rise bulk of Frankfurt, next to the Commerzbank and the new Rhein-Main Tower. Several strategies were used to make the building lighter, less material and more transparent towards the top.

Sobek: "The external façade is designed as a single-skin envelope consisting of laminated glass and stainless steel. The roof skin consists of laminated glass and stainless steel panels and is supported by a grid of hollow steel sections. Owing to a novel energy management system, the building does not need conventional air conditioning systems. The offices are cooled by means of cooled ceilings, cooling panels and component cooling installed in the floors between levels. Each façade is fitted with a window that can be opened manually and a perforated stainless steel screen panel, which acts as sunblind, windbreak, rain-cover and safety barrier. Together with the thermal and solar glazing units, these façade modules reduce energy transmission through the façade to 12 percent. We will use heat strengthened laminated glass on the outside of the insulated units of MAX's façade."