A family house near Ulm demonstrates convincingly that sustainable buildings can also be strikingly beautiful. Photograph: Zooey Braun, Stuttgart, Germany. (photo: Zooey Braun)
A family house near Ulm demonstrates convincingly that sustainable buildings can also be strikingly beautiful. Photograph: Zooey Braun, Stuttgart, Germany.
07.04.2014, 06:19

Sustainable Architecture for the 21st Century

Mies van der Rohe Chair in Architecture at the Illinois Institute of Technology (IIT) and multi-award winning architect, Professor Werner Sobek, discusses the influence of sustainability on design.

The development that has taken place in our office over the last 20 years mirrors the changes that have taken place in the general building industry. Designing, constructing and managing a building has become a much more complex process, with an increasing focus on long-term perspectives rather than short-term profits. Where our services were initially offered as highly specialised designers and structural design engineers in the field of ultra-lightweight facades, this soon extended to the in toto design of building structures, and within just a few years to include facade planning. It was vital to overcome the interface between the load-bearing structure and the facade, which taken together make up approximately 40 to 60 per cent of a building.


The next logical step was to extend our expertise in the fields of energy saving and recycling-friendly design, and to aim to improve the emission characteristics of buildings with the founding of the subsidiary company, WSGreenTechnologies. Interwoven with this evolution of design engineering praxis has been the related orientation to research and experimentation carried out through the medium of an academic chair and the leadership of the Institute for Lightweight Structures and Conceptual Design (ILEK) at the University of Stuttgart. It is this duality of involvement that has enabled our firm to continuously refine and redefine its approach for a sustainable architecture ready for the 21st century.


The following article describes the aspects that we consider most important and that have the biggest influence on our work.



The design of housing is continually used by the practice to further develop its architectural concepts and underpin these with engineering advances. House R128 in Stuttgart (2008) is just such an experiment. It is an attempt to comprehend the archi-structural nature of three-dimensional transparency. The significance of R128 is to be found in the fact that transparency has here for the first time been achieved and experimented with in the third dimension, beyond the prismatic precedents of Mies van der Rohe and Philip Johnson. It is the first building in which interpenetrating sight lines are possible across four storeys.


In order to experiment with three-dimensional transparency and to experience its experiential and psychological attributes, the house was built as a personal lived-in experiment. Such a level of transparency can also be built on a large scale. Architect Christoph Ingenhoven has proven this time and again with his work: particularly significant examples of this are the European Investment Bank in Luxembourg (2007) and the Lufthansa Aviation Center in Frankfurt (2005). The Lufthansa building is located in a very difficult urban environment between the airport, railway, dual carriage way and motorway. Despite this, all of the offices are open, flooded with daylight, naturally ventilated, and offer wonderful views of the green inner courtyards. In this case the ideal of transparency is not restricted to the building envelope, but is continued throughout the inside of the building providing open, communicative structures that encourage interaction. These attributes also apply to the Post Tower in Bonn designed by Helmut Jahn (2003). The offices in this high-rise building are open to views of the surrounding area; it is possible to open windows on every level to allow fresh air into the rooms. These are examples of the experiential and environmental attributes of transparency.


A fundamental research question is: How does transparency relate to other design engineering principles that ultimately contribute to ecological design? Werner Sobek seeks to build structures that do not consume fossil fuels, do not generate any emissions and are completely recyclable. All of these things should belong to the fundamentals of designing; a point that also applies in particular to higher education at our universities, just as much as questions of structural stability, facade technologies and so on.




Lightweight constructions are a precondition for transparency. Lightweight construction means the dematerialisation of objects, to optimise weight to the limit of the possible, reducing integrated grey energy. The search for lightweight constructions is the search for boundaries.


Designing the lightest possible constructions can be equated with feeling one’s way towards the limits of what is physically and technically possible. It is about the aesthetics and physics of the minimal, and it is about stepping across the dividing lines between scientific disciplines. As far as constructions that bridge long span widths, reach great heights or move are concerned, reduction of self-weight load is an economical necessity and is also often the precondition for physical implementation. Irrespective of scale, lightweight design means savings on the mass of material deployed, and for the most part, also with regard to the amount of energy used. It is here that the ecological aspect begins: building light becomes a theoretical and ethical position.


A resolute approach to lightweight constructions requires modifications to the traditional structures of the design process. Establishing system geometries, forming and proportioning load-bearing structures as well as the selection of materials must primarily adhere to the requirement to save weight with other requirements taking on secondary importance; for example, those resulting from architectural considerations or from manufacturing techniques. Moreover, it is not possible to create a design of structural systems of minimal weight on the basis of a simple addition of the geometrically determined building components such as supports, balconies, arches, slabs, shear walls and so on. It is much more the case that the architect or engineer creating a lightweight construction designs spatial force paths, in other words, purely statically conditioned structures, for which he or she subsequently selects suitable materials. Thus the logic of lightweight building is a radical, or fundamental, principle for ecological design. 


One example of researching the boundaries of extreme lightweight construction is the glass dome developed for the ILEK building (2005). The 8.5-metre (27.8-foot) diameter dome consists of glued panes of glass of just 10-millimetre (0.39-inch) thickness. In other words, the ratio of thickness to the span is 1:850. Other examples include the canopy developed for the Pope’s visit to Munich (2006) and the building envelope for Station Z in Sachsenhausen (2005), the latter having been created by the Stuttgart architect HG Merz; the membrane façade for Station Z that was planned by Werner Sobek is stabilised by a vacuum – an example of creative building with energy.




In discussing new structures, the question posed is: What is ‘new’? Developing force conditions has nothing to do with lining up basic, geometrically determined building blocks. The task is much more about developing structures that are nothing other than the materialisation of three-dimensional, perfectly designed systems of forces. This is the only possible way to obtain structures that have a high level of structural logic and make very efficient use of materials Consequently, they radiate a very special form of inherent beauty. 


Designing engineering is about the design of the three-dimensional flow of forces whose design space is dictated by architectural, climatic or other conditions. It is only after these force conditions have been optimised as much as possible that the designer turns to materialising the force fields with the material most suited to the task. For two-dimensional designs this is purely a finger exercise, but a huge amount of effort and creativity is required when such design is undertaken for three-dimensional structural integration. 


New structures frequently involve innovative geometries. In this context, however, it is not simply a matter of optimising the building from an architectural point of view, but also from the standpoints of creating energetic structural planning and production techniques. If this is not accomplished, the resulting buildings tend rather to represent aesthetically motivated endeavours potentially limited in their habitability or usability. 


Working with double-curved structures, or with biomorphic structures or bubble systems, requires a deep understanding of analytical geometry. This alone provides the basis from which it is possible to make assessments regarding the feasibility of producing the structures, as well as with regard to special issues of the building process. The Mercedes-Benz Museum in Stuttgart (2006) is an example of the structural and materialisation conditions of complex geometrical structures. The double-curved, exposed concrete surfaces were created using a large number of formwork panels, each with a different border, produced utilising a water-jet cutting process to a tolerance of less than 1 millimetre (0.039 inches). The formwork panels were curved on site and provided a faceted surface.




If aspects of sustainability and recycling are integrated with complex geometries and dematerialised structures, then the necessity for new tools and methods becomes imperative. Building must make huge changes in the face of rapidly accelerating urbanisation, the induced consumption of energy and the resulting emissions. We have simply neglected to develop the appropriate answers to these problems through research and to develop the tools and methods with which to create the solutions. Today, very few succeed in building structures that fulfil the simple demands required to achieve a Triple Zero rating (zero energy consumption, zero emissions [not just CO2] and zero waste creation). 


First examples such as R128 and House D10 which is currently being planned are experimentally pushing the production of tools in the realisation of ecological values. 


It is now necessary to take a holistic view of building and design processes, considering the entire life cycle and beyond. If the components of a building are analysed, it can quickly be concluded that the load-bearing structure has a lifecycle of 50 years and more; while in facade technology a generation cycle is significantly less than 30 years, and in technical building services the generation cycles are even shorter. Consequently, buildings should be designed in a manner that allows the individual components to be removed and replaced more easily as their various service life-cycles dictate. 


The imperatives of sustainability will lead to fundamental change in the traditional relationships between architects and structural design engineers, and other engineering and management consultants. 


Putting sustainability into practice requires that each individual design engineer takes into consideration complex interrelating issues such as maintenance, repair and recycling. It requires the complete integration of aspects such as energy saving, emissions reduction and more. 


This cannot be achieved with the sequential planning processes as currently practised. We need to institutionalise new approaches to integral, cross-disciplinary design processes. 


This might enable those of us in new integrated teams of the design engineering professions to undertake a comprehensive examination of all relevant aspects of significance for a building and its users across its entire life cycle. It would then be possible to dedicate ourselves to the most important challenges for this century’s architects and engineers: to make ecology breathtakingly attractive and exciting.

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