At the German Pavilion at the EXPO in Milan, a modern design vocabulary with slender technologies, intelligent constructions, traditional materials and a climate concept based on economic dealings with resources and space flow together. “Field of Ideas” already conveys sustainable and creative responses in construction execution to the questions asked at the Expo 2015 Milano, whose theme is “Feeding the Planet, Energy for Life”.
Construction execution in eight steps
After the preparation of the grounds, the construction of the German Pavilion began with the assembly of a rigid frame construction made of standardised system steel.
For the second step, lightweight construction walls made of plasterboard were erected, in order to define rooms and zones on both the ground and first floors: exhibition areas, offices, side rooms, restaurants, VIP lounge, kitchen, storage and visitor lounges.
Along the heights of the landscape level, the retraction of filigree covers follows. Circular recesses, from which the “idea seedlings” sprouted after completion, were already integrated into the reinforced concrete finished parts.
Then came the laying of the wooden decks. Thanks to different glazes and an alternating laying direction, the wooden panelled landscape level symbolises the theme of the German Pavilion, “Field of Ideas”. The surface of the wood material is non-slip and weather-proof thanks to a special surface treatment. This had to be verified both by German and Italian tests.
The next step was to attach the facade. It consists of a wooden pillar construction, to which an adjustable fibre cement lamellar structure was assembled. Four different adjustment angles influence both the light incidence in the exhibition area as well as the optics of the external building cubage.
For the penultimate step, the lightweight steel constructions of the “idea seedlings” were assembled. They reached the site as prefabricated elements and were “planted” in the gaps.
Then followed the covering with an open-pored fabric, which was finished according to a detailed cutting pattern. The lengths of fabric were put up to the so-called clamping pipes by hand. The organic photovoltaic modules (see below) were hung in the filigree steel cable network. This step makes the “solar trees” from the “idea seedlings”.
The space-defining construction works were completed with the interior design of the restaurant, VIP lounge and service areas, as well as the installation of the event stage and the exterior design.
The German Pavilion materials
The use of wood materials creates an individual character with different grains and colourings. Wood is therefore not only an appealing feature, but bears witness to conscious use of renewable raw materials with a neutral carbon footprint as trees balance input and output amounts of CO2 in their life cycle.As well as the freely accessible landscape level, the whole interior and furniture development in the public exhibition areas and the restaurants are also made of wood. Resource-protecting, manufactured compact discs with shaped surfaces combined with a high resistance and functionality are witness to naturalness.
The solar trees, which were planted in the ultra-lightweight construction, are covered with PVC-coated fabrics. The exactly fabricated textile material is extremely light and resistance and appears transparent or opaque depending on the light incidence.
The steel skeleton of the solar trees is also striking. It is made of a sectional steel construction, which thanks to its precise design stretches the filigree surfaces and retains its slenderness despite the large overhangs.
The Solar Trees (“Idea Seedlings”)
The central design element of the pavilion are expressive membrane-covered shelters in the shape of sprouting plants: the “Idea Seedlings.” Their construction and bionic design vocabulary are inspired by nature. The Idea Seedlings link the interior and exterior spaces, a blend of architecture and exhibition, and at the same time provide shade for visitors in the hot Italian summer.
By integrating cutting-edge organic photovoltaic (OPV) technology, the seedlings become Solar Trees. The German Pavilion is the first large international architecture project to use these innovative new products. In contrast with a project using conventional solar modules, the German Pavilion architects had the opportunity to do more than just incorporate existing technology. They had free rein to design the flexible, OPV membrane modules to match their own creative ideas, and to integrate them into the overall design of the pavilion.
The printed hexagonal OPV modules are laminated between clear plastic sheets and attached to a delicate steel net, which acts as both structural support and electrical conductor for the energy generated. The OPV cells generate electricity in a similar fashion to traditional solar cells, with one important difference: the OPV modules can capture light from any direction, and they generate electricity even in hazy conditions. The electricity produced during the day is collected in an innovative storage system at the base of each of the five Idea Seedlings and then used to power a high-performance LED ring at night, to light the trees from below. It is closed energy cycle, based on nature’s model. The solar trees provide for themselves, contribute to reducing the facility’s overall energy consumption and therefore protect resources. At the end of the Expo, the modules will be taken back by the manufacturer and reused.
The façade and climate concept
On a conventional façade with glass elements, door openings and smoke extraction system, the German Pavilion architects in Milan have consciously done without, in order to reduce the use of prime energy. The façade consists of an adjustable lamellar structure. The system made of horizontal fibre-cement plates reduces direct sunlight.
In a parametric design process, four adjustable angles were defined for the façade lamellas, which facilitate optimal light incidence for the exhibition areas inside the pavilion. With its external appearance, the façade lamellas are reminiscent of a horizontal cross-section through the sediment layers in the floor.
Most rooms in the pavilion are naturally ventilated. Only an open-pored membrane to protect from insects forms the end of the room. The climate concept is supplemented partially by a supply air system near to the floor. A so-called sea of cold air ensues in the visitor zones. The warmed air rises and escapes via the open façade areas above. As such, the room temperature is cooled by five to seven degrees Celsius compared to the outside temperature. Only the VIP lounge and the gourmet restaurant are fully air-conditioned.
The housing technology facility is positioned on the roof of the auditorium, in which the pavilion show is taking place, and is surrounded by a membrane sail, which takes the form of a flower bud. Thanks to a central vertical shaft, the interior rooms, such as the VIP lounge, the gourmet restaurant, the exhibition areas and the auditorium are attached.
The whole planning of the housing technology facility was simulated with a 3D model. Thanks to intensive coordination between steel construction, housing technology and architecture in the model, the surface use could be reduced to a minimum.
For the assembly and dismantling of the German Pavilion, particular special attention was paid to simple, modular construction solutions. The builders did without composite materials as much as possible in order to be able to separate and reuse the materials again after complete dismantling, such as the steel skeleton and the housing technology facilities.
The furniture is hired for the most part. After their use in Milan, they are being returned to the manufacturer’s pool and will be reused again. The lights from the exhibition and gastronomy areas are being left to Kaiserslautern University by the German Pavilion and thus to tomorrow’s generation of architects.
Sustainability and temporary construction
Sustainability and temporary construction – both of these terms seem to contradict each other in their original meaning. However, temporary construction is always an experimental field in architecture. Here, new technologies can be accomplished and tested in a short time period, such as the integration of the OPV modules. Time-limited buildings require quick construction times and cost optimisation, thus lightweight construction solutions are already the answer in the concept process. Lightweight construction means concentrating on the optimal material and exploiting its properties effectively – two aspects that are pioneering for resource-protecting construction, also for the future development of construction in general. Already just by reducing the material outlay, the first and at the same time instantaneous step is taken to protect resources.
Lightweight construction has experienced a renaissance in recent years. More and more buildings are implemented with skeleton structures. The expansion of façades with panel materials and membranes is the logical result of this development. With regards to their material use, such textile façades are a particularly optimised material that enables great spans. The fact that membranes have a long lifespan, can easily be re-finished and used again, is an important aspect with regards to sustainability.
By order of the Federal Ministry for Economic Affairs and Energy, Messe Frankfurt has entrusted the German Pavilion Expo 2015 Milan (ARGE) consortium with the realisation of the German Pavilion. ARGE is responsible as the general assignee of planning and construction of the German Pavilion, as well as the exhibition. Schmidhuber from Munich are thus responsible for drawing the spatial concept, the architecture and the general planning, Milla & Partner from Stuttgart for the content-related concept, as well as the design of the exhibition and media. Nüssli from Roth, near Nuremberg, are undertaking the project management and the construction work.