Example: Company headquarters in Switzerland
From a bird’s eye view, the design by Shigeru Ban looks like a gigantic wooden snake. The architect places a particular emphasis on wood in his design, since it is the world’s only renewable building material and hence environmentally friendly, and because the city of Biel is noted for its advanced wood technology. The aim of this extraordinary design is to create an innovative and iconic building for the city by using and combining a wide variety of materials.
The basic structure of the building consists of glued laminated timber trusses arranged in a grid to depict the organic form of a snake curled up on the ground. The bonded wood structure forms the supporting frame.
The diamond-shaped openings produced by the primary supporting structure are enclosed by a wide variety of fill elements. The fillings are designed as bent elements due to the curved shape of the building. The respective element types are selected on the basis of differing requirements in terms of the function of the final building envelope.
Four distinctive element types are used in order to cater for the high requirements in terms of heat insulation, noise insulation, solar shading and design. These consist mostly of a timber frame which is curved or a rounded/3D milled timber frame in varying shapes. This produces 2,800 facade elements in different geometric shapes with the following superstructures, among others:
Some elements are also configured with photovoltaic technology.
The selection of the right type of timber and the determination of the perfect timber drying stage in particular played a key role in the functionality of the facade elements.
The building envelope is in principle a new development. As a free form with the installation elements in timber construction and the techniques used to meet the requirements made on the building physics, the geometric structure is a one-off.
The tests listed below are some of those performed:
An optical model of each of the different installation elements was prepared in the original structure.
In addition, an integrated performance mock-up was built for the wind and driving rain impermeability tests.
All elements were completely prefabricated and delivered to the construction site ready to install. The element size is generally 2.3 m x 2.3 m.
The wooden frame was milled entirely on 5-axis milling systems to arrive at a structure corresponding to its organic building form. The FPO films were bonded under vacuum. Immediately after completion in the plant, the CCF elements were connected to a temporary flushing air supply in order to prevent condensation forming during transport. The photovoltaic elements were bent and bonded in the cold state.
The glass support system was mounted on the previously erected primary timber structure. The prefabricated elements were secured to the timber structure in the corresponding order by means of a crane and were then fitted with press bands. The installation sequence was determined in advance, with the key parameter being the respective weight brought to bear on the supporting structure by the installed element. The installation sequence depended on an even distribution of the loads brought to bear in the continuing installed condition.
Immediately after the CCF elements had been fitted and installed, they were disconnected from the temporary flushing air supply on the construction site and connected to the final air supply previously installed for the building. The installation was carried out with the aid of scaffolding and cranes.
