Key urban planning position
It's no wonder Hadid's design was met with enthusiasm. Phaeno represents a unique experimental landscape – a place to experience the fascinating and exciting world of science and technology. The design perfectly embodies this vision.
Architecture reimagined: The world of phaeno knows no clear boundaries; its dynamic forms awaken a desire for discovery – they are movement made tangible, curiosity made tangible. Furthermore, the building possesses a powerful urban symbolic significance. It forms a counterpoint to the imposing power plant of the Volkswagen factory, the dominant feature of the gigantic industrial complex with its new public attraction, Autostadt. Phaeno is situated within the urban fabric between the actual city centre, the historic VW factory site, and the new Autostadt, thus occupying a key urban planning position.
Through a precise analysis of pedestrian and vehicular traffic flows, as well as sightlines across the site, Hadid's office developed an intersectional composition—a network of relationships that were either refined or newly created. These relationships shape and organize the artificially created topography at ground level, as well as the main floor, which rises to a height of approximately 7 metres as a building slab. At ten points, cone-shaped elements serve as load-bearing components for the main floor and simultaneously house all the supplementary functions of the spatial program: the shop, the entrances, the restaurant, the science theatre, workshops and elevators, and a so-called "Ideas Forum."
"Flowing spaces"
The central theme, according to Zaha Hadid, is "flowing space." The building develops a permeability characterized by a multitude of access points and a comparatively minimalist main entrance, as well as by the blurring of boundaries between interior and exterior. There is no threshold, no clearly definable boundary. The exterior becomes the interior and vice versa. This unique and dense connection between city and building continues inside the exhibition hall. The space is defined by a difficult-to-describe interplay of craters, caves, terraces, and plateaus.
The challenge of exposed concrete
This design presented a particular challenge for its construction. Unlike conventional concrete construction, which typically uses flat formwork systems, phaeno is characterized by the use of custom-made formwork elements and a special cast-in-place concrete mix with site approval. This so-called "self-compacting concrete" (SCC), with its exceptional flow properties that eliminate the need for mechanical vibration, made the technical realization of the building's abstract forms possible in the first place. The underground public parking garage is constructed as a watertight concrete structure. Ten so-called "cones" rest on a 1.10 m thick foundation slab. These cones penetrate the building to its full height and form the load-bearing vertical elements. Their outer walls widen towards the top and, in a vertical view, resemble truncated cones standing on their points. The cross-section of the cones is triangular or trapezoidal with rounded corners. At a height of 6.50 m, they are integrated into the ground floor ceiling, above which lie the numerous interconnected exhibition levels. The building terminates at a height of 16.20 m.
The architect's high standards for the quality of the exposed concrete surfaces necessitated not only self-compacting concrete but also the use of a versatile formwork system with a large proportion of pre-assembled formwork elements featuring precisely applied formwork liners in board formwork. The tender specifications for the total of 27,000 m³ of concrete and 4,800 t of reinforcing steel already specified the use of self-compacting concrete for the exterior walls. To shape the approximately 67,000 m² of concrete surface, 21,000 m² of precisely manufactured formwork were required over the 13-month construction period. Planed board formwork was used on the exterior of the cones. The joint pattern and nailing locations of the individual boards, as well as the position of the tie points, were precisely defined beforehand. Since tapered formwork joints were not permitted, but the cones widened towards the top, a large proportion of the boards had to be cut into trapezoidal shapes. Doka formwork technicians delivered the formwork and scaffolding to the construction site as prefabricated elements. In addition to the standardized Framax frame formwork for the smooth walls and the RS column formwork for round columns with exposed concrete finish, 13,000 m² of formwork were manufactured specifically for the single pouring of the cones. Fitters from the concrete processing company Heitkamp erected the formwork after it had been "artificially aged" on-site by coating it with cement slurry and then brushing off the slurry – ensuring consistent exposed concrete quality from the very first use. Because the cones open upwards, the outer formwork, i.e., the exposed concrete formwork, had to be erected first. The reinforcement was then laid and connected on top, and subsequently the inner formwork was erected. In extreme cases, the exposed concrete formwork, along with some of the reinforcement, remained outdoors for several weeks, protected by a formwork wax that neither completely dried out nor was washed off by rain, even in extreme weather conditions. For the sloping cone walls, which overhang by up to 39°, Doka Eurex 60 550 columns proved their worth, ensuring the reliable transfer of the fresh concrete loads in large numbers. Even after the formwork was removed, some of these columns remained in place, as the structural load-bearing capacity of the sloping cone walls was only guaranteed after they were integrated into the ceiling above.
Cantilevered roof
Like the cones themselves, every steel component of the complex steel roof structure is unique. With over 3,000 nodes, no two intersection angles or node spacings are the same. Such a structure can only be realized with state-of-the-art manufacturing technology, such as that provided by the company Klaus Queck. The individual components were produced automatically and relatively cost-effectively on a computer-controlled production line. The structure itself is designed as an oblique grid of intersecting main beams, approximately 2 metres high, which are not parallel but arranged in a fan-like pattern. They rest freely on steel ball bearings. The self-supporting structure is anchored only at five fixed points within the ascending cone shapes, thus granting visitors an unobstructed view of the elaborate support system.
Perfect development systems
The 50 concrete staircases for the building were supplied by the precast concrete specialist Hieber. The requirements for these were correspondingly high. None of the staircases were painted or otherwise visually enhanced after installation; they were to remain exactly as they had been delivered from the factory to the construction site – with perfectly smooth, exposed concrete surfaces. Hieber was able to win the contract, in part, by convincing the planners that the originally specified sharp-edged staircases were unsuitable for both formwork and practical use. Together, they agreed on the solution now implemented, featuring slightly chamfered edges, which ensures that the edges will not break unsightly under load.
Since elevators, in addition to stairs, provide vertical access in such a building, the irregular geometries presented new challenges for the elevator designers and builders at ThyssenKrupp and their partners. The glass body of the elevator shaft in Cone 7 was precisely adapted to the curve of the cone. In Cone 4, the challenge was to create a system without a visible machine room or cables, which is why a hydraulic elevator with a central piston was chosen. Two platform lifts also provide wheelchair users with unrestricted access to all of the exhibition's experimental stations.
Safe building
Security plays a significant role in a building like phaeno. The Tera 25 high-security locking system from CES contributes to this. In addition to the decentralized entrances, stairwells, restrooms, utility rooms, storage rooms, various types of technical rooms, kitchens, workshops, emergency exits, fire doors, various laboratories, etc., must be locked by different groups of people. Group master keys are held by the responsible phaeno employees, as well as by the fire department, cleaning companies, the municipal utilities, and others. Besides security and flexibility, ease of use was also a key requirement: the key can be inserted vertically, i.e., as usual, and is particularly easy to insert into the cylinder. All locking elements are located in the upper part of the cylinder housing. In the Tera 25 system, there are up to 26 spring-loaded tumbler pairs, arranged radially in 5 rows. The cylinder halves are connected by a stainless steel bar, which is secured in the housing with two tension pins. A hard metal plate installed as standard directly in front of the cylinder core in the cylinder housing ensures reliable drill and pull protection (VdS, class A and B).
Experiments in Glass
In addition to the large exposed concrete surfaces, the building's appearance is characterized by its diverse glass surfaces. Some panes are spherically curved, while others are boldly inclined outwards at an angle of up to 40°. The curved metal-glass facade of the auditorium incorporates glass panes up to 12 m² in size and weighing up to 500 kg. These are complemented by rounded windows in the shape of parallelograms and rhombuses. A large number of these panes were therefore specially developed for phaeno by Securit's glass processing partner, SGDG Berlin-Brandenburg. Using state-of-the-art laser point technology, the models were mostly digitized on-site and then produced in the factory, taking into account the stringent requirements for safety, thermal insulation, and solar control. The majority of the insulating glass used was SGG Climaplus N with Stadip and Securit glazing. A particularly striking aesthetic effect was achieved with the laminated safety glass (VSG) SGG Stadip Antelio Silver.
Phaeno – the experimental landscape – was certainly an exciting and ultimately successful experiment for the participating companies as well.
