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Cofrastra® flooring solution: light weight and high resistance for the balconies of the European Central Bank Headquarters
The new premises of the European Central Bank in Frankfurt comprise a glass office tower, the city's carefully restored old market hall, and a new entrance building. In order to ensure the structure's light weight combined with high resistance, ArcelorMittal's Cofrastra® flooring decks were used for the connecting platforms, balconies, and bridges.
The design for the new ECB premises was chosen in an international urban planning and architectural design competition in 2002. Apart from numerous functional and technical requirements, retaining the fundamental appearance of the listed Grossmarkthalle and incorporating it into the design was one of the major conditions.
The winning concept, developed by Vienna based architects COOP HIMMELB(L)AU, consists of three architecturally linked elements: Frankfurt's existing and carefully restored wholesale market hall, an office tower, and an entrance building that connects the two other elements. The building ensemble also includes an underground car park and ancillary buildings such as the entry control points and the logistics centre. The total gross floor area of the new ECB premises amounts to approximately 185 000 m2. Main construction works started in 2010 and were completed in autumn 2014.
Functionality and sustainability of the new premises were key aspects for the design and continued to play an important role in the subsequent implementation phases. The structural and spatial design has created a working environment that meets various functional requirements and facilitates open communication, thus promoting teamwork and interaction at every level. At the same time, the structural and spatial flexibility of the design means that changing requirements can be adapted to with little effort.
The Grossmarkthalle was built between 1926 and 1928 and has been a listed building since 1972. Until June 2004, it housed the city's wholesale fruit and vegetable market. This large building forms an integral part of the ECB’s new premises and houses the more public areas of the ECB, having retained its fundamental appearance after the careful repair and restoration of its original substance. The construction procedures involved in converting an industrial and utility building into a public institution with an array of functions required the highest level of care. The new main entrance leads to the hall area, which contains semi-public facilities such as a visitors' centre, the lobby, a cafeteria, a conference area, and a staff restaurant. The new facilities have been integrated into the hall at an angle based on a 'house in house' concept in steel-framed structures.
Two polygonal towers are joined by a glass atrium to form an office tower to the south of the Grossmarkthalle. With 45 floors, the north tower is slightly higher than the 43-floor south tower.
The overall structural framework of the office tower consists of reinforced concrete structures in the two towers and a vertical steel frame in the atrium between them. Aside from the twisting of the high-rise and the torsion of its facades, the installation of this steel frame is a particular element of the office tower’s structure.
Thanks to its distinctive silhouette and height of 185 m, the new high rise complements Frankfurt’s skyline. The glazed atrium between the two office towers forms a 'vertical city' where four interchange platforms and bridges create the impression of urban streets and squares and enable people to change from the express lifts to the local lifts. The platforms divide the atrium into three sections of varying height (between 45 m and 60 m). They can be reached via sets of stairs leading from the respective floors above and below, making it easy for staff to move between the two towers.
The two towers house the majority of the workplaces (maximum 2900) at the new premises plus internal meeting rooms. The large council meeting room and the offices of members of the ECB’s decision making bodies are located on the upper office floors.
All floors offer a high level of flexibility to allow for a variety of office configurations, from single offices to larger ones. The offices are located along the outer facades of the towers, and on every floor there is a kitchenette and communal area.
The office tower is covered entirely with glass panels to maximise natural lighting. Depending on the angle of incoming daylight, the high-rise appears translucent from one side to the other.
The entrance building marks the main entrance to the ECB premises, creating an aesthetic and functional link between the office tower and the Grossmarkthalle. Characterised by its asymmetrical design, inclined facades, and generously proportioned windows, it forms a clearly identifiable main entrance to the ECB from the north.
The entrance building itself, covered with aluminium sheets and glass panels, houses a two-storey press centre from where the ECB’s press conferences are broadcast. Temporary workstations for journalists are located above the entrance lobby, and next to the large press conference room there is also a second auditorium.
The various elements of the building ensemble complement one another with their contrasting features and come together to create a remarkable whole. The interplay between old and new and horizontal and vertical is clearly the result of the expressive design of the Grossmarkthalle on the one hand and the modern shaping of the office tower and entrance building on the other.
Urban integration and regeneration
The horizontal market hall structure and the office tower blend together to form a prominent urban building ensemble that shapes the entire city scape. At the local area level, the new ECB premises are an important link between Frankfurt’s east end and the Main River and is helping to change the area from an industrial district into a district with a more service-oriented infrastructure.
Several functional buildings surrounding the Grossmarkthalle to the east and west were removed prior to the construction works which has provided an uninterrupted view of the massive market structure.
The conversion of the 12-hectare site of the market hall, a predominately paved industrial area, into a large, green, landscaped area constitutes one element of the further development of the Ostend district, located just outside the city centre. Together with the other parks in the surrounding area, it contributes to the creation of a 'green lung' for the city of Frankfurt.
Apart from environmental issues, technical efficiency, and functional requirements, sustainability in construction also takes into account reuse and social aspects. The reuse and conversion of the Grossmarkthalle, an integral part of the ECB’s new premises, contributes to the sustainability of the overall building design.
When the annexe buildings were dismantled, the bricks of the facades were carefully removed by hand, cleaned, and preserved in order to use original building materials for the requisite restoration work on the hall.
From the very beginning, it was the ECB’s stated aim that its new premises should be 30% more energy-efficient than stipulated by the Energie-einsparverordnung (German energy saving directive) of 2007. After careful analysis, especially with regard to the facades and technical systems, the energy design features:
- rainwater harvesting
- recycled heat
- efficient insulation
- natural ventilation of offices
- efficient solar protection and low energy lighting
- use of geothermal energy for heating and cooling
ArcelorMittal steel in figures
For the connecting platforms, balconies, and bridges, more than 3000 m2 of ArcelorMittal's composite flooring decks Cofrastra® 40 and 70 were used in order to ensure the structure's light weight combined with high resistance. The undercut geometry of the Cofrastra® profiles guarantee excellent adhesion between the steel and the concrete.
- 2008 - 2014
European Central Bank ECB
- Engineering firms:
ARGE IFFT-ML / Prof. Schott – Prof. Lange,
AS&P – Albert Speer & Partner GmbH,
B + G Ingenieure,
Bollinger & Grohmann GmbH with Grontmij BGS Ingenieurgesellschaft mbH
©European Central Bank/Robert Metsch