Description

Away from the high-rise euphoria in Frankfurt city centre, in the mono-functional office town of Niederrad established in the sixties, the architects Auer + Weber created an office complex that is remarkable on two counts, in terms of both climate technology and organisation.

In an environment of stand-alone buildings and undefined outdoor spaces, the ten to twelve storey new building following the triangular boundary of its site, forms clean edges in the urban space. Horizontal bands of windows articulate the aluminium façade of the massive, raised built volumes that dissociate themselves from the office city. By contrast, an extensive façade opens the building’s southeast elevation towards the urban landscape. A filigree framed glass roof covers the triangular inner courtyard and as the second façade skin, provides acoustic insulation against the noise from the adjacent multilane road. The sophisticated shaping of the interior space, consisting of two-storey-high winter gardens, office areas, and zones for special use on the lower floors, together with a straight-flight cascade-like stairway in the space between the two skins of the façade, visible from the street, becomes a design element of the extensive glazing.

Since the end of last year, the DGZ-Deka Bank has been the tenant benefiting from the spatial variety that the new building offers. A walk through the rooms reads like a textbook on office organisation. The varied tasks of the central administration, bookkeeping, back office, system development and system services, billing and HR all require routine work, concentrated work done by individuals and project work carried out by teams. Instead of implementing a uniform office concept, the bank reacts to the different activities by organising the spaces in a variety of ways. Depending on their responsibilities and preferences, employees work in cell-like offices, group offices and combination-offices. Freelancers who support the project teams from time to time occupy workplaces in the open-plan office on the second floor, which is organised around a “non-territorial” office concept. Independent of the office type, kitchens equipped with bar-height tables, seating areas and conference tables in open zones give the employees the opportunity to engage in spontaneous chat. For scheduled meetings and conferences, the staff reserve one of the rooms suspended in the skeletal structure and which have a direct connection to the atrium. In their breaks, bank staff can relax in the winter gardens, designed as attractive lounge areas in the points of the triangle. Alternatively, they can communicate worldwide in the Internet cafe.

As the main axis and lounge area, the atrium, whose climate is regulated by its glass roof, forms the communicative focus of the building. The high-ceilinged space bathed in light is characterised by sand-coloured floor slabs, plants and expanses of water. A terrace extends the cafeteria into the atrium and, like the scattered seating areas, offers an inviting place to sit and relax. Glass lifts with open balconies in front of the built volumes transport staff to their offices. In the airy heights, steel bridges offer internal shortcuts and an exciting overview of the space.

As the centre point of the building, the atrium is also of prime significance for the design of the climate control system. The main priority was natural ventilation of the new building. The ventilation concept is based on the exploitation of physical laws and natural resources in conjunction with a piping system integrated in the reinforced concrete ceilings with ventilation ducts in each office leading to both the double façade and the atrium. In winter, the building is ventilated via the double façade. Air coming in from outside is warmed in the space between the façade skins and then conveyed to the offices via ventilation ducts or the piping system. In the sides of the triangle, solar ducts take over the function of the double façade. The waste air is carried off via the roof of the atrium and recovered waste heat is used to warm the building. In summer, the air circulation is in the opposite direction. The atrium is transformed into the cool core of the building by means of the highly efficient solar screens above the glass roof and by supplied air cooled in thermal channels. The cool air is conveyed to the offices via the windows or the piping system while the waste air is drawn off via the double façade or the solar ducts. At night, the raw concrete ceilings release the stored heat to the cool night air via the atrium in accordance with the winter principle. When the solar screens are closed, the offices oriented towards the atrium are sufficiently illuminated by a system for diverting light. In excitingly staged spaces, the new building unites pioneering climate control system design with pioneering office design.

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Originally published in: Rainer Hascher, Simone Jeska, Birgit Klauck, Office Buildings: A Design Manual, Birkhäuser, 2002.