(BDT_12_082) Düsseldorfer Stadttor - Building Types Online

Description

In the heart of Düsseldorf’s cultural and media district, the impressive steel and glass structure of the Stadttor [City Gate] towers nineteen storeys over the Rhine and the port district.

Eighty metres tall, it was erected over the entrance of the Rheinuferstrasse, which lies below it, to the Rheinufer tunnel. Together with the Bürgerpark, it forms the provisional end of the promenade along the riverbank. The unusual rhombus-shaped ground plan configuration resulted from the urban environment, the strictures imposed by the tunnel construction beneath it and an optimised orientation with regard to the prevailing wind direction as determined by lengthy testing.

Maximum flexibility was the fundamental requirement for the typical storeys, which have over 780 m² of net floor area. Partition wall systems allow tenants to design both individual room layouts and entire floors. Private offices, group offices, open-plan layouts and combi-offices can be configured as required. Tenants also have a 1500 m² service centre on the ground floor with restaurants, cafés, shops and an ATM.

Of steel composite construction, two office tower legs, with a 58 metre high atrium between them, rise above the three-storey entrance area. The tower block is acclaimed for its atrium and its location at the south portal of the Rheinufer tunnel. Hanging supports counterbalance the weight of the freely hanging double-skin façade, which is then transmitted back to the main supporting columns through the structure of the three upper storeys. The building is stabilised laterally by two triangulated tubular steel space frames. It is this same space frame in the top three storeys that joins the steel towers to each other to form a portal frame.

The façade was to be not only transparent, but also to serve additional purposes: reducing primary energy consumption, providing heat insulation in summer and winter, allowing individually-controlled ventilation, full use of the enclosed space and reducing running costs. The façade was developed on the basis of aerodynamic experiments and thermodynamic simulations. There is a space 90 to 140 cm wide between the external single glazing and the internal insulated glazing. Highly reflective solar protection was mounted directly behind the external façade in the form of solar protection louvres that are centrally regulated for the whole building in correspondence with the prevailing light conditions. The requirement for ventilation on demand and individually controllable room climates made very high demands on the engineering design of the building services and particularly on the design of the ventilation chambers. These chambers, whose inlet and outlet openings are placed one above the other, are electronically controlled by sensors. Using fluid mechanics to optimise vanes inside the chambers, laminar flow conditions were achieved for normal prevailing wind conditions.

The internal façade consists of a glued frame construction using plywood veneer. Casements for office ventilation are built into every second axis; they provide balcony-like access to the corridor façade. Operating experience shows that ventilation can be freely used during about 70-75% of the year. In addition, the air can be mechanically changed twice an hour. Office temperatures are further controlled by heating or cooling ceilings with water carried in copper piping above the suspended acoustic ceilings. Energy supply for this ceiling system is extracted from 14°C ground water using a heat exchanger. The central atrium is an integrated component of the climate control system; it serves in particular for free ventilation of the offices.

The special function area of the inner atrium is provided with single glazing, offering an uninterrupted view from northeast to southwest. In order to withstand the enormous wind force, a rod and tensioned cable framework construction was chosen. Its automatically controlled damped anchorage plates ensure that the forces generated across this immense façade remain in equilibrium hence avoiding deformation damage.