German architecture practice Ingenhoven has broken ground on a new mixed-use development for Düsseldorf. As a "green heart" and urban mountain in the city, the project is being built at Gustaf-Gründgens-Platz. Called Kö-Bogen II, the design reflects the character of the neighborhood while creating a new landmark with views to Hofgarten park. The roofs and facades of the project will feature extensive greenery with hornbeam hedges and plantings as a sustainable model for the inner city.
The design of the two-part project is a direct response to the surrounding urban fabric. With 42,000 square meters of gross floor area, the building provides space for various functions such as retail, offices and local recreation. In combination with a smaller triangular building, the five-story trapeze-shaped main building forms a valley. For the first time since the demolition of the former “Tausendfüßler” overpass, the view has been opened up to the Dreischeibenhaus and the theater. The two buildings of the new development—with their sloping facades—create a dynamic through-passage that opens the view towards the theater.
Kö-Bogen II extends the greenery of the adjoining Hofgarten park into the inner city. The facades of the main building and the sloping roof at a height of 27 meters are all planted. The facade vegetation provides natural cooling, reduces the inner city heat effect, and helps to clean and humidify the air. Likewise, planting has been applied to the walk-on sloping roof of the second triangular building that rises towards the Dreischeibenhaus to a height of ten meters; with its turfed surface, it invites passers-by to rest, take in the sun, and relax.
The design of the green facades and roof in cooperation with the Werner Sobek Group is based on detailed reports on suitable planting and local conditions. The selection of an optimal greening system and hornbeam as a suitable plant species made it necessary to consider the potential for planting in the context of the building and to ensure that the system would be serviceable. The greening on the roof of Kö-Bogen II was carried out in the conventional way with plants in beds, a purpose-designed greening system involving horizontally arranged containers was developed for the north and west facing facades. These are firmly attached to the respective facade using a construction designed for this purpose.
The concept for the design of Kö-Bogen II also includes the re-design of Gustaf-Gründgens-Platz. Originally, this had simply been created as the “concrete lid” of the underground parking garage below—an open space without any amenities and social benefit. In 1992, Christoph Ingenhoven presented his idea of a comprehensive “repair of the city”. This led to the Kö-Bogen project which, in several building phases, was aimed at the revitalization of an urban space that, until 2013, was dominated by an overpass. The re-design of Gustaf-Gründgens-Platz considers the city as a whole rather than to produce a historic reconstruction of the former road layout. The previously closed lid of Gustaf-Gründgens-Platz will now be given fresh vitality with the help of trees, seating, eateries, and an innovative lighting concept.
Kö-Bogen II is scheduled for completion in spring 2020.