Residential tower Alexanderplatz, Berlin
With a height of 150 m, the new high-rise tower on the famous Alexanderplatz in downtown Berlin is an important element of the city’s skyline. Containing a hotel and residential apartments, its volume was largely pre-determined by urban design rules and zoning. The arrangement of transparent and opaque façade elements, balconies, terraces and loggias makes the most of the orientation and grants similar qualities for the apartments. The tower is set back from its site boundaries (except at the base and the hotel), so that all balconies are within the site limits and can be designed as necessary. The outline of the tower still allows for a maximum volume.
For the benefit of the lobby and circulation spaces of the hotel, large voids are cut out, which simplify orientation. Towards the top, the tower is set back in tune with its five different uses: base, hotel, small apartments, larger apartments and penthouses. The modular grid of the structure allows for flexible layouts. The balconies with solid railings and a glass enclosure above are arranged in such a way as to guarantee visual privacy. They are designed to be protected from unpleasant wind pressure. Green terraces in front of the apartments shape the appearance of the tower. The building is made of in situ concrete or pre-fab elements. The façades are clad in metal and natural stone.
The Green-Building concept is based on the DGNB criteria. It will be the first residential tower to meet the Passive House Standard. The façade and climate concept will lead to an energy consumption that is 15% below the German EnEV energy standard of 2009. Natural daylighting, rainwater harvesting, the use of wood, active and passive solar uses make it a “green” building. The number of windows (operable and with triple glazing) varies according to orientation (max. 60%). Two façades feature vertical photovoltaic elements. An external sun shading system prevents overheating in summer. A grey water recycling system helps save drinking water while rainwater is used for irrigation.