Residential building with an inhabited vertical garden in Berlin-Kreuzberg

The design for this residential building was generated from careful attention to the urban and social context. Located on a narrow corner site and sandwiched between two existing residential blocks, this example of respectful urban repair has become a part of the much-loved fabric of the neighbourhood. Designed and constructed to high ecological demands - from the foundations upwards - the building demonstrates how a greener urban future can be achieved through team commitment from day one of the project onwards.  

The site is located at a busy crossroads in an area of Kreuzberg that buzzes with street life. The original corner building had been destroyed by a WWII bomb, and the the site became an unsightly urban scar that has, only now, undergone long-overdue, respectful repair.

With five floors of flats, the corner extension reconnects two damaged residential fragments, and rises to form a graceful tower, acknowledging the Kreuzberg custom of small towers as urban corner locators. The tower's planning epitomises the architect's social and cooperative ambition for the project, as it hosts a communal terrace shared by all residents. This terrace enables the building to support local concerns: it hosted anti-gentrification activists who unfurled banners during recent anti-gentrification demonstrations, giving locals back their voices in a way that would never had been possible had this terrace been allocated to a private apartment.

An inhabited vertical garden 

The new corner building is designed to harmonise with existing buildings in the local area. Without being arrogant or obtrusive, the building still expresses its own strong ecological character both within this Kreuzberg neighbourhood and towards the city of Berlin as a whole.

As part of the building’s green agenda, a vertical “living-wall” has been built on the Glogauer Strasse façade. Rectangular box balconies punch almost theatrically out through the living-wall giving residents the opportunity to stand within the vertical garden. This "urban garden" absorbs traffic pollution and noise from the adjoining street and noticable improves the local micro-climate for both residents and passers-by.

With the top corner of the green "living wall" being both East-facing and located some 20 metres above street level, winter-hardy plants that could reliably survive the Berlin winter needed to be selected for the garden. These plants are reliably watered and nourished all year round through a system of hydroponic irrigation. Twice a year the garden is carefully maintained using a "cherrypicker" from the street below.

On the ground floor level, below the vertical garden, three metre high windows to the street invite passers-by into a new bar with a gently-curved corner entrance. The second street façade to Reichenberger Strasse is quieter, as suits the more homogeneous architecture of this road. The apartment windows here have small French balconies fitting close to the façade. 

Building for a greener future

The ecological footprint of this work of urban repair in incredibly low. It is a tiny site: the whole plot is only 660 square metres in size, and, of this, an area of ​​just 165 square metres had been destroyed in World War II. After the war, the two damaged wings of the building had been left standing, each a separate block, one in the Glogauer and one in the Reichenberger Strasse. They were finally repaired and re-inhabited in the 1970s; the rubble of the ruined central section of the building had been used to fill the damaged corner basement, and the tiny corner site became a private parking lot.

In the early design stages for repair of the block, Dr. Riviere's team of structural engineers undertook investigations into the state of the rubble-filled corner cellar, discovering that the foundations of the original building, and even the hidden cellar walls, were in excellent and stable condition. Riviere thus designed the new corner building to stand on the thick, original, restituted cellar walls and foundations from 1885, slashing construction costs and reducing the volume of concrete required for the project to an absolute minimum.

Designing to avoid the use of external sandwich insulation in a residential area, the facade of the new building was constructed in ceramic blocks insulated with volcanic perlite, which, in combination with locally-manufactured double-glazed timber windows, enable the building to easily surpass Berlin's demanding energy-saving regulations (EnEv). A district heating system ensures that ongoing running costs for residents are affordable as well as fulfilling the highest ecological requirements.

Planning 

A commercial unit was planned on the ground floor of the new building - a bar with table-football and two large screens for live sports events. In order to increase the usable area of ​​the bar and to create space for ancillary rooms (WCs, kitchens, etc.), one commercial unit within the existing wing of Glogauer Strasse 9 was included in the project. Now the ground floor bar extends from the new building into the old, visibly linking the new-build to its older neighbour. Similarly on the top floors a larger apartment was constructed under the new "Berliner" roof to Glogauer Strasse, while a maisonette apartment was built in the new extension above the Reichenberger Strasse wing of the building. Each of these apartments has a terrace towards the courtyard.

On each floor of the new corner building two small apartments are designed to be combined to form a larger residential unit if needed. This allows flexible responses to future family housing needs. Since the local area is defined in the land use plan for Berlin as an M2 mixed construction area, the building's original owners chose to submit a building application for holiday apartments for the new building. But, with long term residential use in mind, the 12 new apartments were planned for easy conversion into family apartments. This paid off - the apartments are now in long-term residential use, as preferred by the local authority and the planning team as a whole.