The area around Berlin Südkreuz regional, long-distance, and S-Bahn station, part of the so-called ‘Schoeneberger Linse’, is developing into a new urban district with an attractive mix of functions (housing, work, culture, and trade).
EDGE Suedkreuz Berlin is a seven-storey office complex consisting of two buildings with a total floor area of approximately 32,000 sqm. The complex stands on an approximately 10,100 sqm site and has been built using sustainable, climate- and resource-saving, and modular hybrid-timber construction techniques. The larger of the two freestanding buildings contains approximately 20,000 sqm of floor space. This makes it – for some time to come – the largest freestanding hybrid-timber building in Germany and one of the largest in Europe. From May 2022 it will be the new German headquarters of the energy supplier Vattenfall Germany.
The new office complex is part of a new urban district. Its planning involved restructuring the area between Sachsendamm, Hedwig-Dohm-Strasse, Hildegard-Knef-Platz, and Lotte-Laserstein-Strasse. The smaller of the two buildings (the ‘Solitaire’) is an elongated freestanding building which continues the line of the façade of the larger office building. The latter is a quadrangle-type structure (the ‘Carré ) with an irregular trapezoidal footprint. The two buildings form a street front facing Hedwig-Dohm-Strasse. In the direction of Südkreuz Station, they create a new urban plaza with green spaces and seating.
The Carré building
The heart of the Carré building is a spacious, light-filled atrium. A two-storey entrance lobby with a clear height of seven metres facing the plaza in front of the building opens up the massive, strictly gridded volume and directs the gaze firmly towards the building’s impressive interior. The 26-metre-high atrium is covered by a transparent ETFE foil roof carried by a wooden-truss construction. The continuous floor-to-ceiling windows in the offices, the glazed entrance area, and the large panoramic window in the building’s lounge additionally contribute to the abundance of daylight. A central highlight is the four treelike shapes of different heights which grow skywards under the foil roof as if in a greenhouse. Their lamellate spruce-wood structure gives them a resemblance to gigantic mushrooms. At ground level, green islands of tranquillity group themselves around their stems. The atrium is additionally enlivened by community and food areas. The crowns of the so-called ‘Trees’ carry platforms for recreation; these form green leisure and communication zones at various heights. The largest is 14.87 metres high and has a platform with a diameter of 6.20 metres; the lowest is 4.28 metres high with a diameter of 7.20 metres. These structures are linked by filigree steps with white railings, which – on the other side of the classical building core – lead via the platforms to the adjacent floors of offices and so form an architectural network of communications. The fifth floor has a sky lounge with panoramic windows and a spacious external terrace. The lounge is openly linked to the atrium space and, like the offices, may be reached on foot via the ‘tree stairs’. In every part of the building – from the supports, beams, windows, and doors to the claddings and railings – wood is visible in all the interior areas, adding an enriching liveliness to the complex’s clear architecture and bringing nature into the individual spaces. The building is an open ecological system. The clear symbolic focus of its architecture is the forest: the origin of wood, the material which defines this building’s character.
Each of the building’s inner corners contains a building core with a safety staircase and elevators. Parts of the roof are extensively landscaped.
The ‘Solitaire’ building
The Solitaire building has a two-storey entrance lobby with a clear height of seven metres. Floors 2 to 7 contain offices. The ground floor houses gastronomic, commercial, and retail spaces. Here too wood is a ubiquitous architectural and design element. The building is entered from the new urban plaza. Vertical access is by means of a central core with a safety staircase and two elevators. The landscaped outside space of the lounge on the building’s roof has a garden-like quality.
Both the Carré and the Solitaire building have a flexible modular ground plan on all levels. This can be adapted to individual requirements in the event of repurposing, enabling the creation of modern, multifunctional work worlds: open-space layouts encourage communication and include retreat areas for more intensive work, as well as conference rooms and special zones such as lounges and team kitchens for informal interaction.
The two buildings in the office complex share a basement garage with 218 e-mobility spaces for tenants. The bicycle room contains approximately 100 bicycle places, including for e-bikes; there are 32 additional spaces in outside areas. Biomethane cogeneration plants ensure efficient heating.
The façades have a regular grid consisting of sustainable and weather-resistant glass-fibre concrete panels. The grid is articulated by horizontal strips and coloured vertical panels. Pylons structure the façades vertically. Glass-fibre pilasters visually reinforce the socle section. The rhythmic façades have a restrained colour scheme which has been chosen individually for each of the two buildings. Two different shades were selected for each façade. In the case of the Carré the colours are Sahara sand for the horizontal strips and terracotta for the vertical structures. The reveals are visually set apart by their silver-grey colour. The Solitaire has corresponding colours: Sahara sand for horizontal elements, silver-grey for vertical elements. The two buildings enter into direct dialogue with one another through their colours and dimensions. The glass bays with fixed glazing and MicroShade solar protection additionally accentuate the façades; these are one-storey in the case of the Solitaire building and two-storey in the case of the Carré. The remaining windows are fitted with anti-glare protection and external sun protectors.
The sustainable façade elements of the two buildings weigh only 30 kg / sqm and are also recyclable. In addition, the façade absorbs CO2 from the air due to the thinly ground cement top layer and thus has a decarbonising effect.
In the construction of the buildings, the focus was on reducing the weight and thus the CO2 emissions as much as possible while combining the aesthetics of the building and the ethical treatment of nature.
The wooden elements, such as wall and ceiling modules, were prefabricated, then assembled and adjusted on the building site. This ensured a precise construction schedule and an especially time-efficient and accordingly economical construction process. The wall elements were made regionally in Neuruppin; the ceiling elements, in Lemwerder and Henningsdorf.
Altogether, 1190 wood-hybrid ceiling elements, carried by 1280 glulam façade supports, and 445 multibox wall elements with a total area of 16,000 m2 were made.
The natural material wood is everywhere in the interior and office spaces and makes an important contribution to a lastingly healthy indoors climate for users. Wood possesses a high heat-storage capacity but limited thermal conductivity. Existing heat is retained for longer in the room than heat from other construction materials. The delayed cooling reduces the amount of energy required. Wood is also lighter and more energy- efficient to transport than mineral construction materials. This project used approximately 3500 cbm of FSC- certified spruce – a total of approximately 1300 trees.
The intelligent combination of wood and concrete in this hybrid construction method saved up to 80% of CO2 per square metre of floor area: only approximately 0.15 tonnes of CO2 per square metre were emitted instead of approximately 0.75 tonnes in conventional construction. Low construction weight, short shell construction times, high reliability in planning and costs, and long durability are other advantages of this construction method. The construction materials used in EDGE Suedkreuz Berlin are extensively recyclable using the principle of cradle-to-cradle recycling.
Reinforced-concrete construction elements were kept to a minimum, being used for fire compartment separation or to stiffen the building. Wood and hybrid-timber elements were installed as the load-bearing framework, especially in the interior; concrete was used for the foundations and basement. The wooden supports and beams carry the building’s overall vertical loads. Since a hybrid-timber building weighs only approximately a third of a building erected using conventional reinforced-concrete construction methods, a foundation slab approximately 30% thinner could be used – which had an additional positive effect on this new office complex’s CO2 balance.
The stairs in the atrium of the Carré are designed as a metal construction in order to avoid unnecessary material consumption with high timber cross-sections and costly metal substructure. The design of the components responds directly to the strengths and qualities of the respective materials and promotes the saving of the resources used and reduces the weight of the components. The roof structure weighs only 45 kg / sqm due to the specially developed metal nodes, the ETFE foil as well as the filigree wooden components, and ensures greater lighting in the atrium below thanks to narrower cross-sections. At the same time, the roof construction can withstand wind loads of up to 100 kg, as each bar can not only bear tensile but also compressive forces.
Supported by the timber hybrid construction method the project is DGNB Platinum pre-certificated and will receive Germany's first WELL Core & Shell Gold certificate.
Architecture firm: TCHOBAN VOSS Architekten
Architect: Sergei Tchoban
Project partners: Stephan Lohre, Karsten Waldschmidt
Team: Julia Angelstorf, Lev Chestakov, Giorgia Fontana, Ulrike Graefenhain, René Hoch, Anastasia Kapustina, Valeria Kashirina, Birgit Koeder, Achim Linde, Fabiana Pedretti, Dennis Petricic, Manuela Peth, Soeren van Ost, Fabio Prada, Anja Schroth, Katharina Stranz, Carolin Trahorsch
Collaborating architects: Service stage 5: granz + zecher architekten GmbH, Berlin; external employees: Carsten Heidtmann, Peter LeRoy, Claudia Zecher
General contractor: ARGE SXB, Suedkreuz Berlin ZECH Bau GmbH, CREE Deutschland GmbH, Rhomberg Systemholzbau GmbH represented by ZECH Bau GmbH, Berlin
Project management: SMV Bauprojektsteuerung Ingenieurgesellschaft mbH, Berlin
Landscaping: service stages 1-4, hochC Landschaftsarchitektur, Berlin; service stage 5, granz + zecher architekten GmbH, Berlin
Structural engineering: Happold Ingenieurbuero GmbH, Berlin; BIT Buero fuer integrale Tragwerksplanung GmbH, Berlin
Building technology: Happold Ingenieurbuero GmbH, Berlin
Interior design: de Winder Architekten GmbH, Berlin
Façades / glass-fibre concrete panels: Rieder Group, Maishofen, Austria
Façades / wall modules: Opitz Holzbau GmbH & Co. KG, Neuruppin
Hybrid ceilings: BWE-Bau Fertigteilwerk GmbH, Lemwerder, thomas allton GmbH, Henningsdorf Solar-shading glazing: MicroShade A/S, Glostrup, Denmark
Roof construction Carré-Atrium metal: Biedenkapp Stahlbau GmbH, Wangen
Roof construction Carré-Atrium Wood / ETFE foil: Temme // Obermeier GmbH, Rosenheim
Photographers: Ilya Ivanov; August 2022: HG ESCH, Laurian Ghinitoiu