EDGE Suedkreuz Berlin, the largest hybrid-timber building in Germany

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. The new office complex is part of a new urban district. 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. In the direction of Südkreuz Station, they create a new urban plaza with green spaces and seating. 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. 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. The crowns of the so-called ‘Trees’ carry platforms for recreation; these form green leisure and communication zones at various heights. 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. 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 Solitaire building has a two-storey entrance lobby with a clear height of seven metres. The building is entered from the new urban plaza. 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. 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. 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. 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. The intelligent combination of wood and concrete in this hybrid construction method saved up to 80% of CO2 per square metre of floor area. 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. 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.