In the area around the Südkreuz station, currently undergoing a major transformation process, the Berlin studio Tchoban Voss has designed an office complex - the new German headquarters of the energy supplier Vattenfall Germany - on a 10,100 m2 plot between Sachsendamm, Hedwig-Dohm-Strasse, Hildegard-Knef-Platz and Lotte-Laserstein-Strasse. The project comprises two seven-storey buildings, the 'Carré' and the 'Solitaire', set around a new square with green spaces and seating. For both, the façades are characterised by a uniform grid of fibreglass and concrete panels in neutral and delicate colours, with a tight rhythmic pattern of horizontal stringcourses and a weave of vertical pilasters, outlining a measured and rational urban facade.

In the "Carré" building, with its trapezoidal layout, the two-storey entrance hall leads to the spectacular inner courtyard, a bright and immaculate space 26 m high with a transparent ETFE roof supported by a mixed wood and steel structure: here the four monumental pillars in lamellar spruce dominate, branching out in the shape of a tree towards the top, supporting resting platforms at different heights and vertical distribution elements (stairs and raised paths), connecting with the office floors and the panoramic terrace on the fifth level. The 'Solitaire' building, with a longitudinal layout and a two-storey 7m high entrance, includes offices on the second to seventh floors and retail and gastronomy on the ground floor. In both buildings, wood is a ubiquitous architectural, structural and design element: from the system of beams and pillars, to the fixtures, doors, cladding and railings - wood is dominant in all interior spaces, contributing to giving the rooms a soft, warm and natural character.

In the construction, an attempt was made to minimise the environmental impact thanks to prefabrication and on-site assembly production process, which made it possible to reduce construction time and costs, and thanks to the choice of a high-performance, lightweight material such as wood used in hybrid technology, which made it possible to reduce consumption and climate-altering gas emissions. In fact, the intelligent combination of wood - predominantly - and concrete - limited to foundations, fire compartmentalisation and stiffeners - made it possible to achieve a weight reduction of one third compared to a conventional construction of similar dimensions and to save up to 80% of CO2 per square metre of floor area. The high performance of wood in terms of high heat storage capacity and low thermal conductivity also allowed for lower energy expenditure during both construction and operation.

An "all-round" work that happily combines formal quality, technological efficiency and ethical responsibility towards the environment, demonstrating that "lightness" - contrary to what Kundera said - is anything but "unsustainable".