Located near the central station of Wiesbaden, Germany, the SOKA.BAU office complex comprises pre-existing buildings and four new constructions set in staggered array along a north-south axis. This layout has several advantages, especially that of channelling and optimizing natural ventilation.
The reinforced concrete structure - composed of structural cores and bracing elements stretching the full 12 metre building width – and the 1.5 m modular grid format of the façade afford great flexibility of all internal space.
The building boasts low energy consumption with winter heating and summer cooling of concrete floor and ceiling blocks by means of embedded pipes carrying hot or cold water according to the season. As a result, however, false ceilings and floating flooring could not be installed since they would have prevented proper functioning of the heat-exchange system.
The façades, notably those facing south, have a multi-layer single skin envelope. The north-facing exteriors are in high-efficiency thermal-insulation wood panels with openings at the top of the panel to allow for natural ventilation. Panels can be opened half-way, completely or closed altogether as weather and wind conditions demand. The natural ventilation of the building afforded by this system provides direct air exchange during summer while in winter, a small convector preheats the incoming air. All services and utilities, from electrical wiring to mechanical and electronic equipment, are contained –in boxlike style - in the façade itself.
A key feature of the south-facing façade is the series of adjustable concave aluminium flaps regulating the amount of natural daylight entering the building. When the sun is high, the panel can be positioned vertically to create shading. The upper section of these movable flaps provides most shade while the middle segment ensures the entry of sufficient natural light into the building.
On the north side, the metal panels are fixed and deflect vertical  daylight onto the ceiling thus illuminating areas furthest from the windows. The long façades behind the flaps comprise a triple glazing mullion and transom assembly.
Another key feature is the separation between central and individual-user control of ventilation and illumination. Centralized mechanical ventilation and artificial lighting are energy-efficient sensor-activated stand-by systems, tripping in only when necessary or when people are present in the room. Both ventilation and lighting can then be regulated manually as required.

Alessandra Battisti