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The central theme during the planning of the GSW Haus was to create a modern office building that could match in every respect the comfort provided by conventional buildings, but which minimised the energy required to do so. The arrangement of components and the use of selected materials resulted in a modern working environment offering a high quality of occupancy, in which the natural ventilation of the building and the use of natural light form important elements of the energy concept.

The western façade is designed as a double-shell structure incorporating an intermediate space that extends the full height of the building and acts as a continuous waste air shaft.

When the heated air rises naturally due to thermal lift, it causes a fall in pressure. This pressure drop can suck out stale air through open office windows and at the same time suck in fresh air from outside, which flows in through the eastern façade. The wind sail, a curved steel structure placed at a height of 85 metres and covered in a textile membrane, increases the pressure drop thus creating the venturi effect.
As a result, occupants of the high-rise slab can ventilate all the offices naturally as required.

In order to cool the thermal mass of the building, the cross ventilation also operates at night. This enables peak daytime temperatures during the hot summer months to be reduced. To facilitate cooling of the thermal mass, the ceilings of each storey are made of concrete and are left bare.

Thermal buffer zones are created on the western façade due to the double-shell construction and, with a smaller clearance, on the eastern façade. These also act as an acoustic shield against traffic noise. When the outside air becomes too cold in winter and draughts could occur, a ventilation system is activated and distributes pre-heated fresh air throughout the building.

When the outside air becomes too cold in winter and draughts could occur, a ventilation system is activated. The rooms are supplied with fresh air from a central system. The warm air is mechanically extracted and then, by means of heat recovery, used to pre-heat the fresh air from outside via heat exchangers.

The extensive glazing of the façade combines with the glazed interior walls and the limited depth of the office floor plans to ensure that optimum use is made of natural light.

To avoid the negative consequences of uncontrolled solar radiation, the western façade is fitted with vertical sun screens. They are installed in the space between the double-shell western façade and can be individually adjusted by the users. The screens are stove enamelled in a total of nine shades of red of varying brightness. In the eastern façade, slat blinds are used in the spaces between the windows. The southern façade is protected by fixed horizontal slats.

Thanks to the generous glazing on the façades and the comparatively narrow floor plan, all workspaces have excellent exposure to natural light, which means that additional lighting during daytime is only necessary in exceptional cases. This generous exposure to light creates cheerful workspaces in which users can control the level of brightness individually (see also effective sun protection).

The eastern and western façades of the building are double-layered glass membranes, which act as thermal buffer zones and as protective acoustic layer that keeps traffic noise from penetrating the interior of the building.

In order to prevent the negative effect of the generous daylight illumination of the building, i.e. the build-up of heat in the offices, the building can be completely shaded by a sun screen system that is installed between the façade layers. This sun screen is extremely flexible and can be individually controlled by the users.

The double façade on the western side of the building is designed as a 1m deep, continuous convection façade. The air between the two layers of glass is heated by the solar radiation and rises to the top by the process of natural convection. This varying volume flow dependent on the climatic conditions is kept constant by means of flaps and thus prevents the building from heating up.

This building also uses the suction created by the upward movement of air inside the convection façade to suck on fresh air from the eastern side through each storey of the building, thereby naturally ventilating all offices in a controlled manner. This ventilation system powered by the convection façade eliminates the need for a mechanical ventilation system during the summer and transitional seasons.

As with the sun protection, the ventilation is also controlled by the user. That's because the ability to open and close windows contributes significantly to the subjective comfort in the workplace. To ensure optimum conditions of sun protection and window opening, the building is also equipped with a central building control system that operates these elements in the absence of the user.

To ventilate heated interiors without causing draughts in winter when the outside air is too cold, a mechanical ventilation system is used to provide a central supply of fresh air to the offices. With the help of heat recovery, the warm waste air extracted from the offices is used to pre-heat the fresh air from outside centrally via heat exchangers.

The ceilings in the building are made of concrete and are left bare. As a result, the storage volume of the primary structure can be used to maintain the correct temperature. In summer, the ceilings are cooled by natural night-time cooling. During the day, this cooling effect is then released into rooms. Likewise, heat is directed into the rooms at night in winter, and then released again during the day. The room acts as a flat source of radiant energy, which increases the sense of wellbeing inside the room.