In contrast to the materiality of the external envelope, in terms of volume the building is oriented more on its neighbours. At ground floor level the large glass cube sits above a solid, slightly recessed stone plinth. Towards Mythenquai this set-back deepens to several metres, creating a covered driveway leading to the main entrance to the building. There is a staff entrance at the rear of the building. All the approach areas are cut out of the otherwise homogeneous wavy glass envelope.
The transparent facades and two atria, which are staggered in relation to each other, ensure that the deep building is supplied with plenty of daylight. The main staircase beside one of the atria connects the entrance level with the four standard floors and the roof storey, which steps back at one point to create a terrace. As well as office spaces the roof level also accommodates numerous meeting and receptions rooms arranged along the representative lake front. As they are zoned only by the incisions for the atria and the four circulation cores the individual office floors can be laid out as required.
A slender loadbearing structure facilitates flexibility in planning the different storeys of the building. A light frame of steel columns and reinforced concrete slabs rises above three solid basement levels built in concrete. The bracing for this composite construction is provide by concrete cores that rise through the entire height of the building.
The glazed twin facade along with its substructure is fixed to the structure by steel brackets. The inner layer of triple glazing functions as a thermal envelope and is held in place by a stick-type facade construction clad with polished stainless steel. The external shell that defines the appearance of the building consists of curved laminated safety glass, which improves the acoustic insulation to the busy street along Mythenquai by between 4 and 10 dB. The gap between the two glass layers is used for ventilation and maintenance access, on the lake side the staff can also use it as a loggia. The sun blinds are also mounted in this space. The curved glass elements were given a sun protection coating on the inside of the outer pane. In combination with the internal white glass facade and the sun shade system that is protected from gusts, this arrangement makes optimal use of daylight in the building
The glass waves used in the outer facade are of two different sizes. From the ground floor to the third floor these glass elements are 2.4 m wide with an amplitude of 46 cm. On the two top floors the width and depth of the waves are each reduced by half. As a result, these two floors differ slightly from the rest of the building and relate to the hipped roof of the neighbouring old building and to the top floor of the Mythenschloss to the north. Through the interplay of reflection, transparency and the wavy external form the facade makes what is happening in and outside the building legible while also reflecting the glow and colour of the sky and of the nearby areas of water in a variety of ways.DR
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