Antwerp Provincial Government Building

Glass mosaic tiles, triangular fenestration and a compact pivoted building volume with a glazed pavilion thrust through at the base make this new provincial government complex for Flanders quite unique. With its 15 storeys and a height of almost 58 metres, the structure rises far above the urban silhouette of Antwerp, attracting attention to itself from afar. The development is located in a park with extensive planted areas and gently meandering paths. That was not always the case. This seat of government was once situated in a modernistic building complex that occupied the entire site; but its rehabilitation would not have been possible in accordance with present-day sustainability standards. What is more, a further development 71 metres high lay in the flight path to the nearby regional airport. In 2011, therefore, the city drew up a competition for a compact new structure that would meet passive-energy requirements. Additional goals were to create as large a public park as possible in this densely developed inner-city location and to relocate vehicles below ground. A crucial aim, though, was to preserve the singular, glazed pavilion from the 1970s. The new structure above was therefore designed in a bridge-like form, for which powerful steel trussed girders between the lift shafts and in the facades were necessary. At a late stage of the planning, it transpired that the retention of the pavilion was not economically viable. A new concept was not an option, so the clients and architects decided to demolish the existing building and replace it with a filigree, glazed new structure, where key functions of the provincial administration are housed: a convention centre that also serves external uses, and the council chamber with its parabolic layout. On the floors above are offices, where 860 people share 660 workplaces. The fact that there are no personal desks any more means an efficient use of space. The partly public library on the 11th and 12th floors overlooks a panorama of the city, and the extensive terrace on the pavilion roof offers views of the park.

The bridge-like construction is of central importance for the appearance of the building, because the trussed girders determine the triangular form of the windows. These are located between the diagonal struts and alternate with bays of concrete clad with glass mosaics. The glazing and the mosaic surfaces are set flush with each other, lending the structure a monolithic appearance, which is underlined by the smooth, gleaming skin. The triangular grid extends over the full height of the building and facilitated the constructional rotation: from the third floor up, namely, the layouts – which become narrower towards the top – are pivoted about the north-west corner, with the result that neighbouring buildings lose no sunlight.

The entire development is in in-situ concrete. To facilitate the slight curvature of some concrete surfaces, the construction firm developed its own flexible shuttering system. The windows are planar, but nevertheless not quite flat in areas subject to torsion. Their triangular shape results in exceptional spatial situations internally: on the one hand, through the different inclinations, which are particularly evident in the open-plan offices; and on the other hand, through the greater incidence of light from above and the view of the sky. Yet only about 40 per cent of the facade is glazed – which reduces the heat intake. A further factor contributing to the passive-house standard is the thermostat-controlled, dynamic simulation technology, which can forecast climatic conditions within the building. The fresh-air supply is controlled by CO₂ measurement appliances in the soffits, and the ventilation system comes into operation only when the CO₂ content of the indoor air is too high. That saves energy, which is generated by 134 solar panels on the roof. These supply a total of 32 kW per annum. The complex is cooled and heated by means of earth borings and a heat pump, and the volume of the concrete elements is used for the thermal activation of the construction. With its provincial government building, Antwerp has created an environmentally sustainable development and a landmark that is open to its citizens.