The competition design for the extension to Kunsthaus Zürich envisages, in a sense, a mirroring of the existing building. The new extension constitutes a companion piece to the older building, both spatially and in terms of its utilization. Taking this premise as the point of departure, Heimplatz square is transformed by means of continuous paving into an urban ‘stone carpet’ linking the two museum buildings across the street that separates them. The new building opens up to Heimplatz with a projecting volume and a cutout portion facing the square, as a generous, welcoming gesture.
Like the institutional architecture along Rämistrasse, the new museum building boasts a substantial footprint, yet it also references the small scale of the buildings immediately adjacent to it through the configuration of the roof structures.
Inside the extension, a system of ‘squares and pathways’ leads visitors to the open-access facilities and through to the garden at the back, as well as into the exhibition spaces. these ‘passageway spaces’ form generously proportioned, light-filled circulation areas that provide orientation and offer vistas to the exterior, while also displaying artworks. They offer information, set the mood, and give visitors an opportunity to linger and relax.
In contrast, the main exhibition spaces are restrained, concentrated, rectangular rooms with light-diffusing glass ceilings. A range of different light solutions allows carefully controlled levels of daylight to enter the exhibition spaces, creating a lively atmosphere with natural light. To achieve this, daylight is focused into the building laterally through skylight superstructures set atop the building. Conversely, this has the striking effect of making the building glow with its own luminosity when the interior is brightly lit during evening events and residual light filters through to the exterior. The height of these skylight structures varies as a function of the depth of the exhibition spaces and the number of glazed faces on each skylight unit. This rule generates a roof landscape with an engaging relief effect.
The load-bearing structure is primarily in concrete, with steel deployed in the skylight areas. The façade is conceived as a translucent and ‘light-bearing’ wall. It is composed of windows and concrete elements with glass bricks in a range of sizes. Some are more transparent or translucent, others less so, to reflect the distinct requirements of the particular parts of the building. Rear-ventilated elements made up of large-format etched glass bricks protect the lateral glazing in the roof-light units and their louvers. Where the glass bricks are set in front of the insulated load-bearing walls, they form ‘peepholes’ affording occasional blurred glimpses of the wall construction. Glass as a construction material thus appears in a wide range of different manifestations: as matt or reflecting glass, as panes, ‘bricks,’ or solar elements; it may appear pixelated, ‘pointillist,’ or as a smooth expanse of glazing. Glass gives the building its characteristic appearance and conveys a sense that this is a museum building, an architectural genre whose primary function lies in harnessing light to enable the visual perception of artworks.