Innsbruck Town Hall Stuns City With GKD Metal Mesh Sunscreen and Roof Facade
Textile structures are like a skin which constantly changes. They can be used to dress buildings as well as people, optically enshrouding them almost completely from view, and then revealing them in novel and surprising forms. This is one of the leitmotifs in French star architect Dominique Perrault's use of stainless steel wire mesh and also one of the core dimensions of his first large-scale project in Austria using this material: the Town Hall Gallery in Innsbruck - a modern administrative center in the heart of the city with galleries, shops, a congress hotel and restaurants surrounded by extensive gardens.
In the course of the 10-year partnership between Perrault and GKD, the architect has repeatedly made use of the material produced by the Dueren-based company in ever-new variants for spectacular projects of both exterior and interior design. The material's filigree textile-like structure sets an optical counterpoint to its extraordinary stability and resistance. In interaction with light and colors, depending on the angle of view, the semitransparent mesh becomes an almost completely opaque refletive surface. This is how Perrault achieves his proclaimed goal of a dynamic tension between presence and absence of architecture, an expression of his desire for constant change, for an "ambiguity" which is also dramatically evident in Innsbruck. In collaboration with the Munich architects Reichert, Pranschke and Maluche, Perrault won the contract for this prestigious project in an architecture competition organized by the city. Under his architectonic direction, the new Town Hall Gallery in the heart of the city would centralize all the departments of the city administration, which had previously been scattered all over Innsbruck. In addition, the building complex with its extensive gardens would become a pulsing, downtown meeting point which would set the office buildings in a context of shopping galleries, hotels, restaurants and a fully refurbished Adolf-Pichler-Platz. The vision was of a new, urban city center which would enhance the whole of downtown Innsbruck with dynamic and multifunctional qualities.
The building complex fills the gap between the previously existing town hall buildings in Maria-Theresien-Strasse and Fallmerayerstrasse with a seven-story building on the west side accommodating city administration offices on its upper floors and an intersecting wing which connects with the town hall building in Maria-Theresien-Strasse. Filing this gap has created a new inner area destined to become an attractive closed court with extensive gardens and cafes and restaurants. On the north side, the composition of the new building complex is rounded off by a six-story hotel and a two-story shopping gallery building. In this multifunctional interplay of buildings, the facade designs reflect the required variation between privacy and openness of this public sphere. Perrault achieves this by playing artfully with transparent, semitransparent and opaque surfaces made of a variety of materials. Strictly speaking, the stainless steel wire meshes used on facades and roofs provide all three of these characteristics. From inside, they act as sunscreens while allowing an unhindered view out. Daylight is guided inwards in a differentiated way.
On both sides, the hotel facade was constructed using altogether 73 horizontally moveable sunscreen panels made of the special mesh type Omega 1508 in the format 8.5 x 7.5 feet per element. The wire mesh has a special density which ensures the required sunscreening effect. Mesh types used by GKD for sunscreens achieve almost the same light transmission values at a 50-degree angle of incidence as conventional sunscreen systems with almost completely closed lamellae. The advantage of stainless steel wire mesh is that it leaves the view outwards free and in addition has a unique, special aesthetic effect. Seen from outside, the juxtaposition and overlay of window surfaces and sunscreen elements give the hotel a chessboard pattern whose apparently serene harmony is challenged in ever-changing, novel ways. The individually adjustable sunscreen elements create punctual light reflections which constantly change, producing ever-new perspectives. The eyebolts and springs which fasten the mesh tightly at the top and bottom were not concealed from sight, as they usually are in other facade constructions. According to Perrault, a "garment" of wire mesh, like a piece of real clothing, deserves visible fasteners to the underlying object. This reinforces the textile-like facade and also the sensual impression of a "dressed" building.
Some of the most extraordinary design elements are the constructions of wire mesh strips stretched over the glass roofs of the shopping center - the Gallery - and the Town Hall's main chamber. The chamber is not only enthroned over the office building complex but also over the whole city, as one of its highest vantage points with a breathtaking panorama. For the roof constructions, Perrault chose a special mesh type he has used many times before. A slight shift of the weft wires gives the meshes of the relatively coarsely structured mesh type "Canisse" a less strictly orthogonal and slightly more slanted orientation compared to many other GKD mesh types. This produces interesting optical effects and refractions. Like trapezoids, diagonally bent wire mesh strips were laid over the glass surfaces of both roofs. There is a seamless transition from the horizontal surface of the roofs to the vertical surface of the facades.
This sort of construction was a first-time achievement for GKD and its partners. As well as ensuring a sunscreen effect inwards and a free panorama view outwards, the construction also has interesting optical effects. In addition to light reflections on the shiny surface of the mesh, the optical overlaying of the mesh panels at their corners creates ever-changing Moire effects when one looks upwards. The technical challenges facing design and statics were the considerable strains of snowload and windforce which were to be expected in view of the Alpine climate and the exposed location. For these reasons, the great weight of the mesh strips themselves had to be precisely balanced and the strips stretched extremely tightly to ensure the required degree of stability for the construction.
With the whole building complex in Innsbruck, Perrault has once more achieved an extraordinary strength and expressiveness in his architecture, in which stainless steel wire mesh plays a central role. In the creative partnership with GKD, internationally acclaimed projects like the French National Library or the Cycling Arena in Berlin have been accomplished. The variety of interpretation of light and color, perspectives, views into and through structures made possible by the material's transparency and reflectivity have made it one of the characteristic elements of his work. In Innsbruck, too, the material unites, in a way that very few other building materials do, qualities of optical versatility and spatial flexibility with the durability and robustness of stainless steel, qualities which are particularly called for in the exposed public area. The Town Hall Gallery in Innsbruck, along with the new GKD works building in Maryland, USA, also planned by Perrault, counts as one of the most interesting joint projects of recent times.