Glass concerto.

The possibilities evoked by the Modern Movement in the use of glass at the beginning of this century are now finally being realized in buildings such as Klaus Kada's stunning new concert hall in St Polten.

St Polten is a small industrial town about 30 miles due west of Vienna. It lies on the river Traisen, a tributary of the Danube. Until quite recently, it had no great buildings and no special history, and was missing from the Michelin guide to Austria. But it happened to be sited right at the centre of the Land of Lower Austria and next to the busy conduit of the Vienna/Salzburg motorway. It was therefore chosen in the 1980s to become the new regional capital, the place where the Landtag (regional parliament) sits, and the site of a regional bureaucracy employing some 3000 functionaries. The new government quarter was located south-east of the town centre, next to the river. Beside the new parliament building and parallel with the river was placed a linear office development 650 metres long, then the decision was made to enliven the area with a cultural centre. A limited competition was held in 1992 for a group of buildings including museum, library, archive and concert hall. Hans Hollein won first prize and his plan was adopted, but many aspects of Kada's scheme were also admired, so while Hollein was given the museum, Kada was commissioned for the concert hall. The museum is yet to be built: Kada's hall opened at the beginning of this year.

This history is significant because Kada's design was initially conceived as part of his own masterplan and later adapted to fit Hollein's scheme. The main difference between the two is that while Hollein sought to focus the cultural development inwardly on a new pedestrian square (Schubert-Platz), Kada intended instead to make the new cultural buildings a link between the government area and the old town centre. Hollein's introverted scheme would seem to be in danger of producing a political and cultural ghetto, but it will be hard to evaluate the success of the new square until all its buildings are complete.

Hollein put Schubert-Platz just where Kada had intended the concert hall to go. Kada had therefore to move his building westward, and to acknowledge the square he rotated it through 90 degrees. His main facade on the axis of the auditorium faces east and fronts the square, but the entrances do not open that way. With another open space to address to the north, Kada made a second front. He placed his main entrances by the north-east corner, still expecting many pedestrians to arrive from the town centre. He has coped rather well with the ambiguity of space and object induced by the Hollein plan, but in town-planning terms this only underlines the problem: the more the concert hall becomes an object in its own right, the less Schubert-Platz reads as an outdoor room. This story has to be told because the building's relationship with its setting is less than convincing, but it is not Kada's fault.

Taken within its own terms, the building is exciting and innovative. From the start, Kada seems to have been interested in the idea of a building-within-a-building (the egg-in-a-box like London's Royal Festival Hall), but with the major difference that a visible gap exists between the auditorium and the peripheral pavilions, the latter having their own rational structures and being capped by their own roofs. In his original masterplan, the concert hall tapered in plan towards the stage, while the outer box was asymmetrical, its acute angled-corner responding to site boundaries. The revised version, straitjacketed by Hollein's plan, has ended up orthogonal both inside and out, but Kada has found other ways to enliven it. The design for the 1200-seat concert hall was restricted too, for it needed to serve also for opera, ballet, and musicals, necessitating a conventional stage with proscenium, orchestra pit and full flying arrangements. So the relationship between 'producers' and 'consumers' had to be the conventional one: there was no question of a centralized arrangement like Scharoun and Wisniewski's Berlin Philharmonic's Chamber Hall which is of similar size (AR March 1988), or for experiments in novel staging or aperspective space. Also, the fashion in halls has seen a return to the linear shoe-box type, which is especially relevant around Vienna with its historically conservative musical tradition and famous Musikverein.

Kada chose not to fight these conditions, and accepted a conventionally symmetrical parallel sided layout. Instead, he harnessed his ingenuity as a designer to make the space as flexible as possible. The stage width can be varied and it can be thrust into the auditorium, the acoustics and lighting can be varied with movable panels. Even the apparent colour of the interior can be changed through lighting. It is a true chameleon of a space.(1)

Kada was obliged to plan the surrounding building in an orderly and compact manner, the foyer being relatively narrow and restricted compared with larger rivals in other European cities. Nonetheless, a glance at the plans reveals what a complex cellular organism he eventually produced. The greater width of the north wing was prompted by the presence at the third level and towards the west end of a small, second 250-seat concert room. Articulated as a dark blue glass box in the north side, this too is a flexible space in terms of acoustics and lighting, serving for lectures and readings as well as chamber concerts. Symmetrically opposite it on the other side of the stage areas are two rehearsal rooms, placed one above the other. Not being public rooms, their presence is not signalled externally. Visually, they are absorbed into a belt of offices and dressing rooms on seven levels, which wraps around the west of the building and round its south-west corner. Being the back, this is treated in a rational and straightforward fashion with a regular glass curtain wall. Only the fly-tower looming above suggests that it is a theatre. There are many lifts and four sets of protected fire stairs. These complex demands might have pressed many architects into damaging compromise, but not Kada.

His greatest stroke of genius was in making so much of the glowing curvaceous mass of the hall. There is a tradition in modern architecture of the expressed auditorium as a curved, raked form, which dates back at least to Melnikov's Rusakov Factory Club in Moscow of 1927,(2) and which went through many variations with Aalto. The difficulty is that for good technical reasons such a hall usually has to be a dead mass without visual or aural connections to the outside world. When articulation of the exciting events within is precluded, what can the architect do to transmit some sense of them?

Kada creates a visual metaphor. He had only the dullest concrete box to start with, but has managed to give it an exciting curved shape just by adding faceted glass 'bodywork'.(3) On the front behind and under the rake it follows approximately the section of the auditorium, but the curve on the sides is quite fictitious. The slight bulge exists entirely in the cladding, but it is enough to give the hall its convex surface - a double curvature. Importantly, the curved wall also contrasts with straight ones opposite. It makes the presence of the auditorium felt everywhere, even linking distant views across the town with close views as one enters. The greenish turquoise glass is a constant presence, sometimes reflective, sometimes glowing mysteriously from within. The material betrays a certain fragility, while the glow hints at the presence of a mystery beyond, and when nothing is happening the lights can be turned off.

The glass cladding would not work nearly as well were it not separated from the solid roofs of the peripheral buildings by a continuous glazed rooflight; transparent glass spanning a void. This, more than anything else, produces the impression of a gap between the auditorium and the rationally structured outer wings, a gap in which the stairs and landings of the foyer occur like so many secondarily added bridges and connections. The gap also stresses the continuity between the green glass cladding that is touched inside and that only seen outside. At night when the whole building is lit up, the space left around the auditorium seems to flow out into the square, leaving the body of the auditorium floating independent of the side pavilions.

Just as the convexity of the hall plays against the orthogonal system dominating the building, so the sloping plane of the ground floor (which extends the sloping paving of Schubert-Platz), plays against the strong horizontals of the building's section. This important gesture helps relate the building to the site, but it also sets off a sequence of natural asymmetries which disengage the symmetrical body of the auditorium from its asymmetrical setting. The rising floor also cuts off the auditorium at an oblique angle in plan, contracting the space on the less important side. The auditorium underside descends almost to the floor, as in Rem Koolhaas's Netherlands Dance Theatre in the Hague (AR September 1988). This is a clever way of producing visual space where there is no headroom for occupation, and is dramatized with artificial light. Because of the asymmetry induced by the sloping floor, the ramps and staircases leading up to the landings and bridges above (and thence into the hall) have to set off in different ways, and have to be differently resolved. This is where Scharoun and Aalto come to mind, for despite the orthogonal frame, Kada has managed to produce festive cascades of stairs and levels according to circulation sequence, as in the Philharmonic or the Essen Opera House (AR June 1989). The parade up and into the auditorium is an occasion to see and be seen, and visitors have ever-changing glimpses of one another across intersecting levels.

Kada's first major building and first appearance in the AR was the Glass Museum at Barnbach near Graz (AR November 1989), which was notably appropriate to its purpose in two ways. First, it used glass not only for the usual windows, rooflights and general glazing, but also as relatively opaque cladding tiles, as a free-standing structural wall, and as floor. Second, it played particularly well on themes of relative enclosure, of interstitial spaces, of transparency and translucency, reflection and refraction. Ten years later, his new building seems to take all these themes further, stunning in its visual effect and in the awesome visual changes between day and night. As before, the hierarchy of structure is part of the story, with primary columns and slabs of concrete, secondary supports for the glazing in lightweight steel. The choice of glass types is also significant, particularly the innovative light green glass of the auditorium, applied in panels hung by the corners on a strut and cable system, every one a different size and shape calculated by a sophisticated computer programme. There are also many other types of glass: the lapped cobalt blue cladding of the small hall and the solar control glass of the foyer, for example, and the structural glass of the vertically cantilevered balustrades. The effect of these glasses is extended by other materials, including translucent plastic sheeting and expanded metal grilles. The combined impression is a shimmering mirage which is surely only appropriate to the festive purpose of the hall. It also seems to echo the hymns to glass by Paul Scheerbart that inspired Bruno Taut's beautiful glass-pavilion of 1914, a first great attempt to exploit the wide possibilities of the material.(4) As with so much of our best fin de siecle architecture, possibilities opened up or only hinted at by the early Modern Movement at the beginning of this century are finally bearing fruit.

1 For these intentions see Kada's statement in the periodical Glas Architektur und Technik (Stuttgart) 5/97, pp26-32.

2 See S. Frederick Starr, Melnikov: Solo Architect in a Mass Society, Princeton University Press 1978, pp134-139.

3 Kada uses the term Korrosserie, which usually refers to the bodywork of a car.

4 'Das bunte Glas zerstort den Hoss' ('coloured glass destroys hatred') was the motto inscribed over the door of Taut's pavilion. Thanks to the detective work of scholars and an elaborate model built for an exhibition in Berlin, we can envisage the effect of the brilliant colours originally used in Taut's pavilion. Coloured photos are published in Manfred Speidel's Bruno Taut: Notur und Fantasie 1880-1938, Ernst und Sohn, 1995.

Architect

Klaus Kada, Graz

Project team

Klaus Kada, Ursula Marzendorfer, Erwin Matzer, Peter Rous, Willi Nakolnig, Heribert Altenbacher, Alexander Forsthofer, Wolfgang Wimmer, Frank Moritz, Robert Clerici, Ronald Schatz, Herbert Schwarzmann, Elisabeth Kopeinig, Claudia Schmidt, Michael Gattermeyer, Ellen Kianek, Roswitha Kung-Freiberger, Hubert Schuller

CAD

Peter Szammer

Project management

Noplan

Glazing

Seele, Lorenzon

Bonded fixing system

Dow Corning 

Metalwork 

Treiber

Photographs

All photographs by Angelo Kaunat except 4,5,9 and 10 which are by Gisela Erlacher and 3 by Rupert Steiner