Space craft.

At first sight, this youth club by Peter Hubner looks as if it is anything but informed by ecological concerns. Yet study shows that it is highly innovatory and radical in its concerns for energy and construction, as well as being a powerful and jolly symbol.

Since the successful realisation of his first youth club more than a decade ago in Stuttgart-Wangen (AJ 23/1/85, pp42-47), Peter Hubner has built others around Stuttgart, always with a considerable degree of participation, and very varied in image (ARs June '85, March '92, August '94). The latest is close to the centre of the village of Moglingen, a few miles north of Stuttgart, and in comparison with the earlier ones has a much neater, more unified appearance.

`The flying saucer came down through the clouds, halted, and dropped lightly on the meadow. The ground beneath it melted, but when it had cooled down, out came the great Scarab, King of the Planetoids. Curious youngsters crept inside only to find it an empty shell. They asked the Scarab why, and he replied enigmatically "on the earth one builds with earth". So they built an earthen city within it.'

This is the story that Hubner tells with some humour and enthusiasm, illustrating his narrative with colourful computer projections, sketches or manual demonstrations with an inverted saucer. Its name is Jufo, UFO but also an acronym: JUgend FOrum, youth forum.

The flying saucer and the city of mud were just two of the ideas thrown up by local teenagers in a `brainstorming' conducted by Hubner to find the first ideas for the building. This procedure, which earlier produced the memorable dinosaur cafe at Stuttgart-Stammheim (AR March 1992, pp41-45), gives the building both an identity and an image, founding it in myth. Until it is completed, the concept gives future inhabitants a focus for their own imaginings in anticipation: later it becomes a real place and a positive landmark.

Equally important, the image gives Hubner a theme to develop while working up a project, spurring on his creative imagination. Part of the brainstorming with Jufo involved getting the 70 or so children to stand on the site in a 22 m circle prefiguring the building. Hubner saw that the shape seemed small in relation to the looming concrete masses of the adjacent schools and sports hall built in the 1970s. It would need a strong identity to compete with them, and this influenced the form.

The potential weakness of the approach is immediately evident: it could remain a one-liner, the initial shock quickly overtaken by boredom. Certainly this would have been the case had Jufo been treated as a stage-set in the manner of many post-modern entertainment buildings and roadside cafeterias, where the image is skin-deep and the joints in the plastic cladding all too painfully evident. But Hubner is more ambitious, and likes to get to the heart of an idea. A machine from outer space should look intelligent, and look as though it works. The inverted saucer lends itself to a lightweight structure with a clear span: a steel-ribbed dome resting on a ring truss. This is connected at only two points to each leg, and the nine legs are the real and only supports, minimising foundations.[1] The pinjointed structural design of the legs dramatises their potential movement and shows the division of structural forces. This has great rhetorical effect, reminding one of the retractable undercarriage mechanisms of aircraft and of the flexible adjustable supports needed by a real spacecraft -- so often in films, so seldom in reality -- when they land on uncertain ground. With Jufo, a static and permanent building, the adjustability is really used just once to set it straight and level, but the fact that the legs work is legible, giving the building a delicacy and poise more exciting and futuristic than the saucer shape on its own. Ingeniously, rainwater is carried down the legs as well.

The smaller dome over the central part -- over 10 m in diameter -- is also technically innovative, being a rigid sandwich formed of two paper-thin (0.23 mm) sheets of stainless steel inflated and filled with polystyrene granules. The latter are stuck together as a solid mass by a glue that is activated by passing steam through it. It is tilted with respect to the main dome, leaving space for a clerestory light of varying height. Driven by an electric motor acting on a toothed rack around its perimeter, the whole central structure rotates. The degree of solar exposure can thus be varied, using the maximum glass area for passive heating in winter but preventing excess heat in summer. The rotation can even be operated to follow or avoid the path of the sun on a daily basis.

Despite the technical innovations, Jufo had to be a relatively cheap building, so the creation of purpose-made futuristic doors and windows was out of the question and could in any case have seemed too literal. Standard frames were employed varying with internal requirements in the usual way, with full glazing on the cafe and small windows on the WCs. This `normal' window wall is detached from the dome at the top by a glazed band which reveals the structural ring truss. The junction at the bottom of the wall is made with a sloping bank of large random stones suggesting disruption and melting of the ground when the UFO landed. This is a successful solution visually, and it allows the surrounding site to be left mainly untouched as a wild meadow, both precluding the need for gardening and enhancing the main idea.

Within the clear unified envelope is an irregular city of mud, hand-built and decorated as a live project by architectural students along with youth club members. This establishes the structure of rooms. After the quick installation of the shell it could be carried out in dry, secure conditions, precluding the difficulties of making a weatherproof envelope with improvised techniques, and without any great hurry. The mud walls have a considerable mass and also serve as a storage medium for the passive solar heating. As in earlier Hubner buildings there are colourful Gaudiesque mosaics of broken tiles and clay reliefs handmoulded in the surface. The many idiosyncratic details show the commitment and creativity of the young builders, but the resultant diversity is tempered by the calming effect of the shiny internal roof surface which is everywhere visible.

The contrast between high-tech envelope and low-tech interior seems at first rather an amusing shock, but it is not just a game of images, for it indicates a real polarity of technique in design and production. The shell was preconceived on an advanced 3D computer drawing system with the help of a leading engineer, the data being transferred directly to the factory, and the precision components being mounted by crane. Mud city in contrast was improvised on the spot by hand and shovel using local earth and unskilled labour. This adds an educational dimension to the project, for it represents rather well the contemporary need to establish a balance between sophisticated but energy-intensive high technology and sustainable but labour-intensive intermediate technology.(2) The mythology of the flying saucer represents a modern view of the heavens and of man's dangerous ambition to conquer them, his hubris perhaps. Mud city represents old mother earth on whom we still fully depend.

[1] Peter Hubner comments: `9 legs, 18 struts, 36 ribs, 144 roof panels -- a "cosmic" order!' Letter to the author 23/7/96.

[2] Or `between cosmic perfection and man-made imperfection' -- comment from Peter Hubner, same letter.