Social engagement.

Organic forms and user involvement make Peter Hubner's new school in Cologne a socially and environmentally responsive haven for learning.

Peter Hubner's architecture is most obviously green in its grass-roofs, untreated timber, and passive solar heating (AR July 1998), but it is also green at a deeper level in terms of social and psychological engagement. The recently completed Waldorf school at Cologne was planned around Rudolf Steiner's holistic philosophy: anthroposophy. This is reflected not only in the kinds of rooms and general spatial layout, but in the demonstration of how the building interacts with the elements, and the inclusion in fitting-out of craftwork by staff and pupils.

Hubner's first job for the anthroposophists was the Morgenstern School, Reutlingen (AR March 1987). Short of money, they approached him for his known skill with low budgets and recycled materials, but they soon found an architect sympathetic to their beliefs and ready to work open-mindedly with them, accepting for example Steiner's ideas about symbolism and colour. The Morgenstern's success led to an invitation to undertake the larger school at Cologne.

The project grew, with Hubner spending about two days per month in Cologne over the four years of the design and build process. He claims that the initial design sessions were the most critical, for a strong idea had to be found on which the attention of the group could be concentrated, an idea to focus enthusiasm and transmit it to others. In this case it was the notion of a centrally-planned main building drawn emblematically as a rose with five petals. This image combined the social centrality of the meeting hall, the beauty of a natural symbol and the significance of the numerical progression 5/10/20 which is at once the growth principle of the rose and the generative geometry of the building.

Waldorf schools exist across Germany, privately run but with state subsidy for some pupils. Although the children take the usual state exams, some like the Morgenstern even dedicating themselves to reversing failures from the state system, the educational goal remains much broader. The anthroposophists try to bring out the whole individual in an integrated way, physically, mentally and ethically, following a path of development advocated by Steiner. The curriculum therefore includes strong elements of arts and crafts, music and drama, as well as academic subjects. There are extensive workshops, and in every school the performance of eurythmy - a kind of dance - has a central role, not only as a discipline to link mind and body, but also as an exchange of communication between performer and audience. Performing before others is regarded as essential for social development and self-confidence, so Waldorf schools are built around a theatrical auditorium as hierarchical centre. This refers back to the original developed by Steiner at the Goetheanum in Dornach, with a linear layout and formal proscenium.

The Waldorf school in Cologne had already existed for 17 years, but was housed in the rented buildings of a former state school. The arrangement could not continue, and there was in any case need for expansion. Since the school authorities had no capital, money was borrowed against personal guarantees from parents, an important if largely invisible form of participation. The construction of new buildings also meant defining the school's architectural identity for the first time, and this was an issue that the anthroposophists took unusually seriously. All too often these days, institutional buildings are seen in terms of square metres of floor-space or financial assets on the balance sheet, but the school staff and parents recognized the deeper issues: that the organization of a building reflects and determines social relationships, for example, and that the qualities of space and light in a classroom affect the learning of children. It was important to get such things right besides making a positive image of the kind of world in which they wanted to live.

A site was acquired on the periphery of Cologne in a working-class housing area called Chorweiler. A brave new world from the 1960s, it is dominated by broad highways, tall blocks of flats, and a pedestrianized shopping mall, though on the other side of the school site some old meadows persist. The choice of location was encouraged by the relatively low price of land.

The new school consists of two buildings, each developed around one of the two largest social rooms: the auditorium and the sports hall. Both are placed to the north of the generous site with car parking behind them, leaving the southern area free for a sizeable landscaped garden. Orientated to the north-western boundary, the sports hall faces its open glazed front south-east to enjoy some winter solar gain. The auditorium on the other hand had to be blind, a black box for performances, so it runs north from the centre of the main school block engulfed by the main volume and surrounded by other rooms. Between the two buildings runs a street-like space, which must be traversed to arrive at the east-facing main entrance. An area of circular paving with some perimeter seating - an outdoor room - terminates this street, mediating between the two buildings and marking the transition into the garden area. This is as yet the most evident gesture by landscape architect Christof Harms, but the rest of the garden will unfold as plants gradually mature.

The main school building contrasts its tail of auditorium with a head of classrooms, a radial three-storey arrangement on three levels facing from east through south to west, They open inwards onto a central hall, the clear and unmistakable heart of the school, which serves as the main communications axis and foyer to the auditorium. Its spectacular glass roof, supported by a tree-like column, admits skylight and sunlight. Beyond its social and visual function, this vertical hall also serves as the main ventilation shaft, using the stack effect to exhaust warm air through vents at the top while sucking in fresh air at the bottom. Air is admitted from peripheral intakes through a series of large, radially placed underground pipes. While moving slowly through them, air can exchange heat with the mass of the earth under the building, being cooled in summer and warmed above zero in winter to lessen the heating load. An additional wide duct runs northward to supply fresh air at the bottom of the main auditorium. The single active airhandling element in the whole complex is the roof-top fan, which sucks air from the volume of the auditorium.

A large number of classrooms were needed, both specialized and general, with the usual Steiner stipulation that they be not rectangular and boxy but more polygonal and open in character. Needs of individual teachers and for particular types of activity and equipment were taken into account, and also the significance of various kinds of seating layout. The more important rooms - the eurhythmy room and main music room, for example - are generally more regular and symmetrical, while ancillary and storage rooms are tucked into left-over corners, so there is a legible hierarchy of formality. But all rooms have individual characters, which both differentiate them from one another and prevent repetition. That the building consists of a society of rooms is as evident in the external form as it is in the plan. Workshops and a caretaker's flat, which were added to the main rectangular volume of the sports hall, are even more clearly articulated than the main classroom block. This grouping resulted in a very economical arrangement.

Main building work was achieved by conventional contract, with concrete internal walls and floors and timber roofs. The 3D computer system routinely used in Hubner's office allows all junctions and angles to be calculated, along with cutting schedules for components when necessary, so the complexities can be handled reasonably easy. A contractor was found who was prepared to take the challenge without inflating the cost, and the school was achieved at about 20 per cent below the normal cost of a state school its size, including extras like the auditorium and eurhythmy room. Hubner and his team claim that the staff, parents and pupils were constantly involved throughout the design and build period, and at every level of decision, so it is impossible now to unravel who suggested what. They have become friends, and the project has taken on a life of its own. As it grew, staff from the school took an increasing role. They undertook the whole construction of the workshops which were added lean-to fashion to the contractor-built sports hall. Staff also became involved in finishes, including tiling, joinery, paintwork and landscaping. There is a long-term intention to replace the cheap standard doors with hand-made ones lovingly produced on the premises with the pupils. In this way the school can mature and grow, and it is typical of such participative architecture that it is never finished.

The school's messy vitality may be difficult to trap within the photographic frame, and its atmosphere may be best appreciated by its users who have their own role in the story, but that is surely right. Buildings for life must register our habits and bear the scars when we adopt new ones. Preserving the memory of their creation, they must also adapt to growth and change.