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NATURAL GROWTH

building study - In their treatment of the exterior of a school at Obernai in Alsace, Duncan Lewis and Scape find new ways of integrating building and landscape, in a project that will continue to evolve

Adapting found, natural materials has been a consistent tactic of site integration for the British-born architect Duncan Lewis and his Bordeaux-based studio, Scape. In previous projects this has involved either the direct use of the site's resources as building materials - the processing of found wood or stone - or more sculptural techniques, such as casting.

Studies for schemes in the Loire proposed subtle dialogues with the region's exposed geology, including its mimicry through the creation of concrete casts. In southern Norway, at the edge of the town of Fredrikstad, trees felled during site clearance provided both cladding and decorative detailing: brightly coloured tree casts in thermomoulded plastic are seen on the facades of the school's classroom blocks (AJ 22.5.03).

The cast replicates an element of the immediate environment, transferring it to the surface of a building, where it becomes ornament. But Lewis' use of casting was not simply some contemporary, site-specific evolution of the theme of 'rustication'.

Behind it lay the idea that the relationship between architecture and landscape could be rethought at a much deeper level.

Lewis always intended that the building would express a natural and dynamic process; that it would grow, evolve and seasonally increase its degree of connectivity with its site. At Obernai, in the region of Alsace, progress in this direction has come by way of an unusual application of an agricultural technology: namely, hydroponics.

For Obernai's new school, situated on the edge of town, between garden suburbs and parkland, Lewis has moved a significant step closer to the realisation of, as he puts it, 'architecture as ecosystem'.

Unlike the school at Fredrikstad, where Lewis was involved in all aspects of the project, at Obernai he was responsible for both the architectural and landscaping strategies of the exterior of the school, but not its interior design. This let him focus attention on a more thorough solution to the skin of the building.

The vertically mounted hydroponic panels, which occur on all elevations of the school, were developed in collaboration with a company called Soprema, also from Alsace.

A full-scale prototype panel was tested on site, through all the seasonal changes of a year. The panels comprise a metal framework, which receives individual boxes of vegetation supported by a 40mm layer of soil substitute - a peat, perlite and vegetal fibre mix. A hydroponic drip system, attached to the rear of the panels, irrigates throughout the year and introduces extra nutrients approximately every six months. In all, there are over 1,000m² of panel surface, supporting more than 50 different species of plant.

These are mosses, lichens, grasses, small Alpine shrubs, a few miniature succulents - essentially tundra species, capable of existing on meagre nutrients and shallow soil depths. Here and there, self-seeded specimens have found their way between the controlled planting and seem equally happy to root on the vertical. Grouped and positioned according to their capacity to tolerate shade, a more-or-less even degree of growth has occurred on all facades and, in general, productivity has exceeded expectation.

The frameworks are simply bolted onto the building's inner skin - concrete in some areas, copper-sulphate treated ply-panelling in others. Metal beams support the panels away from the building at marginally varied angles and depths, giving an effect of shallow relief. The hydroponic plants will, in fact, make up only half of the facades' vegetal mass when the complex reaches maturity. Bare metal frameworks interspersed between the panels are to receive the downward growth of vines, which are planted on the roof of the school, and climbers will spread from their bases. The outer skin of the school will eventually be formed entirely of plant matter. Its maintenance will thus be gardening.

There are functional, even pragmatic aspects to the role of the vegetation. Lewis hopes that the plant groupings will be distinct enough to provide colour coding and directional orientation for the complex. The vines and creepers will act as sun filters, and create a diversity of ambient qualities in the interior. The plant mass as a whole is expected to promote thermal inertia for the buildings.

When I visited the Obernai school, the surrounding terrain was still a building site.

But seeing the building in this state demonstrates more acutely that this project is not just a question of architecture in a landscape, but of architecture as landscape reconfigured.

Nature has been disturbed and reassembled with advantage. The designed, architectural 'ecosystem' both mimics, and will eventually merge with, the ecosystems around it.

The school's vertical meadows echo the lichens on the bark of the site's mature trees.

A branch of one tree has been severed just short of the top of a hydroponic panel on an elevated section of the school - from certain angles it appears to grow into it. Maintenance will undoubtedly continue to prevent such fusions, but on a more delicate level - of leaf, twig, frond and blossom - the surface area of contact between the building and surrounding plant life will increase, until ecosystems interpenetrate: the crossing of insect colonies, the sharing of parasitic plant species, cross-fertilisation.

The potential interpenetration of architecture and landscape systems is anticipated by the visual dynamic established between the building and its wider context. As one might expect, the panels disturb the distinction between foreground and background, as they have an almost identical tonal value to the surrounding landscape, and are affected by light in a similar way.

The facade also stages a complex game with our conventional expectations of architecture. From certain views the panels make the physical limits of architectural form indistinct; from others, they appear as slices cut out of the building. When seen en masse from an oblique angle they even appear like mirrored surfaces, as if they were glass panels reflecting a landscape, or passing reflected views between them.

The theme of the vine runs throughout Lewis' conception of the building, informing its spatial logic and its relationship to the wider landscape, which is dominated by the wine industry. He wanted to continue the linear geometries of viticulture found outside the town into this new, municipal building at its edge. The school comprises three strips of building, running in a north-south axis, linked at the southern end by a circulatory passage formed by adapting standard greenhouses. This tripartite division corresponds to the three communities housed within the complex: a nursery school to the west; an elementary school in the centre; and facilities for town groups and administrative and assembly rooms to the east.

Each strip relates differently to the topography of the site. The eastern section rises from ground level up on to pilotis where the ground dips toward the municipal park to the north. The central section is entirely elevated, on the same irregularly angled pilotis.

To the east the building remains earthbound and, moving through it, one descends with the slope of the site.

The second phase of landscaping will increase tree density on the site, and include planting of actual rows of vines between the three linear strips of school building. In fact, the view from a hill north of Obernai shows that Lewis is not the first to breach the boundary between town and country in this manner.

A number of small plots within the town are already under cultivation as vineyards.

Lewis' use of vines has other implications, as it dissolves not just the town/country distinction, but also puts into play a number of others. It crosses the divide between the agricultural and horticultural use of plants, between practices of industrial husbandry and municipal gardening. Questions arise, for instance, about the status of the fruit of this interstitial garden. Will the yield be communal or harvested privately, or will it simply be decorative? If decorative, does one regard the rotting of the fruit on the vine as part of its decorative cycle, or does one harvest anyway to preserve the vines' neatness?

One might say, then, that Lewis' vine garden just creates dilemmas for future maintenance contractors. But those grey zones of confusion between botanical categories and landscaping practices perhaps give glimpses of his true radical credentials. They underline the fact that his ambitions for a synthesis between architecture and landscape are not driven merely by aesthetics.

Lewis'designs ultimately address issues of habitation in the broadest sense of the term.

They pose a playful challenge to our current modes of living. The school community will develop and evolve patterns of habitation and learning specific to the school's unique set of propositions.

Here, institutional conventions that separate landscape from town, recreational space from spaces of rules and control, and work from play, are questioned by a series of playful hybridisations. A school where people circulate through greenhouse passages and the building grows daily; this Obernai project is a courageous realisation of the kind of system that, until now, has been largely in the realms of speculation or fantasy.

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