SHUTTERED ROOMS.

Distinguished by formal rigour and a concern for energy use, this complex of compactly planned, mixed tenure housing blocks on the edge of Innsbruck is animated by an external skin of folding shutters.

Housing (of both the state subsided and private sector funded kind) accounts for over a third of construction work in Austria. Regulated by planning laws and cost constraints, opportunities for innovation are limited, with the result that towns and cities tend to be dominated by dull residential developments. In this apparently reductivist area of architectural activity, Baumschlager & Eberle have applied themselves to researching and evolving a successful housing type based on a compact, doughnut-shaped plan with an inner ring of servant spaces and an outer ring of served rooms. The building envelope is usually formed from balconies and loggias, creating a semi-public layer enclosed by an external skin of folding or sliding shutters. By adapting and modifying this basic type to various conditions, Baumschlager & Eberle have gradually developed it in terms of architectural form, constructional composition and ecological performance. The particular character of this approach is not to seek the outlandishly spe cial, but rather to aspire to the highest standards for what is normal.

The latest in this series of housing projects is for a site on the western edge of Innsbruck. Dramatically framed by alpine peaks, it extends an existing residential area. The complex contains 298 flats of varying sizes (from one to three bedrooms) divided more or less evenly between rental and ownership. Apartments are organized in six identical blocks between five and seven storeys high. Cars are relegated to a subterranean park, so freeing up the areas between the blocks for gardens and communal social spaces. Pollarded lime trees mark the edges of paths and will mature to provide enclaves of shade.

Each of the blocks follows the same compact arrangement of flats tightly planned around a central lightwell and service core. Each has a single communal entrance that penetrates through the block to the central space; from here you either take the lift or stairs to communal galleries on each level that lead to individual apartments. Flats are simply and economically planned with a narrow strip of kitchens and bathrooms on the lightwell side serving larger living spaces facing out to views and light. Each flat has access to a balcony that runs continuously around each floor. Inner faces of the blocks are clad in vertical strips of cherry. Folding shutters made of copper and balustrades of translucent toughened glass give protection from the elements and provide privacy. The changing concertina rhythms generated by the shutters (which will surely have a much greater degree of lyrical randomness than the regimented patterns shown here) animate the geometrically stern facades.

As with Baumschlager & Eberle's previous projects (AR January 2000), the lnnsbruck housing is characterized by a thoughtful degree of energy conscious environmental control. The highly compact plan reduces the surface area to volume ratio. Walls are highly insulated and windows are triple glazed, in order to minimize heat loss. Each apartment is equipped with a compact ventilation unit with heat recovery, as well as a small heat pump for air heating and a boiler for hot water. The controlled air ventilation system provides a constant, comfortable supply of fresh air as well as optimizing space heating and minimizing ventilation losses. It also maintains a balance of relative humidity, reducing problems of building deterioration due to pollution, humidity or mould.

Around 70 per cent of the annual hot water demand is covered by a solar powered system. Solar collectors with a surface area of 140-l90sqm per block heat water in storage tanks located around the perimeter of the underground car park. During the summer, domestic hot water is warmed in the solar tanks and supplied to individual flats. Any extra heating is carried out by the heat pumps. In winter, solar energy is used to preheat fresh air in the controlled ventilation system. Rainwater is collected from the roofs and used to flush the lavatories, accounting for over half the annual demand.

This conflation of energy saving measures gives rise to a very low annual heating requirement, compared with more conventional housing developments, with consequent cost savings and reductions in carbon dioxide emissions. Combining formal precision with ecological inventiveness, Baumschlager & Eberle's architecture shows what can be achieved even in the most unpromising of programmes.

Architect

Baumschlager & Eberle, Lochau, Austria

Project team

Carlo Baumschlager, Dietmar Eberle, Gerhard Zweier, Herwig Bachmann

Structural engineers

Mac Wallnofer, Fritzer & Saurwein

Environmental engineer

GMI Ingenieure

Landscape architect

Kienast Vogt

Photographs

Eduard Huebert/Arch Photo