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Last month, 15 years after it was first proposed, the Austrian city of Linz finally completed its showcase for sustainably technology known as SolarCity.

The high-density masterplan was drawn up back in 1995 by a consortium of leading European architects including Foster and Partners and Richard Rogers Partnership. As its name suggests, the original aim was to make the most of solar energy, through the use of south-facing windows, roof-mounted solar collectors, insulation and internal heat sinks.

Over the 15-year development period, the city council expanded its goals to embrace sustainability in its broadest sense, including wastewater recycling, combined heat and power plants fuelled by biomass, low car usage and the social integration of diverse population groups.

Built for £20m, the 16,540 m2 district centre, designed by Munich practice Auer + Weber, contains shops, a cafe, restaurant, health clinic and community hall. The accommodation is laid out as six parallel strips of two-storey blocks running north to south. These are separated by narrow arcades yet linked together by a transverse gangway on the upper floor. All the buildings are clad in horizontal tongue-and-groove boarding, which adds to the sense of uniformity.

At its heart, the complex opens out into a pedestrianised square. With cafe tables spilling into it in warm weather, this is the social hub of SolarCity’s 6000 inhabitants.

As well as all the other energy-conserving features, the town-centre buildings rely on ingeniously controlled natural ventilation to lower heat loss in winter and increase cooling in summer. Ventilation is generated by the natural stack effect generated by the heat of the sun.

The air passes through floor voids, which exploit the floors as heat sinks, and wall vents, which incorporate noise dampers. In summer, the ventilation is linked to groundwater via boreholes to provide cooling, and in winter, heat is reclaimed from exhaust air by heat exchangers.

As a result the buildings consume less than 44 kWh/m2 a year – just a quarter of what is used in typical shops and community buildings. And it won Auer + Weber an award from the Leading European Architects Forum as its members’ choice of best sustainable project.

A pedestrianised square with café is the social hub of the district centre and the whole SolarCity