The desire to create a passive net zero building within a dense urban fabric guided the design of the Schlaues Haus. The extension connects to the old renovated building, creating a footprint of 12 x 33 m (39 x 108 ft) and forming one air volume.
The urban situation of this small, 12 meter wide property enclosed by buildings on either side required a sophisticated daylight strategy. A vertical corridor between the new South façade and the old building maximizes daylight. It provides sufficient daylighting in the depth of the building complex and at the same time acts as a solar chimney to exhaust air. This allows for natural cross ventilation on all floors of the new and old building. The south facing façade is equipped with fixed micro-louvers integrated into the glazing, providing sufficient shading, while the angled south-west facing section requires retractable blinds; heat losses and solar gains were balanced through thermal modeling.
The energy supply system is a geothermal heat exchanger for heating and cooling, while photovoltaic panels on the roof provide electricity.