Built for a family of six, this house near Vienna has a post-and-rail outer skin and a reinforced concrete thermal-storage core. The full-height south-facing absorber wall is clad with black dolomite and is exposed to direct solar radiation that enters through a sloping roof light above the living hall. Together with low-temperature panel heating in the ground floor slab, this covers the basic thermal needs of the house. The panel heating is fully activated only when peak loads occur. The passive energy concept is supported by an air circulation system in which warm air drawn from the top of the absorber structure is blown out over the large area of east-facing glazing. In summer, sunshading is provided by fabric blinds.