Previously, the architect's family home, built in 1966, stood on the generous meadow property on the fringe of the town. Lacking any thermal insulation, it was replete with thermal bridges, outdated building services and a high degree of radon contamination. Completely retrofitting the basement with waterproofing would have been a solution, yet a hardly feasible one. All of these aspects rendered a renovation too expensive. Situated on the same spot as its predecessor, the new building and its 20 m long southern facade directly face the midday sun. Its cubage and dimensions correspond to a duplex - and, indeed, the structure could be divided into two residential units with separate entrances, garden access and staircases, simply by creating a partition wall. The multi-purpose room on the ground floor features all connections required to install a second kitchen. The bathroom in the entrance area could be allocated to either unit. At the moment, one half of the house serves as a guest apartment when the adult children pay their parents a visit.
Only the concrete exterior walls bear the loads of the roof and the floor slabs. The latter span freely across 8 m. In the interior, only lightweight wood stud walls were built in, enabling easy floor plan changes at a later date. Only at a second glance, the function of the facades as producers of energy becomes clear. The cover glazing is satinised and tinted in anthracite grey with a slight hint of brown. For aesthetic reasons, Nadia Vontobel accepted the resulting slightly reduced energy yield. The roof features highly efficient modules with anti-reflective coating. The design of the building is adapted to their standard dimensions. Photovoltaic modules in custom formats were only required along the inclined roof surfaces. The southward facing roof surface features a 35° inclination. It achieves high yields in summer and in winter, generating roughly 58 % of the overall yield. The facades contribute a significant 34 % share - mostly in winter, exposed to the low standing sun, while the roof is covered in a layer of snow. In order to store energy, a 3000 l heat storage tank is available, calculated to cover two days worth of heating should there be no solar power. Acquiring an electric car equipped for bidirectional charging is also planned, which would allow intermediate storage of surplus power. JS
