A concept for generations. In Salzburg, near the historic centre of Mozart’s city, this wooden house was built on a vacant lot, which offers the possibility of later expansion into a 2-family house. The sustainability concept consists in giving the family the option of a simple extension (not conversion), instead of unnecessarily building too large and bulky today. “We only build what is really needed. Because every square meter consumes energy”, says Christoph Mösl – one of the 3 brothers of m3-ZT. The floor plans of the floors are fluid, the areas for vestibules and corridors are reduced to a minimum. For example, the corridor area on the upper floor is only 3 m2. Domestic quality woods. Spruce, fir and larch – from local forests. In the (still) single-family house of the Andreas family, system solid wood was constructively installed, the windows are also made of larch wood. From the Attica, you have a wonderful view of the High Salzburg Fortress. Outside, larch shingles were installed in the areas without a canopy, and larch cladding in the areas with a canopy. A larch wood pergola with summer vegetation protects the glass surfaces from overheating. The building services concept consists of a PV system and a wood-tiled stove in the living room, which uses a buffer tank to produce hot water for heating the entire house.