In the competition for the new kindergarten in Senden, we advised lbgo architects on environmental strategies and indoor comfort measures. The concept bases on a radical reduction of mechanical systems and relies on the intrinsic characteristics of materials. The classrooms are built with structural timber while the central core is made of concrete. The exposed timber walls and ceilings provide sufficient thermal mass and facilitate the humidity regulation. The building is naturally ventilated, cooled and heated through active slabs combined with a heat pump using ground water. The roof geometry provides protection from direct solar radiation in summer, it allows daylight to penetrate the building in winter and mid seasons. The facade has been optimized to guarantee high levels of daylight autonomy in all the classrooms facing south, offices and services with lower requirements face north.