In Heusenstamm, about 14 km south of Frankfurt am Main, there is an apartment building with 5 residential units on a 724m² plot. The property was solidly built. In the basement there are cellar rooms for each unit and 8 underground parking spaces (car elevator-system) with a ramp in front of the entrance and an underground driveway turntable to facilitate the exit. A gas boiler with solar energy support is installed as the heating system. The rooms are heated by underfloor heating. All apartments are equipped with an exhaust air system. There is a rainwater tank in the garden. The house was built according to the Kfw Efficiency 55 standard.