A Self-Sufficient Solar House, Freiburg, Germany

A self-sufficient solar house in Freiburg, Germany, that requires no external energy supply is presented. Its entire energy demand for heating, domestic hot water, electricity and cooking is supplied solely by solar energy. The combination of state-of-the-art energy-saving technologies with highly efficient solar systems minimises the disparity between the solar radiation input and the building's energy demands in winter. The remaining seasonal energy storage is accomplished by electrolysis of water during summer with electricity from a photovoltaic generator. Pressurised storage of hydrogen and oxygen allows reconversion to electricity by fuel cell as well as the catalytic combustion of hydrogen for cooking and a back-up for space heating. The house has been occupied by a family since completion in October 1992. First results indicate that the building performs as predicted in terms of its thermal behaviour. Occasional restrictions in the electricity supply have been necessary due to unreliable fuel cell operation.