This paper introduces and evaluates a novel heating and cooling concept employing thermo-active building systems and environmental energy, harnessed from two 11-m(3) rainwater cisterns for a 285-m(2) residential building in passive house standard in Germany. The building strives for a significantly reduced primary energy use with carefully coordinated measures, such as high quality building envelope, by means of vacuum insulated panels, supply and exhaust air system with heat recovery, reduced solar heat gains (solar shading), and the integration of thermal solar collectors and photovoltaic in the plant system. On this premise, a comprehensive long-term monitoring in high time-resolution was carried out for the building for two years with an accompanying commissioning of the building performance. Measurements comprise the energy use for heating, cooling, and ventilation, as well as the auxiliary equipment, the performance of the environmental heat source and sink (rainwater cistern), thermal comfort, and local climatic site conditions. The analysis focuses on the performance and the efficiency of rainwater cisterns as natural heat source and sink as well as the heat pump system. The paper discusses the performance of thermo-active building systems, investigates the thermal comfort, determines the efficiency of the heating/cooling system, and evaluates the total end and primary energy use of the building. (C) 2009 Elsevier Ltd. All rights reserved.