Issues relating to the reduction of CO₂ emissions and energy consumption are currently more important than ever before. In the construction engineering and automotive sectors research and development efforts are focused closely on efficient buildings and automobiles. The designated target is a reduction in greenhouse gas emissions and overall energy demand.However, almost all approaches focus solely on either "buildings" or "mobility." By considering both aspects as a single holistic system, further energy saving potential arises due to synergetic effects. The goal of current research projects relating to Smart Homes and Vehicle to Building (V2B) is to smooth the electrical load profile on a household level rather than to reduce the individual-related total energy consumption and thereby the CO₂ emissions.In contrast to this, the present paper aims to suggest possibilities and synergetic effects indicating how a holistic consideration of both elements, "buildings" and "mobility," can contribute in reducing individual-related total energy consumption. A system is presented which consists of a plug-in vehicle and a residential building. The holistic system includes thermal and electrical energy sources, storage units, sinks, connections to a public power grid and a gas distribution system. The system components are in part mobile and in part stationary units. A combined heat and power (CHP) unit enables the conversion of energy in the form of natural gas into thermal and electrical energy to supply both the building and the vehicle. By intelligent use of the system components, the total energy consumption can be minimized while the demand for thermal and electrical energy as well as basic needs for mobility will be covered. Beyond that the system allows charging of the vehicle with an improved system-internal electricity mix in comparison to the mix supported by the utility.