Achieving improved energy efficiency for future buildings is a well established imperative under European legislation. However, parallel evolutions in the energy supply side are anticipated to have a similarly significant impact of how the buildings should behave from an energy point of view in the future. Particularly, the growing penetration of renewable energy systems(RES), the development of the smart grid and the roll out of smart meters are causing big changes on the demand side of the electricity system, including the residential sector. Two anticipated changes have to do with the spread of electric vehicles and the electrification of residential thermal loads. Those evolutions are not only going to change residential electricity consumption quantitatively but also qualitatively. Typical electricity demand patterns and profiles will be significantly affected. However, another change will come from the deployment of the technologically advanced communication infrastructure that will provide the option of demand response capabilities even to residential customers. The IEA Technology Roadmap [1], for energy efficient buildings, identifies four technologies that in the future will boost the environmental performance of the particular sector: solar thermal collectors, combined heat and power units, heat pumps and thermal energy storage. It is worth mentioning that the last three technologies of building energy systems are actually the ones which display the highest potential for demand response. Thus, the main question arising is how to select and control the energy systems of future buildings in such a way that will optimise not only the energy performance of the building itself but the energy performances of buildings when considered part of a larger integrated electrical grid system.