||Economic growth is increasing the demand for energy. Information and Communication Technologies (ICT) have been identified to play an important role in reducing the energy intensity and increasing the energy efficiency of the European Union (EU) economy. ICT will not only improve energy efficiency and help combat climate change, they will also stimulate the development of a large leading-edge market for ICT enabled energy-efficiency technologies that will foster the competitiveness of European industry and create new business opportunities. As ICT are today pervasive to all industrial and business domains, they are expected to generate deep impacts in energy efficiency of buildings of tomorrow. Although versatile statistical information is available on energy consumption in different buildings, there is still limited understanding about the potential of ICT to reduce energy consumption. In order to put ICT at the core of the energy efficiency effort and to enable reaching its full potential, it is necessary to foster research and development (R&D) into novel ICT-based solutions and strengthen their take-up — so that the energy intensity of the economy can be further reduced by adding intelligence to components, equipment and services. In this paper, ICT based support tools to energy efficiency in the so-called smart buildings are investigated. The state-of-the-art in ICT for smart buildings is discussed with focuses on the role of ICT and key fundamental fields in which R&D efforts are needed to enable the energy efficiency in future smart buildings. Five key areas including design and simulation tools, interoperability/standards, building automation, smart metering and user-awareness tools have been identified where there is potential to improve energy efficiency through the use of ICT, and they are considered as the next generation ICT for future smart buildings. As an energy efficient housing example, the Lighthouse built in the UK is discussed in detail along with its ICT integrated building services and demonstration data of energy use. This gives a better understanding of the impacts of ICT on the energy efficiency in buildings. The paper concludes that in order to achieve the energy efficiency in buildings, further support of multidisciplinary R&D and innovation demonstrating the potential of ICT based solutions are needed to foster and accelerate the deployment of energy efficient solutions in buildings.