In the context of doubling energy use worldwide by 2030, with 80% remaining carbon energy, and in which buildings account for more than 40% of the total energy consumption, it is appropriate that buildings contribute "intelligently" to reduce consumption, contribute to the increase of renewable energy production and become a key node of the energy grid related to energy and transport of the eco-city. Moreover, these "smart buildings" will be in the near future aggregating a huge amount of data through numerous sensors. They will be connected to the neighbourhood, to the city and to the territory. Big data analytics and cloud computing will bring new services to inhabitant and citizen. We are presenting in this paper, the smart building "GreEn-ER", which is a new building in the centre of the eco-city in Grenoble, France. It has been designed with many "green" ideas and is a "living lab" supporting research and teaching in the field of sustainability. This paper is focusing on the energy field and deals with electrical micro-grid interaction.