Distributed Generation is driving a paradigm shift in traditional power systems, allowing the production of renewable electricity and thermal energy close to the main energy consumption nodes (e.g., buildings). In this sense, thermal networks and electrical grids for Smart districts /cities have a key role, allowing the interconnections of distributed energy resources (renewables, combined heat and power generators, etc storage systems, and loads (electrical and thermal), locally dispatching supply and demand. In the present work, a multi-energy system for a new nearly zero energy and low carbon district near Milan (Italy) is proposed and analysed. After the evaluation of thermal and electrical energy needs of the district, an innovative thermal and electrical multi-energy system is designed with the specific aim to integrate multiple renewable energy sources (i.e., photovoltaics and groundwater energy) and energy storage technologies (i.e., sensible thermal storages), obtaining the best matching with thermal and electrical loads. Final results demonstrate the achievable benefits of the proposed solution, which can be successfully applied in several contexts.