In the current context of the energy transition, specific interest has arisen around the concept of Renewable Energy Communities. These consist of collective cooperations of energy related activities which have the potential to improve the sustainability of the whole energy system but require accurate analyses of both the energy demand and potential production from Renewable Energy Sources before implementation. Therefore, a strong need for tools supporting all interested actors in dimensioning and managing the energy community emerges. Geographic Information Systems are powerful tools to model extensive areas by spatially displaying and integrating multiple data to produce new information. This study presents the findings of the DT4Energy.com project, implemented in Ivrea, Italy. The project goal was to develop a Urban Digital Twin platform to support decision-making for the creation of a new energy community by leveraging earth observation and detailed energy data. Both authoritative sources (as the Energy Performance Certificates) and proprietary information (as consumption data made available by the project partners) have been integrated into a 3D geometric model to model the total energy demand. The potential electricity production from solar energy has been evaluated through solar radiation modelling from open-source GIS tools. Thanks to the developed platform it is possible to verify the compliance with the normative requirements and the consumption and solar production profiles, and to quantify the self-consumption potential and the possible benefits of the energy community. The findings highlight the potential of the platform and outline future developments.