This deliverable – and the Use Case (UC) repository it presents – is the output of the work conducted in Task 1.4: Definition of Business and System Use Cases for U2Demo Pilots of the U2Demo project. For the definition of UCs, the flexible assets of energy communities (ECs) of the four demo sites in the Netherlands, Belgium, Italy and Portugal were analysed, including the inventory of the present and future needs. This resulted in the identification of 10 Business Use Cases (BUCs). The BUCs were categorised into the three categories: (1) Current operation of the EC, (2) EC operation with internal market models and P2P models, (3) Operation of the EC with flexibility/ancillary services. These BUCs address the current operation of the ECs, as well as the future operation of the ECs including additional flexible assets, additional flexibility markets and different market model structures. As the infrastructure and the needs of the demo sites vary significantly, the BUCs are modelled pilot-specific, but can be easily applied to ECs with similar structures. The BUCs are modelled in Sparx Enterprise Architect® software, version 16, with the open license Modsarus® plugin2 [1]. The models show the objectives and preconditions of the BUCs, the roles participating and the information exchanged between the roles. The modelling was done according to the UC methodology proposed in IEC 62559-2:2015 [2]. The resulting UC repository is available on the U2Demo GitHub public community, the link is provided in this report. The UC repository and the identified data exchanges are key for development of the platform architecture in Work Package (WP) 3 and for the development and implementation of the algorithms in WP2 and WP4, respectively. Thus, this task provides the basis for a successful development and implementation of the tools developed in the U2Demo projects in the demo sites