ESDL is a modelling language created to describe complete (hybrid) energy systems in one uniform format. It allows to describe information about the individual energy system components, how they are connected, how they are used (e.g. using energy production or consumption profiles), where they are physically located (on the map), what they cost (now and in future). Furthermore information about buildings in an area, energy potential, KPIs (on buildings, areas, or any assets) can be described. Possible applications are facilitating interoperability between different energy transition models and publishing open data on energy systems.