The CityGML Energy Application Domain Extension (ADE) was released in 2018 with the purpose to offer an open and standardised data model to facilitate multi-scale Urban Energy Modelling applications. The Energy ADE is based on and extends the international open standard CityGML 2.0. It has been used since its release in several national and international projects, mainly focusing on the simulation and computation of the building energy performance based on the integration of semantic 3D city models and several other sources of information. The technological innovations (e.g. the release of CityGML 3.0 in 2021) as well as experiences and feedback collected in the years since its release have contributed to forge several new ideas to improve, enhance and update the Energy ADE. Since 2024, work has been in progress to harmonise and implement such ideas, targeting towards a so-called Energy ADE 2.0. This paper provides an overview of the development process of the conceptual model so far, and presents a selection of the major changes and improvements that have been made to the original data model of Energy ADE.