The Joint Research Centre's Integrated Database of the European Energy System (JRC-IDEES) compiles a rich set of information allowing for highly granular analyses of the dynamics of the European energy system, so as to better understand the past and create a robust basis for future policy assessments. JRC-IDEES contains a consistent set of disaggregated energy-economy-emissions data for each Member State of the European Union, covering all sectors of the energy system. This data complies with Eurostat energy balances while providing a plausible decomposition of energy consumption into specific processes and end uses. As such, JRC-IDEES has several key applications for energy-related research and policy analysis, such as the parameterization of energy system models and the assessment of past and prospective policies.