The “Real Value of Energy Efficiency, REFEREE” project strongly advocates the principle that energy efficiency measures will be key for delivering the European Green Deal, which sets out the roadmap for making Europe the first climate-neutral continent by 2050 and, in this framework, aims to (1) analyze and quantify the direct and indirect non-energy impacts of energy efficiency investments and to (2) develop easy-to-use tools to support policy makers at the national, regional and local level. REFEREE will help households, businesses, financing institutions, policy makers and other relevant stakeholders to evaluate the multiple impacts of their energy efficiency choices. It will encompass the assessment of energy efficiency investments in a variety of ecosystems, including low income regions and socially imbalanced societies. To fulfil these objectives, the project will design and develop an integrated set of analysis tools from the macro-economic level to the micro level at consumer and firm scale. Through a user-friendly interface, it will then develop a Policy Support System will allow policy makers, businesses, financial institutions and others to better understand the real value of energy efficiency policies and their cost effectiveness. It will also allow them to develop more effective plans, means and measures. To maximise the impact of the REFEREE policy support tool, stakeholders will be involved from the inception of the project, through concrete opportunities for its co-development, pilot studies, and focused dissemination and communication actions. Thanks to a unique consortium structure and strategic partnerships, REFEREE can offer an unprecedented effort of dissemination and exploitation with focus on state, municipal as well as entrepreneurial decision makers in the framework of the multilevel governance approach.