The original feature of this paper is the development of a toolkit for the decarbonisation of Mediterranean islands. The defined methodology was aimed to develop framework, skills and capabilities, coordinating and tailoring predictive assessment tools, analysing three alternative scenarios for the penetration of renewable sources into the energy system by 2030, consistently with a rationale of integration between technologies, production sectors and available funds. The findings of the research cofinanced by the European Programme Interreg Med (2014-2020) support Local Authorities by developing more effective methods and databases to plan and manage interventions in favour of the energy and cultural transition also through energy communities.