This editorial discusses the contributions of the papers belonging to the virtual special issue (VSI) of Energy Reports dedicated to the series of four SDEWES Conferences on Sustainable Development of Energy, Water and Environment Systems held in Cologne (Germany), Sarajevo (Bosnia and Herzegovina), Gold Coast (Australia) and Buenos Aires (Argentina) in 2020. High quality review papers and original research articles presented at the SDEWES Conferences relevant to the Journal are included in this VSI for a total of 20 accepted articles invited by the Guest Editors. Published papers deal with key research topic related to clean energies, advance energy technologies, building-plant design solutions, energy management measures, policies and regulations capable to ensure that all countries and regions develop and implement expertise and technologies to tackle climate change and make progress towards a net zero energy economy. Such a complex goal poses some major challenges and calls for the effort of scientists and stakeholders to commit to develop and carry out multidisciplinary approaches towards the sustainable development of modern cities for a decarbonized economy. This process is also crucial for achieving a successful and just energy transition, necessary to reduce sources of conflict and iniquity typical of geopolitical tensions, to avoid causes of uncertainty in the long run to the sustainable development Agenda, towards energy security, environmental protection, and the affordability of energy.In this framework, the Sustainable Development of Energy, Water and Environment Systems Series Conference represents a platform for the development of inter-sectoral collaborations among scientists and stakeholders and it promotes the development and improvements of advanced energy technologies and systems for the sustainable and just transition. The SDEWES Conferences brought together around 1000 researchers from all over the world working in the field of the sustainable development. According to the papers published in the VSI of Energy Reports dedicated to SDEWES Conferences, the editorial is subdivided in several sections based on the relevant topics on which the VSI papers are focused: renewable technologies for the energy efficiency of buildings and communities, advanced technologies and tools for the energy efficient design of buildings and systems, challenges and opportunities of policies and regulations to support the energy transition and meet the sustainable development targets.