The 16th conference on Sustainable Development of Energy, Water and Environment Systems (SDEWES) has been successfully held on October 10−15, 2021 in Dubrovnik, Croatia. The Chair as well as the initiator of SDEWES series, Prof. Neven Duic, who is the professor in the University of Zagreb, Croatia, serves as the associate editor of Energy Storage and Saving (ENSS), and this special issue (SI) is the first-time collaboration between SDEWES and ENSS. A total of 6 papers were selected for publication. This SI in ENSS mainly addressed the topics related to sustainable energy application (e.g., solar photovoltaic, wind and biomass energy), residual reuse, energy saving of direct heating and cooling, thermal energy storage integration and heat exchanger optimization. The series of SDEWES conference provides a good platform to discuss the most recent development in advanced technologies, methods for distinguished researchers in the field of sustainable energy utilization, energy exploitation, energy policy, etc., which has rich experience on soliciting high-quality manuscript. ENSS, which is an international, peer-reviewed Open Access journal, has established the SI for the 17th SDEWES in 2022, and will go on to cooperate with the SDEWES series in 2023. Manuscripts are welcomed to the 18th SDEWES held in Dubrovnik, Croatia on September 24−29, 2023.