A preface to the special issue of optimization and engineering dedicated to SDEWES 2019 conference

Global warming and climate change call for urgent minimization of human activities on the environment. Therefore, there is a great need for the improvement of resource efficiencies by integrating various life-supporting systems. The challenge is on the energy, water and environment systems to integrate and become more sustainable. This field of research has received increased attention over the past years with studies across the energy, water and environment systems that optimized different engineering problems. This Special Issue is motivated by the Sustainable Development of Energy, Water and Environment Systems Conference held in October 2019, in Dubrovnik, Croatia. The purpose of this review introduction article is to provide a brief introduction to the field and the articles included in this Special Issue.