Gustav Lorentzen Conference is important conference attracting an international audience with an interest in natural working fluids, including system owners, operators and end users, academic researchers, policy makers, contractors, manufactures of components and many other stakeholders. The conference is therefore not only an opportunity to present the findings in front of the relevant audience, but also a meeting place where all the specialists can share their views and knowledge to each other. This year, the conference was held from June 18 to 20, 2018 at the Universitat Politècnica de València, Spain.