The Department Environmental Psychology of IZES gGmbH in Saarbrücken was founded out of the Research Group Environmental Psychology (FG-UPSY) lead by Prof. Dr. Petra Schweizer-Ries. The department Environmental Psychology analysis the psychological and social factors connected to energy production and consumption. Main goal of the research is to develop new ways and recommendations for a sustainable and socially acceptable transition of the energy system. Looking from a systemic perspective, qualitative and quantitative research methods are used in interdisciplinary and transdisciplinary approaches. Besides the research on acceptance and participation processes in the context of energy transition, a focus is on the psychological factors determining an energy-efficient usage on household, community and organisational levels as well as the involvement of several user groups into the transition process.