ENERGY-SIM 2018, the 4th International Workshop on Energy-aware Simulation, co-located with the 9th ACM/SPEC International Conference on Performance Engineering (ICPE 2018) is an International workshop on energy-aware simulations. The workshop focuses on a broad range of research challenges in the area of energy-aware simulations where simulation tools and techniques are used in order to better understand and model environments which include the use of energy. Energy research is an interdisciplinary field covering, but not limited to sciences, engineering and computing sciences, and we encourage papers with such interdisciplinary elements.