DIMOSIM is a bottom-up, physical simulation platform for district energy systems. It can be used to simulate new or existing districts with or without energy networks. The platform models energy-related equipment on any level of the district (zone, building and district level) and allows thus the simulation of a large number of energy concepts. It has been built for simulating energy concepts as well as to test energy management strategies via emulation techniques. It has a built in stochastical modelling of occupant and equipment behavior.