Energy efficiency measures often fail due to the disproportionate assessment effort in regard to their benefit. Especially in the planning stage, the lack of transparency represents a constraint for implementation. With the use of simulation models, it is possible to predict the energy demand and assess optimization potentials during the early planning stage. The implementation of measures can be aided by simulation models in order to accomplish an energy efficient design and operation. During operation, simulation models serve as virtual sensors, which reduce the cost and effort of implementing an energy monitoring system. In the focus of the research „Energy Simulation in Production“, simulation models of all energy-relevant components of a factory system are developed and are made accessible in the form of application software.