Today simulation is playing an important role at multiple steps within the life-cycle of a process plant. For the future it is expected that simulation will be integrated in the plant life-cycle and the backbone of an integrated engineering process. To simulate the different aspects of a plant multiple domains are necessary. Usually each domain requires specific simulation capabilities, thus multiple specialized tools are used along the life-cycle. Reusing simulation models throughout the life-cycle would be very beneficial. This paper investigates existing approaches for model reuse and co-simulation and motivates the creation of a standard for co-simulation from a process industry perspective.