Outsourcing to Energy Service Companies (ESCos) is an arising concept in the Cure market. Market supply and demand of Energy Service Companies should be aligned to benefit from energy savings and lowering energy costs. The research method of Analytical Hierarchy Process is used to give insight in the needs and considerations for a hospital in their decision to outsource and the relative importance of key performance indicators that can be incorporated in energy performance contracts. System Dynamics in combination with Monte Carlo simulation is used for a sensitivity analysis of a specific business case. The two methods proved to be useful in estimating risks influences and bandwidths of key performance indicators. Several expert interviews have been organized to verify and validate the results.