Business districts account for the largest part of energy use in the Netherlands. However, these districts have up to now received little attention with regard to their energy use and efficiency. The mid-sized manufacturing industry is characterized by high energy intensity and high saving potentials. The high and concentrated energy use of these companies makes them interesting clients for the energy service industry. The feasibility of these ESCos is influenced by the factors; ‘’Demand of energy’’, ‘’Energy prices’’, ‘’Subsidies’’ and ‘’Technology development’’. To study the influence of these factors, a system dynamics (SD) model was made. From this study can be concluded that outsourcing energy related services to an ESCo by the mid-sized manufacturing industry is certainly interesting for both parties.