[en] Due to changes in the Dutch energy sector insight is needed in the consequences for the decision making process with respect to energy supply in large new estates. The main purpose of the study on the title subject is to trace the moments in the decision making process where interventions from Novem cause an optimal effect on the realization of energy efficient new estates. In order to test the impact of the assumptions on the decision making process and the impact of the applied tools use is made of existing knowledge on the decision making process and available experience in the participation of employees of Novem (the so-called process managers Optimal Energy Infrastructure (OEI)). An overview is given of the programmes OEI and Loreen (local and regional energy conservation) and how it functioned so far and the consequences of the liberalization of the energy market for those programmes are outlined and discussed. 80 refs