The housing sector is responsible for 33% of total CO2 emissions in the Netherlands. As such, large reductions in CO2 emissions can be gained by increasing the energy performance in the existing housing stock. Yet, several barriers make this difficult. Renovation investments and maintenance costs are high while badly needed norms for energy improvement are absent. Furthermore, market developments and sectoral policies reflect a complex institutional environment in which many actors are interdependent, but also lack an individual sense of urgency regarding energy consumption. In this article, we try to determine how multi-level governance in Dutch housing affects the outcomes of policies aimed at CO2-reduction in the existing housing stock. We examined two housing sectors in the Netherlands: social housing and owner occupancy. We focus on policy implementation problems in the early 2000s. It turns out that the complex multi-level environment severely impedes the realization of ambitious policy goals.