One-third of the greenhouse gas emissions in The Netherlands are due to the use of fossil fuels in buildings. 56% of this figure concerns energy use in housing. Due to the facts that The Netherlands contains many houses that can be rated as obsolete - below modern construction standards - and the low yearly turnover rate of houses - only 1% - chances for large-scale energy conservation and the reduction of green house gas emissions lay with improvements in the current housing stock. Due to different reasons chances for large-scale utilization are being missed. The question why the technical reduction potential is not met to the full extent, is central to this study. To answer this question several possible explanations are relevant that are present in the implementation of public policies aimed at energy conservation in renovation projects in residential areas. Because they relate to processes in a complex institutional context it was decided to go with a study design that included case studies. Three empirical studies were conducted. First, a large-n study was done on the degree of ambition-setting. Second, a comparative study was done on the degree of achieved energy performance enhancement. Third, a comparative analysis was conducted on the application or non-application of renewable- or other innovative energy systems. Both qualitative and quantitative research methods were applied in the empirical studies. The results of the study implicate that the technical reduction potential is still far from being achieved. The study also shows that policy ambitions do not correspond with the achievement of policy goals. Outcomes in local renovation projects on residential sites are related to three explanatory factors: inter-organizational collaboration, intra-organizational characteristics of housing associations, and the influence of instruments that derive from climate policies. Attention is also paid to the implications of the empirical study results on recent developments in policy and practice.