Greater energy efficiency can be achieved in existing dwellings thanks to longer lifecycles, slow replacement rates, and technical innovations. Many such dwellings are located in dense urban neighbourhoods, where urban renewal projects are undertaken. Local government can encourage the setting of ambitious goals as a stepping stone to realizing energy efficiency goals that achieve high levels of energy efficiency. The research question which this paper addresses is: to what degree do local governments influence ambitions to conserve energy in existing housing sites? To examine this issue, thirty-three sites in the Netherlands were studied using a quantitative analysis. The results show that collaboration between local authorities and local actors increases the level of ambition to conserve energy. However, local authorities intentionally selected sites with poor energy efficiency, so it would be easy to meet ambitious energy conservation targets. Collaboration between local authorities and local actors turns out to be the key factor in selecting those sites. Moreover, there is little sign of genuine ambition. This article contributes to the debate on energy conservation policies in local housing sites. The study provides starting points for systematic, empirical research into the realisation of energy conservation in existing housing, especially in large-scale refurbishment projects. (C) 2010 Elsevier Ltd. All rights reserved.