Investments in the energy performance of houses offer good prospects for reducing energy consumption and CO2 emissions. However, people are not easily convinced of the need to take measures to improve the energy performance of their houses, even when financial benefits outweigh the costs. This article analyses the factors that influence the decision for improving the energy performance of existing homes, including policy instruments. Subsequently, the article provides policy suggestions on how to stimulate energy performance improvements. Both owners and tenants (50-70%) support government policy on energy performance improvements to existing homes. Nevertheless, people also have strong feelings of autonomy regarding their homes. Our results underline the importance of well-informed and competent decision-makers. Introducing the use of Energy Performance Certificates (EPCs) into the tax system for energy and residential buildings might therefore be an effective way to increase the interest of owners in the EPC, improve the use and effect of this informative instrument, and make the first step towards bridging the tension between autonomy and more stringent instruments.