The INSULATE project focused on the assessment of national programmes to improve the energy performance of existing housing stock, including cost-effective and proven measures such as government-supported improvements in thermal insulation. The project’s specific objectives included developing a common protocol for assessing the impacts of a building’s energy performance on indoor environmental quality and health; establishing an integrated approach for the assessment of environmental and health information, including demonstrating the use of relevant environmental and health indicators; demonstrating the effects (both positive and negative) of energy efficiency on Indoor Environment Quality (IEQ) and health in up to three different European countries; developing guidelines to support the implementation of related policies; and facilitating transnational networking and the dissemination of information.