Existing buildings are responsible for over 40% of the world’s total primary energy consumption. An impressive amount of energy could be saved simply by applying energy-efficient technologies.Yet, various market barriers inhibit energy efficiency improvements in existing buildings and result in energy savings that are significantly lower than potentials. Financial barriers — including the initial cost barrier, risk exposure, discount-factor issues and the inadequacy of traditional financing mechanisms for energy-efficient projects — play a major role. Policies that may help to overcome financial barriers to improving energy efficiency in existing residential buildings are the focus of this study.The publication provides illustrations of policies and measures implemented in five IEA member countries and the European Union. Each case includes relevant background and contextual information, as well as a detailed evaluation of each policy according to five pre-defined criteria: relevance, effectiveness, flexibility, clarity and sustainability.Promoting Energy Efficiency Investments aims to inform policy makers and offers ideas on the most effective policies, programmes and measures available to improve energy efficiency in existing residential buildings.