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. This 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.