A big share of the world’s energy consumption results from residential heating and cooling. Increasing energy efficiency can make a strong contribution to lowering greenhouse gas emissions in this sector. At the request of the World Bank, we assessed the market for various types of energy efficiency retrofits for residential housing. The assessment focused on the medium-income housing and involved suggestions on addressing current regulatory, financial and technical barriers to the scaling of relevant technologies. Moreover, we formulated recommendations for the design and implementation of financing mechanisms for these energy efficiency technologies.