Energy is a primary factor of economic development and presently it is impossible to fully decouple economic prosperity and the demand for energy. However it is possible to use energy in a more efficient, smarter way. The book aims to contribute to low carbon growth of transition economies through providing a piece of missing information for evidence-based design of new policies related to buildings. The book studies the ways of assessing the potential and costs of carbon dioxide mitigation and applies this knowledge to develop and run such a model for a case study of the Hungarian residential sector. The results may be replicated for other types of buildings and for other countries with similar climate and economic conditions. The book is useful for policy-makers working on a low carbon agenda; professionals dealing with energy issues in buildings such as architects, building managers, and municipal officers; researchers, as well as households interested in energy savings.