The need to achieve energy efficiency standards in new and existing buildings has triggered both research and design practice aimed at reducing their carbon footprint and improving their indoor comfort and functionality conditions. In this view, a dedicated scientific effort has to be spent while dealing with historical architectures needing to preserve their key testimonial knowledge into the society. Therefore, tailored retrofit strategies have been investigated and implemented without compromising their architectural value, especially when new uses are foreseen in those buildings. This review classifies different examples of the use of energy efficiency approaches and the integration of renewable energies in historical buildings, including solar and geothermal energy, and the use of heat pumps and other high-efficiency Heating Ventilation and Air Conditioning systems.