The Conference is devoted to providing a deep overview on the retrofit design of the historical and existing buildings; the themes related to the energy performances, to the indoor air quality, to the energy sustainability and to the innovations on buildings and their systems will be proposed. The necessity of reducing energy consumptions in existing buildings is an important goal for all Countries that seek a rational use of resources and the reduction of CO2 emissions. Interventions in existing and especially historical buildings must be carefully designed and defined both for the existence of static and/or historical constraints, both for use requirements, operational, maintenance and cost. The energy performance of buildings shall be defined on the basis of methodologies, which include, in addition to thermal characteristics, other factors that play an increasingly important role such as heating and air-conditioning installations, application of energy from renewable sources, passive heating and cooling elements, shading, indoor air-quality, adequate natural light and satisfactory indoor noise level . The conference aims to analyze the main technologies in plants and equipments applicable today in existing buildings to improve energy performance, indoor environmental quality and sustainability.