Passive Envelope Measures for Improving Energy Efficiency in the Energy Retrofit of Buildings in Italy

The Italian territory is characterized by a big increase in energetic demand, especially for cooling, mainly related to climate change but also to the poor quality of a consistent construction sector, such as the suburban 1960–1980 building stock. At the same time, the cost of fuel and electricity due to the recent war events forces us to find alternative solutions to save energy in buildings. This study proposes building envelope passive design strategies to improve the energy efficiency of residential buildings in the Mediterranean climate, which is typical of the Italian territory. The main purpose is to provide an overview of potential passive measures to improve the energetic quality of construction in response to the above-mentioned issues and consequently to the increasing restrictions of energy regulations (passive buildings and NzeB). A categorization of passive measures is provided by exploring three different passive behaviors: heat reduction, heat gain, and heat protection. Specific energy-efficient measures for building retrofit are investigated according to this classification, including solar greenhouses, natural ventilation techniques, and radiative, convective, and conductive heat transfer through opaque and transparent envelopes. As the building envelope is mainly responsible for heating exchange and accounts for 50% of the overall energy balance, it is concluded that the “ad hoc” design of building envelopes can significantly improve the overall thermal performance of residential buildings.