The building sector greatly contributes to energy consumption and Greenhouse Gas emissions, relating to the whole building life cycle. Boasting a huge building heritage of historical and architectural value, Europe faces challenging retrofit perspectives, as the potential for high energy efficiency has to be exploited while preserving the buildings’ original characteristics. The present work aims to feature the influence of a passive strategy on a heritage building in a mild climate. As historical its façade cannot be modified, its large glazing areas involve multiple issues, such as an increase in the heating (QH) and cooling (QC) energy demands and the risk of thermal discomfort. Thus, window replacement was proposed for retrofitting. A dynamic simulation model in TRNSYS was validated with experimental data collected by the continuous monitoring of walls of different thicknesses and orientations. Solutions from replacement with Double Glazing Units (DGUs) with improved thermal insulation, to internal shading activation were applied. All configurations were compared in terms of QH, QC, thermal performance of the building and user comfort (Fanger). Low-e DGU enabled the saving of up to 14% of the annual energy demand, and shading also offered good results in summer, reducing QC by 19%. In summer, DGU involved a maximum PPD reduction of 10 units.

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This study analyses the energy consumption of a social housing built in the 80’s. This building typology is deteriorating over time with increased energy consumption for air conditioning and indoor comfort that is well below the standard. This typology is also widely diffused in the city’s building stock, especially in its suburbs. Thus, the energy efficiency of public social housing represents a major concern for the Italian national scene, and its improvement represents an effort of critical importance. However, public funding is significantly reduced compared to the past and. In addition, it is often difficult to act on passive systems, such as installing thermal insulation, or replacing terminal units inside apartments. In these cases, as an energy retrofit, it may be appropriate to evaluate the possibility of preserving as much of the existing distribution and supply system as possible, while modifying the thermal energy generation system. In general, where the boiler is not obsolescent, the idea is to propose a hybrid generation system with the inclusion of a heat pump (HHP), which could be implemented with renewable energy equipment, properly installed in the building. The main goal of the present work was to evaluate through dynamic analysis different HVAC scenarios, to assess the optimal configuration of the system for residential use. The results show that a hybrid system can lower the primary energy consumption up to 28%, thus allowing the employment of renewable energies within the social housing building stock.

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