During the first COVID outbreak, schools were seen as a substantial issue regarding the spread of the disease, since schools are the most densely occupied indoor environment continuously over time. The infection risk of SARS-CoV-2 could reach large levels, especially in locations with inadequate ventilation rates, according to the current knowledge of airborne transmitted diseases. The first main drive to reduce viral concentration is dilution, provided by infiltration, air change through aeration (window opening), mechanical ventilation; the second drive is filtration. After a brief investigation of the prescriptions and requirements for ventilation in school rooms stipulated by Italian law, the present work compares the energy requirements for ventilation in two main cases—window opening (and infiltration) and mechanical ventilation—the effect of wearing or not wearing a mask is also considered. Afterward, the focus is shifted to the infection risk assessment, comparing the two different ventilation techniques as mentioned above. Not only is it found that window opening is far from an effective technique for controlling the spread of the disease; it is also found that for the same amount of thermal energy needed, mechanical ventilation can reduce the individual infection risk by a factor of 3, thus providing a better IAQ. It is also proved that mechanical ventilation, in terms of infection control, can not only replace but even outperform the effect of masks.

In new and refurbished buildings, different energy sources are usually exploited to reach the Near Zero Energy Building target. Heat pumps and renewables are the most common adopted technologies. The coupling of the different components with a control logic conceived to exploit all energy contributions causes an implied design complexity. In this paper, two case studies were reported regarding the use of multisource heat pump systems: as main novelties, the correct design of the solar field (thermal or photovoltaic/thermal) in relation with the other sources (ground heat exchangers, ventilation heat recovery) for a given building and climate was reported in order to balance the energy drawn and injected into the ground around the year, and to attempt to reach the independency from the electric grid. Moreover, the relatively complex (compared to conventional heating or cooling) system controlling for multisource heat pump plants was simulated. The paper reported on the design of the plant, of the control logic, and the energy performance of two original multisource heat pump systems by means of dynamic simulation. In one case, real measured data were available as well. Very high primary energy ratios were obtained due to suitable control logics of the multisource plants, around 1.4 (based on measured data) and 4.7 (based on simulated data) for the first and second case, respectively. As a consequence, non-renewable primary energy consumptions of 37 and 3.9 kWh m⁻² y⁻¹ were determined, respectively.

The increasing urgency of the energy transition, particularly in ecologically sensitive regions, demands spatially informed planning tools to guide renewable energy development. This study presents a Multi-Criteria Decision-Making (MCDM) approach to assess the suitability of the Gargano district in southern Italy for the implementation of Renewable Energy Communities. The analysis combines expert-based weighting and the Weighted Linear Combination method to evaluate seven key criteria grouped into environmental, socioeconomic, and technical dimensions. The resulting suitability scores, calculated at the municipal scale, highlight spatial disparities across the district, revealing that areas with the highest potential for Renewable Energy Community (REC) deployment are largely situated at the boundaries of the Gargano National Park. These zones benefit from stronger infrastructure, higher energy demand, and fewer environmental constraints, particularly with regard to wind energy initiatives. Conversely, municipalities within the park exhibit lower suitability, constrained by strict landscape regulations and lower population density. The findings provide valuable insights for regional planners and policymakers, supporting the adoption of targeted, environmentally compatible strategies for the advancement of citizen-led renewable energy initiatives in complex territorial contexts.

The residential sector is currently responsible for approximately 30% of the final energy consumption and 12% of direct CO₂ emissions in Italy, mainly due to the heating and cooling of buildings and the use of domestic hot water. Such figures show a significant potential for reducing non-renewable primary energy utilization to comply with the decarbonization constraints of the European Union. In this context, the purpose of this work is to provide a quantitative assessment of the effect of a different number of actions (eight for energy savings, four for energy efficiency and two for the installation of renewable energy plants) that could be implemented at the national level to reduce the consumption of natural gas in the residential sector. Two typical residential buildings are dynamically simulated using Trnsys^®, and the savings from energy, economic and CO₂ emissions points of view are evaluated in the different climatic zones of Italy. The most effective action foresees the replacement of natural gas boilers and old air conditioners with modern heat pumps and air/air chillers as well as the installation of a controlled mechanical ventilation system with heat recovery. This solution allows for non-renewable primary energy savings of 58% and an economic savings on annual energy costs of 72%.

In this paper, an innovative hybrid condensing radiant tubes heating system for an industrial building is modelled in three climatic zones of Italy using dynamic simulation software. Radiant tubes are coupled with an air–water heat pump, the latter serving an air heating system with terminals located in the building. The energy performance of the hybrid heating system is optimized by evaluating the best nominal power of the heat pump, the cut-off temperature in a bivalent parallel operation, the bivalent temperature in a bivalent alternative operation, and the peak power of the photovoltaic system on the roof of the building. Energy savings between 40% and 80% are calculated with respect to traditional heating systems, considering the different configurations of the system and the climates. An economic analysis also allows the evaluation of the economic advantages of this hybrid heating system for industrial buildings.

The sustainable rehabilitation of existing buildings is essential to achieve urban resilience, resource efficiency and seismic risk reduction. This study investigates an integrated retrofit strategy that combines vertical extension with inter-story isolation to simultaneously enhance seismic performance and energy efficiency, creating additional usable space without additional land consumption. The inter-story isolation mechanism reduces seismic demand by decoupling a new and existing structure and introducing beneficial damping effects, whereas vertical extension improves a building’s envelope to reduce energy demands for heating and cooling. A tailored design methodology for integrated intervention is presented, according to which, for the structural part, a two-degrees-of-freedom dynamic model is adopted to design the characteristics of the isolation layer. The methodology is applied to a case-study building located in L’Aquila, Italy, where two alternative vertical extensions, one rigid and one lightweight, are analyzed. Time-history analyses and energy simulations for annual primary energy demand are carried out to assess the structural and thermal performance of the integrated retrofit. The results indicate that the proposed solution can reduce top-floor acceleration by up to 35%, inter-story drift by 30–35%, base shear by over 30% and primary energy demand by 11%, demonstrating its effectiveness in improving both seismic safety and energy performance. The main novelty of this study lies in the systematic integration of inter-story isolation with building envelope enhancement through vertical extension, offering a unified design framework that merges structural and energy retrofitting objectives into a single sustainable intervention.