Emanuele de Lieto Vollaro

Heating, ventilation, and air conditioning (HVAC) systems are essential for indoor air quality and thermal comfort but can simultaneously act as vectors for microbial contamination, particularly bacteria and fungi. While the COVID-19 pandemic intensified focus on airborne viral transmission, bacterial and fungal contamination in indoor environments remains a persistent and significant health risk. This study presents a detailed case study of a restaurant HVAC system, analysing the impact of different ventilation strategies on bacterial contamination, infection transmission risk, energy consumption, and thermal comfort. By focusing on a real-world application, the research evaluates practical challenges and trade-offs associated with HVAC operation modifications aimed at mitigating microbial risks while maintaining acceptable energy and comfort levels. The research compares three operational scenarios: normal operation with air recirculation, 24 h operation with 100% outdoor air, and extended operation periods. Results demonstrate that while strategies emphasizing outdoor air intake and extended operation reduce infection probability by up to 60–65%, they simultaneously increase energy consumption by over 1700% and compromise thermal comfort parameters. In the h24 case, the pre-heat coil rises from 2421.7 to 43,923.7 kWh and the post-heat coil from 24,812.8 to 152,970.4 kWh, while the Plus 2 h strategy reduces the energy penalty by roughly 42–51% with respect to the h24 case. The findings are contextualized within current research on bacterial and fungal risks in HVAC systems, highlighting the critical need for balanced ventilation strategies that integrate health protection, energy efficiency, and comfort considerations.

The building sector accounts for nearly 40% of total energy consumption in Europe, with heritage buildings posing a critical challenge due to conservation constraints. This study investigates two protected heritage sites—Palazzo Ruspoli in Cerveteri and Palazzo Vitelleschi in Tarquinia—to identify effective energy retrofit strategies integrating high-efficiency windows, HVAC and lighting systems, and photovoltaic (PV) solutions for both on-site and virtual self-consumption within Renewable Energy Communities (RECs). Energy surveys, modeling, and simulations were performed to evaluate technical, environmental, and economic impacts. The results show contrasting outcomes between the two cases: at Palazzo Vitelleschi, the combination of efficient systems and rooftop PV reduced non-renewable primary energy demand and CO₂ emissions by 73.5%, with a 10.7-year payback period; at Palazzo Ruspoli, REC-based virtual self-consumption achieved net-negative carbon emissions (−240%), a 95% reduction in non-renewable energy demand, and a 19.4-year payback period. These findings demonstrate that heritage buildings can move beyond carbon neutrality and actively offset emissions through shared renewable generation. The proposed simulation-based framework provides a replicable method to balance conservation and sustainability, supporting the decarbonization of the historical built environment.

Within a city, there is a lack of space for the installation of photovoltaic panels, especially in cities with significant artistic heritage. Hence, there is a need to identify new spaces for the installation of renewable energy systems capable of supplying part of the city’s energy demand. Large infrastructures for public use such as stadiums, because of their characteristics, can become an essential resource for surrounding communities by installing photovoltaic panels on their roofs. This innovative approach can supply renewable electricity to the local community, aligning with the concept of renewable energy communities (RECs). This study focuses on the Olympic Stadium in Rome, exploring a new way to produce and share the electricity generated. An energy simulation of the photovoltaic plant was carried out by means of a transient calculation tool System Advisor Model (SAM). Then, the energy output from photovoltaics was correlated with the stadium, streetlight, and household electrical energy demands. The results highlight the suitability of the photovoltaic plant and the energy, economic, and environmental advantages derived from its exploitation.

The current global context, marked by crises such as climate change, the pandemic, and the depletion of fossil fuel resources, underscores the urgent need to minimize waste. Cogeneration technology, which enables simultaneous production of electricity and thermal energy from electricity generation waste, offers a promising solution to enhance energy efficiency. Its widespread adoption, particularly in the European Union, where several cogeneration systems are in place, demonstrates its growing popularity. Italy alone has 1865 high-efficiency cogeneration units, contributing significantly to total cogeneration energy generation. Micro-cogeneration, specifically, has attracted attention for its potential to reduce energy waste and environmental impact. This study focuses on assessing the technical and financial feasibility of a micro-cogeneration plant using natural gas-fuelled internal combustion engines, considering different scenarios of plant operating strategies in order to optimize energy production, minimize waste, and mitigate environmental footprints associated with conventional methods. Additionally, it provides valuable guidance for policymakers, industry stakeholders, and decision-makers invested in sustainable energy solutions. By advancing micro-cogeneration technology, this study aims to promote a more sustainable and environmentally conscious approach to energy production. The methodology applied is based on the development of a numerical model via RETScreen Expert 8 and it was calibrated with one-year energy bills. The study was performed by focusing on the analysis of the annual energy savings, greenhouse gas emission savings, tonnes of oil equivalents savings, and financial parameters such as Net Present Value (NPV), Internal Rate of Return (IRR), Profitability Index (PI) and Payback time (PBT). The results show, using a micro-cogeneration system in a big complex of buildings, that the financial parameters can continually increase with the plant’s capacity with the electrical load following, but with a loss of the recovered heat from the cogenerator because it may reach values that are not necessary for the users. When the thermal load variation is much more significant than the electrical load variation, it will be useful to design the plant to follow the thermal load variation which allows the full utilization of the thermal and energy production from the plant without any waste energy and choosing a system capacity that can optimize the energy, emissions and financial aspects.

It is well-known that the occurrence of urban heat islands (UHI) is related to climate change and urbanization. Urban locations experience local overheating throughout the summer, which is uncomfortable and it has a detrimental impact on buildings ability to consume energy. In this study, a methodology was developed to assess the urban heat island effect in a localized urban area and to evaluate the effects of different kind of mitigation strategies. The numerical model was developed using the ENVI_met tool and it was calibrated with weather data and albedo measured inside the examined area and near the simulated domain. The procedure adopted overtaking the limit of the software in reproducing accurate weather conditions without calibration. Finally, combination of extensive mitigation strategies (cool pavements, greenery, grass pavers) with local strategies (shading) were investigated. An experimental and numerical investigation of a square in Rome was exanimated to evaluate the possible solution for mitigating outdoor air temperatures. Results of the paper affirm that an intervention on the pavement albedo and the increase of vegetation inside the square, lead to an improvement of the air thermal conditions. In particular, the application of the grass pavers would lead to the greatest benefits. A maximum decrease in the air temperature of 1.2 °C was obtained through the application of cool material, while the reduction reaches up to 2.88 °C when a grass paver is applied. The improve of the vegetation can bring to a maximum decrease of 1.46 °C, while the use of shading projecting roof allows a reduction up to a maximum of 2.07 °C.

A significant portion of Europe’s historical buildings have significant potential for energy efficiency. Social policy is typically opposed to energy retrofits because it is concerned about damaging historical or cultural sites. Contrarily, there are several approaches to energy efficiency that may be used with historic structures while also retaining the region’s architectural constraints. The findings of this study demonstrate that historical structures, which are typically not targets of energy efficiency technology because of architectural constraints on the building or in the neighbourhood, may also achieve a meaningful decrease in energy usage and GHG emissions. The significant energy-saving capability of this type of building is emphasized in the historical structure taken into consideration. The historical building object of the present study was built in the beginning of the 1900s and it was selected by the Ministry of Culture for energy efficiency improvements.

It is well known that the construction sector is one of the main sectors responsible for energy consumption in the current global energy scenario. Thus, buildings’ energy software become essential tools for achieving energy savings. Climate and its implications for building energy performance are a critical threat. Hence, the aim of this study is to evaluate the climatic conditions in urban and suburban areas of Rome, estimating the incidence of the Urban Heat Island (UHI) phenomenon. To this end, meteorological data obtained from three different areas (two airports and one inside the city) were examined and compared. Then, TRNSYS software was used to create a simple building, in order to assess the impacts of various climatic situations on building energy performance. The study revealed significant percentage differences both in terms of energy needs for heating, from −20.1% to −24.9% when the reference stations are, respectively, Fiumicino and Ciampino, and for cooling, with a wider range, from +48.7% to +87.5% when the reference stations are Ciampino and Fiumicino. Therefore, the study showed the importance of more accurately selecting sets of climate values to be included in energy simulations.

Most cities worldwide suffer from serious air-quality problems, which have received increasing attention in the past decade. The most probable reason for the air-quality problems is the urban population growth, combined with a change in land use due to increasing urban areas. The emission of air pollutants is caused by different anthropogenic processes which can be categorized into the sources of urban traffic, industry, and domestic heating. Dispersion and dilution of air pollutants are strongly influenced by meteorological conditions, especially by wind direction, wind speed, turbulence, and atmospheric stability. With an increasing number of people living in cities, there is the need to examine the correlation between air pollution, local climate, and the effects these changes have on global climate. New interdisciplinary research studies are needed to increase our understanding of the interactions among these aspects. The aim is to analyze the pollutant condition in Rome and the other provinces of the Lazio region with qualitative and quantitative analysis, in order to understand which are the main pollutant sources and what is the correlation of habits of the population on air pollutant emissions.

The urban heat island (UHI) phenomenon is strictly related to climate changes and urban development. During summer, in urban areas, the lack of green zones and water sources causes local overheating, with discomfort and negative effects on buildings’ energy performance. Starting from this, an experimental and numerical investigating of the climatic conditions in a university area in Rome was achieved, also assessing the occurrence of the UHI phenomenon. The analyzed area was recently renewed, with solutions in contrast to each other: on one side, an old building was re-designed aiming at high performance; on the other hand, the neighboring areas were also refurbished leading to large paved surfaces, characterized by high temperatures during summer. A calibrated numerical model was generated through ENVI-met software and eight different scenarios were compared, to mitigate the overheating of this area and to analyze the influences of the proposed solutions in terms of air temperature reduction. The analysis of this case study provides information on potential mitigation solutions in the urban environment, showing that goals and priorities in the design phase should concern not only buildings but also external areas, also considering university areas.