One of the key aspects of a smart city is to reduce CO₂ emissions by adopting different strategies that can also improve the quality of life of citizens. Current metropolises present additional issues compared to traditional cities, such as extremely heavy traffic and abandoned spaces. This paper, therefore, proposes two interventions aimed at improving the smartness of the municipality of Rome: the implementation of a photovoltaic field in an abandoned space used to charge electric buses and the implementation of smart traffic lights that optimise the traffic flow. To measure the impact and effectiveness of those interventions, key performance indicators (KPI) were defined to point out the benefits of the analysed strategies, and a quantitative matrix approach was applied. The aim was to establish a correlation between the different scenarios proposed, assigning numerical indices to each of them that can comprehensively express their impact on the identified smart axes. The results obtained showed the importance of selecting appropriate performance indicators to assess the impact of interventions. Furthermore, the findings revealed that the scenarios with the greatest number of indicators are not necessarily the most advantageous. Overall, the simulations indicated that the proposed interventions could produce a significant reduction in emissions due to the implementation of renewable energy production.

In this era of perpetual advancement and innovation, the term “smart” is frequently misused. Linking smartness to a city should reflect and solve multiple problems with a single solution. A city, district, or area can only be smart when it contemplates different development axes rather than having just a single strength. This work is an effort to make an area of Varanasi in Uttar Pradesh, India, smart by concentrating the actions on five principal axes—Environment, Energy, Mobility, Community, and Economy. Practical indicators have been selected and well formalised to obtain an output value that can support the methodology to rank each action in its executable manner. Software like ENVI-met (to simulate greening and pollution) and PVSyst (to simulate rooftop solar PV) have been used to simulate the actions proposed, and a detailed discussion for each result has been presented. The methodology involves the creation of a model based on morphological, structural, and environmental data, as well as using SWOT analysis and community feedback to identify key areas for intervention. The results demonstrate the effectiveness of the proposed interventions, with notable reductions in CO2 emissions, improved air quality, and significant energy savings through the implementation of Nature-Based Solutions, solar PV systems, and electric mobility.

Ultra violet (UV) solar energy can cause several negative effects to the skin and eyes in case of overexposure. To protect people from erythemal damage, personal erythemal exposure must be carefully assessed when outdoor activities are carried out. The direct measure with scientific instruments is impracticable to common people, and indirect methods assess the exposure only on the horizontal plane: this work developed a mathematical model to assess erythemal exposure to all the body districts. UVA irradiance and erythemal irradiance were measured on several inclined planes, oriented to the four cardinal directions, in seven environments with multiple sky conditions. The UV erythemal (UVE) ratio between erythemal irradiance on an inclined plane (Iery°) and UVA irradiance on a horizontal plane (IUVAh) was calculated. The results indicate that the UVE = Iery°/IUVAh is variable across the day and depends on the plane orientation, its degree of inclination, and sky conditions. Mathematical models to calculate erythemal exposure in clear, intermediate and overcast sky conditions on planes with different inclinations and orientations were derived from the daily trends of the UVE = Iery°/IUVAh. The application procedure of the mathematical model to the vertical plane oriented to the south is provided as an example.