# Urban Overheating Impact: A Case Study on Building Energy Performance
## 4 Conclusions  
This work aimed at quantifying the UHI phenomenon of the city of Rome through the analysis, processing and comparison of temperatures, relative humidity and wind speeds collected for two years (2019-2020) by the Ciampino and Fiumicino airport stations and from the weather station located in a central neighborhood of Rome, typical of the urban fabric that characterizes the heart of the city. The study revealed not-negligible differences between the various climatic parameters in the three locations. Comparing the average monthly air temperatures, the lowest values were observed for Fiumicino, and progressively higher temperatures were registered in Ciampino and finally in Rome. The highest temperatures recorded in Rome confirm the occurrence of the UHI phenomenon in the city. In the summer, the greatest differences in monthly average temperatures were recorded between the stations of Rome and Fiumicino, with values equal to \(2.68\ ^{\circ}\)C in June 2019 and \(2.05\ ^{\circ}\)C in June 2020. In the case of the stations of Rome and Ciampino, the greatest temperature differences were recorded in February 2019 (\(1.81\ ^{\circ}\)C) and February 2020 (\(1.63\ ^{\circ}\)C). Additionally, from the analysis of the data relating to wind speed (Figure 3), significant differences emerged based on the different positions in which the stations were located, especially those of Fiumicino and Ciampino airports compared to that of Rome. Fiumicino had the highest average values compared to Ciampino and Rome, registering an average value of \(12.6\ \mathrm{km/h}\) in the two-year registration period. On the contrary, Rome station recorded the lowest value, with an average of \(2.44\ \mathrm{km/h}\). These differences highlighted the influence of the building texture, able to reduce wind flows. The results reveal significant values of the monthly UHII assumed during the day and night. However, the trends recorded in 2019 differ from those of 2020: while in 2019 the greatest differences were reached during the night, in 2020 there were greater diurnal values. If the climatic conditions are compared to Fiumicino, maximum diurnal and nocturnal UHIIs equal to \(4.5\ ^{\circ}\)C and \(3.8\ ^{\circ}\)C can be observed. When this comparison is performed taking into consideration Ciampino, the diurnal and nocturnal UHIIs become equal to \(3.8\ ^{\circ}\)C and \(2.9\ ^{\circ}\)C, respectively. Based on the obtained results, in order to countermeasure UHI, it is necessary to consider more suitable cooling strategies in the city. In this regard, the expansion of green areas and the installation of passive building solutions [39; 40; 41; 42] such as green roofs [43]could positively affect urban areas due to their microclimatic action and evaporative cooling. On the other hand, in historical cities (such as Rome), these aspects need to be considered together with architectural constraints. The effects that variations in climatic conditions could have on buildings' energy needs were evaluated through TRNSYS. Heating results highlight percentage differences ranging from \(-20.1\%\) to \(-24.9\%\) when the reference stations are Fiumcino and Ciampino, respectively. The percentage difference related to the cooling energy needs shows a wider range, from +48.7% to +87.5% when the reference stations are Ciampino and Fiumcino, respectively. As already mentioned, these results highlight the issue of using specific climate data. Nevertheless, the problem is related to the aim of simulations. Energy models can be predictive during the design phase or they can be used for energy retrofit, but in this case calibrated models are needed. Therefore, utilizing meteorological data from airports or peripheral regions (outside the urban fabric) for building energy modeling is not recommended, as it may result in incorrect estimations of building energy demand, particularly when considering constructions in a high-building-density neighborhood.