# Urban Overheating Impact: A Case Study on Building Energy Performance
## 3 Results and Discussion  
### UHI in Rome: Climatic Data Comparison  
The first step of this study focused on the analysis of temperatures, relative humidity and wind speed values registered by the meteorological stations of Rome, Ciampino and Fiumicino during the years 2019 and 2020 (Figures 3-5) in order to assess the different climatic scenarios. Comparing the average monthly air temperatures, the same trend can be observed from Figure 3 for all three selected stations. In particular, the values obtained from Fiumicino and Ciampino airport stations (renamed in the following figures as \"FCO\" and \"CIA\") are characterized by very similar values during the two years. On the contrary, air temperatures in Rome are always characterized by higher values, confirming the UHI impact within the city. The Rome meteorological station was appropriately selected not only for the completeness of the data collected, but also for its central position, in a densely built neighborhood of the city center. Figure 3: Monthly temperature values monitored in Rome, Fiumicino and Ciampino. Figure 2: Simplified illustration of the simulated building. Fiumicino and Ciampino recorded maximum percentage differences in terms of average monthly temperatures equal to 7% in 2019 and 6% in 2020. Fiumicino was characterized by lower temperatures than Ciampino, especially in the summer months of June, July and August, with temperature differences, respectively, equal to 1.07, 0.74 and 1 \({}^{\circ}\)C in 2019, and equal to 0.77, 0.94 and 0.92 \({}^{\circ}\)C in 2020. In June, July and August, the greatest differences in monthly average temperatures can be noticed when analyzing data related to Rome and Fiumicino. Indeed, for these summer months, the monthly differences are, respectively, equal to 2.68, 2 and 2.29 \({}^{\circ}\)C in 2019, and 2.05, 2.14 and 1.97 \({}^{\circ}\)C in 2020. By comparing Rome and Ciampino weather data, the greatest temperature differences can be observed during February 2019 (1.81 \({}^{\circ}\)C) and February 2020 (1.63 \({}^{\circ}\)C). Furthermore, comparing the average values of the monthly temperatures recorded during 2019 and 2020 by all stations, very low percentage differences can be observed. In particular, they are equal to 0.1% for the Rome station, 1.1% for the Ciampino station and 0.5% for Fiumicino. This was also confirmed by the analysis of the monthly average temperature differences recorded over the two years for each meteorological station. Therefore, the observed temperature trends highlighted the existence of the UHI in Rome. This is also indicated by the wind speed analysis (Figure 4). Significant differences occur due to the different positions of the data acquisition points. Fiumicino has the highest average wind speed values. During 2019, wind speed values between 10.71 and 16.37 km/h were observed, with an annual mean value of 12.8 km/h. In 2020, values between 11.22 and 14.06 km/h were acquired, with an average wind speed equal to 12.36 km/h. Analyzing Figure 4, wind speeds recorded in Ciampino are higher than those logged in Rome, with an average annual value equal to 10.51 km/h during 2019, and 10.46 km/h during 2020. Rome is characterized by the lowest wind speed values, with annual averages equal to 2.36 km/h in 2019 and 2.52 km/h in 2020, and maximum peak values of 3.08 km/h in February 2019 and 3.52 km/h in May 2020. The results obtained through the meteorological station located in Rome confirm that the city is characterized by significantly different air circulation flows when compared to neighboring areas, as the tall buildings hinder and reduce the wind flows. The percentage differences relating to the average annual wind speed values recorded by the stations in the two-year period are comparable, with variations equal to 6.6% for Rome, \(-0.5\%\) for Ciampino and 3.4% for Fiumicino. As previously mentioned, the comparisons were also carried out in terms of relative humidity (RH) (Figure 5).