## 3 Results
### Experimental Results Summer 2018  
The monitoring campaign was carried out between 15 June and 5 September 2018. The recorded average temperatures are 19.6 \({}^{\circ}\)C in June, 24 \({}^{\circ}\)C in July, and 23.3 \({}^{\circ}\)C in August. Two periods of six consecutive days were chosen as representative of the summer results in 2018: 10-15 July and 2-7 August. Concerning the representative days in July, the highest recorded outdoor air temperature is 31.9 \({}^{\circ}\)C on 14 July at 2:00 p.m., the lowest is 13.6 \({}^{\circ}\)C on 10 July at 6:00 a.m. The average air temperature over six days is 24.2 \({}^{\circ}\)C. The maximum daily temperature variation is 15.8 \({}^{\circ}\)C on 10 July. The highest solar irradiance on the Southeast facade over the period is 509 Wm\({}^{-2}\) on 10 July. Concerning the representative days in August, the average air temperature over six days is 25.4 \({}^{\circ}\)C; the maximum peak is 33.5 \({}^{\circ}\)C on 7 August at 2:00 p.m., while the minimum peak is 17.3 \({}^{\circ}\)C on 6 August at 5:00 a.m. The maximum daily temperature variation is 16.0 \({}^{\circ}\)C on 6 August. The highest solar irradiance on the Southeast facade over the period is 475 Wm\({}^{-2}\) on 6 August. Figures 4 and 5 show the comparison between outdoor air temperature and global solar irradiance on a Southeast oriented surface during the selected periods. Since the analyzed surface is Southeast oriented, solar irradiance has its maximum values around 10:00 a.m., while the maximum air temperature values are reached around 2:00 a.m. for both periods. Figure 4: Outdoor air temperature, solar irradiance on Southeast, and sol-air temperature for 10–15 July. The minimum air temperatures are recorded between 6:00 a.m. in July and 5:00 a.m. in August. The sol-air temperature shows the correlation between outdoor air temperature and solar irradiance: Indeed, it represents an outdoor air temperature value, which includes incident solar radiation, radiant energy exchange with the sky and outdoor environment, and air-to-air temperature exchange [27]. The sol-air temperature is defined by a measured outdoor air temperature, solar irradiance on a tilted surface of fixed orientation of the mockup (South-East), surface absorptance coefficient for solar radiation (for light-colored surfaces, usually assumed \(\alpha\) = 0.3), and external surface heat transfer coefficient (25 Wm\({}^{-2}\) K\({}^{-1}\)). The following experimental data are the external and internal surface temperatures of walls W1 and W2 and the heat flux through the wall compared to solar irradiance on the Southeast facade, outdoor air temperature, and indoor air temperature of the mockup. The simultaneous monitoring of two different insulating systems, i.e., Wall 1 and Wall 2, allows the various solutions to be compared in both the selected summer periods. Figure 6 shows a comparison between external surface temperatures of W1 and W2 during the first analyzed period (10-15 July): The temperature of wall W1 is always lower than wall W2 during the daytime, while the opposite behavior is shown during the nighttime. Specifically, the highest values are recorded on 15 July, namely, 33.5 \({}^{\circ}\)C for W1 and 35.5 \({}^{\circ}\)C for W2, while the maximum difference between the daily maximum and minimum external surface temperatures is 15.8 \({}^{\circ}\)C for W1 and 20.0 \({}^{\circ}\)C for W2 on 10 July. Therefore, the XPS insulating system, wall W2, is more thermally stressed than W1, due to higher peaks in external surface temperature and large fluctuations in daily temperature. External surface temperatures during the second analyzed period (2-7 August) for the two different insulated walls are shown in Figure 7. The highest recorded values are 37.2 \({}^{\circ}\)C for W1 and 39.3 \({}^{\circ}\)C for W2 on 7 August, while the largest difference between the daily maximum and minimum external surface temperatures is 18.3 \({}^{\circ}\)C for W1 and 22.3 \({}^{\circ}\)C for W2 on 6 August.