## 2 Materials and Methods
### In-Field Measurements Results
#### 3.2.3 Test_2  
Test_2, without any mechanical ventilation, was carried out from 16 to 21 October. Moreover, the day characterized by the highest solar radiation and by the highest internal/external temperatures was selected for detailed analysis (17 October). Coherently with Test_1, the following data were analyzed for the analysis of the monitored results:  
* Surface temperatures (Ts)
* Heat flux (HF_m)
* PCM temperature (T_PCM)
* Mean radiant temperature (T\({}_{\rm mr}\))  
The monitored indoor surface temperature values of the roof are plotted in Figure 14a for the overall period. A reduction of the temperature peaks in Room B (PCM Y) and Room C (PCM X), compared with the reference configuration (Room A), can be seen. Focusing the analysis on the reference day (Figure 14b), the maximum temperature reached in cell B (with Infinite R\({}^{\rm TM}\) 23) was \(\sim\)0.6 \({}^{\circ}\)C lower than the maximum value in cell A (from 21.1 \({}^{\circ}\)C to 20.5 \({}^{\circ}\)C). A more evident reduction in the temperature peak (about 1.2 \({}^{\circ}\)C) was observed in Room C, with Infinite R\({}^{\rm TM}\) 21 (from 21.1 \({}^{\circ}\)C to 19.9 \({}^{\circ}\)C). Figure 14: Surface temperature: (**a**) whole period; (**b**) the reference day (17/10). Figure 13: Calculated mean radiant temperature (Tmr): (**a**) whole period; (**b**) the reference day (8/10). Similarly to the Test #1 analysis, the presence of the PCM in the layers led to a shift in the temperature peaks: the maximum temperature in reference room (A) was reached at 18:00 while a delay of about 45-60 min was observed in Rooms B and C.  
The heat flux results (Figure 15) confirm those of the temperature analysis. A comparison of the data collected on the reference day (17 October) revealed that:  
* a heat flux reduction of \(\sim\)20% (from 8.5 W/m\({}^{2}\) to 6.8 W/m\({}^{2}\)) can be achieved in the daily peak values if Infinite R\({}^{\text{TM}}\) 23 is applied (Room B). * a heat flux reduction of \(\sim\)47% (from 8.5 W/m\({}^{2}\) to 4.5 W/m\({}^{2}\)) can be achieved in the daily peak values if Infinite R\({}^{\text{TM}}\) 21 is applied (Room C). The PCM effect can be observed during daytime, when a significant heat flux reduction (gains) occurs for PCM X (similar to those observed in Test_1), while a lesser reduction of the heat fluxes (\(\sim\)20%) can be achieved with PCM Y  
The temperatures of the PCM layers are plotted in Figure 16a,b for Infinite R\({}^{\text{TM}}\) 23 (Room B) and Infinite R\({}^{\text{TM}}\) 21 (Room C), respectively. A comparison with the enthalpy vs. temperature values was carried out to assess the latent heat storage capacity exploitation of the PCMs. Similarly to Test #1, a lower temperature variation can be noticed in the cell equipped with the Infinite R\({}^{\text{TM}}\) 21 layer (cell C), while Infinite R\({}^{\text{TM}}\) 23 (cell B) shows a higher temperature variation. * Infinite R\({}^{\text{TM}}\) 23 (Room B) shows a temperature variation of between 14.8 \({}^{\circ}\)C (8:00) and 21.4 \({}^{\circ}\)C (16:30), with an amplitude of 6.6 \({}^{\circ}\)C.
* Infinite R\({}^{\text{TM}}\) 21 (Room C) shows a temperature variation of between 15.5 \({}^{\circ}\)C (8:00 am) and 20.7 \({}^{\circ}\)C (17:00 pm), with an amplitude of 5.2 \({}^{\circ}\)C.  
Compared with Test 1, both PCMs show a higher daily temperature variation. As it is possible to observe by combining the temperature trend with the partial enthalpy plot, both the PCMs operate without a good exploitation of the latent heat capacity. In the case of PCM Y (Infinite R\({}^{\text{TM}}\) 23), it is worth underlining that it operates fully below the melting temperature. Therefore, the small peak temperature and heat flux reduction in Room B, compared to Room A, depends mainly on the solid state sensible heat capacity of the PCM, which slightly increases the thermal inertia of the component. If the mean radiant temperature is considered, the trends are in agreement with the surface temperature profiles.