## 3 Results and Discussion
### MAA Correlation with the Environmental Conditions

Table 4: Environmental parameters measured during the experimental campaigns for each investigated configuration (OD_OW, CD_OW, OD_CW, OD_CW, and CD_CW). Figure 5 shows the CO\({}_{2}\) concentration within the room as a function of the difference of the main environmental conditions (temperature, pressure, air velocity, and relative humidity). The CO\({}_{2}\) concentration monitored step by step within the room does not seem to be significantly affected by the environmental conditions (white dots with black edges); however, the maximum values reached in each experimental campaign (red dots) seem to be. In fact, the higher maximum values of CO\({}_{2}\) were found in the following range: \(\Delta\)T in 7-9 \({}^{\circ}\)C, \(\Delta\)P in \(-\)3-3 hPa, \(\Delta\)v in \(-\)0.27-0 m/s, and \(\Delta\)RH in \(-\)34%--10%. This analysis was studied in depth by considering the different configurations and each specific case study. In particular, Figure 6 shows the maximum values of CO\({}_{2}\) for the four room configurations  
and for the two investigated case studies (case study 1 in white and black edges, case study 2 in red). As expected, the maximum value of concentration also depends on the room configuration, and it varies significantly for the two investigated case studies. The highest values of CO\({}_{2}\) were reached in the case study 1, which also seems to be more affected by the environmental conditions, contrary to the one monitored in the case study. CO\({}_{2}\) values monitored in case study 2 are in fact very close to each other, so they do not seem to be significantly affected by both environmental conditions and room configurations. Based on these results, the MAA indicator was calculated for each experimental campaign. Figure 7 shows all the MAA values and the average ones calculated for each configuration and case study. As highlighted, the MAA increases exponentially varying the room configuration; in particular, for both case studies the highest values were calculated for the last configuration (CD_CW), which can be considered the worst room configuration. The average values calculated for OD_OW, CD_OW, and OD_CW are very close for the two case studies and equal to 4.7-5.3 min, 17.2-22.1 min, and 31.1-33.1 min for Terni (1) and Perugia (2), respectively. Only for the CD_CW configuration, a higher difference of the MAA mean value was focused (163 min vs. 143.6 min); according to the results, in all the configurations, a higher MAA value was found for the case study 2, probably due to both the higher window airtightness and bigger volume of the room. Figure 6: Correlation between CO\({}_{2}\) concentration and environmental conditions divided for case studies and experimental campaign configuration. Once the MAA was calculated, the correlation with environmental conditions was investigated. Firstly, the correlation of MAA with environmental parameters was investigated considering each case study and each room configuration. Results are shown in Figures 8 and 9. In these figures, the following criteria and legend were adopted:  
1. The configurations related to open windows (OD_OW and CD_OW) are shown in Figure 8, the ones related to closed windows (OD_CW and CD_CW) are shown in Figure 9;
2. Case study 1 is always drawn with white indicators and black edges, while case study 2 is drawn in red;
3. The MAA values related to the open door configurations (OD_OW and OD_CW) are reported on the left ordinate of Figures 8 and 9, the ones related to the closed door configurations (CD_OW and CD_CW) are on the right ordinate. Interesting correlations can be found when considering the mean difference of all the environmental parameters. MAA increases when the difference between the indoor and outdoor mean temperature increases, in all the studied configurations, except for OD_OW (case study 2) and OD_CW (case study 1): the dependence is emphasized for the configurations with the closed window, where a higher slope of the regression lines is found.