## 3 Results and Discussion  
### Microclimate Monitoring of Vasari Corridor  
This section summarizes the main results of the microclimate monitoring in the Vasari Corridor museum. For each monitoring position, temporal profiles, minimum, medium, and maximum values, daily gradients, and the performance index of the monitored parameters were evaluated. The latter evaluates the quality of the indoor environment in relation to the conservation of the exhibited objects. The monitored data were critically analyzed with the aim of highlighting the main criticalities and potentialities for the artwork conservation in this type of environment. Figures 8 and 9 present the time profiles of T and RH, respectively, measured in positions A (Lungarno) and B (Ponte Vecchio) for the whole year 2017 with respect to the outdoor values (EXT). Since the Vasari Corridor is not equipped with an HVAC system (non-air-conditioned museum), the indoor T and RH values monitored inside the museum environments follow the trend outdoor climate conditions. Nevertheless, the indoor conditions are significantly dampened with regard to the hourly and daily fluctuations. The diagrams highlight the stabilization of T and RH inside the Vasari Corridor compared to the outdoor conditions; the maximum outdoor temperature daily variation (\(\Delta\)T\({}_{24}\)) is equal to 17.5 \({}^{\circ}\)C, and the maximum outdoor relative humidity daily variation (\(\Delta\)RH\({}_{24}\)) is equal to 27%, while the indoor daily variation is equal to 2.2 \({}^{\circ}\)C for temperature, with a delay of about 4 h, and 5% for relative humidity. The parameters monitored in the two positions (A and B) have a similar trend. However, position B in Ponte Vecchio, characterized by large windows, is much more exposed to the atmospheric agents with respect to position A in Lungarno. \begin{table}
\begin{tabular}{c c c c c} \hline
**Type of Artefact** & **T [\({}^{\circ}\)C]** & **\(\Delta\)T\({}_{24}\)[\({}^{\circ}\)C]** & **RH [\%]** & **\(\Delta\)RH\({}_{24}\)[\%]** \\ \hline “Paintings on canvas, oil pains on canvas” & 19 \(\div\) 24 & \(\leq\)1.5 & 35 \(\div\) 50 & \(\leq\)6 \\ “Organic material in general” & 19 \(\div\) 24 & \(\leq\)1.5 & 50 \(\div\) 65 & \(\leq\)5 \\ \hline \end{tabular}
\end{table} 
Table 5: Reference values recommended by the Italian D.M. 10.05.2001 [16] for the conservation of “paintings on canvas, oil pains on canvas” and “organic material in general”. Therefore, it has higher temperatures (and lower relative humidity values) in summer and lower temperatures (and higher relative humidity values) in winter. Figure 10 shows the PI monthly values for T and RH daily variation for the positions A and B. The PLAT24 is low, especially during summer period and mostly for position A, while  
Figure 8: Time profiles of T values measured in 2017 in positions A (Lungarno), B (Ponte Vecchio), and outdoor (EXT). Figure 9: Time profiles of RH values measured in 2017 in positions A (Lungarno), B (Ponte Vecchio), and outdoor (EXT). the RH values remain more constant, and the PI\({}_{\text{ARH24}}\) is higher, especially in position B, throughout the year. This means that the building envelope is not able to dampen the effects of outdoor temperature daily variation within the acceptable range for the conservation of the artworks, especially in the summer period. Instead, the passive control of the daily variation of RH is more effective, especially in position B. Historical Climate of Vasari Corridor: Calculation of the Target Values for T and RH  
A further contribution to the analysis of the measured data is the determination of the historical climate of Vasari Corridor, i.e., the target values included in a statistical range suggested by UNI EN 15757:2010 [17]. In the case of the need of installation of HVAC systems, it is possible to dimension them in order to regulate the microclimatic control as a function of the historical climate typical of each monitored environment, instead of standard reference values.