## 2 Material and Methods
### Methodology
#### 2.2.3 Microclimatic, Indoor Air Quality, and Biological Monitoring  
Following the procedure for measurement of microclimatic parameters as suggested by UNI 10829:1999, a preliminary survey [6] was carried out using portable devices (Tinytag Plus 2-TGU-4500, Gemini Data Loggers Ltd., West Sussex, UK) for measuring indoor air temperature and relative humidity [30]. This preliminary monitoring campaign took place for about a year, between 2019 and 2020, in which sensors were installed at different points of the Hall for different periods, with a recording setting of 10 min. The aim of this monitoring campaign was to characterize the indoor microclimate of the Hall, moving the sensors to different points to evaluate both horizontal differences (different points at the same level) and vertical differences (between the two levels of the room, floor level and mezzanine), in the conditions corresponding to the normal management of the environment. Based on the results obtained in this first phase, the continuous monitoring positions were properly identified by taking into account the fruition needs of the environments and the operating requirements of the instruments (avoiding contact with local disturbances affecting their proper functioning, such as proximity to heat sources and direct light), as well as the geometric characteristics of the environment. At the beginning of 2021, in fact, a new set of dataloggers was installed (datalogger Wi-Fi Testo) at the specific points of the main hall selected for the preliminary study, as shown in Figure 3[31]. More attention was paid to the side opposite the windows, where two sensors were placed on the two levels of the hall [32], along the same vertical (bookcase \"K\"). This continuum monitoring concerned not only the thermo-hygrometric parameters but also lighting and air quality. Obviously, the new sensors had specific requirements for the Hall as regards wireless radio connectivity; in fact, thanks to the wireless system, the recorded parameters were stored in the Cloud for over a year and were available online, on any device (computer, smartphone, tablet). Another important action was setting the acceptability ranges (according to the librarians) of the measured parameters and the relative alarms that, in real time, warn by message or email. In addition, all sensors were equipped with covers suiting the context of the Hall. For a clearer comprehension of the results of this study, each measuring point will be identified with the letter of the bookcase where the logger is situated, and a number \begin{table}
\begin{tabular}{c c} \hline \hline
**CO\({}_{2}\) Concentration Level [ppm]** & **Evaluation** \\ \hline \textless{}1000 & Acceptable values \\ \textgreater{}1000 and \textless{}2000 & High values (stuffiness) \\ \textgreater{}2000 & Unacceptable values (poor ventilation) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Classification of CO\({}_{2}\) levels [29]. corresponding to the level of the Hall (0 for the floor level and 1 for the mezzanine-level). Figure 3 shows the sensors' positions in the Hall. Obviously, the chosen points are representative of the critical part of the Hall (the side opposite the windows) and not of the entire Hall's conditions. For this reason, more dataloggers should be installed at different points, compatibly with the wireless radio connectivity of the Hall. The recording interval was set at 15 min for each sensor. The sensors and their measured parameters are presented in Table 6.  
The thermo-hygrometric data recorded by the sensors were post-processed in order to characterize and investigate indoor conditions; in particular, temperature and relative humidity were evaluated using the temporal profile, the minimum, medium and maximum values and the daily gradients for the measured points of the hall (K0 and K1). At the same time, a Performance Index (PI) was calculated both for temperature and relative humidity.