# Thermal Comfort and Sustainability in University Classrooms: A Study in Mediterranean Climate Zones
## 3 Results
### Outdoor and Indoor Environmental Conditions  
The outdoor environmental conditions during the trials showed significant variations (Table 5). The average temperature was 28.24 \({}^{\circ}\)C, with a maximum of 33.29 \({}^{\circ}\)C, recorded during a test at ESS, and a minimum of 21.49 \({}^{\circ}\)C, measured in the early morning during a test at ESE. Relative humidity ranged from 33.33% to 76.15%, with an average of 50.62%, reflecting temporal variations in the timing of the measurements. Air velocity averaged 12.80 km/h, ranging from 9.49 km/h to 16.38 km/h. Table 6 compiles the average indoor environmental conditions in each of the tests carried out in the two selected university centres, classified according to the number of occupants (N), the state of doors and windows (CW: windows closed, OW: windows open, CD: doors closed, OD: doors open) and the mode of operation (AC: air conditioning, NV: natural ventilation). The average values presented correspond to those calculated over the entire duration of the measurements. Overall, the classrooms showed an average \(T_{op}\) of 25.90 \({}^{\circ}\)C, with a maximum of 31.33 \({}^{\circ}\)C (ESS03) and a minimum of 22.94 \({}^{\circ}\)C (ESS04). \(RH\) averaged 49.02%, with extreme values of 63.11% (ESE07) and 32.75% (ESE03). Air velocity (\(v_{a}\)) is low in general, with an average of 0.03 m/s, a maximum of 0.08 m/s (ESE02 and ESS04) and a minimum of 0.00 m/s in several tests (ESE06, ESE09, ESE10 and ESS02). When comparing the results of the AC and NV tests with international thermal comfort standards, such as ASHRAE 55 [2] or EN 16798-1:2019 [51], relevant differences emerge. On the one hand, these regulations recommend operative temperatures in the range of \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**University**} & **Classroom** & \multirow{2}{*}{**N**} & **Windows/Doors** & **Operation** & \(T_{a}\) & \(T_{g}\) & \(T_{sur}\) & \(T_{op}\) & \(RH\) & \(v_{a}\) \\  & **Code** & & & **Mode** & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) & (\({}^{\circ}\)C) \\ \hline \multirow{8}{*}{ESE} & ESE01 & 16 & CW/OD & NV & 26.14 & 25.56 & 24.88 & 25.51 & 48.96 & 0.03 \\  & ESE02 & 19 & OW/OD & NV & 27.03 & 26.22 & 25.79 & 26.41 & 33.99 & 0.08 \\  & ESE03 & 21 & OW/OD & NV & 27.32 & 26.49 & 26.06 & 26.69 & 32.75 & 0.07 \\  & ESE04 & 6 & CW/CD & AC & 22.38 & 22.82 & 23.49 & 22.94 & 48.02 & 0.01 \\  & ESE05 & 42 & OW/OD & NV & 25.39 & 25.29 & 25.26 & 25.33 & 57.54 & 0.04 \\  & ESE06 & 10 & CW/OD & NV & 25.59 & 25.56 & 25.57 & 25.58 & 51.60 & 0.00 \\  & ESE07 & 24 & CW/OD & NV & 26.69 & 26.28 & 25.80 & 26.25 & 63.11 & 0.04 \\  & ESE08 & 13 & CW/OD & NV & 25.57 & 25.31 & 25.25 & 25.41 & 53.22 & 0.01 \\  & ESE09 & 17 & CW/CD & AC & 24.95 & 24.42 & 24.24 & 24.60 & 59.44 & 0.00 \\  & ESE10 & 9 & CW/CD & AC & 24.96 & 25.29 & 24.66 & 24.80 & 59.36 & 0.00 \\  & ESE11 & 14 & CW/CD & AC & 24.48 & 26.19 & 24.86 & 25.17 & 53.44 & 0.01 \\ \hline \multirow{4}{*}{ESS} & ESS01 & 20 & CW/CD & AC & 24.67 & 24.59 & 24.57 & 24.62 & 47.00 & 0.02 \\  & ESS02 & 13 & CW/CD & AC & 24.47 & 24.27 & 24.15 & 24.31 & 38.67 & 0.00 \\ \cline{1-1}  & ESS03 & 20 & CW/OD & NV & 31.24 & 31.33 & 31.42 & 31.33 & 39.40 & 0.05 \\ \cline{1-1}  & ESS04 & 30 & CW/OD & NV & 29.73 & 29.63 & 29.51 & 29.62 & 48.74 & 0.08 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Summary of indoor conditions. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Air Temperature (\({}^{\circ}\)C)** & **Relative Humidity (\%)** & **Air Velocity (km/h)** \\ \hline Mean & 28.24 & 50.62 & 12.80 \\ SD & 2.99 & 10.91 & 2.08 \\ Max & 33.29 & 76.15 & 16.38 \\ Min & 21.49 & 33.33 & 9.49 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Summary of outdoor conditions. 23 to 26 \({}^{\circ}\)C [2; 51] to be considered a comfortable environment.