# Thermal Comfort and Sustainability in University Classrooms: A Study in Mediterranean Climate Zones
## 3 Results
### Subjective Thermal Responses  
This section analyses the subjective responses on thermal sensation and preference and degree of comfort of the 274 students surveyed (195 with NV and 79 with AC). Thermal Sensation, Comfort and Preference Votes  
Table 7 presents a summary of the average ratings for each thermal category analysed in the different classrooms, together with the mode of operation and the indoor operative temperature. As can be seen, classrooms with natural ventilation (NV) presented, on average, a TSV of 1.33, indicating a thermal sensation between slightly warm and hot, accompanied by a TCV of 3.35, suggesting a level above slightly uncomfortable. In these classrooms, only 13.33% of occupants reported a \"Neutral\" thermal sensation. On the other hand, the average \begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**University**} & **Classroom** & **Operation** & \multirow{2}{*}{\(T_{op}\) (\({}^{\circ}\)C)} & \multirow{2}{*}{**TSV (SD)**} & \multirow{2}{*}{**TCV (SD)**} & \multirow{2}{*}{**TPV (SD)**} \\  & **Code** & & & & & \\ \hline \multirow{8}{*}{ESE} & ESE01 & NV & 25.51 & 0.75 (\(\pm\)0.68) & 2.63 (\(\pm\)0.50) & \(-\)0.63 \\  & ESE02 & NV & 26.41 & 1.15 (\(\pm\)0.76) & 3.31 (\(\pm\)0.82) & \(-\)0.84 \\  & ESE03 & NV & 26.69 & 1.19 (\(\pm\)0.93) & 3.24 (\(\pm\)0.99) & \(-\)0.76 \\  & ESE04 & AC & 22.94 & \(-\)0.33 (\(\pm\)0.52) & 2.67 (\(\pm\)0.52) & 0.17 (\(\pm\)0.41) \\  & ESE05 & NV & 25.33 & 0.95 (\(\pm\)0.82) & 3.00 (\(\pm\)0.88) & \(-\)0.69 \\  & ESE06 & NV & 25.58 & 1.00 (\(\pm\)0.67) & 3.10 (\(\pm\)0.87) & \(-\)0.80 \\  & ESE07 & NV & 26.25 & 1.50 (\(\pm\)0.88) & 3.45 (\(\pm\)0.98) & \(-\)0.75 \\  & ESE08 & NV & 25.41 & 1.00 (\(\pm\)0.82) & 3.00 (\(\pm\)0.82) & (\(\pm\)0.51) \\  & ESE09 & AC & 24.60 & \(-\)0.59 (\(\pm\)0.87) & 2.35 (\(\pm\)0.49) & 0.23 (\(\pm\)0.44) \\  & ESE10 & AC & 24.80 & \(-\)0.55 (\(\pm\)0.53) & 2.56 (\(\pm\)0.53) & 0.56 (\(\pm\)0.53) \\  & ESE11 & AC & 25.17 & \(-\)0.71 (\(\pm\)0.83) & 2.57 (\(\pm\)0.76) & 0.21 (\(\pm\)0.43) \\ \hline \multirow{8}{*}{ESS} & ESS01 & AC & 24.62 & \(-\)0.20 (\(\pm\)0.69) & 2.40 (\(\pm\)0.60) & 0.15 (\(\pm\)0.49) \\  & ESS02 & AC & 24.31 & \(-\)0.15 (\(\pm\)0.80) & 2.77 (\(\pm\)0.93) & \(-\)0.15 \\ \cline{1-1}  & ESS03 & NV & 31.33 & 2.70 (\(\pm\)0.73) & 4.70 (\(\pm\)0.73) & (\(\pm\)0.22) \\ \cline{1-1}  & ESS04 & NV & 29.62 & 1.73 (\(\pm\)1.01) & 3.70 (\(\pm\)1.06) & \(-\)0.80 \\ \hline \end{tabular}
\end{table} 
Table 7: Average values of subjective votes. TPV was \(-0.76\), reflecting an inclination towards cooler conditions. In contrast, in the air-conditioned (AC) classrooms, the average TSV was \(-0.42\), indicating a thermal sensation in the neutral range [2], while the TCV was \(2.55\), suggesting that students were more comfortable with this mode of operation. The mean TPV of \(0.20\), in this case, showed the students' preference for maintaining almost the same thermal conditions in the classrooms. These results show that, although air conditioning generates a somewhat cooler thermal perception, it provides a higher level of comfort than NV classrooms, possibly due to the ability of this system to maintain more stable conditions and closer to the range preferred by students. NV classrooms, perceived as warmer, are more uncomfortable, probably influenced by exposure to thermal fluctuations and outdoor environmental conditions. When comparing the results of this study with those reported by other authors, significant differences are observed for the same operating temperature ranges measured in this study. For example, [PERSON] et al. researched thermal comfort in three climatic zones in Ecuador. In that study, it was found that students in AC classrooms indicated cooler thermal sensations (TSV = \(-0.35\)) and showed a higher level of comfort in NV classrooms, with a TCV of \(1.44\). Thus, almost half of the occupants (49.37%) experienced thermal neutrality. Also, in terms of thermal preference (TPV), students were more inclined towards warmer environments [43].