# Thermal Comfort and Sustainability in University Classrooms: A Study in Mediterranean Climate Zones
## 3 Results
### Comfort Temperature
#### 3.4.2 Griffiths Method  
Table 9 compares the comfort temperatures (\(T_{c}\)) calculated using Griffiths' method, considering three values of the \(\alpha\) constant applied to the TSV scale in the AC and NV modes of operation. The values of the \(\alpha\) constant used were 0.25, 0.33 and 0.50, by the recommendations of multiple authors [53; 54; 55; 72].  
In the AC mode, \(T_{c}\) decreased slightly with increasing \(\alpha\), from 26.23 \({}^{\circ}\)C (\(\alpha\) = 0.25) to 25.42 \({}^{\circ}\)C (\(\alpha\) = 0.50). In addition, the standard deviations also decreased significantly, decreasing from \(\pm\)3.18 \({}^{\circ}\)C to \(\pm\)1.71 \({}^{\circ}\)C. These results indicate that higher \(\alpha\) values generate more consistent \(T_{c}\) estimates with less scatter. In the case of the NV mode, similar behaviour occurred, with \(T_{c}\) increasing from 21.42 \({}^{\circ}\)C (\(\alpha\) = 0.25) to 24.14 \({}^{\circ}\)C (\(\alpha\) = 0.50). Standard deviations also decreased as \(\alpha\) increased, from \(\pm\)3.52 \({}^{\circ}\)C to \(\pm\)2.15 \({}^{\circ}\)C. However, compared to the AC mode, the NV mode exhibited greater variability in \(T_{c}\) estimates for all \(\alpha\) values. This is due to the more significant fluctuations in environmental conditions, which directly affect the thermal perception of occupants in naturally ventilated spaces [43; 47; 62].  
Overall, the results show that the AC mode provides higher comfort temperatures with less variability compared to the NV mode, reflecting a more controlled environment. The choice of \(\alpha\) equal to 0.50 stands out as the most suitable for calculating \(T_{c}\) since it provides the most consistent and accurate estimates in both modes of operation. For this reason, this value was selected for all calculations performed in this study. It is important to note that numerous previous studies have also recommended the use of this value, supporting its applicability and reliability in the analysis of comfort temperatures [22; 43; 47; 72; 73].  
The comfort temperature calculated using 0.50 as the regression coefficient was very similar to the neutral temperature (25.80 \({}^{\circ}\)C) calculated from the linear regression of the thermal votes observed in the AC tests. In this case, uniformity in thermal conditions minimises discrepancies, as occupants more consistently perceive temperatures close to neutral. Whereas, in NV classrooms, the comfort temperature estimated through [PERSON]'s method has a difference of more than 2 \({}^{\circ}\)C with the neutral temperature (22.00 \({}^{\circ}\)C). This difference is because, at higher temperatures, students tend to experience feelings of thermal comfort at slightly lower values than the measured temperatures [22; 54].  
In previous studies conducted in classrooms equipped with AC, the calculated comfort temperature (\(T_{c}\)) showed minimal variations compared to the results obtained in the present work [43; 47]. This is because these systems maintain more stable and controlled indoor thermal conditions. In contrast, research conducted in regions with a Mediterranean climate during the spring and summer seasons, under NV conditions, reported \(T_{c}\) values approximately 3 \({}^{\circ}\)C lower than those recorded in this study [74; 75; 76]. This difference could be explained by the higher outdoor temperatures present during the measurements in this work, which raise the indoor temperature in the absence of mechanical control of the environment [22; 77].