*3.3. Mean Values of Occupants' Votes*

The mean thermal sensation vote (TSV) of the students in both seasons was "slightly warm", with a value of +0.32 on the ASHRAE scale in winter and +0.38 in midseasons, having a SD of between 0.93 and 0.83, respectively. This can be identified as a common situation among poorly ventilated and crowded spaces. Even with open windows the actual air-removal capacity looked very limited as previously evaluated (Table 6). These thermal perceptions were higher (+0.10 points) when windows

were open, highlighting an excess of heat release of the heating system due to inefficient regulation and the wish of the users of dissipation. In this case, the occupants' thermal preference vote (TPV) expressed was softer and closer to neutrality than the TSV, not fitting at all with the perceived thermal sensations (R<sup>2</sup> <sup>=</sup> <sup>−</sup>0.47, moderate correlation), as showed by Teli et al. [14,53].


**Table 6.** Mean values of occupants' votes obtained during the field measurements related to seasons and windows' and doors' operation.

TSV is the thermal sensation vote, TPV is the thermal preference vote, PDacc is the thermal environment rejection percentage, TCV is the thermal comfort vote, and EPV is the environmental perception vote.

The average thermal environment rejection percentage (PDacc) expressed by students, based on a scale from 1 (acceptance) to 0 (rejection), was low and homogeneous in both seasons, with a mean value of 0.81 in winter conditions and 0.85 for midseasons. In addition, thermal acceptance was, in general, slightly better in classrooms with closed windows in both seasons, but in the case of closed windows and open doors. The thermal comfort vote (TCV) allowed us to qualify this acceptance-rejection PDacc index, given that less than 70% of students found "comfortable" the thermal environment in winter conditions compared to more than 80% in midseasons. This percentage increased to 96% for students with "comfortable" or "a bit uncomfortable" votes in winter conditions, but without reaching 92% in midseasons. By contrast, the number of users who, accepting a slight discomfort, considered the acceptable environment was superior in winter than in midseason, where the feeling of discomfort was slightly more marked, can be seen in Figure 8.

**Figure 8.** Accumulated frequency for the environmental perception and thermal comfort votes, related to seasons and windows' and doors' operation.

The mean environmental perception vote (EPV) showed during winter a 1.03 value (slightly bad odor), with low differences regarding windows' operation (less than 0.03 points); in midseasons, EPV was more favorable (0.61), with more than 0.10 points of difference regarding windows' operation. Figure 8 also shows the accumulated distribution of the EPV, in which less than 35% of students voted "without odor" in winter, while more than 50% voted it during midseasons. In addition, almost 30% of students perceived a slight odor or worse in winter in comparison to the midseasons, with 10%. Finally, around 7% of students voted "bad odor" or worse in winter, while there were no votes in this way during midseasons.

During the winter there is a more evident feeling of a poorly ventilated (not healthy) environment, in line with the measured CO2 values acting as a token of the indoor ambient renovation state. The operation of windows produced little to no effect on the improvement of the environmental quality, especially during the winter. Although it was found that the opening of windows in this period generated noticeable dilution of the interior atmosphere, it was still insufficient to guarantee pleasant environments.

During midseason, although the ventilation mechanism was less effective (by means of a lack of thermal differential), the capability of diluting the indoor environment to threshold levels was perceived by the users as somewhat better. The assessment of these user perception-thresholds was a key aspect of research, since it will allow the design of more adequate and well-accepted spaces.
