## 4 Discussion
### RQ\({}_{5}\): What Standard Models of Thermal Comfort Were Employed to Assess the Bus Cabins? Table 10 displays the studies conducted in bus cabins that employed standard models of thermal comfort. Thus, it is possible to observe that [PERSON]'s Predicted Mean Vote-Predicted Percentage Dissatisfied (PMV-PPD) model, present in the ISO 7730 and ASHRAE 55 standards, was the most employed. Moreover, [PERSON]'s model was utilized in two studies [31; 48] and the adaptive model in only one [49]. Of the studies that intended to assess only the thermal comfort in bus cabins (see Table 9), six [10; 16; 18; 19; 51; 54] did not specify or did not work with standard models but they remain relevant since an article is usually a summary of a larger research and many things are not mentioned in that summary or aimed to evaluate microclimate conditions in the bus cabins where the parameters of thermal comfort were not used in their amplitude. Moreover, of the studies that analyzed the comfort of drivers [18; 19; 49; 50; 51; 52], only Unal [49] employed a standard model to assess the drivers' cabins. \begin{table}
\begin{tabular}{c c c} \hline \hline
**References** & **Norms** & **Models** \\ \hline [PERSON] et al. [11] & Not informed & Not informed \\ [PERSON] [48] & ASHRAE 55 & Gagge Model \\ [PERSON], [PERSON], and [PERSON] [9] & ASHRAE 55 and ISO 7730 & PMV–PPD \\ [PERSON] et al. [13] & Not informed & Not informed \\ [PERSON] et al. [18] & Not informed & Not informed \\ [PERSON] et al. [14] & Not informed & Not informed \\ [PERSON] and [PERSON] [15] & ISO 9886, ISO 10551, and ASHRAE 55 & PMV–PPD \\ [PERSON] [49] & ASHRAE 55 and ASHRAE 62 & Adaptative \\ [PERSON] and [PERSON] [31] & ASHRAE 55 & Gagge Model \\ [PERSON] and [PERSON] [50] & Not informed & Not informed \\ [PERSON] et al. [19] & Not informed & Not informed \\ [PERSON] et al. [51] & Not informed & Not informed \\ [PERSON], [PERSON], and [PERSON] [52] & Not informed & Not informed \\ [PERSON], [PERSON], and [PERSON] [5] & Not informed & PMV–PPD \\ [PERSON] [10] & Not informed & Not informed \\ [PERSON] et al. [53] & ISO 10551, ISO 14505-3, and ISSO 7726 & PMV–PPD \\ [PERSON], [PERSON], and [PERSON] [46] & ASHRAE 55 & Not informed \\ [PERSON] et al. [16] & ASHRAE 55 & PMV–PPD \\ [PERSON] and [PERSON]. [17] & ASHRAE 55 & Not informed \\ [PERSON] et al. [54] & ASHRAE 55 & PMV–PPD \\ [PERSON] and [PERSON] [47] & Not informed & Not informed \\ [PERSON] et al. [55] & ISO 7730 and ASHRAE 55 & PMV–PPD \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Standards and models employed in thermal comfort studies in bus cabins. Among the papers, eight investigated all six parameters (see Table 8) and worked with a standard model (see Table 10) of thermal comfort, discovering the temperature ranges of thermal comfort and neutrality of the cabins. [PERSON] et al. [53] concluded that, in air-conditioned buses and trains with short and long routes, the indoor air temperature for a sensation of thermal neutrality was 26.2 and 27.4 \({}^{\circ}\)C, and the zones for thermal comfort ranged from 22.4 to 28.9 \({}^{\circ}\)C and 22.4 to 30.1 \({}^{\circ}\)C, respectively. According to [PERSON], [PERSON], and [PERSON] [9], among the projected scenarios of air outlet angles of the air-conditioning system in their experimental study, an air temperature of 23 \({}^{\circ}\)C and air velocity of 0.3 m/s provided the best performance with PMV = +0.2 (neutral) and PPD = 5% dissatisfied. [PERSON] and [PERSON] [15] found that a range of indoor air temperature of 20.9 \(\pm\) 0.6 \({}^{\circ}\)C corresponded to a comfort zone for electrical buses in cold climates. Finally, [PERSON] et al. [16] developed an air-conditioning control system capable of reducing fuel consumption that would maintain an indoor temperature of 25 \({}^{\circ}\)C, whose PMV would be \(-\)0.25 (neutral) and PPD 8% dissatisfied.