# Ventilation Strategies to Ensure Thermal Comfort for Users in School Buildings: A Critical Review
## 3 Results
### Natural Ventilation Strategies  
The studies with natural ventilation strategies are shown in Table 6 and Figure 7. In these, different groups have been created within each strategy in order to analyze the results by climate at a later stage, irrespective of the presence or absence of cross ventilation and of air conditioning. Additionally, the seasons during which the individual studies are conducted (Summer (S), Winter (W), Spring (SP), or Annually (A)) are specified. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**Air Conditioning**} & \multicolumn{2}{c}{**1**} & \multicolumn{2}{c}{**3**} & \multicolumn{2}{c}{**4**} \\ \hline
**Climate** & **Ventilation** & **Heating** & **Cooling** & **a** & **b** & **2** & **a** & **b** & **a** & **b** \\ \hline \multirow{4}{*}{Semi-arid} & \multirow{2}{*}{Cross} & Yes & No & - & - & [39] (W) & - & - & - & - \\ \cline{3-10}  & & No & No & - & - & [40] (S) & - & - & - & [51] (S, W) \\ \cline{3-10}  & & Yes & No & - & - & [39] (W) & - & - & - & - \\ \cline{3-10}  & \multirow{2}{*}{Single-sided} & No & No & - & - & [40] (S, & - & - & - & - \\ \cline{3-10}  & & No & No & - & - & - & - & - & - & - \\ \hline \multirow{4}{*}{Tropical} & \multirow{2}{*}{Cross} & Yes & No & - & - & - & - & - & - & - \\ \cline{3-10}  & & No & No & - & - & - & - & - & [49] (W) & - \\ \cline{3-10}  & & No & Yes & [37] (S) & - & - & - & - & - & - \\ \cline{3-10}  & & No & No & [37] (S) & [49] (W) & - & [49] (W) & - & - & - \\ \hline \multirow{4}{*}{Oceanic} & \multirow{2}{*}{Cross} & Yes & No & - & [53] (W + & - & - & - & - & - \\ \cline{3-10}  & & No & No & - & - & - & - & - & [42] (S) & - \\ \cline{3-10}  & & \multirow{2}{*}{Single-sided} & Yes & No & [48] (W) & \begin{tabular}{c} [53] (W + \\ SP) \\ \end{tabular} & \
\begin{tabular}{c} [48] (W) \\ \end{tabular} &
\begin{tabular}{c} [48] (W) \\ \end{tabular} & - & [38] (W) & - & - \\ \cline{3-10}  & & No & No & [46] (SP) & [38] (S, & [48] (SP) & [46] (SP) & - & - \\ \cline{3-10}  & & No & [48] (SP) & W) & [48] (SP) & [46] (SP) & - & - \\ \cline{3-10}  & & & & & & & [38] (S) & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 6: References with natural ventilation strategies. In the analyzed articles, the study of cross ventilation predominates in semi-arid, Mediterranean, and continental climates, especially in continental climates where no cases of single-sided ventilation have been analyzed. In contrast, single-sided natural ventilation strategies are predominant in tropical and oceanic climates. Natural ventilation is the most commonly used method in the majority of climates, and in some cases it performs well, as is the case with the Mediterranean climate during periods without extreme temperatures, which is characterized by milder and more favorable temperatures. Nevertheless, in most instances, it must be complemented by active systems. It is observed that, regardless of the climate, most schools and educational buildings implementing natural ventilation strategies are predominant in tropical and oceanic climates. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**Air Conditioning**} & \multicolumn{2}{c}{**1**} & \multicolumn{2}{c}{**3**} & \multicolumn{2}{c}{**4**} \\ \cline{2-10}  & **Climate** & **Ventilation** & **Heating** & **Cooling** & **a** & **b** & **a** & **b** & **a** & **b** \\ \hline \multirow{4}{*}{Mediterranean} & \multirow{2}{*}{Cross} & Yes & No & - & - & - & - & - & - & - \\ \cline{3-10}  & & No & No & [47] (W) & [43] (Y) & - & [47] (W) & - & - & - \\ \cline{2-10}  & \multirow{2}{*}{Single-sided} & Yes & No & - & - & - & - & - & - & - \\ \cline{3-10}  & & No & No & - & [54] (S,,, SP) & [50] (W) & - & - & - & - \\ \hline \multirow{4}{*}{Continental} & \multirow{2}{*}{Cross} & Yes & No & - & - & [41] (W) & - & - & - & - \\ \cline{3-10}  & & No & No & - & - & [41] (S) & - & - & - & - \\ \cline{3-10}  & & Yes & No & - & - & - & - & - & - & - \\ \cline{3-10}  & & No & No & - & - & - & - & - & - & - \\ \hline \hline \end{tabular}
\end{table}