## 9 Discussion  
This section discusses the comparison of some of the results obtained in this work with other research available in the literature. [PERSON] and [PERSON] [23] evaluated the thermal effectiveness of a white reflective coating on the exterior surface of a concrete roof in Kuwait. The authors of the previous research built a test cell to perform a series of experiments and then developed a numerical model validated with experimental data. They simulated white and gray roof thermal performance in the season with the highest solar radiation and outdoor air temperature. The results showed that the temperature of the interior surface of the white roof was 6 \({}^{\circ}\)C lower than the temperature of the gray roof. Further, the white roof caused a reduction of the heat flux of 50%. Because Kuwait's climate is warm and dry, such as the climate of Hermosillo, it is worth comparing the results of the current research with those obtained in [23]. Besides the type of climate, the indoor air temperature and the roofs' thermophysical properties studied in the previous research were very similar to the values used in this work. Table 3 indicates that the temperature of the interior surface of SWR1 was 10 \({}^{\circ}\)C lower than the temperature of the SGR. At the same time, the heat flux of SWR1 was 42% smaller than the corresponding to the SGR. Here, we mention only SWR1 because this roof had the same absorptance (\(\alpha=0.2\)) as the white roof studied in [23]. However, the solar absorptance of the gray roof analyzed by [PERSON] and [PERSON] (\(\alpha=0.8\)) was greater than the absorptance of the SGR considered here (\(\alpha=0.67\)). Therefore, this main factor for the reduction of the heat flux presented in [23] was more significant than the reduction of the heat flux presented in the current research. On the other hand, as can be noticed above, the temperature reduction presented \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**City** & **Roof** & \(T_{es}\) (\({}^{\circ}\)C) & \(T_{is}\) (\({}^{\circ}\)C) & \(Q_{R}\) (\(\frac{\textbf{W}}{\textbf{m}^{2}}\)) & \(HG\) (\(\frac{\textbf{W}\cdot\textbf{b}}{\textbf{m}^{2}-\textbf{day}}\)) \\ \hline \multirow{4}{*}{Monterrey} & IGR & 60 & 27.7 & 17.1 & 260 \\  & IWR1 & 43 & 26.3 & 9 (\(-\)47\%) & 128 (\(-\)51\%) \\  & IWR2 & 42 & 26.2 & 8 (\(-\)53\%) & 117 (\(-\)55\%) \\  & ITR & 63 & 28 & 19 (\(+\)12\%) & 291 (\(+\)12\%) \\ \hline \multirow{4}{*}{Hermosillo} & IGR & 69 & 29 & 25 & 439 \\  & IWR1 & 50 & 27.4 & 15.4 (\(-\)39\%) & 276(\(-\)37\%) \\  & IWR2 & 49 & 27.2 & 14.6 (\(-\)42\%) & 262 (\(-\)40\%) \\  & ITR & 72 & 29.3 & 27 (\(+\)7\%) & 459 (\(+\)6\%) \\ \hline \multirow{4}{*}{Villahermosa} & IGR & 58 & 27.7 & 13 & 273 \\  & IWR1 & 41 & 26.3 & 7 (\(-\)46\%) & 140 (\(-\)49\%) \\ \cline{1-1}  & IWR2 & 40 & 26.1 & 6 (\(-\)54\%) & 128 (\(-\)53\%) \\ \cline{1-1}  & ITR & 61 & 28 & 15 (\(+\)15\%) & 304 (\(+\)11\%) \\ \hline \multirow{4}{*}{Merida} & IGR & 63 & 27.9 & 19 & 284 \\ \cline{1-1}  & IWR1 & 44 & 26.4 & 10 (\(-\)47\%) & 139 (\(-\)51\%) \\ \cline{1-1}  & IWR2 & 42 & 26.2 & 9 (\(-\)53\%) & 126 (\(-\)56\%) \\ \cline{1-1}  & ITR & 66 & 28.2 & 21 (\(+\)11\%) & 318 (\(+\)12\%) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of the thermal evaluation of insulated roof in four cities of Mexico (Average peak values for the different variables). by [23] was smaller, but this difference occurred because the thickness of the roof analyzed in Alqalaf and Alawadhi was 0.15 m, which was greater than the thickness of the single roof; therefore, the thermal inertia of the roofs was the other factor that caused the slightly different results. Thus, the information presented above demonstrated that the findings of this research work were consistent with what other researchers have reported. Another contribution of this research that is important to discuss is the influence of thermal insulation on the roofs' thermal performance. This effect can be obtained by comparing the results presented in Tables 3 and 4.