## 10 Conclusions  
A computational tool was used to simulate the thermal behavior of insulated and non-insulated concrete slab roofs with traditional and solar reflective coatings in four cities with warm climates in Mexico. This simulation tool is a computer model based on the finite volume method that numerically solves the heat conduction equation in an unsteady state. The simulations were done using the weather data for the week with the highest outdoor air temperature. Two traditional and two solar reflective coatings installed on the exterior surface of the roofs were considered, and the following was concluded:  
Regarding the simulation of the single roofs, SWR2 was the best configuration to minimize the heat transfer. Due to the small solar absorptance of the coating, SWR2 presented a peak exterior surface temperature up to 16 \({}^{\circ}\)C lower than the temperature of the SGR. Further, the peak interior surface temperature of SWR2 was up to 11 \({}^{\circ}\)C lower than the SGR. Thus, SWR2 diminished the heat flux and the daily heat gains up to 57% and 54%, respectively.  
The insulated roofs simulations indicated that the surface temperature reduction of the exterior surface due to the reflective coatings was more significant than the single roofs. IWR2 was the configuration with the best thermal performance. The maximum temperature reduction provided by IWR2 was 19 \({}^{\circ}\)C lower than the temperature of the IGR. IWR2 provided a maximum interior surface temperature reduction 1.6 \({}^{\circ}\)C, which was very small. This effect occurred because the thermal insulation maintained the interior surface with small oscillations. IWR2 reduced the peak heat flux and the daily heat gain up to 54% and 15%, respectively.  
This research highlights the importance of selecting the type of coating to be used in building roofs well. In the terracotta coating, this color had a solar absorptance equal to 0.7, which was just a little higher than the absorptance of the gray color of bare concrete (\(\alpha=0.67\)). The difference in the solar absorptance for these two roofs may seem insignificant, but as shown in the Results Section, the STR had a daily heat gain between 9 and 11% higher than the SGR. Similarly, the ITR had a daily heat gain between 5 and 12%higher than the IGR. These results demonstrated that even a small increment in the solar absorptance could cause a significant increment in the daily heat gain of the roofs.  
Because in buildings situated in warm climates, the roof is a source of unwanted heat, applying a coating with a lower absorptance causes a lower amount of energy to be absorbed by the roof's exterior surface. Therefore, the heat traveling through the roof structure is reduced, and then, the roof exhibits better thermal performance. Since Solar Reflective Coating # 2 was the material with the smallest solar absorptance, this coating improved both the single and insulated roof thermal behavior. Finally, because most buildings in Mexico have bare gray or terracotta roofs, there is a great potential for using reflective coatings as a retrofitting technique in this country. This research demonstrated that white reflective coatings are an excellent alternative to improve the thermal performance of roofs, which could lead to energy savings and mitigating greenhouse gas emissions from buildings.  
This research received no external funding.  
The author acknowledges CONACYT-Mexico for the support given through the System of National Researchers program (Sistema Nacional de Investigadores, SNI). The author also acknowledges the Servicio Meteorologico Nacional-Comision Nacional del Agua (SMN-CONAGUA) for providing the weather data used for the simulations. Finally, the author is grateful to [PERSON] from CENIDET for the Finite Volume Method course.  
The author declares no conflict of interest.