Assessment of the reflectivity and emissivity impact on light metal roofs thermal behaviour, in warm and humid climate

The light metal roof is one of the roof typologies most used in low latitude regions with warm and humid climates. The low installation cost is one of the benefits of this typology, however, they offer only low resistance to the heat flux. In order to analyse strategies to reduce the indoor overheating in this climates, this investigation addresses the impact of reflectivity and emissivity on the light metal roof thermal behaviour. The study was carried out with dynamic simulations, considering the climate of a city in the south coast of Ecuador (Santa Rosa, 3°27'S). This analysis has parameterized the interior surface temperature in function of the reflectivity and emissivity, which has been validated with the measurements of several samples with different radiative properties. The analysed samples show that the effect of the aging and the use of different paints have a higher impact on the increase in emissivity than on reflectivity. In conclusion, the results show that the radiative parameter with the highest influence on interior surface temperature reduction is emissivity