No abstract

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.

In cold regions, the reduction in envelope thermal transmittance is often the dominant parameter in ensuring thermal comfort in buildings. However, countries in warmer climates have also adopted this same strategy, often neglecting other parameters that are more influential in their respective climate regions that can achieve thermal comfort. This study focuses on passive building strategies to ensure a building’s thermal comfort conditions in Mediterranean climates in the winter. This monitoring study compares two dwellings during the winter in Barcelona, Spain, in order to analyze the impact of not only the envelope’s thermal properties on indoor temperature, but also the role of other factors such as outdoor temperature and solar gains. The dwellings were built in different decades, each following distinct building technical codes, diverse construction techniques, and building materials. The methodology used in this study is based on thermal measurements, meteorological data, and spreadsheet calculations. Comparing these results with the recent updates in Spain’s technical code and other studies, the investigation demonstrates that to achieve a suitable indoor thermal temperature in a passive way, especially in Mediterranean climates, incorporating other factors such as the combination of thermal inertia and solar gains can be more effective than a strategy mainly focused on reducing thermal transmittance. This analysis demonstrates that a building’s thermal performance does not mainly depend on envelope thermal transmittance, but rather a complex system involving a set of variables such as thermal inertia as well as solar gains, based on parameters such as building orientation and urban context.

The data contained in this article refers to the measurements of climatic factors during an entire year in low latitudes regions with warm and humid climates, in Santa Rosa city from Ecuador. Since the geographical location and the importance of cloudiness in these regions, these measurements have focused on the solar radiation flux, cloud cover and sky temperature. The data obtained have been configured in a weather file for energy calculations, which has been used in the research article “Assessment of the reflectivity and emissivity impact on light metal roofs thermal behaviour, in warm and humid climate” [1] .