Resumen de Comportamiento térmico de la cubierta en un clima cálido húmedo. Repercusión energética en el edificio
The central scope of this thesis is the architectonic element THE ROOF within the context of regions with warm and humid climates near the equator. The constant population growth in the world has been reflected, in these regions, with a high horizontal expansion of the city, where the low height buildings are the most extended urban typology. This fact added to the high and constant solar radiation determines that the roof is the main source of heat gains inside the residential buildings.
In the last decades, the Coast Region of Ecuador has experienced a significant change in the use of roofing materials, with a general tendency to increase heavy concrete roofs to the detriment of light metal roofs.
There is a general belief that concrete roofs, given their material characteristics, offer better environmental conditions than metal roofs, and consequently a lower energy demand. Therefore, the increased use of heavy concrete roofs "seems to have" a thermal purpose. However, these covers have a higher investment cost for the user, and in addition, and very important, they have a higher embodied energy.
Based on the above, the general objective of this research is to analyse and compare the thermal behaviour of these two covers, through measurements and simulations, in order to answer the question: WHAT ROOF TYPOLOGY OFFERS A LOWER OVERHEATING OF THE INTERIOR SPACE IN THE CLIMATE OF THIS REGION, THE LIGHT METAL ROOF OR THE HEAVY CONCRETE ROOF? After the measurements of the climatic conditions of this region made in situ, it has been determined that the CLOUDINESS plays a fundamental role in the amount and type of solar radiation received in the roofs, as well as in the cooling capacity of the sky.
Consequently, the cloudiness is the climatic factor that has the greatest influence on the thermal performance of the roofs in this region. The consideration of this aspect in the energy analysis of the roofs has resulted in variables that in other climates have a high impact on the roof thermal behaviour, such as inclination, orientation or thermal resistance, can be cancelled in this climate.
The interior surface temperature of the light metal roof drops more than that of the heavy one during the night period but, despite what is commonly believed, during the day the interior temperature of the metal roof maintains a thermal performance almost equal to the concrete roof, given the increase of reflectivity to the visible and in particular to the increase of thermal infrared emissivity contributed by the use of suitable paints.
Therefore a light metal roof with values of thermal infrared emissivity and visible reflectivity above 0.70 has a better thermal performance than the heavy concrete roof with the same radiative properties and with a higher thermal resistance.
