This experimental study is a contribution to the search for solutions to reduce indoor heat gain through sheet metal roofing in hot weather. It has evaluated the thermal impact of two different sheet metal roofs insid...This experimental study is a contribution to the search for solutions to reduce indoor heat gain through sheet metal roofing in hot weather. It has evaluated the thermal impact of two different sheet metal roofs inside of two identical test buildings in sunny weather and cloudy weather conditions. Test building 1 has a single sheet corrugated roof and the building 2 is covered with roof made from top to bottom with corrugated sheet metal, a 12 mm thick serpentine copper tube in which water is circulated, a sheet of aluminium foil acting as a heat reflector, a 4 cm thick polystyrene panel and a 1.5 cm thick plywood. A maximum reduction of 15.1˚C in the temperature of the inner face of the test Building 2 roof was obtained comparatively to the temperature of the inner face of the test Building 1 roof consisting of a single sheet of metal at the warmest hours. In addition, the simple corrugated sheet metal roof of the test building generates high and varied temperatures inside the building. Whereas the proposed heat recovery roof favours low and relatively uniform temperatures inside the building. The proposed sheet metal roof construction technique is very effective in reducing the heat gain through the roof considerably;thus improving the thermal comfort inside sheet metal roofed dwellings. Hot water has been produced by recovering heat from the metal sheet of the roof of test building 2. The temperature of the hot water produced reached of 39˚C. This study could be also an alternative for the reduction of energy consumption due to the use of mechanical means for cooling of sheet metal roofed houses and the reduction of the use of fossil fuels for domestic hot water production.展开更多
Regions near latitude 0are characterized by warm-humid climate and also by high cloudiness.In these regions,metal roofs has been the most widely used typology.However,in the last decades,the use of heavy concrete roof...Regions near latitude 0are characterized by warm-humid climate and also by high cloudiness.In these regions,metal roofs has been the most widely used typology.However,in the last decades,the use of heavy concrete roofs has increased significantly.Given its material characteristics,this roof typology offers a higher thermal resistance and thermal mass than a metal roof.Most strategies focus on the use of these characteristics,as well as the use of high reflectivity and emissivity.However,the impact of cloudiness on the effectiveness of these strategies has been little addressed.This research focuses on the impact of reflectivity and emissivity change on the thermal performance of these two roofs in a cloudy warm-humid climate.To achieve this objective,simulations validated with measurements were used.The results show that the efficiency of reflectivity and emissivity is lower in this region compared to other regions.The impact of these properties is further reduced with increasing thermal mass or decreasing thermal transmittance,so the effectiveness of reflectivity and emissivity is minimal on the concrete roof.Finally,this study supports that a metal roof with a reflectivity and emissivity above 0.70 can offer lower daily average temperatures than a concrete roof.展开更多
文摘This experimental study is a contribution to the search for solutions to reduce indoor heat gain through sheet metal roofing in hot weather. It has evaluated the thermal impact of two different sheet metal roofs inside of two identical test buildings in sunny weather and cloudy weather conditions. Test building 1 has a single sheet corrugated roof and the building 2 is covered with roof made from top to bottom with corrugated sheet metal, a 12 mm thick serpentine copper tube in which water is circulated, a sheet of aluminium foil acting as a heat reflector, a 4 cm thick polystyrene panel and a 1.5 cm thick plywood. A maximum reduction of 15.1˚C in the temperature of the inner face of the test Building 2 roof was obtained comparatively to the temperature of the inner face of the test Building 1 roof consisting of a single sheet of metal at the warmest hours. In addition, the simple corrugated sheet metal roof of the test building generates high and varied temperatures inside the building. Whereas the proposed heat recovery roof favours low and relatively uniform temperatures inside the building. The proposed sheet metal roof construction technique is very effective in reducing the heat gain through the roof considerably;thus improving the thermal comfort inside sheet metal roofed dwellings. Hot water has been produced by recovering heat from the metal sheet of the roof of test building 2. The temperature of the hot water produced reached of 39˚C. This study could be also an alternative for the reduction of energy consumption due to the use of mechanical means for cooling of sheet metal roofed houses and the reduction of the use of fossil fuels for domestic hot water production.
基金supported by Catholic University of Cuenca,project code PICODS21-35HC+AI acknowledges the Spanish Ministry of Economy,project code:BIA2016-77675-R and PID2020-116036RB-I00.
文摘Regions near latitude 0are characterized by warm-humid climate and also by high cloudiness.In these regions,metal roofs has been the most widely used typology.However,in the last decades,the use of heavy concrete roofs has increased significantly.Given its material characteristics,this roof typology offers a higher thermal resistance and thermal mass than a metal roof.Most strategies focus on the use of these characteristics,as well as the use of high reflectivity and emissivity.However,the impact of cloudiness on the effectiveness of these strategies has been little addressed.This research focuses on the impact of reflectivity and emissivity change on the thermal performance of these two roofs in a cloudy warm-humid climate.To achieve this objective,simulations validated with measurements were used.The results show that the efficiency of reflectivity and emissivity is lower in this region compared to other regions.The impact of these properties is further reduced with increasing thermal mass or decreasing thermal transmittance,so the effectiveness of reflectivity and emissivity is minimal on the concrete roof.Finally,this study supports that a metal roof with a reflectivity and emissivity above 0.70 can offer lower daily average temperatures than a concrete roof.
