Performance Assessment of Sustainable Composite Roofing Assemblies Using Experimentation

In hot climatic zones all buildings that have roofs directly exposed to the sun imparts significant heat gain inside the buildings. The significant problem of excessive cooling demand inside the building can be addressed using reflecting and insulating materials as a retrofitting solution. The present paper elaborates application of sustainable reflecting-cum-insulating (R-I) materials over the flat concrete roof surface for reducing the impact of heat gain inside the buildings. The composite R-I assemblies used for thermal performance assessment includes aluminum sheet, broken glazed tiles, expanded polystyrene (construction waste), sawdust (industrial waste), mineral fiber board (recycled content 38%), and false ceiling panels (recycled content 90%). These materials were placed in two different combinations as a composite heat barrier assembly for exposed concrete roofs of the two model rooms in an educational building over the considered geographic location. In comparison to the untreated concrete slab, the applied composite R-I assemblies resulted in an overall increase in thermal resistance of the first and second assembly by 1.9 and 3.9 times, respectively. Over a period of a year under experimentation, the first and second retrofitted assembly resulted in 6% and 19% reduction in surface temperature, respectively. The considered R-I materials for the experimentation have proved to be a thermally efficient, lighter, and cost-effective solution for energy conservation inside the buildings. The R-I product can further be applied on larger roof areas by the designers to reduce the cooling load of the built environment, as well as to increase the occupants comfort over the local climatic zone.