Simulation of Thermal Performance and Cost Benefits of Cool Roof Options through Building Engineering System Software
Authors: Aftab Ahmed Sahito; Rizwan Ahmed Memon; Khanji Harijan; Pervez Hameed Shaikh
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The cool roofs in buildings is a promising option to deal with summer Urban Heat Island (UHI) effects. In context to that, studies on different cool roof materials are widely available; however, there is a dearth of studies on insulating material benefits and implication for tropical and sub-tropical climate zones. This work investigates thermal performance, energy savings and cost benefits of cool roof materials. For this study, simulation of various cool roof materials such as Marble, Expanded Polyurethane Spray (EPS), Poly Vinyl Chloride (PVC), Spray Polyurethane Foam (SPF) , Extruded Polystyrene Foam (XPS), Thermocol sheet, Asphalt tile, Gypsum tile and Jumbolon-board have been carried out using Energy Plus software package. The results of zone air temperature show that maximum zone air temperature occurs in the month of May. The maximum zone air temperature obtained for conventional roof is 32.1oC, whereas that for Thermocol sheet, SPF, XPS, Jumbolon-board, EPS, marble, PVC, Asphalt tile and Gypsum tile is 28.8, 28.9, 28.8, 29, 29.1, 31.9, 30.5, 30.2 and 30.7oC respectively. Conventional roof surface outside and inside temperature difference is 2.90C, whereas, roof surface outside and inside temperature difference for Thermocol sheet, XPS, Jumbolon-board, SPF, EPS, marble, PVC, asphalt tile and gypsum tile is 9.2, 9.3, 8.7, 7.5, 8.1, 3, 3.1, 3.3 and 2.20C, respectively. Notably, XPS, Thermocol sheet, SPF, Jumbolon-board, EPS, Marble, PVC, Asphalt tile and Gypsum tile cool roof materials can save around 5.47, 5.38, 5.35, 5.15, 4.93, 1.09, 2.62, 2.31 and 2.18 MWh annually, respectively for the selected building. The payback period for marble, PVC, gypsum tile and asphalt tile is above 1 year, whereas the effective payback period obtained for XPS, Thermocol sheet, SPF, EPS and Jumbolon-board varies from 3 to 6 months. It is concluded that the cool roof materials may be used effectively to save energy and cost.