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A solar water heater with heat pump as an auxiliary (SWHHP) was investigated in terms of system energy efficiency, environmental impacts and economic costs including global warming externality evaluation. The information data were compared with those of a conventional electric heater (EH) and a common solar water heater with electrical heater as an auxiliary (SWHEH). A profile of hot water consumption during a day was selected from a children nursery office in Chiang Mai, Thailand of which the average daily amount of hot water at 50oC was about 610 liters. In term of system energy efficiency, the SWHHP consumed less electricity consumption significantly compared to the EH and the SWHEH. For environmental impact aspect in term of global warming, the life cycle assessment (LCA) was applied to evaluate the impacts due to their raw material and conventional energy consumptions during the system operation over the entire life of 10 years. It was found that in each unit, the main impact came from electricity consumption of the system operation. The SWHHP was also the best system that gave the lowest environmental impact. For economic analyses, the SWHHP showed the SPP of 3.94 years and IRR of 21.80 % at the optimum area of 4 m2. When the environmental impact was considered, the SWHHP could reduce CO2 around 75.04% and 66.45% compared with the EH and the SWHEH, respectively. The SWHHP also gave the best solution when the external cost was included.
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Faculty of Engineering and Technology
Mahanakorn University of Technology
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