Effect of Utilizing Different Building's Roof Material on Rainwater Harvesting System's Payback Period, Water and Energy Savings, and Carbon Dioxide Emission Reduction

摘要

This study aims to investigate the effect of using different roofing materials in office building on rainwater harvesting system annual energy savings and carbon dioxide (CO_2) emissions reduction which relates to the payback period. This paper includes modelling of different rain water harvesting concrete tank sizes for an office building which is used to supply water for toilet flushing and irrigation purposes. It is found that the optimized roof material for the catchment area is slate tiles with a 0.9 run-off coefficient. A total of 2870 MJ of energy can be saved and 830 kg of CO_2 can be reduced annually with a payback period of 20years, using a 32m~3 concrete tank.