Carbon dioxide reduction from an intensive green roof through carbon flux observations and energy consumption simulations

Green roofs have the potential to reduce carbon dioxide directly through photosynthesis and indirectly through building energy savings. Most previous studies either focused exclusively on the direct or indirect CO2 reduction of GRs, resulting in an incomplete assessment. A comprehensive assessment of the CO2 reduction potential of GRs would aid in promoting their use as carbon credits in the carbon trading market. This study quantifies the total CO2 reductions from a newly built intensive green roof with yearlong carbon flux observations and building energy simulations. Our results indicate that direct and indirect carbon reductions from IGR significantly differ, with the monthly direct and indirect CO2 reduction ratio ranging from 1:5 to 1:130. Direct and indirect CO2 reduction exhibits significant seasonal trends, with peak direct reduction in autumn and peak indirect reduction in summer. Overall, the total annual CO2 reduction from this IGR system is 4355.6 g CO2 center dot m (-2), of which 46.6 g CO2 center dot m (-2) and 4309 g CO2 center dot m (-2) were direct and indirect, respectively. Further research should evaluate the longterm integrated carbon reduction over the life cycle of the GRs. The findings of this study could provide evidence to leverage GRs as a nature-based solution to achieve net-zero carbon emissions.