Effect of using construction and demolition waste as substrate on methane and carbon dioxide emissions from green roofs

Green roof is a technology that can provide ecosystem services to urban areas, but there are still few reports on greenhouse gas emissions from green roofs. In this study, the methane (CH4) and carbon dioxide (CO2) emissions during 5 years of operation on green roofs impacted by the construction and demolition waste (CDW) as a green roof substrate have been investigated by four configurations of green roofs (Ligustrum.vicaryi with CDW, Nephrolepis.auriculata with CDW, Liriope.spicata with CDW and local weeds with local natural soil) during Aug. 2012 to Aug. 2013 and Feb. 2016 to May. 2017. The results show that after 5 years of operation, the CH4 of green roofs decreased by 120.85%, and the CO2 of green roofs increased by 139.33%. The Global Warming Potential (GWP) shows that green roofs using the CDW as a substrate have been considered as a source of carbon, ranking at a lower level. After five years of monitoring, the CDW with L.spicata was the best configuration for the lowest value of GWP (1.82 kg CO2eq m−2 year−1) on green roofs. Results indicate that CDW was feasible to use as the green roof substrate.