Efficiency estimation of urban metabolism via Emergy, DEA of time-series

Evaluating the efficiency of urban metabolism is an effective tool to quantitatively analyze the relationship between social, environmental and economic input and output in an urban ecosystem. In this paper, there are the combination Emergy synthesis, Principal Component Analysis (PCA) and Date Envelopment Analysis (DEA) of time-series approach to comprehensive assessment urban metabolism for the first time. DEA of time-series has the advantage of fully considering the technology changes every year, it can reflect clearly the overall situation of urban metabolism, including the use of various resources and the development of environmental sustainability cycle. The results show that, with the overall efficiency of metabolism ensured a generally steady rise in Changsha, the trend of urban environmental load rate is increased obviously, there is facing the huge pressure of ecosystem in Changsha. This paper suggests that government and enterprises should take measures to promote the construction of the eco industrial park, gradually realize industrial symbiosis, upgrade through the adjustment of energy structure and industrial structure.