Evaluating old community renewal based on emergy analysis: A case study of Nanjing

• Quantifying the benefits of community renewal activity based on emergy analysis. • The asset appreciation is one small part of economic benefits from renewal activity. • Social and environmental benefits from the renewal in China are not significant. • The inflow of materials is much higher than labor & services in the renewal. • More than 40% of the emergy has not been exploited in the renewal activity. Renewal of old communities is an inevitable process in urban development. Old community renewal brings multiple benefits to communities and their residents. However, existing studies on the benefits of old community renewal usually focuses on single aspects, such as energy savings or property value increase. An integrated framework that provides a holistic assessment of community renewal benefits is missing. To address this limitation, this paper proposed an emergy-based method to quantitatively assess the benefits systematically from economic, social, and environmental perspectives. Based on the emergy theory, the proposed method coverts various input and output during community renewal process into one standard unit—the solar emjoule (sej). The method was tested in a case study of a community renewal project in Nanjing, China. It was found that the emergy input in the case study was 3.46E+19 sej, while the output from the renewal activity is 1.82E+19 sej. The main benefit of old community renewal of the case study came from the maintenance minimizing and appreciation of fixed asset. Only 1.04% of total benefits of community renewal were social and environmental benefits. This study provides an integrated quantitative approach for benefits evaluation in community renewal projects. Decision makers could use the emergy analysis to conduct holistic assessment of community renewal activities and make informed decisions regarding old community renewal.