Urban sustainability assessment of Taiwan based on data envelopment analysis

The rapid process of urbanization brings forth growing concerns about the sustainability of cities. This study adopts an extended urban metabolism framework to assess urban sustainability and utilizes a data envelopment analysis (DEA) model with undesirable outputs that takes pollutions into account in order to measure the aggregate urban input–output efficiency of Taiwan׳s 22 administrative regions. The model not only compares aggregate urban efficiency, but also identifies which input or output item should be adjusted and what the target values are. The results indicate that Taipei City and Lienchiang County are the most sustainable cities in Taiwan. This study also proposes several indices, categorized as resource efficiency and pollution efficiency. In terms of resource efficiency, the findings present that Taiwan needs to improve its electricity and water efficiencies the most. With regard to pollution efficiency, garbage efficiency performs the best. Finally, industrial structure has a strong influence on resource efficiency and pollution efficiency.