Are smart cities more ecologically efficient? Evidence from China

As a new mode of urbanization, smart city both influences the environmental load and economic performance of cities through technology effect, resource allocation effect and industrial structure upgrade effect. So comes the natural question: has smart city construction improved the eco-efficiency of cities In China? How does the impact change over time? Is the impact heterogeneous across cities? Based on Green Solow model, this paper adopts the Super-efficiency SBM model to measure the eco-efficiency of 152 prefecture-level cities in China covering the period 2003-2016, and then DID model is applied to investigate the impact of smart city pilot policy on eco-efficiency. On the whole, the smart city construction significantly improves the eco-efficiency, and the multi-stage DID results reveal that the promotion effect is increasing over time due to the annual superposition. Furthermore, the impact is heterogeneous across cities. Although the promotion effect on medium-sized cities is less than that of large cities, the promotion effect has actually weakened when the urban population size exceeds 5 million. Moreover, the lower the level of city's economic development, the greater the role of smart city construction in promoting eco-efficiency. The research conclusion is of great practical significance for the reform of urban governance model and the realization of high-quality urban development.