The green code of heating revolution: exploring the impact of China's northern clean heating pilot on the green total factor energy efficiency.

To address severe air pollution caused by winter heating, China has implemented a mandatory clean heating policy in northern regions. Although the environmental benefits of this policy have been recognized, its net impact on green total factor energy efficiency (GTFEE) and the underlying mechanisms remain unclear. This paper regards this policy as a quasi-natural experiment. Based on the panel data of 300 Chinese cities from 2006 to 2022, we use the multi-period difference-in-differences model for causal identification. We find that the GTFEE of pilot cities increased by an average of about 6.5% after policy implementation, and this finding remains robust after excluding contemporaneous environmental policies, providing empirical evidence from China for the Porter hypothesis. Heterogeneity analysis shows that policy effects are more prominent in non-coastal cities, high-tech endowed cities, and high administrative level cities, reflecting the key role of local capacity in policy implementation. The mechanism inspection identified four main transmission paths: industrial structure upgrading, government governance capacity improvement, environmental regulation strengthening, and green technology progress. This study not only provides new evidence from northern China for the Porter effect induced by command-based environmental regulations, but also suggests that future environmental policies should focus more on matching local endowments to achieve precise governance and synergistic efficiency.