## 7 Conclusions  
The carbon emission behavior of the integrated regional energy system (RIES) under the carbon-peaking target is crucial for guiding system capacity configuration and implementing carbon reduction policies. Despite limited research in this area, this paper addresses this gap by analyzing the carbon emission behaviors of RIESs, using a building  
Figure 14: Sensitivity analysis of renewable energy quotas and green-certificate-trading prices. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Green-Certificate-Trading Price (CNY/Unit)** & **0** & **25** & **50** & **75** & **100** & **125** \\ \hline Fossil energy subsystem load rate & 31.34\% & 28.05\% & 26.40\% & 25.76\% & 25.23\% & 24.80\% \\ \hline \hline \end{tabular}
\end{table} 
Table 12: The load rate of the fossil energy subsystem changes at a renewable energy quota of 10%. cluster in an economic zone of Shanghai as an example. Similar to a study by [PERSON] et al. [21], our study emphasizes the role of renewable energy integration in reducing carbon emissions within RIES configurations. By employing an extended STIRPAT model, we predict the carbon-peaking trajectory in Shanghai, aligning with the work of [PERSON] et al. [2], who also utilized enhanced models to assess socioeconomic impacts on emissions. The goal is to offer valuable insights for the construction and planning of the energy system in Shanghai. The following constructive conclusions can be drawn from this work:  
1. The predictive analysis of the extended STIRPAT model, considering the existence of the environmental Kuznets curve, reveals that in the three development scenarios of rapid, steady, and green developments established based on China's and Shanghai's development plans and relevant policies, the carbon-peaking target in Shanghai can be achieved as early as 2025 or as late as 2035;
2. Three typical RIES system configurations are proposed based on different levels of renewable energy penetration. The analysis of the carbon emission behaviors of the RIES systems constrained by the carbon-peaking target reveals that the CP-RIES system, entirely powered by renewable energy, is not constrained by the carbon-peaking target and can meet the target on its own. However, even with the carbon-peaking target constraint, the FP-RIES system relying on traditional fossil energy cannot meet the carbon-peaking requirement. Additionally, a significant finding is that different operational modes have significant impacts on the system's carbon emission behavior. The analysis results show that the FEL mode exhibits a significant low-carbon performance, while the FTL mode performs poorly in terms of carbon reduction, especially for the HP-RIES system when operated in the FTL mode, making it difficult to meet the carbon-peaking requirements;
3. The analysis of the four carbon-reduction policy scenarios, based on carbon-trading and green-certificate-trading mechanisms, demonstrates that carbon reduction policies through market mechanisms can optimize the allocation of loads in different RIES systems, effectively suppressing the overall carbon emissions across RIES systems. The low-carbon impact of the carbon-trading mechanism is more significant compared to that of the green-certificate-trading mechanism, but it comes with relatively higher marginal abatement costs. Furthermore, the sensitivity analysis of key design parameters of carbon reduction policies reveals that the carbon-trading price, green-certificate-trading price, and renewable energy quota have significant impacts on the carbon emissions across RIES systems. Increasing these three factors will actively promote carbon emission reduction, with the carbon-trading price having a more pronounced effect. This study has certain limitations.