## 5 Discussion  
The increase of FP significantly affects the increase of the newly added area of PBs [58], which is the most effective policy to promote the development of PBs [37]. After a slight increase in FP, the effect of promotion on the development of PBs is not apparent. Expanding the amount and scope of subsidies for PB development is necessary. The research results of [PERSON] et al. also show such characteristics [26]. The high construction cost is still the main obstacle to the development of PBs. The government must increase financial subsidies to compensate for the incremental cost of developing PB projects [9]. The higher the project subsidy, the greater the improved effect of the newly added area of PBs and reduced carbon emissions. This result is consistent with the research by [PERSON], et al. (2024) [9]. This study further proposes the positive correlation between PB promotion and FP intensity, providing precise recommendations for policy design. However, a substantial increase in subsidies will increase the financial pressure on the government and lead to many real estate enterprises joining the PB market, quickly bringing adverse effects to the construction market [34]. Therefore, with the government's financial permission, various enterprises involved in PB development, design, production, and construction should be given the highest possible financial subsidies [59]. The level and scope of subsidies shall be gradually expanded. Set attractive subsidies according to the project assembly rate and standardization level, and improve the enthusiasm of relevant industries to invest in PBs [27]. However, this study has not yet established a clear boundary between the subsidy scale and market saturation, and further simulation and verification are needed in future research based on regional fiscal capacity and the PB market's carrying capacity. The increase in the production of prefabricated components and the application of energy-saving technology can significantly improve the scale of PBs and reduce carbon emissions [60; 61]. PTP mainly provides tax incentives for the R&D of PB technology and the production of prefabricated components, which significantly affects the development of PBs. According to Figures 6e, 7e, and 8e, and Table 4, when the PTP is increased by 10%, it can produce a noticeable promotion effect, but when the PTP is doubled, it cannot make benefits match the investment. Therefore, there is no need to increase tax incentives significantly. The government can increase the intensity of tax incentives within a reasonable range, based on the actual financial situation. According to the simulation results, this reasonable range should be around 10% but should not exceed 20%. The enterprises benefiting from PTP in Shenyang are mainly prefabricated component suppliers and R&D institutions. The coverage of PTP is small, and it is impossible to study the possible improvement effect of PTP on other enterprises. In the future, the government can consider expanding the application scope and beneficiary groups of PTP. Technological innovation and achievement transformation promote the development of PBs, generating high economic and environmental benefits [37]. R&DSP supports technological innovation and research achievement transformation related to PBs, the policy with the most significant effect on carbon emission reduction. Regarding the supply of PBs, the R&DSP will produce good results only when it needs to be increased by 20% or more. Regarding carbon emission reduction, R&DSP has a sustained effect, and the reduction of carbon emissions rises significantly with the improvement of R&DSP. Technological innovation and technical personnel training are essential means to promote the development of PBs [10]. The government should invest funds vigorously to encourage the research and development of new technologies for PBs, supporting enterprises and research institutes in their cooperation on technical research.