## 5 Discussion
### Recommendation  
In response to the above summary, the following recommendations are made:  
1. Maintaining a stable market, increasing the resilience of the PBSC, and increasing the proportion of emission reduction groups. Sections 4.3 and 4.4 demonstrate that maintaining system stability and enhancing initial emission reduction intentions can facilitate PBSC emission reduction. The consumer market drives, while the supply market supports. To promote the implementation of emission reduction strategies by participants in the PBSC, the following measures should be taken: (1) Enhance public environmental awareness and acceptance of PB to boost consumers' willingness to pay [29]. (2) As the general organizer, the government should introduce policies to stabilize the market and prices, alleviating construction companies' concerns over carbon emission reduction [50]. (3) The PBSC should enhance risk resistance through stronger cooperation among participants to better adapt to market changes. 2. Participants in PBSC should reduce costs, increase efficiency, and improve capacity in production, promotion, and co-operation. Sections 4.5.1 and 4.5.2 indicate that the direct costs and benefits significantly influence enterprises and those engaged in construction should actively participate. The first is to reduce costs via technological innovation and upgrading, corporate R&D cooperation, and construction collaboration [38]. Secondly, use advertising and packaging design to promote emission reduction concepts, expand the market, publicize high-quality projects, and set industry benchmarks to guide more projects to reduce emissions [56]. Thirdly, actively seek opportunities for cooperation [16; 37]. For example, reduce employment and training costs via school-enterprise cooperation; lower procurement costs through long-term supplier relationships; decrease R&D costs by collaborating with research institutions; and share resources and complement strengths with peer enterprises via strategic alliances to undertake large-scale projects and achieve standard emission reductions. 3. Enhance the internal communication and information-sharing mechanisms within the PBSC, focusing on participants at both ends of the PBSC, with appropriate external intervention for optimization. Section 4.5.4 highlights that focusing on the beginning and end of PBSC agent, enhancing coordination, and avoiding the \"free-rider\" effect can promote emission reduction. Enhancing information flow within PBSC promotes collaborative emission reduction, while ensuring information security prevents free riding [83]. PBSC participants should form alliances, enhance communication, and optimize the PBSC operation process [36]. Upstream owners should initiate the establishment of an information-sharing platform. Downstream end-user enterprises should actively respond to enhance PBSC synergy, increase joint abatement benefits, and mitigate the adverse impact of free-rider behavior [17]. The information-sharing platform should adopt the following optimization measures: (1) Use API, EDI, and other real-time data exchange technologies to realize real-time data transmission and update and enhance PBSC synergy. (2) Employ firewalls, intrusion detection, and defense systems to enhance privacy protection, ensure data security, and prevent free-riding by downstream participants. (3) Establish a project-centric information-sharing database, reduce information redundancy through standardized design, and enhance collaboration efficiency. The government, industry associations, and other entities can intervene in the PBSC to guide the establishment of a cost-compensation mechanism, optimize the benefit-distribution mechanism, reduce free-riding, and enhance participants' enthusiasm for emission reduction [41]. 4. External parties in PBSC should insist on punishment over reward and adopt differentiated instruments. Negative incentives play a significant role in reducing emissions.