Multi-agent Evolutionary Game Analysis On Public-Private-Partnership Green Retrofits Of Existing Buildings

The Public-Private-Partnership green retrofitting projects of existing buildings bring into play the role of market players to drive the development of green renovation of existing buildings by introducing social capital.However,the PPP model has not been applied much in the actual existing building green retrofitting projects,and there are difficulties and problems such as cooperation and coordination in the retrofitting projects due to the different interests and goals of various stakeholders.This paper aims to promote the application of the PPP model of green retrofits of existing buildings and improve its cooperation and coordination mechanism.Using relevant theories such as an evolutionary game,system dynamics,stakeholder theory,and transaction cost theory,this paper analyses the interest demands,behavior,and conflict of interests of stakeholders by constructing a framework for analyzing the conflict of stakeholders in the PPP model of green retrofits of existing buildings;establishing The evolutionary game model and system dynamics model of the three parties are established,and the evolutionary path of cooperation and coordination among the three parties is elaborated through case simulations and analysis from different perspectives,such as different levels of government incentives,subsidies,retrofitting costs and benefits of each party.The main conclusions are:(1)The hierarchical analysis method and entropy power method were combined to determine the main influencing factors and the degree of influence on the promotion and application of the PPP model for the green retrofits of existing buildings.The factor of cooperation mechanism > the factor of institutional guarantee > the economic factor,the stronger the guarantee of cooperation mechanism,the greater its synergistic effect,and the greater the possibility of project stakeholders maintaining stable cooperation.(2)The main root causes of the conflict among core stakeholders in the PPP model of green retrofits of existing buildings are the lack of motivation for cooperation among all parties,the large differences in the objectives of stakeholders and information asymmetry.(3)Based on the simulation analysis of the multi-subject evolutionary game model and the system dynamics model,it is found that under the strong government intervention policy,it is possible to achieve lower incentive costs to promote green retrofitting.From a long-term perspective,positive incentives dominate in the early stage of green retrofits development,and negative incentives in the middle and late stages of development work better.Under the same level of subsidies,investment enterprises are more sensitive to subsidies,which means that when the government’s subsidy capacity is limited,it makes more sense to prioritize subsidies to enterprises,and there is a subsidy efficiency optimum for government subsidies.(4)Finally,more complete cooperation and coordination mechanism are constructed,and relevant countermeasures are proposed to promote the cooperation of multiple subjects in the PPP mode of green retrofits of existing buildings,which is of great significance to stabilize the cooperation relationship between various interest subjects in the PPP project of green retrofits of existing buildings.