A green building is an outcome of a design philosophy which focuses on increasing the efficiency of resource use. This paper presents a conceptual model in simulating the risk behaviors of decision makers in influencing the decision making of selecting green building designs by using 3 difference processes including benefit-cost analysis, multi-criteria decision-making, and Nash equilibrium game. The proposed approach allows the project owner and the consultant to assess the green building cost and effectiveness of performance for different design alternatives during the early design stage. A two-person nonzero sum game is considered in this paper to model the interactions between both players with respect their different utilities and different risk behaviors. The results of the case study show the consultant plays an important role in influencing the developer's choice of selecting a desirable green building design alternative.