Multi-objective decision-making for sustainable construction: Designing an interactive method for multi-actor project settings

Today’s constructions need to meet a growing list of performance demands with often contradicting objectives. Sustainability-related objectives typically need to be balanced against other objectives, such as structural safety or costs. These interdependencies lead to complex decision spaces with a diversity of potential optimal solutions. Novel multi-objective optimisation models could support decision-making in such settings but are rarely customised to the diverse needs of various project actors. This study therefore explores how such models could be used for multi-actor decision-making. Through adopting a design science research methodology, we developed an interactive method for implementing multi-objective optimisation models in construction projects. The iterative design process consisted of identifying the problem, formulating the design objectives, developing the interactive method, demonstrating the method in participatory test sessions, and evaluating its application. It was found that the interactive method supports stakeholders with interpreting design optimisation results, (re)formulating design preferences, and selecting their most preferred design solution. This ultimately contributes to more balanced and well supported sustainable design solutions.