An Interval Type-2 Fuzzy TOPSIS Approach for Green Supplier Selection in Sustainable Construction

• Proposes an integrated interval type-2 fuzzy TOPSIS framework that more accurately models uncertainty and ambiguity in expert judgments than conventional crisp or type-1 fuzzy approaches. • Develops a domain-specific, triple-bottom-line-oriented evaluation scheme with 15 criteria grouped into five categories, enabling holistic and transparent assessment in sustainable construction. • Conducts extensive sensitivity analysis showing ranking stability under plausible weight variations, thereby enhancing procurement managers’ confidence and providing rich “what-if” decision insights. • Demonstrates that the proposed approach is readily implementable for green supplier selection, facilitates ESG-oriented procurement, and can be flexibly adapted to different regional contexts and project types. Sustainable development has become a critical objective across industries, including construction. Achieving this goal requires effective supplier selection, which supports the triple bottom line of sustainability. However, supplier selection is challenging due to the need to deal with multiple attributes and the inherent uncertainty and vagueness in the available information. This paper proposes an IT2F-TOPSIS approach for selecting green suppliers. Uncertainty in preference is represented using trapezoidal interval type-2 fuzzy sets, after which the TOPSIS method is applied to rank supplier alternatives. In this work, fifteen criteria, including both cost and benefit factors, are identified through an extensive literature review and refined through consultation with five experts, grouped into five categories. Based on the defined fuzzy weights, the proposed approach is applied to rank the top three suppliers in Vietnam. Furthermore, a sensitivity analysis of the criterion weights is conducted to examine the robustness of the proposed solutions.