Circular economy-based design alternative selection model for construction projects

The growing adoption of circular economy (CE) principles in construction requires systematic approaches to evaluate design alternatives. This study develops a CE-based model enabling decision makers to systematically assess and compare alternative building designs by their circularity performance. The proposed framework integrates circularity-related criteria identified through an extensive literature review and Focus Group Discussions (FGDs). Pythagorean Fuzzy Analytic Hierarchy Process (PF-AHP) is employed to determine criteria weights, while Fuzzy TOPSIS is used to rank alternative design options. The applicability of the model is demonstrated through a hypothetical design case. The findings indicate that circular design selection should extend beyond material-related considerations and also incorporate environmental, consumption-related, social, and financial dimensions. Material recyclability emerged as the most influential criterion with a global weight of 0.095, followed by wastewater reduction (0.078) and raw material consumption (0.072). The material impact dimension obtained the highest aggregate weight (0.309), followed by environmental (0.260) and consumption-related (0.232) dimensions, while social (0.106) and financial (0.094) dimensions ranked comparatively lower. The integrated PF-AHP–Fuzzy TOPSIS framework provides a systematic and transparent approach for evaluating circular design alternatives. Unlike previous studies focusing on contractor evaluation or general sustainability assessment, this research supports more informed and consistent early-stage design decision-making.