Development of a fuzzy-based critical risk index for circular building projects: a taxonomic prioritisation in a less-developed market

Circular building projects are widely promoted, yet in less-developed markets their uptake is held back by risks assessed only in part. This study develops a critical risk index (CRI) for circular building projects in Ghana. Sixty-eight risk factors in nine taxonomies were rated by 76 construction professionals and academics recruited through purposive and snowball sampling. Normalised values (NV) screened the factors, fuzzy synthetic evaluation (FSE) produced criticality indices (CI), and Kruskal–Wallis, ANOVA and Dunn tests examined differences among taxonomies, with equal-weight, threshold and leave-one-out robustness checks. Forty-eight factors were critical (NV ≥ 0.450). Technological risks ranked first (CI = 4.07), followed by financial (CI = 4.03), material (CI = 4.01), health and safety (CI = 4.00), design (CI = 3.99), regulatory (CI = 3.98), organisational (CI = 3.98), stakeholder (CI = 3.94) and supply chain risks (CI = 3.90), giving an overall CRI of 3.98. The taxonomies differed significantly (H(8) = 25.88, p = 0.001), but only at the two ends of the ranking, which were stable under all checks. Circular construction risk in Ghana stems mainly from capacity deficits in digital infrastructure, finance and secondary materials markets, and risk responses need to proceed in parallel.