An Empirical Framework for Sustainable Building Materials Selection in Residential Construction: Evidence from Tanzania

Despite rapid urbanisation and mounting housing demand in Tanzania, material selection in residential construction remains guided by short-term cost and contractor familiarity rather than systematic sustainability evaluation. A prior systematic review identified nineteen critical factors influencing sustainable building material selection across environmental, economic, and social-cultural dimensions, but two gaps limited its practical utility. First, it could not determine which factors Tanzanian construction professionals actually prioritise or how local priorities compare with global patterns. Second, no operational tool translated those factors into structured guidance for early-stage material evaluation. This study addresses both gaps directly. A structured questionnaire survey was administered to 156 registered construction professionals, including architects, engineers, and quantity surveyors, with experience in residential construction across Tanzania. Factor importance was assessed using the Relative Importance Index, supported by descriptive analysis, within a triple-bottom-line evaluation structure covering environmental, economic, and social dimensions. Results show that environmental factors dominate professional priorities. Material environmental impact, ecosystem protection, and waste management ranked highest overall. Economic factors occupy intermediate positions, with life-cycle cost consistently prioritised over initial affordability, indicating growing attention to long-term value in material selection. Social and cultural factors ranked lower overall, with health and safety as the notable exception. These findings challenge the assumption that economic criteria dominate decision-making in developing-country construction contexts and demonstrate measurable alignment with environmental sustainability objectives among Tanzanian construction professionals. The resulting framework organises empirically derived factor priorities into a weighted evaluation matrix for early-stage material assessment, where detailed performance data is often limited. This supports more transparent and defensible sustainability-informed decisions in residential project delivery. Future research should apply multi-criteria decision-making techniques such as the Analytic Hierarchy Process and validate the framework through implementation-based case studies, enabling the development of computational decision-support tools.