An empirical framework for sustainable building materials selection in residential construction: evidence from Tanzania

Abstract Across developing countries, the selection of building materials still relies on short-term costs and practitioners’ familiarity rather than structured sustainability assessments (SSAs), despite rapid urbanisation and rising housing demand. A prior systematic review identified 19 factors across environmental, economic, and socio-cultural dimensions; however, it did not establish their relative importance in any specific context or provide an operational tool to translate these factors into structured guidance for early-stage material evaluation. This study addresses both gaps in Tanzania, a rapidly urbanising developing country, through a structured questionnaire survey distributed to 326 registered construction professionals, yielding 156 usable responses from architects, engineers, and quantity surveyors with residential project experience. The reliability of the 19-factor instrument was confirmed using Cronbach’s alpha, which showed good to excellent internal consistency. Factor importance was evaluated using the Relative Importance Index (RII) within a triple bottom line framework. The results indicate that environmental factors dominate professional priorities. Material environmental impact, ecosystem protection, and waste management were the highest-ranked factors. Economic factors follow, with the life-cycle cost ranked above the initial cost, showing attention to the long-term value. Socio-cultural factors ranked lower overall, although health and safety remained important. These findings challenge the assumption that cost dominates decision-making in developing countries and align with the sustainability objectives of Tanzanian professionals. This study developed a weighted evaluation matrix that translates ranked factors into a practical tool for early stage material selection, where detailed data are often limited. Future work should apply multi-criteria methods, such as the Analytic Hierarchy Process, and validate the framework through case-based applications, including testing the transferability of these priorities to other developing-country residential construction sectors.