Investigating Carbon Retrofit Adoption in Nigeria: A Multi-Theory PLS-SEM and fsQCA Analysis

The building sector is a major source of global carbon emissions, making the decarbonization of existing buildings essential for climate mitigation. However, carbon retrofitting remains under-adopted in developing economies such as Nigeria, where financial, technical and institutional barriers constrain uptake and limited research explains how these factors jointly shape professionals’ adoption intentions. This study investigates the determinants of carbon retrofitting adoption intention among built environment professionals in Lagos State, Nigeria. Drawing on four complementary theoretical frameworks - the Theory of Planned Behavior (TPB), Diffusion of Innovations (DOI), Institutional Theory and the Unified Theory of Acceptance and Use of Technology (UTAUT) - the study examines how cognitive evaluations, technological attributes, normative influences and institutional pressures shape professionals’ willingness to implement carbon-oriented retrofit measures. A hybrid analytical design integrating Partial Least Squares Structural Equation Modelling (PLS-SEM) and fuzzy-set Qualitative Comparative Analysis (fsQCA) was applied. Survey data from 110 professionals were analyzed to estimate linear effects and uncover multiple causal pathways that lead to high adoption intention. PLS-SEM captured the direct influence of environmental awareness, cost perceptions, regulatory support, technical feasibility, peer influence, trust in providers and performance expectations, while fsQCA identified alternative combinations of these factors that jointly foster strong adoption intentions. All seven hypotheses (H1–H7) were supported, with cost savings and expected performance benefits demonstrating the strongest predictive effects. The results underscore the need for targeted capacity-building initiatives, credible provider networks, financial incentives and profession-driven advocacy to accelerate retrofit uptake. The study provides one of the first multi-theory, dual-method insights into carbon retrofitting adoption in Sub-Saharan Africa.