Developing a conceptual framework for Net-Zero Energy Building (NZEB) retrofitting of university buildings in tropical climates

Abstract

The global shift towards Net Zero Energy Buildings (NZEBs) has increased academic and policy interest in sustainably retrofitting existing buildings, especially in Higher Education Institutions (HEIs). University campuses or Higher Education Institutions constitute a substantial infrastructure network due to their extensive scale and varied construction typologies, with both direct and indirect environmental impacts. These campuses also serve as major energy consumers, living laboratories, and sustainability exemplars, offering a unique opportunity to advance NZEB transitions. Despite this increasing commitment, retrofitting existing university buildings, mainly in tropical climates, remains fragmented, technically skewed, and insufficiently theorised. Most retrofit initiatives and academic research still focus on technological solutions such as renewable integration and energy-efficient systems, while ignoring the crucial roles of occupant behaviour, economic realities, policy environments, and institutional structures. Many studies lack an integrated conceptual framework that systematically integrates technical retrofit solutions with institutional, behavioural, and policy dimensions, particularly in tropical climates and developing country contexts. Therefore, after an in-depth study of the conceptual, empirical, and theoretical literature, this study develops a conceptual framework to enable retrofitting existing university buildings to achieve NZEB performance in tropical regions. The study adopts Socio-Technical Systems Theory and Diffusion of Innovations Theory as additional lenses to better understand the dynamics of innovation adoption, implementation, and organisational behaviour in university environments. Addressing this gap is important to support integrated retrofit solutions, improve policy and administrative decision-making, and advance sustainable campus growth aligned with climate mitigation. The study concludes that achieving NZEB in tropical HEI’s requires a holistic socio-technical approach that integrates technical solutions with behavioural, economic, institutional, policy and innovation-related factors. It recommends that university managers, policymakers, and built-environment professionals adopt integrated retrofit strategies supported by stakeholder engagement, institutional capacity, appropriate financing, and enabling policies and regulations. The proposed framework provides a basis for informed retrofit decision-making and future empirical validation in tropical HEIs.