Green Housing Retrofits as Complex Micro-Projects: Delivery Pathways and Whole-Life CO2

Residential retrofitting is a cornerstone of national strategies for achieving net-zero emissions by 2050. Yet, despite decades of policy incentives, adoption remains limited, delivery performance is uneven, and realised carbon reductions often fall short of predictions. This paper conceptualises housing retrofit projects as complex micro-projects—small in scale but marked by technical, organisational, and social inter-dependencies that challenge conventional project delivery. Drawing on an integrative review of 56 studies, we synthesise evidence across the Owner, Supplier, and Delivery domains to identify the managerial, coordination, and communication barriers that shape whole-life CO₂ outcomes. By framing these challenges through concepts of static and dynamic complexity, the study demonstrates that performance shortfalls stem less from technological gaps than from fragmented project organisation and weak cross-domain coordination. The review contributes an evidence-based understanding of how complexity affects retrofit delivery, outlines implications for policy and practice, and proposes a research agenda for improving assurance, learning, and verification in housing retrofit management.