Energy performance gap in zero-energy buildings: A socio-technical complexity framework for risk assessment and mitigation

• Explored ZEB complexity’s impact on energy performance risk (EPR) • Bridged theoretical concepts and practical perceptions of ZEB complexity • Developed a Technical-Organisational-Environmental complexity framework for ZEBs • Revealed dominant influence mechanisms driving the energy performance gap (EPG) This research investigates how zero-energy building (ZEB) complexities influence energy performance risks (EPRs) and contribute to the energy performance gap (EPG). Despite the increasing adoption of ZEBs to meet net-zero carbon targets, the persistent discrepancy between predicted and actual energy use remains underexplored from a complexity perspective. Drawing on socio-technical systems (STS) theory and project complexity theory, this research develops an integrated Technology–Organisation–Environment (TOE) complexity framework to systematically link ZEB complexities with EPRs across the project lifecycle. A two-step mixed-methods approach was employed, combining a systematic literature review (SLR) and semi-structured interviews with 12 UK industry experts. The research identified 23 complexity factors, categorised into nine overarching themes, and demonstrated that technical, organisational, and environmental dimensions are equally significant and interrelated, influencing EPRs through structural, socio-political, and emergent mechanisms. Notably, emergent influences marked by uncertainty and dynamism were pervasive, and socio-political factors played a critical role in shaping organisational and environmental outcomes. The framework fills a gap in existing EPG frameworks by integrating project-specific complexities and extending complexity and risk management theory into the energy performance domain. It also provides decision-makers with a structured tool to better assess, manage, and mitigate complexity-driven risks.