Powering efficiency: A lean six sigma 4.0 agenda and roadmap for sustainable energy enhancement

This study advances the understanding of Lean Six Sigma 4.0 (LSS4.0) as a strategic framework for enhancing energy performance in industrial operations. A scoping review identified 29 barriers and 30 drivers, which were refined through focus group interviews into twelve critical barriers and seven key drivers. Empirical techniques, Fuzzy Delphi and Fuzzy DEMATEL, were applied to prioritise these factors and reveal their causal interrelations. Key results indicate that training and technical qualification influence at least five major barriers, including resistance to change and lack of standardisation. At the same time, production cost reduction emerged as the most significant driver, overcoming capital investment constraints. These interdependencies informed the development of a research agenda, followed by a structured implementation roadmap aligned with the DMAIC cycle and tailored to varying levels of digital maturity. The roadmap incorporates operational and sustainability KPIs, such as cycle time reduction, energy consumption per unit, and carbon footprint, to guide continuous improvement under energy-efficiency goals. The study contributes both theoretically and practically by offering a replicable framework that supports the integration of LSS4.0 into diverse industrial contexts, bridging gaps in empirical evidence and providing actionable insights for organisations undergoing digital and sustainable transformation.