Application of life cycle assessment for enhancing sustainability of district heating: A multi-level approach

District heating (DH) is a proven heat generation and distribution technology that enhances energy efficiency and reduces carbon emissions at scale, making it a key component of sustainable energy strategies. Compared to traditional heat generation methods such as using onsite fossil-fuelled combustion boilers or electrically driven heating systems, DH offers superior environmental advantages, particularly when renewable energy and waste heat are deployed as primary fuel energy mix. To comprehensively evaluate the sustainability of DH, life cycle assessment (LCA) is widely adopted to determine environmental impacts across all life cycle stages, from material extraction to disposal. This systematic review identifies the absence of a unified, adaptable framework for LCA application in DH systems. To address this, the study proposes a structured multi-level framework, interpreting methodological diversity across component, facility, and network levels. Component-level studies offer insights into specific technologies and materials; facility-level assessments focus on operational performance and energy sources; network-level evaluations provide holistic system impacts. Aligning studies within these analytical levels enables fairer comparisons, supports cross-regional learning, and promotes methodological integration. Recurring challenges include inconsistent methodologies, varying system boundaries, and limited local data. Emerging technologies such as hybrid systems, smart grids, and energy storage remain underrepresented in LCA studies. Tools like SimaPro, GaBi, and OpenLCA are widely used, yet the rapid evolution of DH systems calls for more tailored applications. This review supports the development of standardised, yet flexible LCA practices and proposes a refined multi-level framework to guide comprehensive, context-specific evaluations. It emphasises the importance of validating approaches across diverse contexts and strengthening LCA’s contribution to the design of sustainable, low-carbon DH solutions for urban energy systems. Multi-level LCA approach categorises DH systems into component, facility, and network levels. Current LCA research on DH systems focuses on Europe, with gaps in Asia and the US. Tools like SimaPro, GaBi, and OpenLCA support detailed LCA analyses of district heating. LCA for DH systems faces challenges like data gaps, system boundaries, and variability. The proposed workflow enables tailored, actionable LCA assessments for diverse DH systems.