Hybrid life cycle assessment (H-LCA) for buildings and construction materials: A systematic review and meta-analysis

Abdulrahman Bakindi, Aoife Houlihan Wiberg, Jonathan Norman, Ellie Marsh, Stephen Allen

The construction and building sectors are crucial in combating climate change due to their significant embodied and whole-life carbon emissions. With the population and building floor area projected to rise significantly by 2050, robust assessments are needed to identify eco-friendly solutions. Life cycle assessment (LCA), particularly process-based (P-LCA) and input-output (I-O LCA) methods, is extensively used for assessing environmental sustainability. However, both approaches have drawbacks. Hybrid life cycle assessment (H-LCA) addresses these drawbacks by combining the strengths of both methods.

This paper presents a systematic review and meta-analysis of the current status of H-LCA in the context of buildings and construction materials. It explores the methodologies and approaches currently employed in H-LCA, the current challenges and opportunities, and future directions. A comprehensive search across four research databases identified 46 studies.

The review reveals that the adoption of H-LCA within the building and construction sectors has been slow but is gradually increasing. There is a noticeable lack of methodological clarity, with varied sources, databases and tools used in these studies, as well as a preference for national I-O (IO) tables over Multi-Regional Input-Output (MRIO) tables.

Furthermore, the review finds that when addressing issues in their H-LCA models, such as correcting double counting, researchers use various strategies and methods suited to their particular goals, aims, and datasets. These models differ greatly, making a straight comparison between them difficult. The review combines the results of these papers and conducts a comparative analysis. The analysis shows that H-LCA generally yields higher values than P-LCA and I-O LCA methods in providing comprehensive results.

Finally, this paper identifies several limitations in current H-LCA practices and concludes by discussing potential solutions to address them.