Investigating differences between life cycle assessment tools on major infrastructure schemes

An essential part of managing whole life carbon impacts of High Speed Two (HS2) Euston Station is quantifying, monitoring and reporting whole life carbon emissions through a Life Cycle Assessment (LCA) process. The LCA process initially provides a baseline which identifies carbon hotspots and allows for the monitoring of progress towards the contractual 50% whole life carbon reduction target. It also informs the Euston Station aspiration to reach net zero carbon, set within the wider context of the UK’s legal obligation to net zero carbon transition by 2050. Furthermore, whole life carbon management aligns with the vision that ‘HS2’s stations will be amongst the most sustainable stations in the world’.

Whole-life carbon for Euston Station is managed and quantified in line with Royal Institute of Chartered Surveyors (RICS)[6], HS2 Technical Standard – Carbon footprinting and life cycle assessment[5], EN-15978[7], PAS2080[8], BS EN ISO14040[9] and BS EN ISO14044[10] standards and guidance on a bi-annual basis.

Several life cycle inventory and LCA tools are available for carbon quantification, providing a basis to focus on key carbon reductions in ‘hotspot’ areas. However, recent academic studies highlight the lack of transparency in these tools and difficulties comparing reported impacts between differing software platforms.

Similar issues were explored while performing the LCA for Euston Station. Two web-based LCA tools were used, and the outputs compared. This paper presents the findings and explores the difference and lack of transparency in Lifecycle Inventory (LCI) data sources, emissions factors (materials and transport), inconsistency in the scope of life cycle modules found across LCA tools, comparability and reproducibility of results within and across these tools.

This paper aims to improve understanding of the limitations across LCA tools to inform robust and transparent reporting of whole life carbon impacts across the industry. This understanding can be developed and adapted for other HS2 contracts along the route, as well as other infrastructure projects.