Inventory Indicators in Life Cycle Assessment

Kapitel i bok, 2021

This chapter presents the concept of inventory indicators, which are indicators assessed at the inventory level by aggregating inventory flows at the start of the impact pathway. Although the ISO 14040 standard prescribes that a life cycle assessment (LCA) should contain an assessment of environmental impacts, inventory indicators are frequently applied for assessing energy and water use, but sometimes also for assessing waste generation, land use, material use, and emissions. For energy use, the cumulative energy demand is probably the most common indicator, which considers all renewable and non-renewable primary energy. Other energy use inventory indicators consider only non-renewable, or fossil, energy, and some consider secondary rather than primary energy. For water use, common inventory indicators include water extraction (or withdrawal), water consumption, the blue water footprint, and the green water footprint. Contrary to midpoint and endpoint indicators, inventory indicators do not consider which potential impacts the aggregated elementary flows might have. Therefore, inventory indicators have the drawback of being simplified in terms of impact modeling compared to midpoint and endpoint indicators. However, inventory indicators also have benefits: they are easy to apply, easy to interpret, and can serve as proxy indicators for damage at the endpoint level. In particular, they can be used also in cases when midpoint and endpoint characterization factors are lacking. Because of these advantages, inventory indicators are foreseen to play a role in LCA also in the future.