How to visualize and interpret Life Cycle Assessment (LCA) results?

LCA results can help decision-makers identify and evaluate the environmental impacts of their processes. Effective visualization is crucial for accurate interpretation of LCA results and to derive the right conclusions. These sections here highlight common ways of visualizing results - how to read the charts and key things to note when trying to understand the results.

 

Image
Thumbnail
Source: https://constructsteel.org/solutions/life-cycle-assessment-report/

What does the graph show?

  • The diagram (Fig. 8) visualizes relative impacts in 9 different environmental categories for six different roof designs

  • Scale: Expressed in % for easier comparison across impact categories
  • The relative impacts are internally normalized
    • i.e. in the case of Abiotic Depletion and Ozone Layer Depletion the CS roof has the highest impact and impacts of other roof types are shown relative to the CS roof; in other environmental categories, the impacts of bitumen are used for normalization and impacts of all other roof types are shown relative to bitumen

What's the value of showing data in this format?

  • Provides an overview of several products and impact categories in one single graph

  • Allows us to identify which roofing system in comparison to others may have highest or lowest environmental impacts for a variety of environmental impact categories
  • Not only focuses on one environmental impact and shows whether the system that leads in one environmental category is also the most preferable in other categories e.g.; one option may perform fairly well in one environmental impact category but result in more negative impact in another category. This can allow us to identify potential trade-offs.

Points of interest:

  • It would not be possible to present the same information in absolute values because

    • they carry different units (Abiotic (fossil) depletion is measured in GJ, Global Warming Potential in tonnes CO2eq)
    • Even if they, have similar units such as kg they should not be put in the same graph because e.g. the impact on ocean eutrophication of 3 kg of Phosphate cannot be directly compared to the harmfulness of 3 kg of R11eq on the Ozone layer)
  • The graphic can be a bit misleading, since values are plotted in %, yet each environmental category shows additionally the unit in which the impact is measured (e.g. tonne CO2equ )