Impact assessment in the PEF initiative

One of the goals of the Product Environmental Footprint (PEF) Initiative is to offer a standard for impact assessment, so it is easier and more meaningful to compare products. This is the story of how the initiative chose its recommended set of methods from among the huge number of available options.

An LCA study sometimes ends up including up to 2000 elementary flows, each with its own potential environmental impacts. These potential impacts are evaluated for magnitude and significance in the life cycle impact assessment (LCIA) phase, using one of a large variety of LCIA methods. Some of them are focused on a single issue, e.g. carbon footprint, whereas some encompass multiple environmental themes. Some measure the potential impacts at the end of the environmental mechanism (endpoint level), whereas others do it at the midpoint level. Some stop at the level of characterization and others choose to include the optional steps of normalization and weighting.

This range of available methods was a challenge for the European Commission’s Environmental Footprint initiative. It is vital to use a single impact assessment method since one of the objectives of the PEF initiative was to establish a way to compare environmental footprints. Which LCIA method should be used for environmental footprinting?

Baseline EF impact assessment method

Providing a recommendation for a single EF impact assessment method requires scientific research and extensive expert debates on each of the four steps of LCIA: classification, characterization, normalization, weighting.

Classification and characterization

The first two steps of LCIA are classification and characterization. In 2011, as part of the ILCD Handbook, the European Commission published Recommendations for Life Cycle Impact Assessment in the European Context. The document reports how existing impact assessment models were evaluated at midpoint and endpoint levels per impact category according to a set of criteria, including scientific qualities, applicability to LCI datasets, and stakeholder acceptance. The report’s recommended methods to use in the European context were adopted as baseline EF impact assessment methods for the PEF and organization environmental footprint (OEF). To reflect recent developments of impact assessment, the methods for a few impact categories were modified.

The chosen approach is a midpoint-level method, with a list of characterization factors that can be found here (version 2.0). For the EF Rules pilot phase, the baseline method is used with 16 impact categories. The table below shows the impact categories, the scientific studies used to determine them, and the units in which the impacts are expressed.

List of recommended models at midpoint, together with their indicator, unit and source. Highlighted rows: the differences compared to the PEF guide (2013).

Normalization and weighting

The EF pilot phase will use the European normalization factors listed here as the baseline, based on a 2014 technical report by the Joint Research Centre of the European Commission. The report describes the territorial production-based inventory for the European Union. PRé was involved in developing the accompanying database.

PEF Series - Classification - characterisation

In the EF pilot phase, the use of single scores is also being explored. To obtain single scores from a multi-impact approach, weighting needs to be applied.  The weighting set to be used was developed as hybrid evidence- and judgment-based weighting set that includes also aspects of the robustness of the results (the weighting report can be downloaded here and the weighting set here).

Strengths and limitations of the recommendations

Among the strengths of the recommendations, the following two can be named: 

  • Transparent and scientifically sound recommendations. The recommended models and characterisation factors are the result of a scientifically sound and robust study. The process of making the recommendations was designed to be transparent: there was public consultation and opportunity for interested stakeholders to provide comments and feedback.
  • Spatial differentiation available for some impact categories. Namely acidification, terrestrial eutrophication, land use and water scarcity – spatially differentiated characterisation factors are being used. This means that there are different characterisation factors per country, at least for the EU member states. For instance, for the role of airborne emission of ammonia in acidification, the difference between countries is almost three orders of magnitude.

On the other hand, the selection procedure also has some limitations:

  • Several of the impact categories received a low level of recommendation. They should be applied with caution, and may even need to be excluded while calculating a single score and testing communication vehicles.
  • Not all environmental areas are addressed by the default method.  Biodiversity, for instance, is not covered by default. Instead, each pilot explores the assessment of biodiversity and reports it as additional environmental information, e.g. with a proxy based on forest management systems by intermediate paper products.
  • Not all elementary flows are characterised, which makes it impossible to include their potential impacts. Chemicals are a typical example, as new chemicals are released to the market at high speed. To close this gap, the laundry detergents pilot is trying to characterise important detergent ingredients during the course of the pilot.
  • A common LCIA challenge is the mismatch between the LCI inventory and the LCIA method. This is also the case here. For the baseline EF impact assessment method, problems arise with the use of spatially differentiated characterisation factors. Many are still not used in current life cycle inventory databases. In my opinion, the accuracy and precision of the impact assessment method should be leading. 
  • In the pilot phase, the identification of the most relevant impact categories is done starting from the normalised and weighted results of each representative product or organisation. There are still extensive debates on the use of normalisation and weighting to define the most relevant impact categories. Damage modelling would considerably reduce this problem because it produces only three scores. However, the Commission has so far not adopted this alternative.

Future outlook

The field of life cycle impact assessment is evolving very rapidly. Many new characterization models have been developed since the recommendations were made in 2011. The EF pilots are aware of this: while the choices outlined in this article were an excellent first step in the direction of accuracy and standardization, the pilots aren’t standing still. Many are currently using alternative methods for sensitivity analysis.

The Commission is also aware of the progress being made. The European Commission’s Joint Research Centre is working on an update of LCIA methods on toxicity.

Learn more about PEF

If you want to learn more about our role in the PEF initiative, please contact us. See other episodes of this series:

Marisa Vieira

Director of Solutions

The time of the industrial revolution is over. Now it is time for the green revolution to go full steam ahead! Everybody needs to be involved in this process, therefore I aim to guide individuals and businesses in understanding the trade-offs between impacts. This will help them make informed decisions, which will truly help sustainable living thrive."

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