Guidance For Modelling The Use Stage In The PEF Approach

For many product groups, the use stage can contribute much to the overall environmental impact. However, underlying modelling assumptions make it difficult to pinpoint exactly how much. Standardising the modelling approaches can greatly reduce the uncertainties in the calculated use-stage impact. The Product Environmental Footprint Category Rules (PEFCR) and Organisation Environmental Footprint Sector Rules (OEFSRs), developed by the Product Environmental Footprint (PEF) initiative, are assessment standards for all LCA practitioners. In this edition of the PEF series, we describe the PEF initiative’s guidance on the use stage.

By Laura Golsteijn on October 24, 2016

The PEF approach provides guidance on modelling the use stage in an issue paper called Guidance and requirements for handling the use stage in PEFCRs (De Schryver et al; Version 5.1 – January 2016). The issue paper addresses the definition of the use stage and provides guidance for modelling the use stage with the PEFCR and for reporting the use-stage results, including an example for dry pasta. I’ll walk you through these topics and the new terminology in the following summary of the issue paper.


What Is Included In The Use Stage?

As the name suggests, the use stage describes how the product is expected to be used by the end user or consumer. The use stage starts at the moment that the end user starts using the product and includes all activities and products needed for a proper use of the product. All waste produced during use is excluded from the use stage and considered part of the end-of-life stage. The use stage ends as soon as the product leaves the place of use and goes to the end-of-life stage. If the product is reused, then all processes required for the reuse are also excluded from the use stage. Examples of processes that are included in the use stage are shown in the figure below.






The figure illustrated how the use stage fits in with other processes in the life cycle, and provides examples of processes that are included in the use stage.


Within the use stage, you can distinguish product-independent and product-dependent processes. This distinction is relevant for the guidelines on reporting.


Product-independent processes

Product-independent processes have no relationship with the way the product is designed or distributed. Therefore, even if the producer decides to change the product’s characteristics, the environmental impacts from the use stage will remain the same for all products in this product category. Think about the energy use for boiling one litre of water when preparing coffee, or the washing machine required for the use of heavy laundry detergents.


Product-dependent processes

Product-dependent processes are determined or influenced by the product design, either directly or indirectly, or are related to the instructions for use of the product. Because product-dependent processes depend on the product characteristics, they can contribute to differentiation between two products. Examples of these processes include instructions on cooking durations, dosing instructions, and recommended serving or storage temperatures. An example of a direct dependent process is the energy use of electric equipment when used in normal conditions.


Guidance On Use-stage Modelling

Modelling of the use stage can be done in different ways, and each PEF pilot project chooses which method to apply to their LCA standard. The issue paper distinguishes the ‘Main Function Approach’ and the ‘Delta Approach’.


Main Function Approach

The PEFCR use the Main Function Approach if the processes of the use stage are related to the main function of the product and can be modelled fully. This happens, for instance, when modelling the total cooking time and related gas consumption for boiling pasta.


Delta Approach

Alternatively, it may be the case that the use of a product influences the environmental impact of another product. Think of, for instance, a rechargeable battery. The energy that is required by the charger when charging the battery is not determined by the amount of energy stored in and released from the battery. Instead, it depends on the energy losses in each loading cycle – which can be caused by the charger or the internal losses in the battery. Therefore, in such cases, the excess consumption shall be allocated to the product responsible for the additional consumption. The way to do this is to use a reference value for consumption, i.e. a minimum consumption essential for the function. Any additional consumption above the reference (the so-called ‘Delta’) is supposed to be allocated to the product responsible for the additional consumption.


The technical secretariat of each PEF pilot chooses the approach for their PEFCRs. If they choose the Main Function Approach, the default datasets presented in the PEFCR will reflect the reality of the market situation as much as possible. Of the PEFCR uses the Delta Approach, the reference value for minimum consumption will be given.


Guidance On Reporting The Use Stage Results

The issue paper provides a stepwise approach for the technical secretariats of the PEF pilot projects to develop guidance on modelling a product’s use stage in their PEFCR. There is good news for those who fear that most of the impact comes from the use stage, especially if the product can’t influence it or if there are large uncertainties associated. The guidance is that all results should be reported in two ways: once with all life cycle stages, and once while excluding the use stage. This way, you can still compare the impact from manufacturing and end of life, even if they are dwarfed by the use phase.


Several other reporting guidelines apply to all processes belonging to the use stage, both the processes defined as most relevant (see guidance Table D-1 for the requirements) and others. The PEFCR will:

  1. Indicate which use-stage processes are product-dependent and which are product-independent
  2. Identify the processes for which default data shall be provided.
  3. Prescribe for every process whether the Main Function Approach or the Delta Approach should be used.

Furthermore, the PEFCR communication section shall follow the preliminary reporting guidelines below.




Aligning The Final PEFCR And The Use Stage Guidance Paper

The issue paper by De Schryver et al. set out guidance and requirements for modelling the use stage. As the technical helpdesk for the PEF initiative, PRé has a close view on how these requirements are implemented. Earlier this year, PRé analysed how current PEFCRs/OEFSRs deviate from the requirements included in the by De Schryver and others, to learn from the implementation. Here are a couple of issues I’d like to flag.


More detailed process specification – From our analysis it appeared that, due to the level of aggregation of data, it is often unclear what the most relevant processes are. When the most relevant process is defined as, for instance, ‘washing’, does that that mean that ‘electricity for washing’ is the most relevant? Or are other processes, like the water or detergent used for washing, the most important? For the final PEFCRs/OEFSRs, we recommend that the pilots specify the processes to such a level that the data can be adapted to a specific product and that no more discussion is possible about the interpretation.


Better definition of the use stage – We also noted that the use-stage results are often not reported separately, although the use-stage paper states that they must be reported separately from other life cycle stages and not as additional information. In the current PEFCRs/OEFSRs, guidance for the use stage is often very fragmented or implicit. There is a high level of accordance between the use stage paper and the draft PEFCRs/OEFSRs. To align with the use stage paper, we recommend that the pilots define the use stage more clearly and follow the approved use-stage paper’s guidance in the final PEFCRs/OEFSRs.


Learn More About PEF

For more details and the example for dry pasta, I refer to the original issue paper. If you want to learn more about PRé’s role in the Product Environmental Footprint initiative and what it is doing in developing impact assessment standards, please send me an e-mail. See other episodes of this series:

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“I am eager to increase the environmental awareness of our society, and I believe that everyone can contribute to a more sustainable world, every day. At PRé we provide companies with both the knowledge and the tools to improve their products and services. I am excited to work for an organisation that is involved in developing sustainable initiatives.”

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