EPD Comparability

EC3 aims to facilitate product procurement based on EPD reporting, with the acknowledgment that not all EPDs should be compared to one another when their calculation rules and assumptions are not the same. The table below outlines criteria that would ideally be aligned for EPDs before comparisons should take place. The “Treatment in EC” subsections describe how EC3 facilitates comparability in terms of these criteria. It is Building Transparency’s hope that future iterations of digital EPDs and PCRs will account for these criteria to facilitate more robust comparisons.

The rest of this section follows the following structure:

Criteria name Description | Treatment in EC3 | Notes

Criteria for Comparing EPDs

Scope

Includes the functional unit, product category definition, and period of validity.

EC3 converts EPD results to match the default declared units of each product category. The specification filters and options allow users to select EPDs with equivalent function as necessary for the application.

System Boundary

Includes the life cycle stages and modules included in the analysis. It is critical to compare data only when they have an equivalents system boundary.

EC3 focuses on facilitating procurement-phase comparions within product categories. While EC3 does collect EPD data on all life cycle stages, it only uses A1-A3 data from the EPDs when it comes to comparisons and statistics.

The assumption is that use phase replacement and end of life disposal of products in the same category is mostly equivalent (there are some exceptions).

When comparing across product categories, it may be critical to account for the life cycle stages that EC3 does not currently cover. It is up to the user to account for adequate replacement cycles and end-of-life disposal scenarios in cross-category comparisons.

LCI Background Data

There are several major life cycle inventory (LCI) datasets, which can lead to different EPD results.

Treatment in EC3: EPDs in the same product categories have identical declared units. The specification filters and options allow users to select EPDs with equivalent function as necessary for the application.

Data Quality

Collection of LCI data can be at a variety of levels of quality when it comes to the methods of collecting data (e.g. expert judgment vs direct measurement), selection of background data and it's relevance (geographical, temporal, and technological).

EC3: This may be treated in future versions of EC3 if data quality indicators are consistently found in EPDs.

Impact Assessment Method

There are a variety of impact assessment methods, each will provide slightly different impact assessment results.

EC3 applies an uncertainty factor to EPDs when the EPD has a different LCIA method than the user’s default LCIA method.

Many products result mainly in carbon dioxide emissions when it comes to carbon footprint (i.e., GWP) and the characterization factor for CO2 is always 1. Differences in reported LCIA methods matter mostly for non-CO2 dominated production chains, and for non-GWP impact categories.

Use Phase & End-of-Life (EOL) assumptions

EPDs should have consistent use phase and EOL calculations and assumptions for their life cycle impacts to be comparable.

Not treated in EC3 thus far. EC3's focus to date has been on enabling users to make procurement decisions within the same material categories, with the assumption that use phase replacement and end of life disposal of products in the same category is equivalent.

When comparing across product categories, it may be critical to account for the life cycle stages that EC3 does not currently cover. It is up to the user to account for adequate replacement cycles and end-of-life disposal scenarios in cross-category comparisons.

Allocation

Method by which input or output flows for a process is partitioned between product systems that are linked. Allocation methods should be the same for EPDs to be comparable. Some PCRs leave the choice of allocation to the discretion of the LCA practitioner (e.g. mass versus economic allocation).

Not treated in EC3 thus far.

Cut-off Rules

Cut-off rules enable LCA practitioners to conduct an LCA without having to model 100% of the system by omitting non-relevant life cycle stages, processes, and flows. Cut-off rules for EPDs should be the same for EPDs to be comparable. A common methodology is for a cut-off of no more than 1% of total energy consumption and 1% of the total weight of material from each process.

Not treated in EC3 thus far.

PCR Version

PCRs are usually updated every five years. If changes occur in the update, EPDs produced under different PCR versions may not be comparable.

EC3 keeps track of PCR versions so users can determine if two EPDs have the same PCR version or not.

Difference in PCR or PCR version does not necessarily mean that EPD data under other PCRs and versions cannot be aligned for a valid comparison of EPDs.