Impact Categories for EPDs

An Environmental Product Declaration (EPD) is an independently verified document that provides transparent and comparable data on the environmental impacts of a product throughout its lifecycle. This article offers insights into Life Cycle Impact Assessment (LCIA) and the impact categories used in EPDs, highlighting their importance in evaluating and communicating a product’s environmental performance.

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What is Life Cycle Impact Assessment (LCIA)?

According to the ILCD handbook, Life Cycle Impact Assessment (LCIA) is the methodology for translating a Life Cycle Inventory into natural environment, human health, and natural resource impacts or Impact Categories. In a Life Cycle Assessment, the emissions and resources consumed to produce a specific product are compiled and documented in a Life Cycle Inventory. An impact assessment is then performed to understand the impacts in the categories being considered. These impacts may include climate change, ozone depletion, eutrophication, acidification, human toxicity (cancer and non-cancer related) respiratory inorganics, ionizing radiation, ecotoxicity, photochemical ozone formation, land use, and resource depletion. The emissions and resources are assigned to each of these impact categories and are then converted into indicators using impact assessment models. Different emissions and resources consumed, as well  as different product options, can then be cross-compared in terms of the impact indicators.

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What are common Life Cycle Impact Assessment (LCIA) methodology used in EPDs?


The CML methodology was developed by CML – Department of Industrial Ecology, Leiden University, Netherlands, aiming to provide best practice for midpoint indicators, operationalising the ISO14040 series of Standards. The CML-IA is a database that contains characterisation factors for life cycle impact assessment (LCIA), which is required by EN 15804+A1 standard. 


TRACI is an environmental impact assessment tool which provides characterization factors for Life Cycle Impact Assessment (LCIA), industrial ecology, and sustainability metrics and can be applied to processes, products, facilities, companies, and communities. This impact assessment method was developed to represent the conditions in the USA, and that is in line with the EPA policy. 


In 2021, the European Commission proposed the Product Environmental Footprint (PEF) as a common way of measuring environmental performance. The PEF is the EU recommended Life Cycle Assessment (LCA) based methods to quantify the environmental impacts of products (goods or services). Tools, documents and packages related to the Environmental Footprint scheme is provided in European Platform on LCA | EPLCA. For all required impact categories according to the EN15804+A2 standard, the characterisation factors from EF reference package shall be applied. 

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EPDs using different LCIA methodologies, what do you need to know?

Incomparable results

EPDs utilising various Life Cycle Impact Assessment (LCIA) methodologies can yield different results for the same Life Cycle Inventory (LCI). For instance, even though TRACI and CML both report on some indicators with similar units, these are not directly comparable. In some instances the differences are minor, however this is not always the case and sometimes they can be significant. This variation arises because each LCIA methodology employs distinct information regarding impact categories, indicators, characterisation methods, units, and characterisation factors.

In the example below, we investigate an INTERFACE modular carpet EPD which reports the impact based on both TRACI and CML. The GWP impact appears similar when measured in the same unit. However, the ODP and EP indicators differ in both units and impact. In CML, the indicator is called Photochemical Ozone Creation Potential (POCP), while in TRACI, it is referred to as Smog Formation (SFP). Additionally, CML reports on Abiotic Depletion Potential (ADP) for elements, a metric not included in TRACI.

In another example, we look into Stevenson ready-mix concrete EPD, which reports impact based on both CML (EN 15804+A1) and PEF (EN 15804+A2). The impact results are noticeably different, mainly due to the new reporting categories and the changed reporting units. For more information, please refer to this support post: Updated EPD Standard: EN 15804+A2.

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Considerations in using EPDs in a LCA study – Take Care When Comparing

There are several considerations to keep in mind when using EPDs in your LCA study, as these can vary on a case-by-case basis. Below, we share some insights and recommendations.

1/ Compare EPDs to EPDs

  • EPDs of construction products may not be comparable if they do not comply with a standard or if they are produced using different Product Category Rules (PCR).
  • EPDs within the same product category but from different programs or utilising different PCRs may not be comparable

2/ Compare generic data to EPDs

  • As mentioned above, LCIA methodology employs distinct information regarding impact categories, indicators, characterisation methods, units, and characterisation factors. When comparing generic data to EPDs, do pay attention to the difference, in particular the reported impact categories, indicators, and units. 

3/ Using EPDs with different methodology in a LCA study

  • For LCA studies that align with European Standard: EN 15978 and rating schemes that require alignment to EN15978, we recommend using product EPDs that are verified to be compliant with EN 15804 standards to ensure the results are comparable, consistent, transparent.
  • For LCA studies that do not adhere to any specific standards or rating schemes, you may consider using various EPDs that apply different methodologies in your LCA study, however caution should be used when interpreting the results it is recommended that a sensitivity analysis is conducted before drawing any conclusions. 

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