Comparing Environmental Product Declarations (EPDs)

EPDs provide a wealth of information on a product's environmental impact, including greenhouse gas emissions, energy consumption, water use, and waste generation. This information can be used to compare the environmental performance of different products and to identify areas for improvement in product design and manufacturing processes.

EPDs are particularly useful in industries with high environmental impacts, such as construction, where building materials and products can have a significant impact on the environment. However, there are some pitfalls in their use that need to be taken into consideration.

Comparing EPDs from different product categories

EPDs that cover different product categories are not directly comparable because they often have different environmental impacts and methods for calculating those impacts. Different products have different characteristics and lifecycles, which can result in different environmental effects, making direct comparisons difficult.

For example, the environmental impact of a wall panel and a ceiling tile cannot be directly compared because they have different functionalities, and their manufacturing and usage phases have different environmental effects.

How do EPD’s assumptions influence the assessment?

Different assumptions made about the product's lifecycle or environmental impacts can also affect the results of the EPD. For example, assumptions about the energy mix used in manufacturing, the end-of-life disposal method, or the transportation distance can affect the EPD results. These differences can make it challenging to compare EPDs and draw valid conclusions about the relative environmental performance of different products.

Here's an example of some common assumptions that may be made when conducting an environmental product declaration (EPD) for a product:

  • System boundary: This defines the scope of the EPD, including which life cycle stages are included and which are excluded. For example, an EPD for a product might include the production, use, and transport but exclude end-of-life.
  • Functional unit: This specifies the quantity, or the service provided by the product that is used as a basis for comparison. E.g. square meter vs kilograms.
  • Data quality: Quality of data used in EPDs can be variable, including the accuracy, completeness, and representativeness of the data.
  • Assumptions about the product use: Assumptions could include how long the product is used for, how it is maintained, and how it is disposed of at the end of its life.

These assumptions can affect the results of the EPD and may need to be clearly defined and explained to ensure transparency and comparability.

How can we ensure EPDs are comparable?

To ensure the comparability of EPDs, it is essential to check that the methodologies and data sources are the same, and that the source used transparent and consistent reporting practices as well as clearly defined the assumptions made during the assessment.

Digital tools for comparing EPDs and assessing the footprint of an entire project (e.g. Prodikt) rely only on third-party verified data and also allow for comparison within product categories, facilitating users to make the most sustainable choice.

Read the article below to learn what to expect from a proper EPD.

Follow this link to access Ecophon’s EPD download centre:


Download our EPDs


Text: Douglas MacCutcheon, PhD. Global Concept Developer for Sustainability at Saint-Gobain Ecophon