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Environmental Product Declaration (EPD): How to Read and Understand it

Sustainability is becoming a crucial consideration in construction. Engineers, architects and designers are increasingly turning to Environmental Product Declarations (EPDs) to help make informed choices for their construction projects. EPDs not only help in assessing the environmental impact of materials used in building projects but also provide insight into the wider lifecycle impacts of a product (through analysing the underlying Lifecycle Assessment). In this article, we will help you understand what an EPD is, how to read it and how to utilise the data to make sustainable choices.

What is an EPD?

An Environmental Product Declaration (EPD) is a standardised document that details the environmental impact of a product based on its lifecycle assessment (LCA), generally from raw material extraction through to disposal. EPDs are critical in the construction industry as they provide transparent and verified information that influences design and construction decisions for improved environmental performance.

Key Sections of an EPD

1. Product Definition

This section includes a detailed description of the product, its application, and its functional equivalence. Understanding this helps ensure the product meets the needs of your project.

2. LCA Parameters

An outline of the scope of the lifecycle assessment (LCA) including the system boundary, data quality, and assumptions made. These parameters define the limits/boundaries and reliability of the assessment. The boundary is a critical element that outlines if the product is being considered from Cradle to Gate, Cradle to Grave or Cradle to Cradle – essentially the extent of the lifecycle.

3. Environmental Impact Indicators

This section presents quantifiable environmental data such as global warming potential (CO2 emissions), ozone depletion, acidification, eutrophication, and resource depletion. These indicators help to compare different products and to choose the one with the least environmental impact. Typically, an EPD reports on 5 to 10 environmental impact categories. The number can vary depending on the product type, the standards applied, and the nature of the lifecycle assessment (LCA) conducted for the product. Some EPDs might provide more detailed breakdowns, including sub-categories within each major impact area.


Below is an EPD example for a Surface-treated steel screw for indoor use and a Surface-treated steel screw for outdoor use by Västsvensk Byggskruv. You can find this EPD here on the Environdec as well as several other EPD databases: Data (

This product has a declared unit (ie – per kg of steel), instead of a functional unit (ie - per screw). This is because the specific use case of the screws cannot be defined as there are many use cases. If the company wanted to, they could define a specific use and use a relevant Product Category Rule (PCR), or they may create their own PCR through the proper channels. Because there is no functional unit, this also means that emissions that arise from the ‘use’ stage will not be included as shown by the not declared (ND) in the ‘use stage’ below.

Table 1: Modules declared

In this EPD, they have reported on all requirements for construction products as per EN 15804 and the Construction products PCR rules: CONSTRUCTION PRODUCTS: PCR 2019:14. These are shown in the table below:

Table 2: Mandatory indicators according to EN 15804

It is best to refer to the details in table one to understand what module D is for example.

Module A1 is the ‘Raw materials’ section, it’s likely that they have used ‘background data’ to estimate this, and this will be provided from the ‘Ecoinvent’ database.

To an untrained eye, scientific notation such as 3.52E+00 of KG CO2-e can be difficult to interpret. The E+00 simply denotes the position of the decimal point; 3.52E+00, is simply 3.52 KG CO2 eq.

From looking at the Climate change total (Global Warming Potential) figure in column A1, this is made up of climate change fossil, climate change from Land use/land use change, and climate change ‘biogenenic’. From the notation of the E-03, and E–02 in the later we can see that the vast majority of GWP comes from fossil fuel origins. If all the transport and raw material processing was largely done with renewable energy, this climate change category may be closer to zero, but we may see increases in other categories, for example, an increase in ‘water use’ from hydro may also cause stagnation, which may lead to nutrient accumulation in reservoirs increasing the amount of eutrophication. It may cause an increase in Ecotoxicity as there is the potential for release of lubricants or other chemicals, and the accumulation of heavy metals or other pollutants in sediments) could have ecotoxic effects.  There may even be an increase in Climate Change - Land use and LU Change, which the construction of the hydro plant may contribute to. 

4. Additional Information

Some EPDs include information on the product’s impact on human health, ecological toxicity, and end-of-life stage.

5. Verification

This section confirms that the EPD has been independently verified, ensuring the data's credibility and neutrality. Verification can be internal or external, with external verification providing higher reliability.

How to Effectively Use EPDs

Through the collection of robust and verified information products can be compared and understood, not just in one environmental category, but many. 

  • Material Selection Use EPDs to compare the environmental impacts of similar products and select the one that best meets your project's sustainability criteria.

  • Design Optimisation Integrate EPD data early in the design process to influence architectural decisions, structural systems, and material choices that can significantly reduce the overall environmental footprint.

  • Compliance and Reporting Green building certifications in NZ, such as LEED, GreenSTAR, HomeSTAR and Living Building Challenge, require or reward the use of products with EPDs. Incorporating EPDs is beneficial in achieving higher certification levels.

  • Stakeholder Communication EPDs provide a basis for communicating the environmental impact of chosen materials to clients, contractors, and regulatory bodies, enhancing the project's transparency and credibility.

As the construction industry continues to advance towards sustainability, the role of EPDs is becoming more important. For engineers, architects and designers mastering how to read and apply the information provided by EPDs is essential for making environmentally responsible decisions. By embracing this practice, engineers not only contribute to global sustainability efforts but also add significant value to their projects.


If you want your team to get training on how to read and utilise EPDs, get in touch with us and we can organise a training session for you.


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