Comparing Environmental Product Declarations (EPDs) is a powerful way to support life cycle assessment (LCA), procurement decisions, and sustainability reporting. However, EPDs can differ widely in how they are verified, how specific their data is, and what standards they follow. This guide explains the different types of EPDs, how they are created, and how to compare them effectively.
What is an EPD?
An environmental product declaration (EPD) is a document that transparently reports the environmental impact of a product or material throughout its lifecycle. EPDs support carbon emission reduction targets by making it possible to compare the impacts of different materials and products in order to select the most sustainable option for buildings or infrastructure.
A third-party verified EPD is usually valid for five years and is generated according to relevant standards. Construction EPDs are based on the ISO 14040/14044, ISO 14025, EN 15804, or ISO 21930 standards. The environmental impacts are assessed according to specific Product Category Rules (PCRs), which ensure consistency and comparability across similar products.
Different Types of EPDs
EPDs can be categorized in two ways: by the specificity of the data (how precise the product source is) and by the verification method (how the document was approved).
1. By Data Specificity
When selecting materials, the stage of your project often dictates which type of EPD is most suitable.
Industry Association EPDs: Most suitable for early design stages. These are developed by an industry association and cover an average product produced by multiple companies operating in the sector and region (e.g., VDZ in Germany or Mineral Product Association in the UK).
Individual Company, Product Average EPDs: Most suitable when the manufacturer is identified but the specific product composition is uncertain. These represent an average of a group of similar products produced by one manufacturer across one or more plants.
Individual Company, Product and Plant-Specific EPDs: These represent a specific product produced from a specific plant. This represents the highest level of precision as it normally reflects what was actually used in a specific project.
2. By Verification & Application
EPDs also differ in how they are verified for validity.
Third-party Verified EPD: The most widely recognized type, published by an EPD program operator and verified by an independent party in compliance with ISO 14025. These are accepted by almost all regulations and valid for 5 years.
System Verified EPD: These are automatically generated for large numbers of products by a verified system. While the system is verified, the individual documents are not manually checked, which can raise transparency concerns. These are common for products like ready-mix concrete.
Project EPD: Created for a specific contract or tender. These are non-published documents verified internally rather than by external operators. They allow for scaling EPDs without the cost of external verification for every single declaration.
Third-party verified EPD — for any purpose
Third-party verified EPDs are the most widely recognized type of EPD, they are required by many regulations and certification schemes and accepted by almost all. As well as being third-party verified in compliance with ISO 14025, they are published by an EPD program operator and can be used for almost any purpose. A third-party verified EPD is valid for 5 years unless the parameters change.
Some EPD program operators offer Variant EPDs that are based on an already published third-party verified EPD. Variant EPDs must be similar to the third-party verified EPD they’re based on; they must be manufactured using a similar process, from similar raw materials, and for a similar function. This type is also in compliance with ISO 14025.
Project EPDs — for contracts & tenders
Project EPDs are created for a specific project or contract. They are non-published documents verified internally by designated qualified personnel or through a company’s established quality management processes, rather than being reviewed by external program operators or made publicly available. Project EPDs facilitate the scaling of EPD adoption without the expenses associated with third-party verification for each declaration. Although Project EPDs comply with ISO 14025, they are distinctly marked as “Internally Verified” to clarify their verification status. Some program operators assign shorter validity for Project EPDs.
System verified EPDs — for EPDs at scale
Automatically generated EPDs for a large number of products which are generated by a system on-demand, meaning the individual documents themselves are not subject to direct verification, but the process or system generating them has been verified. The verification is done on the system that produces the EPDs, ensuring that it meets certain criteria. However, this means the final document itself is not necessarily individually checked or verified. The need for scalable EPD solutions, such as system verified EPDs, has arisen due to the growing demand for environmental documentation in the construction industry. However, system verified EPDs raise concerns around transparency since these automated systems don’t always provide the same level of scrutiny as traditional, manual verification processes. These documents are widely used in building LCAs for certain product categories, such as ready-mix concrete.
For an EPD to qualify as third-party verified, the verification process must clearly indicate that the final EPD document has been reviewed and approved by an independent verifier. System verified EPDs don’t always meet this criterion, which could be an issue for certain certifications or standards that require explicit third-party verification. To ensure your EPD is third-party verified make sure to always check that the verification statement clearly mentions that the final document has been viewed and verified by a verifier. In traditional third-party verified EPDs, a third-party verifier confirms that the life-cycle assessment (LCA) and the EPD document conform to standards (ISO 14025, EN 15804).
Important Note on Verification: To ensure your EPD is third-party verified, make sure to always check that the verification statement clearly mentions that the final document has been viewed and verified by a verifier. In system verified EPDs, only the generation process or method will be noted as verified, as shown in the example below:
The EPD Development Process
The development of EPDs is a multi-stakeholder process involving four key parties:
The Manufacturer: Responsible for collecting all primary plant data (e.g., raw materials, logistics, utilities).
The LCA/EPD Consultant: Manages the process and uses the manufacturer's data to develop LCA models compliant with standards (e.g., EN 16757 for concrete).
The Third-Party Verifier: An independent verifier who reviews the final drafts and results to ensure compliance with standards.
The EPD Programme Operator: An independent institution that publishes the verified EPD and ensures adherence to standards through control and training.
How to Read an EPD
EPDs provide valuable insights about a product’s environmental performance at a glance. To effectively compare different EPDs, or to go through the most important information, you should focus on these five key points:
Key Sections of an EPD
Most EPDs cover the following six standard areas:
General information: Manufacturer details, product description, reference standards, and EPD scope.
Product lifecycle information: Which lifecycle modules (A1-A3, etc.) are covered.
LCA methodology: The method used to assess the life cycle.
LCA background information: Data quality assessment and result interpretation.
Environmental impact data: The core data table showing emissions and impacts.
Verification statement: Confirmation of the EPD's accuracy and validity.
The 5 Key Points to Focus On
To effectively evaluate an EPD, focus on these five specific elements:
1. Reference Standards
The reference standards ensure that the EPD is produced using reliable, recognized methodologies. Construction EPDs are based on ISO 14040/14044, ISO 14025, EN 15804 (versions EN+A1 or EN+A2), and/or ISO 21930.
In the example EPD below, you can find this information under EPD Standards, Scope, and Verification:
2. Period of validity
This ensures that the environmental impact data provided is up-to-date (typically valid for 5 years for third-party EPDs). After this period, the EPD should be reviewed or updated.
3. Verification
Verification adds credibility, confirming that a third-party organization has reviewed the data and processes. Some certification schemes require third-party EPDs, whereas some accept internally verified versions as well.
4. The Environmental Data Summary
This section provides key information about the product’s impacts:
GWP-total, A1-A3 (kg CO₂e): Measures the total carbon footprint contributing to climate change.
GWP-fossil, A1-A3 (kg CO₂e): Focuses specifically on emissions from burning fossil fuels during production.
5. Declared Unit
Found under the product description, this is the reference point for measuring impact (e.g., "1 kg of concrete" or "1 cubic meter"). It standardizes the data so that impacts are compared on the same basis.
Comparing Different EPDs
Manufacturers, architects, and engineers often need to compare EPDs to choose products with the lowest environmental impact. To make a fair comparison, avoid these common pitfalls:
1. Varying Declared Units
Issue: EPDs may use different declared units (e.g., per m² vs. per kg), leading to incorrect comparisons.
Example: A floor tile EPD declared per m² vs. a carpet tile EPD declared per piece.
Solution in One Click LCA: Convert declared units to a common functional unit using the tool's built-in unit conversion features.
2. Functional Unit vs. Functional Relevance
Issue: EPDs present impacts per declared unit, but real-world use may require comparisons based on performance.
Example: Comparing insulation materials per kg instead of per unit of thermal resistance delivered.
Solution in One Click LCA: Define functional units that reflect actual performance requirements (e.g., thermal resistance, load capacity) and adjust quantities accordingly.
Compare the life cycle impacts on the LCA tools on Construction material page to include full life cycle impacts to your comparison. If you only want to compare manufacturing emissions, Material Compass is the easiest tool to do the comparison.
3. Scope of the EPDs
EPDs might report different life cycle stages and impact categories based on the standards they follow:
Cradle-to-gate (A1-A3): Covers extraction of raw materials to manufacturing.
Cradle-to-grave (A1-C4): Covers lifecycle, from extraction to disposal.
Cradle-to-cradle (A1-D): Covers the entire lifecycle, includes possible End of life benefits, such as recycling at the end of life.
Issue: EPDs might report different life cycle stages (Cradle-to-gate A1-A3 vs. Cradle-to-grave A1-C4).
Example: One EPD covers disposal (C4) while another stops at manufacturing (A3).
Solution in One Click LCA: Pay close attention to the EPD version filters or use generic assumptions to cover missing life cycle stages (e.g., C module scenarios based on the market).
4. Impact Assessment Methods (LCIA)
The environmental impact categories vary depending on the reference standard the EPD is aligned with. Common categories include:
Global Warming Potential (GWP)
Ozone Depletion Potential (ODP)
Acidification Potential
Eutrophication Potential
Photochemical Ozone Creation Potential
Issue: EPDs may follow different LCA standards (e.g., EN 15804+A1 vs. EN 15804+A2), which affects how impact categories like Global Warming Potential (GWP) are calculated.
Solution in One Click LCA: Avoid mixing A1 and A2 EPDs directly. Ensure you compare comparable impact categories with similar units. In case you compare EPDs following different standards, ensure that you compare comparable impact categories with similar units and check the background assumptions (for example for bio-based products on how biogenic content has been declared) to avoid inconsistencies.
5. Differences in Product Composition or Performance
Some products might have different expected lifespans and performance expectations. Comparing them on a per-year basis (e.g., GWP over 50 years of service) can provide a clearer picture, especially if one product lasts significantly longer.
Issue: Products may serve the same function but differ significantly in durability or lifespan.
Example: A composite wood panel vs. a solid wood panel with different lifespans.
Solution in One Click LCA: Utilize the service life inputs to account for differences in product lifespan and replacement cycles.
Other relevant considerations:
System boundaries
Understand what is included in each EPD. Some may cover additional or fewer processes, such as transportation, energy use in operation, or end-of-life disposal.
The system boundary should be consistent to ensure all aspects of the product’s lifecycle are accounted for similarly.
In One Click LCA's building and infrastructure tools, it is possible to use some typical regional scenarios to cover missing life cycle impacts or to make a fair comparison according to specific standards.
Data quality and sources for the EPD
The EPDs can be made with different background data (life cycle inventory). Primary data (from actual manufacturing processes) is generally more reliable than secondary data (from databases or literature). Products with well-documented, high-quality data are easier to compare accurately. You can find this information in the 'LCA background information' section.
Geographical and temporal differences
Geography can influence the environmental impact of a product (e.g., energy mix in manufacturing locations or transportation distances). Similarly, temporal differences (the year the data was collected) matter, as technologies and regulations change over time. Where necessary, apply regional loclisation factors or prioritize EPDs that match your project location and time frame.
Material composition and recyclability
Consider the materials used and their potential for recycling or reuse. A product with a high environmental impact during manufacturing might offset this by being highly recyclable or having a long lifespan.