EPDs in Steel 101(Part 2): How Do You Read an Environmental Product Declaration (EPD)?

Environmental Product Declarations (EPDs) are essential tools for construction professionals, providing the information needed to make informed decisions for specifying steel in construction projects. By offering transparent and standardized data on the environmental impacts of steel products, EPDs assist construction professionals in selecting materials that align with sustainability goals and regulatory requirements.

The information in this article is part of a three-part series and pertains to understanding and utilizing cradle-to-gate Type III verified EPDs. These EPDs align with ISO 14025 and 21930 standards and follow the North American Product Category Rule (PCR) for Designated Steel Construction Products, ensuring consistency and reliability in the data provided. All of Nucor’s EPDs are Type III verified.

Learn about the fundamentals of an Environmental Product Declaration here: EPDs in Steel 101: Part 1

EPDs provide necessary information to understand a product’s environmental impact throughout its lifecycle, making it essential to know how to interpret them to utilize the data effectively.

Understanding the EPD Categories

EPDs are typically organized into six standard categories, each offering critical insights into various aspects of a product's environmental profile based on a life cycle assessment (LCA). Understanding these categories is crucial for effectively interpreting and applying the data in your construction projects.

Why It Matters

Understanding these categories allows you to evaluate the environmental impacts of steel products, ensuring that material choices align with performance standards, project goals and sustainability requirements.

The six typical categories in an EPD include:

1. 1. Product Definition and Information: Details about the product, including its composition, intended use and technical properties.
2. 2. LCA Calculation Rules: The methodology and standards used for life cycle assessment calculations, ensuring transparency in the results.
3. 3. LCA Results: Quantified environmental impacts across the product's life cycle stages, specifically cradle-to-gate for most steel products.
4. 4. LCA Interpretation: An analysis of the results to provide meaningful, objective conclusions and insights.
5. 5. Additional Environmental Information: Supplementary data, such as certifications or material recovery potential, to support sustainability claims.
6. 6. References: Sources and supporting documentation to validate the EPD's accuracy and credibility.

Product Definition and Information

This section provides a high-level overview of the steel product and its context within the EPD. Key components include:

• General information: Includes manufacturer details, product description and a clear explanation of the declared unit.
• Program and operator details: Identifies the EPD program, program operator and relevant dates (including the issue date and period of validity), ensuring the information is third-party verified and current.
• Product-specific information: Covers intended uses, technical specifications, potential applications and market relevance, giving users insight into the product's function within a project.

Life Cycle Assessment (LCA) Calculation Rules

The LCA Calculation Rules section of a Type III EPD outlines the framework and methodology used to evaluate the environmental impacts of a product. It establishes the scope of the assessment, typically focusing on a cradle-to-gate approach (A1-A3 within the LCA), which includes raw material extraction, transportation and manufacturing. This standardized methodology ensures consistency across different products, using a functional unit such as "per metric ton of steel" to provide a reliable basis for evaluation.

This section also details the data sources, quality, geography and allocation rules, which clarify how environmental impacts are divided among co-products or shared processes, if applicable. Defining the impact categories, such as global warming potential (GWP) and energy use, provides a clear framework for interpreting the results (found in the following EPD sections).

Including assumptions, limitations and adherence to standards like ISO 14025 and ISO 14001 reinforces transparency and credibility, ensuring stakeholders can trust and utilize the data for informed decision-making.

LCA Results and Interpretation

These categories offer an in-depth examination of the quantified environmental impacts of steel products, specifically focusing on North American life cycle impact assessment (LCIA) results. To clarify, an LCA contains the overall data about the product’s environmental impact, the life cycle inventory (LCI) data is a list of all processes studied within the LCA and the LCIA is the data that showcases the specific impacts using a characterization model to input information into an EPD.

These results are essential for comprehending the broader implications of specifying sustainable steel for projects.

The following key indicators and metrics will be reported within an EPD upon completion of the LCA (the following impact category summary was created in partnership with Nucor and an LCA practitioner):

• Global Warming Potential, GWP 100 (kg CO2 eq)
  Global warming potential (GWP) refers to the measure of how much specific greenhouse gas (GHG) emissions contribute to an increase in the earth’s temperature in relation to long-running averages. In accordance with The Intergovernmental Panel on Climate Change (IPCC) recommendations, when calculating GWP, the standard time frame is based upon a 100-year time frame and represents the heat-trapping capacity of the gases relative to an equal weight of carbon dioxide, excluding biogenic carbon. An EPD could feature variations, like GWP including biogenic carbon or GWP including land use change, to showcase specific use cases.
• Ozone Depletion Potential, ODP (kg CFC-11 eq)
  Stratospheric ozone depletion represents the decrease of the protective ozone within the stratosphere caused by emissions of ozone-depleting substances (ODS), characterizing a product’s potential to destroy ozone based on a chemical’s reactivity and atmospheric lifetime.
• Acidification Potential, AP (kg SO2 eq)
  Acidification potential (AP) measures the potential of emissions that contribute to acidification in the environment, such as soils and bodies of water. It is primarily caused by the release of sulfur dioxide (SO₂), which reacts with water vapor and other chemicals to form acidic compounds, which can lead to harmful environmental effects, such as lowering the pH of the terrestrial ecosystem or causing corrosion damage to buildings and infrastructure.
• Eutrophication Potential, EP (kg N eq)
  Eutrophication occurs when excess nutrients (nitrogen or phosphorus compounds) are released into surface and coastal water, causing the rapid growth of aquatic plants or algal bloom. This often leads to low oxygen levels (hypoxia) in the water, resulting in biodiversity loss, including fish and other organisms. Additionally, the growth of certain algal species can result in toxic releases that negatively impact human health.
• Smog Formation Potential, SFP (kg O₃ eq)
  The smog formation impact category characterizes the potential of airborne emissions to cause photochemical smog, which occurs when sunlight reacts with NO_X and volatile organic compounds (VOCs), resulting in tropospheric (ground-level) ozone (O₃) and particulate matter. Potential effects of such smog creation include increased human mortality, asthma and loss of plant growth.
• Abiotic Resource Depletion Potential of Non-Renewable (Fossil) Energy Resources, ADP_fossil (MJ, LHV)
  ADP_fossil, also called fossil fuel depletion, measures the depletion of non-renewable fossil fuels (e.g., coal, oil and natural gas), because when these resources are depleted and resource quality declines, the cost and environmental impact of accessing the fossil fuels increases.

How Do You Analyze and Compare Construction EPDs?

EPDs are only comparable if they comply with the same document, use the same sub-category PCR where applicable, include all relevant information modules and are based on equivalent scenarios with respect to the context of construction projects.

For example, you can compare product-specific EPDs, such as one rebar EPD with another, but not across different product types. Due to the variables in LCA methods and other data calculations, cross-product comparisons are unreliable.

When you are comparing product-specific EPDs of the same product type, analyze the key impact categories and values for the most relevant environmental impacts that meet your project's specific needs. Also consider these additional details to enhance transparency and usability.

• Material composition and recycled content: Looking at the percentage of recycled materials used in the steel product provides insight into its sustainability and contribution to circularity. For example, steel made using recycled metal with EAF technology vs. steel made in a traditional blast furnace (BF-BOF). Learn about the two ways to make steel.
• Certifications and standards referenced: Verifications such as ISO 14025 or EN 15804 ensure the EPD aligns with recognized environmental reporting standards.
• Verification and validity: Identifying the third-party verifier and checking the validity period of the EPD (typically five years) ensures you are using accurate and current data.

Nucor: Dedicated to Transparency in EPDs

Nucor’s commitment to sustainability aligns with our dedication to transparency in our manufacturing processes. By sharing accurate data through tools like environmental product declarations, we enable customers to make informed decisions that align with their sustainability goals, foster accountability and drive continuous improvement.

Find information about our environmental standards and EPDs here: Nucor EPDs.

Have questions about sustainability for an upcoming project? Reach out to Nucor’s team of specialists today