I want to start this column by saying I am frequently surprised when we get a call from producers requesting EPDs that the first question is: “I have a big project coming and I need EPDs, can you explain what they are? And how do I get one?” This column will focus on what they are, so the many of you out there that have EPDs can stop reading now. For the sake of space, I’ll save the “how do I get an EPD” for a future column.
Overview
Environmental Product Declarations (EPDs) are increasingly important in the construction industry, particularly for materials like ready-mix concrete. This is because concrete is usually about 50 percent of the embodied carbon in a large vertical project and 90 percent in a horizontal (road product).
An EPD is based on and verified according to International Organization for Standardization (ISO; www.iso.org/standards.html) documents. Declarations are verified, specifically under the ISO 14025 and ISO 21930 standards, ensuring that the data presented is accurate and reliable. EPDs therefore provide transparent and comparable information (between products with similar performance criteria) about the environmental impact of a product.
Unraveling Comparability
Comparability is often misunderstood. For example, you cannot compare concrete to wood, but buyers can compare two 5,000 psi concrete mixes that are designed for the same purpose in a construction project. These mixes by definition will meet the same constructability requirements, and their environmental impacts will be comparable.
Carbon benchmarks such as those recently published by the U.S. General Services Administration set standards by strength class. This is an over generalization. Consider a 5,000 psi slab on grade mix versus a 5,000 psi suspended slab mix. The latter will require very high early strength. It will have a much higher portland cement content and a much higher carbon impact than the slab on grade mix. These challenges are being recognized by ACI CODE-323-24: Low-Carbon Concrete – Code Requirements (www.concrete.org; note this month’s Guest Editorial, page 6). With hats off to ACI Committee 323, the standard shifts the emphasis from the individual mix designs to the whole project’s weighted carbon impacts. This approach allows the producer to design mixes across the project, meeting constructability requirements while minimizing carbon across mix designs.
What EPDs Measure: A1-A3 Impact
EPDs for ready-mix concrete in North America measure the environmental impacts associated with the product’s life cycle stages A1 to A3, also known as “cradle-to-gate”:
- A1: Raw Material Supply. This stage covers the extraction and processing of raw materials used in the production of concrete, such as cement, aggregates, and admixtures.
- A2: Transportation. This stage involves the transportation of raw materials from their source to the manufacturing site.
- A3: Manufacturing. This stage includes the actual production process of ready-mix concrete, encompassing all activities within the plant.
The impacts measured in these stages include greenhouse gas emissions, energy consumption, water usage, and other environmental factors. By focusing on these stages, EPDs provide a clear picture of the environmental footprint of producing ready-mix concrete up to the point it leaves the plant. This range is a general standard for construction products, but also focuses on what producers can control: Raw material, supply chain and local energy consumed.
The Case for Cradle-to-Grave EPDs
While cradle-to-gate EPDs are valuable, some industry experts argue that cradle-to-grave EPDs would provide a more comprehensive assessment of a product’s environmental impact. Cradle-to-grave EPDs extend the analysis to include all life cycle stages, from raw material extraction (A1) to the end-of-life disposal (C4) and beyond, including the use phase (B1-B7). This writer’s view is that cradle to gate EPDs are a very practical choice because they measure with the exception of A4 (Transport to job site) everything that the producer can control or directly influence. That said, in Europe, stakeholders have chosen to take the more holistic approach and require cradle-to-grave EPDs, the benefits of which include:
- Holistic View. They offer a complete picture of the environmental impacts throughout the entire life cycle of the product, including use and disposal.
- Informed Decision-Making. Stakeholders can make more informed decisions regarding the sustainability of materials and products.
- Enhanced Transparency. They provide greater transparency and accountability for all stages of the product’s life cycle.
In the 80-100 year service life of a building, downstream impacts are difficult to estimate. Stages past A4 are influenced by various factors, including how the concrete is used in construction, maintenance practices, and end-of-life management. As a result, while cradle-to-grave EPDs offer a more comprehensive view, they also introduce uncertainties that can be challenging to accurately measure and manage.
EPD Requirements in Construction
While U.S. government requirements for EPD submittals will soften in the next four years, the demand for EPDs in construction is growing. This demand is driven by state regulatory requirements, cities, large builders, owners, and investors. It’s also unlikely that all of the world’s largest cement and concrete producers will pull back their commitments to Net zero by 2050 because of a U.S. federal policy shift—one that is transitory relative to the longer term investments required to make concrete the low carbon material of choice.
In conclusion, EPDs play a crucial role in promoting transparency and sustainability in the construction industry. By providing standardized and verified information about the environmental impacts of concrete, EPDs enable stakeholders to make informed decisions and drive improvements in environmental performance. While cradle-to-gate EPDs are currently the norm, the shift towards cradle-to-grave EPDs could offer a more comprehensive understanding of a product’s environmental footprint, despite the challenges associated with managing and accurately measuring downstream impacts.