Just when concrete producers were getting familiar with sustainability-related acronyms two new ones are gaining popularity. They’ve already appeared in project specifications in California, and as of March 2013, they are included in the draft of LEED Version 4. They are EPDs and PCRs.
EPD stands for “environmental product declaration,” which is a Type III label (according to ISO 14025, regarding environmental labels and declarations). EPDs are similar to nutritional labels for food or Material Safety Data Sheets (MSDS), except they list a set of pre-determined environmental impacts for a given unit, such as a cubic yard, of the product. These labels list environmental impacts, but they don’t evaluate whether a product has a better or worse value in any given impact category.
EPDs are created from PCRs, or “product category rules,” that have two main purposes. First, PCRs set how a life-cycle assessment (LCA) is performed to determine the environmental impacts for a given product category, such as unreinforced concrete. This ensures consistency in procedures and interpretation of commonly used LCA standards (ISO 14040 and ISO 14044.
Second, a PCR establishes what environmental impacts and other information is reported in an EPD for a given product category. This ensures consistency in reporting.
In November 2012, the Carbon Leadership Forum (CLF) at the University of Washington released a U.S.-specific PCR for concrete — with input from the NRMCA. Then in February 2013, the World Business Council for Sustainable Development announced a new PCR for unreinforced concrete. These two PCRs were developed through the same ISO 14025-based process, and differ in one primary way: allocation of supplementary cementitious materials.
In the U.S., most of concrete’s embodied environmental impacts are produced during cement manufacturing. Supplementary cementitious materials are often used to lessen concrete’s environmental impact, because their environmental impacts are allocated to the primary products manufactured — steel (for slag) and electricity (for fly ash). In the WBCSD product category rules, the environmental impacts of slag and fly ash are allocated to the concrete.
If a specification requires an EPD, the concrete producer must follow these basic steps:
1. Research industry-average EPDs
Because EPDs are new to the U.S., many specifications and the current draft of LEED allow submitting an industry-average EPD rather than a company or product-specific EPD. If an industry-average EPD isn’t available or permitted, then a producer must create its own.
2. Contact a program operator
Not only does the program operator verify and create EPDs for concrete producers, it can also serve as a guide in the general EPD-creation process. Several entities serve as program operators, including ASTM, ICC-ES, NRMCA, and UL Environment.
3. Perform a life-cycle assessment according to a PCR (if needed)
If an LCA has already been performed on concrete mixes that require an EPD (according to the program-operator’s PCR), then the producer can skip this step. However, Type III EPDs are LCA-based, so an LCA must be performed before creating an EPD. Unfortunately, this is often the most time-consuming and costly part of the process.
4. Create an EPD
From the PCR-based LCA, the program operator creates an EPD. The program operator also ensures that an independent verifier reviews each EPD. Typically a fee is associated with one or both parts of this process.
According to Lionel Lemay, NRMCA senior vice president of sustainable development, “the concrete industry is uniquely positioned to [participate] in the movement toward transparency through EPDs, providing concrete with a competitive advantage over other building materials.”
In the U.S., most greenhouse gas emissions and other environmental impacts embodied in concrete are produced during the manufacturing of cement. Thus, it is common practice to use SCMs to lessen concrete’s environmental impact. This is due to how the environmental impacts of SCMs are allocated. In the U.S., environmental impacts due to steel production (for slag) or electricity generation (for fly ash), among others, are allocated to the primary product manufacture, steel or electricity, respectively. In the World Business Council on Sustainable Development’s product category rules (PCR), steel and electricity environmental impacts for the slag and fly ash are allocated to the concrete.