Dr. Chait Bhat, Ph.D., LCACP is the Sustainability Engineer for the Asphalt Institute.
In a previous edition, we discussed the systemic organizational improvements required to develop Product Category Rules (PCRs) and Environmental Product Declarations (EPDs) at the pavement-level considering the full life cycle. That June 2023 article focused on the importance of developing PCRs and EPDs from a holistic scope of “cradle-to-grave” covering the entire pavement life cycle and not just from a “cradle-to-gate” scope covering construction materials only.
As per the language in different federal and state Buy Clean policies, EPDs would be the go-to medium for assessing low-carbon materials among various types of construction materials. There is a widespread misunderstanding that EPDs can only be developed for the scope of cradle-to-gate while a Life Cycle Assessment (LCA) is most suitable to cover the rest of the pavement life cycle stages.
This article takes a step back and compares the steps/processes involved in developing just an LCA with the more rigorous processes required for developing an EPD. I will also discuss the relationship between an LCA and an EPD.
Formal process of developing a PCR
The fundamental methodology underpinning the development of EPDs is laid out in the ISO standards1,2. The first step for developing an EPD would be to develop a Product Category Rule (PCR). Let us look at the PCR process in detail.
A PCR provides over-arching rules (e.g., scope of products/services covered, data used to quantify potential environmental impacts) to develop EPDs. A program operator is an entity that oversees the development of a PCR and verifies EPDs. ISO Standard 219301 published in 2017 serves as the core PCR for all construction products and services. It includes a broad set of rules that apply to all construction materials like asphalt, concrete, steel as well as construction works such as pavements and buildings.
A program operator works with the industry of the construction material (product), upstream stakeholders (i.e., raw material producers, etc.) and downstream stakeholders (i.e., public agencies, etc.) to form a PCR Committee. This group oversees the development of a sub-category PCR which adheres to all the rules of the core PCR and provides specific information and rules pertaining to the individual product. For example, the Asphalt Institute has hired Smart EPD as program operator. SmartEPD has formed a PCR committee with twenty participants that includes asphalt binder industry stakeholders as well as external stakeholders such as the Environmental Protection Agency (EPA), Federal Highway Administration (FHWA) and many others. The committee will develop a sub-category PCR for asphalt binder that will then undergo a rigorous, formal and transparent public review process.
PCR needs an LCA
A third-party verified industry average LCA supports the development of a sub-category PCR. LCAs can vary in scope from “cradle-to-gate” (material extraction to production gate) to “cradle-to-grave” (material extraction to end-of-life). If there is already an industry average LCA, the PCR committee reviews the sufficiency of that LCA. If there is no LCA on that product, the PCR committee provides guidance for developing an LCA.
Development of EPD
EPDs can be developed for various scopes such as cradle-to-gate or cradle-to-grave, and various granularities (details) such as product-specific, facility-specific or industry-average. After the completion of the underlying LCA and the PCR, an EPD tool may be developed at an industry association level. Individual EPDs may also be published by different product manufacturers provided they adhere to the same PCR and underlying LCA. The EPD tool or individual EPDs are further subjected to review by the program operator and external reviewers to check for compliance with ISO standards 140252 and 21930, the sub-category PCR and the underlying LCA.
Difference between just an LCA and an EPD
The development of an EPD is a rigorous process that includes an LCA and PCR. If done properly, EPDs and PCRs require the involvement of diverse stakeholders and multiple external reviews that enhance the credibility of the EPD. In contrast, an LCA can be commissioned by a single organization and may be used for a variety of purposes with or without external review.
Consider an example where an agency has expressed an interest in quantitatively assessing the environmental sustainability of multiple pavement life cycle scenarios involving preservation, maintenance and rehabilitation strategies. Options include conducting only a pavement LCA study or to develop a pavement-level EPD. The key differences between these two approaches are described below.
Pavement LCA study: Coordinate with the agency stakeholder to establish assumptions such as treatment timing, expected performance, etc. and then perform the computations to calculate potential environmental impacts such as Global Warming Potential (GWP).
Pavement-level EPD: Develop a subcategory PCR and an underlying LCA by involving a program operator and a PCR committee made up of internal stakeholders such as multiple divisions within the agency as well as external stakeholders such as AASHTO/ASTM, industry and other agencies. Both the PCR and the underlying LCA would be subjected to third-party review as well as a public comment period. The outcome could be in the form of an EPD tool for the agency to conduct various assessments, or stand-alone EPDs, both subjected to third-party review.
LCAs that are not subjected to the PCR and EPD development process will go without an assessment by PCR committees involving internal and external stakeholders. This can lead to isolated decision-making, lack of standardization and higher subjective bias which could result in LCAs based on less reliable assumptions. Conversely, the PCR and EPD process would result in EPDs with enhanced credibility.
As associations develop cradle-to-gate EPDs for their respective materials and processes, the rigor of the EPD process should be extended to include the full pavement life cycle. Encouraging project-specific pavement-level EPDs and not just pavement LCAs will allow for interactions and review by a diverse group of stakeholders on topics ranging from the definition of pavement treatment scenarios to assumptions on the longevity of these treatments in an objective manner. This will support developing pavement-level comparable EPDs in a standardized and transparent manner.
1. ISO 21930, Sustainability in buildings and civil engineering works — Core rules for environmental product declarations of construction products and services, 2017
2. ISO 14025, Environmental labels, and declarations — Type III environmental declarations — Principles and procedures, 2020