Quantifying Environmental Impact
PCRs and EPDs
All construction materials, including cement and concrete, have environmental footprints—the impact their production and use have on the environment. Product Category Rules (PCRs) and Environmental Product Declarations (EPDs) work together to help us calculate their potential influence.
PCRs
A Product Category Rule is a set of regulations, requirements, and guidelines that help us to define standards for a material. It also ensures that comparable data and analysis methods influence the development of similar products.
EPDs
An Environmental Product Declaration is a report developed using a PCR for a specific type of material. This independently verified and registered summary includes all environmental impacts of a material’s production.
Scope of PCRs
A PCR can look at the entire life cycle of a product or it can focus on certain portions of the life cycle.
A Truncated View
The PCR for cement offers a “cradle-to-gate” overview, which considers the manufacturing process but does not include how the material affects the environment beyond the production plant. As PCRs evolve and more information is known, it may be possible to include impacts beyond the manufacturing process.
Weighted Impact
Placing boundaries around the production process helps us to quantify the environmental effects of manufacturing. Some PCRs only include the impacts of making a specific amount of a material, such as one metric ton of cement.
Lifecycle Quantification
EPDs are developed using PCRs. They’re like the required nutritional labeling on food packages, which allow an efficient comparison of products. An EPD provides consistent, transparent information on a material’s broad environmental impacts.
An EPD conveys the environmental significance of the manufacturing process—but it does not quantify long-term impact.
Understanding cement’s full impact requires lifecycle assessment (LCA) of projects comprising the material. This would examine environmental factors such as:
- How cement is transported to a site
- Construction processes
- Service life of the built structure and repair or maintenance procedures
- Disposal or recycling of the material after a building’s use phase
Industry Average EPDs
Per governing standards, EPDs are only valid for up to five years but may be updated more frequently. Current industry average EPDs in the U.S. are based on the 2020 Cement PCR (NSF 2020) and were last published in 2021. They cover four categories of cement:
- ASTM C150 portland cement
- ASTM C595 portland-limestone cement
- ASTM C595 blended cements
- ASTM C91 masonry cement
The current PCR and industry-average EPDs for cement are linked below.
