A road cannot have an environmental product declaration. Its cement can, its binder can, its aggregate can, and so can the mixture that leaves the plant, but the finished pavement cannot, and the reason is procedural rather than technical. Every declaration has to be written under a product category rule, and FHWA’s own pavement carbon methodology states in a footnote that no such rule exists for pavement life-cycle assessment in general, which is why the federal tool cannot generate pavement declarations even though it performs the underlying calculation.
That single fact governs most of what follows. The disclosure system that federal and state purchasing rules now run on is a system for describing manufactured products, and a highway is not one. What agencies are buying with these documents is confidence about suppliers.
What the document is, and which rulebook governs it
An EPD is a standardized disclosure of a product’s environmental impacts, based on a life-cycle assessment and published under rules set before the assessment begins. Colorado’s transportation department, which has had to define the term operationally in a policy that contractors are held to, describes it as a third-party verified document summarizing the life-cycle assessment of a single product and publicly disclosing its environmental impacts. The type that counts is Type III, which carries quantified data using predetermined parameters. The relevant standards are ISO 14025 for the declaration and ISO 21930 for construction works, with the product-level assessment performed under ISO 14040 and ISO 14044.
Almost all of these documents stop at the plant gate. The FHWA Sustainable Pavements Program states that most construction material EPDs in the United States carry a cradle-to-gate scope, covering modules A1 for raw material extraction and processing, A2 for transport to the plant, and A3 for manufacturing. What that boundary excludes, and why the exclusion matters more for a pavement than for a window, is the subject of how highway projects measure embodied carbon.
Facility-specific is a different claim from product-specific
The most consequential distinction in this field is the one buyers most often skip. Colorado’s policy separates three kinds of declaration. A facility-specific EPD attributes impacts to a single manufacturer and a single manufacturing plant. A product-specific EPD represents a product from one manufacturer that may be made across several plants. A supply-chain-specific EPD is product-specific and additionally models key upstream processes with supply chain data rather than generic averages.
California’s purchasing rule turns that taxonomy into an eligibility test. Under the Buy Clean California Act the declaration must be a facility-specific manufacturer declaration, independently verified against ISO 14025 and developed under the applicable product category rules, and the Department of General Services excludes industrywide declarations and fabricator declarations outright. Caltrans applies the same logic in the materials list it maintains for those products, requiring the declaration to be facility-specific and to represent a single location, to be developed under a valid and applicable product category rule, to state its validity period, and to be entered into the department’s materials data system under a designated project identifier.
An industry-average declaration and a facility-specific declaration for nominally the same product are answering different questions. The first describes a sector. The second describes a plant that can be inspected.
The federal test is a percentile, not a comparison
Section 60506 of the Inflation Reduction Act of 2022 gave FHWA money to reimburse the use of construction products whose embodied greenhouse gas emissions are, in the statute’s phrase, substantially lower than the estimated industry average for similar products. Congress left the definition of that phrase to EPA. EPA issued its Interim Determination on December 22, 2022, and its interpretation is worth stating exactly, because it is not the test most people assume.
A material qualifies if its global warming potential, taken from an EPD, sits in the best performing 20th percentile when compared with similar materials. If nothing in that percentile is available at a project’s location, the threshold moves to the lowest 40th percentile. If nothing in that band is available either, a product qualifies by being lower than the estimated industry average. Unavailability at each step has to be documented, explaining how the search was conducted and how the selected material was validated as better than the industry average for the applicable product category and region.
Nothing in that test compares a product with a competing design. Each one is scored against the distribution of its own category, and the fallback structure means the practical threshold in a thin regional market is the industry average rather than the 20th percentile, an outcome the policy anticipates rather than treats as failure.
The eligible categories are asphalt mixtures, concrete and cement, steel across a long list of shapes including reinforcing bars and cold formed framing, glass including flat and processed products, and assemblies made up of at least 80 percent qualifying material by total cost or weight. Where an ENERGY STAR energy performance indicator exists for the category, the plant’s current score has to accompany the declaration.
Two states, two lists
The two most developed state programs cover different materials, and for a highway agency the difference is the whole point.
Buy Clean California, at Public Contract Code sections 3500 to 3505, applies to structural steel, concrete reinforcing steel, flat glass and mineral wool board insulation. Asphalt and concrete are not on the list. DGS sets each limit at the industry average of facility-specific global warming potential for the material, the rule has applied to public works contracts awarded on or after July 1, 2022, revised limits took effect on January 1, 2025, and the next review is scheduled for January 1, 2028. A program that omits the two materials that dominate a road’s material mass is a building-oriented program that highway projects also happen to be subject to.
Buy Clean Colorado, enacted as House Bill 21-1303 in July 2021, was written the other way. Its eligible materials are asphalt and asphalt mixtures, cement and concrete mixtures, and steel, and the statute splits by asset class: C.R.S. 24-92-117 covers buildings, and C.R.S. 24-92-118 covers road, highway and bridge projects. CDOT’s policy took effect on January 1, 2025 and was revised that June to align with a standard special provision. Limits were set by benchmarking the EPDs published for CDOT materials between October 2, 2021 and November 18, 2024, and a contractor must obtain an EPD for an eligible material before it is installed. The initial collection effort applies at a $3 million project threshold, which the policy says may be lowered later, and CDOT states it may add module A4, which covers transport to site, to the emissions it counts.
New Jersey uses a third instrument entirely. Rather than limiting what an agency may buy, the state pays the producer: Form 337 of the state’s corporation business tax is a Low Embodied Carbon Concrete Tax Credit, and eligibility runs through approval by the Department of Environmental Protection followed by a credit certificate from the Division of Taxation. The qualifying judgment there sits with the environmental agency rather than the transportation department, which is a different administrative theory of the same problem.
What expires, and what gets an uncertainty factor
Colorado’s policy contains two admissions that most procurement documents leave out. EPDs typically expire after five years, so the benchmark data behind a limit value ages out and the limits have to be reissued. And uncertainty factors may be applied to the global warming potential figures shown in EPDs to account for data that is not facility-specific or supply-chain-specific, which is a formal way of saying that a generic declaration will be penalized relative to a measured one.
The limit values themselves are set under ISO 21678, and CDOT is explicit that they are limit values rather than targets: the highest acceptable level for a supplied material, covering modules A1 through A3 only.
What two declarations can honestly be compared on
FHWA’s methodology report sets out the cautions in a table of questions an analyst should ask before using EPD data, and the warning above the table is the strongest statement any federal document makes on this: discrepancies in the way EPDs are developed may lead to results that are not indicative of actual differences in the products. EPDs do not always contain the same impact categories and typically report a narrower set of indicators than a full assessment. The choice of upstream data sources within an EPD is often not specified in the underlying product category rule and is not harmonized between different rules. Comparability rather than measurement is the binding constraint on every disclosure instrument in the sustainability section.
So the questions worth asking of any two declarations are the ones the report lists. Who developed it, and is an industry average or a manufacturer-specific figure appropriate for the purpose. Which product category rule was used, and is it still inside its validity period. What is the declared unit, and how does it translate to the quantity in the project. What are the system boundaries. What years is the data from. Which impact assessment method produced the numbers, given that different methods calculate the same impact category differently.
Declarations written under the same rule, with the same declared unit, the same boundary and comparable background data can honestly be set against each other. Anything less is a comparison of paperwork. That constraint is why the federal program scores products against their own category distribution instead, and it is why the disclosure regime remains a supplier qualification system rather than a design instrument. The material-side arguments it is meant to settle are taken up in low-carbon concrete and in asphalt versus concrete. It cannot become a design instrument until somebody writes a product category rule for a pavement, and until somebody agrees to maintain it.