Ask precast concrete products manufacturers about concrete strength, water-to-cementitious ratio or air content, and they immediately can provide accurate details.
Ask for a product’s global warming potential and expect a puzzled look.
While strength, durability and cost remain important numbers for specifier selection criteria, global warming potential (GWP) likely will soon join that select group.
Case in point: Starting July 1, the Colorado Department of Transportation is requiring GWP data in the form of type III product specific environmental product declarations (EPD) for precast concrete products – one of many authorities requiring the data.
Regulations and transparency
Sustainability-related initiatives and regulations are nothing new. Demand for this has ebbed and flowed for decades. Some affect precast concrete manufacturers, specifically those who supply to building construction projects.
Precasters supplying to the underground infrastructure sector typically avoided these regulations, but those days are over. The tide is coming in fast, and it is targeted at underground and transportation infrastructure products.
There is a growing push asking for increased transparency and newfound limitations on the sustainable impacts of construction products. In December 2021, significant progress was achieved. That is when President Biden signed Executive Order 14057, titled Catalyzing Clean
Energy Industries and Jobs Through Federal Sustainability.
This order focuses on five primary goals, including one most significant for the precast concrete industry: net-zero emissions from federal procurement no later than 2050, including a Buy Clean policy to promote use of construction materials with lower embodied emissions.
The key word within this initiative is “carbon.”
Carbon emissions. Low-carbon materials. Carbon footprint. Embodied carbon. We have all heard these terms, and there is no doubt this chemical element is the target.
To be precise, the target is carbon dioxide, the primary greenhouse gas (GHG) that traps heat in the atmosphere.
Carbon and other gases, including methane and nitrous oxide, absorb heat at different rates. GWP measures how much energy the emissions of 1 ton of a gas absorbs over a given time relative to the emissions of 1 ton of CO2. The larger the GWP, the more a gas affects the Earth’s temperature compared to CO2. GWP of a given material is expressed in equivalent kilograms of CO2 or kg CO2 eq.
CO2 is naturally present in the atmosphere, but human activities continue to add a considerable amount. The combustion of fossil fuels – such as coal and natural gas – and fuel-burning transportation are the main contributors of human generated GHGs.
Industrial processes such as cement production also contribute, primarily from two sources: fuel combustion to heat kilns and calcination, a chemical reaction resulting from heating certain raw materials.
Cement production often is mentioned when discussing industrial emissions. However, when considering only industrial processes, it is far from the greatest source. According to a 2020 Environmental Protection Agency study, cement accounts for less than 3% of U.S. CO2 emissions, well below other materials such as petroleum (21.8%), chemicals (22.2%) and iron/steel (9%).
Nonetheless, through its inherent use of cement, concrete has become one of the main targets in Buy Clean legislations and related regulations.
Government authorities obtain information on a construction material’s GWP through a standardized report that has been around for many years: the environmental product declaration – or EPD.\
Who is requiring EPDs?
On a federal level, the U.S. General Services Administration (GSA) was the first government entity to implement GWP-related standards. In March 2022, a memorandum issued by the GSA announced the implementation of new national standards for low embodied carbon concrete and environmentally preferable asphalt.
The new standard calls for contractors to provide product-specific cradle-to-gate Type III EPDs for each concrete mix design specified in the contract and used at the project. The requirements apply to all GSA projects that use at least 10 cubic yards of concrete. Precast is not specifically mentioned in the language.
On a state level, the aforementioned Colorado DOT currently is requiring type III product-specific EPDs for concrete used on projects with an estimated cost of $3 million or greater. Precast concrete structures such as manholes, pipe and box culverts will be added to that requirement on July 1. California, Washington, Oregon, Massachusetts and Georgia have similar policies in place, and more states are close behind.
On a county level, King County, Wash., wrote its 2020 Strategic Climate Action Plan with commitments for specifying low-carbon materials in the county’s capital projects. That plan specifically mentions concrete. This year, the county will require EPDs for concrete. By 2024, it will require a maximum global warming potential for all concrete products.
The ABCs of EPDs
The first step in getting a plant- or product-specific EPD is to conduct a life cycle assessment (LCA) of the facility’s processes and products. This assessment takes data supplied by the manufacturer and converts it into impacts. The data is taken from a 12-month period, usually the preceding calendar year, and is broken down into three main categories:
- Product. Quantity of materials used from cement to reinforcing to form release to water. This also includes the amount of products that are manufactured at the precast facility.
- Energy. How much energy is consumed to make the final precast structure? From electricity to power the plant to the fuels used in the fork trucks.
- Waste. How much waste is generated during the manufacturing of the precast structure? This includes wastes sent to landfill, recycling facilities and incinerators.
The resulting LCA report can be long and complex, so an EPD serves as a summary for all or specific products breaking down the data to the essential information jurisdictions are seeking. Life cycle assessments are written according to certain parameters and conditions that are laid out in another document – a product category rule (PCR).
A PCR addresses specific products and is created and maintained by a committee. There are PCRs for reinforcing steel, cements, ready mix concrete and precast concrete.
EPDs are defined by International Standards Organization 14025 as “quantifying environmental information on the life cycle of a product to enable comparisons between products fulfilling the same function.”
Think of an EPD as a nutrition label, such as one on a cereal box that defines serving size and amounts of calories, fat and sugar. This enables a consumer to compare different products based on dietary impacts.
In a similar way, an EPD is a standardized list that defines a product in terms of volume or weight unit along with environmental impacts such as acidification, smog creation potential and global warming potential.
With nutrition labels, dieters may focus specifically on one indicator, such as calories. With EPDs, jurisdictions most often are interested in global warming potential over other indicators.
Not all EPDs are the same
There are different types of EPDs. Type II EPDs are self-declared and require no verification. Type III are third-party verified EPDs, and those are required within the construction industry.
Within Type III, there are varieties based on scope.
- Industrywide EPDs. In 2015, NPCA partnered with PCI and CPCI to create industrywide EPDs based on information supplied by members of all three associations. Representative North American EPDs were created for three categories: underground products, aboveground structural and architectural/insulated wall panel.
- Facility-specific EPDs. These are based on data from every product manufactured in one plant or a group of plants owned by the same company in one geographic location. Depending on product diversity and manufacturing methods, multiple facility-specific EPDs would be needed. For most NPCA members, one EPD should cover all products.
- Product-specific EPDs. These are the gold standard. Based solely on data from a product’s materials and manufacturing, this EPD covers multiple sizes for manholes, box culverts sound walls, etc., as long as the functional unit is based on cubic yards or tons of concrete used.
Type III product-specific EPDs predominantly are required by jurisdictions.
Life cycle assessments and EPDs also are written for specific stages of a product’s life cycle. For precast concrete, that assessment summarizes raw materials extraction and manufacturing, shipping materials to a facility, manufacturing, storage, shipping products to a job site, installation, usage and disposal.
The life cycle of a product is divided into four main categories:
- Product stage
- Construction process stage
- Use stage
- End-of-life stage
The phases under a manufacturer’s control end at the time a precast product ships. Once in the contractor’s hands, a precaster has no official “control” over its installation, use and end of life.
That is why scope is cradle-to-gate, meaning the precast facility’s gate. Impacts are measured from raw material extraction and manufacturing to storage.
The omission of these later stages in a precast product’s life cycle leaves out the most sustainable attributes of precast concrete:
- Local availability. Reduced transportation compared to alternative material products.
- Ease of installation. Reduced site impacts and schedules.
- Durability. Length of use phase that far exceeds other materials.
- Low maintenance. Related to durability but lowers impact related to repair and replacement.
- Resilience. Holds up to natural and man-made disasters better than other materials.
- Carbon uptake through carbonation. Natural process when concrete reacts with CO2 in the air and removing it from the atmosphere. (Can absorb 100% of the CO2 emitted due to calcination in the cement manufacturing process for the amount used in the product.)
- Recycling. Precast concrete structures can be crushed and recycled at end of life for other uses.
Why would precast concrete manufacturers not include the most relevant stages in concrete’s sustainable performance? Unfortunately, these later stages are not in the manufacturer’s control.
But be assuaged. The intent is not to use EPDs to make material choices. It is to gather data, benchmark and to foster improvement.
Getting an EPD
If all of this sounds daunting so far, fear not. While the process of getting to a final verified EPD involves many parties and processes, NPCA is prepared to assist members through every step. The process starts with getting a life cycle assessment conducted on an entire precast facility.
Even though EPDs may only be required for certain products such as manholes or retaining walls, all products made at the facility must be considered for the assessment. NPCA can guide members to third parties who require data to write the assessments.
NPCA already has an EPD survey created on an Excel format to help members gather the data. NPCA members also have access to an on-demand video presented by Emily Lorenz, an independent consultant and expert in LCAs and EPDs. Lorenz provides background and goes through the steps on the spreadsheet to enter the appropriate data.
Chart 2 below is an excerpt from the spreadsheet. First, total tonnage of precast products produced in 2022 is entered in the appropriate categories. These categories are defined on the first page of the spreadsheet. Yellow cells indicate where data must be entered.
For this example, the plant makes retaining walls and architectural fence panels as well as utility, stormwater and sanitary structures.
For one of the cements, the plant used 200 tons, and it was delivered by truck from a cement plant 89 miles away. The 200 tons is entered along with the distance under the appropriate mode of transport. All other cements used also must be included.
This plant uses electricity from the grid as well as gasoline, diesel and some heavy fuel oils.
Once all data is entered, the third-party service writes the life cycle assessment. Once that is done, EPDs are written using the same software. The EPD must then be verified by an approved third-party verifier. Some product-specific EPD software can be preverified.
Once the EPD is verified, it is ready to be submitted to the contractor or authority. The good news: EPDs are valid for five years.
Not over yet
Once an EPD is written and submitted, work is not over. Most jurisdictions, including the Colorado DOT, are just looking for disclosure at this point. There is no failing grade. Just submit your numbers. However, by 2025, the policy dictates that CDOT must establish a benchmark based on the accumulated data since 2022. That means products will have to be at or below certain global warming thresholds.
The General Service Administration skipped the data gathering and went straight to the benchmark. For a standard mix concrete with a specified compressive strength from 4,500 to 5,499 pounds per square inch, the maximum GWP per 385 kg/m3 CO2 eq. (648.94 lbs/yd3 CO2 eq).
How will facilities measure up to these benchmarks? They won’t know until they figure out where they are now. It’s like stepping on the bathroom scale.
Precast manufacturers may have to evaluate their production process and see where they can trim impact. Strategies include buying local when possible, enhancing production efficiencies, implementing plans for energy reduction and cutting down waste. Along with helping a product qualify for a Buy Clean policy, this also could save the plant on costs. Getting an EPD written is the first step in a significant facility improvement.
Having an EPD in hand also could lead to expanding markets. These policies will evolve from simple disclosure of product GWP-related information to targeted reductions to qualify that product for use.
Precast concrete is positioned to take advantage of these requirements since mixes can be modified to reduce GWP by using numerous strategies, including use of supplementary cementitious materials (fly ash, slag), admixtures to lower cement demand, carbon capture and other evolving technologies. Competitors to precast concrete such as steel and plastic are not as easily modified to reduce GWP.
Some work up front that could pay off in many ways. Regardless of where legislation is in your state, get started now and gather the data.
Claude Goguen, P.E., is the director of outreach and technical education at NPCA.