On Sept. 19, New York's Gov. Kathy Hochul announced the adoption and release of mandatory rules establishing greenhouse gas emissions limits on concrete for most state-funded public building and transportation projects. The National Ready Mixed Concrete Association, the New York Building Congress and several environmental groups support the action, which takes a gradual approach to lowering embodied carbon in concrete on state projects.

“Adopting Buy Clean Concrete Guidelines marks a monumental step in our journey towards a more sustainable and eco-friendly New York State,” Gov. Hochul said during the announcement. “By setting mandatory emissions limits on concrete used in state-funded projects, we're not just leading by example but creating a tangible roadmap for reducing greenhouse gas emissions across the board."

The guidelines also support Gov. Hochul’s Leading by Example Executive Order 22, under which state agencies are required to collect New York-specific data for common construction materials, including the ubiquitous concrete. For concrete, the data will be used to tighten the state's initial requirements for greenhouse gas emissions (GHGs) from production.

The initial mandatory emissions limits, measured in kgCO2e, are based on 150% of the National Ready Mixed Concrete Association's regional baselines, equivalent to 150% of the average emissions for concrete mixes in the Eastern region. That means the state’s reduction targets are less strict than those established by the global warming potential (GWP) benchmark mixes of NRMCA, which has been collecting data from its members since 2014.

“New York state set targets slightly more lenient than ours as a way to encourage more participation and get more data so they can develop [lower-emission] benchmarks specific to New York by January 2027," says Lionel Lemay, NRMCA’s executive vice president of structures and sustainability, who was involved in the development of the state's rules. “After many discussions, I’m convinced they probably did the right thing.”

The state’s guidelines apply to state agency contracts exceeding $1 million that involve the use of more than 50 cu yd of concrete, or New York Dept. of Transportation contracts exceeding $3 million that include at least 200 cu yd of concrete. The guidelines include exceptions for emergency projects and those requiring high-strength or quick-cure concrete and do not apply to state authorities. 

The mandatory limits will go into effect starting on Jan. 1, 2025. The guidelines require environmental product declarations (EPDs) for all mixes to be used on state construction projects, according to Georgina Parsons, associate commissioner for communications & media in the state Office of General Services (OGS), which is administering the program.

Maximum Global Warming Potential (GWP) Limits for Low Embodied Carbon Concrete
(relevant for Phase 1 and Phase 2)
Specified compressive strength (f'c in PSI) Maximum Global Warming Potential Limits for Low Embodied Carbon Concrete (kilograms of carbon dioxide equivalent per cubic yard - CO2e kg per cu yd )
0 - 2500 275
2501 - 3000 302
3001 - 4000 360
4001 - 5000 434
5001 - 6000 458
6001 - 8000 541
These limits reflect 150% of the Eastern Region average GWP figures from the National Ready Mix Concrete Associations’ “A Cradle-to-Gate Life Cycle Assessment of Ready-Mixed Concrete Manufactured by NRMCA Members – Version 3.2 “(Jul 2022), page 62


NRMCA benchmark mixes represent average designs from each region in the U.S. and a national average design. There are nine mixes per region, six with normal weight aggregates ranging from 2,500-psi to 8,000-psi compressive strength, and three with lightweight aggregates from 3,000 psi to 5,000 psi.

In 2021, NRMCA reported a 21% reduction in concrete’s carbon footprint since 2014, when it started collecting data for its benchmarks. The group established its benchmarks by surveying members about plant operations—mostly energy use—and materials they use to get an average of environmental impacts, including GWP. The group publishes benchmarks periodically on its website in a document called the LCA and Benchmark Report. The benchmarks represent the average of impacts for different concrete strengths. The next report is due out in the middle of next year. 

“New York simply took our benchmarks and multiplied them by 1.5 to basically make the benchmarks higher to include more producers in the process,” says Lemay. “If you simply went off of our benchmarks, which are averages, then in theory, 50% of the producers might be above the benchmark and eliminated from participating on projects,” he explains.

The state's "relatively easy-to-achieve carbon footprint targets" in the first and second phases of the program are 50% above the averages set by NRMCA, explains Lemay. In the third phase, starting in 2027, the state will set more aggressive goals by lowering the limits based on the earlier data collected. The more-aggressive goals “will begin to ratchet down the average carbon footprint of concrete,” says Lemay.

The state program’s three phases are: 

Phase 1: Voluntary concrete GWP limits and EPDs. Between Jan. 1, 2024, and Dec. 31, 2024, contracts for relevant projects will ask for the EPDs of concrete mixes, where available, and use the EPDs to compare against New York State’s voluntary concrete GWP limits. 

Phase 2: Mandatory concrete GWP limits and EPDs. Starting Jan. 1, 2025, New York State’s voluntary concrete GWP limits above will become mandatory limits. Between Jan. 1, 2025 and Dec. 31, 2025, contracts for relevant projects will require concrete mixes procured to certify a GWP lower than the state’s GWP limit in the relevant compressive strength category, in the form of an EPD, and require additional certifications as required by each agency.

Phase 3: Revised mandatory concrete GWP limits and EPDs. Starting Jan. 1, 2027, or at an appropriate date, New York state will revise (lower) the mandatory concrete GWP limits (see chart above for current limits).

Partnership Developed Guidelines

Following Gov. Hochul’s signing of State Finance Law §136-d, which called for these guidelines to be developed, OGS partnered with the New York State Energy Research and Development Authority and convened a stakeholder and expert group to help develop the guidelines. The group included state agency and authority officials, among them the Dept. of Transportation, Dept. of Environmental Conservation, the Metropolitan Transportation Authority and the Port Authority of New York and New Jersey, which has its own guidelines.

The group also included licensed professional engineers, licensed registered architects, representatives of the construction industry, representatives of an accredited school of civil engineering, and knowledgeable sources from think tanks, nonprofit environmental organizations and academia, says OGS.

The guidance enacts several recommendations from New York’s Climate Action Council Scoping Plan, including those for making embodied carbon transparent and adopting lower carbon specifications for high-intensity materials for state projects. It also implements recommendations to identify carbon intense materials and develop standards for reducing the environmental impact of building materials, according to OGS. 

New York reports it is on a path to achieving a zero-emission electricity sector by 2040, including 70% renewable energy generation by 2030 and economy-wide carbon neutrality by mid-century. This includes investing more than $35 billion in 120 large-scale renewable and transmission projects across the state, $6.8 billion to reduce building emissions, $3.3 billion to scale up solar, more than $1 billion for clean transportation initiatives and over $2 billion in NY Green Bank commitments, according to OGS. 

These and other investments are supporting more than 165,000 jobs in New York’s clean energy sector in 2021 and over 3,000% growth in the distributed solar sector since 2011. 

Other jurisdictions that have adopted rules to lower the carbon footprint of concrete include New Jersey, Pennsylvania, Colorado and Denver, Maryland, Portland, Ore., and Marin County, Calif. Many others are in the process of adoption, including California, Connecticut, Minnesota and Massachusetts. States that have so far rejected such rules include Washington and Hawaii. 

With the U.S. General Services Administration, the Federal Highway Administration and other agencies "setting targets for concrete and other materials, likely more states will follow,” says Lemay, who doesn’t see any problems with concrete producers meeting the mandates.

He adds that the governmental policies "will take years to have an impact, but by setting a target most companies are going to say, ‘I can beat that, I want to satisfy my customer!’