EPA must prioritize life-cycle emissions in building materials policy

In order to prevent global temperatures from rising by two degrees Celsius this century, the United Nations estimates that annual global emissions must drop by 30 percent by the decade’s end.

Meeting this urgent goal will be difficult for all sectors, even those which have a clear path to decarbonization. For instance, we know that we must transition the electrical grid to low carbon sources, and we must also transition land-based transportation to electrical sources.

But there are some sectors — particularly engineering materials production — for which the solution is more complex. In some materials industries, required processing temperatures are so high that electrification is impractical. In other industries, carbon plays a fundamental role in transforming ore into materials. For these sectors, climate innovation is ongoing.

Policy aimed at these sectors must drive materials with low lifetime carbon impact to market while fostering innovation.

In the U.S., a key policy tool is the government purchasing specification. The government is one of the largest buyers, if not the largest, of many materials. It can shape markets with its pen and pocketbook.

It is critical that we set up relevant policies correctly. The climate impact of materials does not stop at the factory gate, nor when they are put into service. The climate performance of products and systems relies on the materials used to construct them.

As a practical example, consider electric vehicles. High energy density batteries make these vehicles possible. While such batteries produce more emissions during their manufacture, the product they are used in has life cycle benefits over other vehicles. In shifting land-based transportation to lower-emitting energy sources, they offer long-term benefits.

The impact of materials can only be evaluated by considering their life cycle impacts: the emissions associated with materials from the cradle to the grave. Purchasing standards must account for the lifecycle to achieve climate goals.

The last year has seen legislation that allows the federal government to use purchasing to take a leadership role in the low-carbon transition. Sections 60503 and 60506 of the Inflation Reduction Act (IRA) provide over $2 Billion in funding for construction materials and products with “substantially lower levels of embodied greenhouse gas emissions” for the General Services Administration and the Federal Highway Administration. Embodied emissions are defined as those “associated with all relevant stages of production, use, and disposal.” This wording gets it right. Materials have environmental impacts across their whole life cycle.

The Environmental Protection Agency released an interim determination to comply with IRA rules which focuses “on reducing major industrial emissions from the production of U.S. construction materials and products.” However, in failing to consider use and disposal, it does not fully meet the goals of the IRA.

Lowering production emissions is a critical first step, but it is imperative that the EPA put into place now a process and timeline to characterize the life cycle impacts of materials. The IRA itself endorses this in its references to other systems. For example, Section 40007 outlines funding for sustainable aviation fuel which will “reduce or displace, on a lifecycle basis, United States greenhouse gas emissions associated with air travel.”

Materials in the built environment have significant life cycle impacts. Concrete sequesters carbon dioxide during its use and at end-of-life. Recent studies have estimated that this sequestration could range up to thirty percent of cement process emissions depending on the final form in which the cement is used.

Similarly, if we use materials to make our roads stiffer across the U.S., we would have the same effect as offsetting half a percent of our road transportation emissions. If we boosted the reflectance of our infrastructure by lightening pavements, we could cool our overheated cities and offset over 17 million tons of carbon dioxide each year.

When we choose a construction material without considering its life cycle impacts, we not only miss an opportunity to reduce use phase and end-of-life emissions, but we can unintentionally worsen them.

The IRA’s “buy clean” requirements provide a vision to reduce the environmental impacts of materials. The EPA’s interim rules are a pragmatic step towards realizing that vision. It is imperative that we do not stop there. Life cycle impacts must be included in the EPA’s rules specifying “low-carbon” construction materials.

We challenge the EPA to create a process with an aggressive timeline to apply life cycle impact models to their materials specifications. Within one year, we could have interim rules that extend these specifying rules to consider life cycle embodied emissions.

Within two years, we should have rules that define how whole life cycle analysis is used to guide materials specifying decisions.

Only then will we be able to guide towards solutions which are sustainable in every sense of the word.

Dr. Randolph Kirchain is the Director of the MIT Concrete Sustainability Hub, where Dr. Hessam AzariJafari serves as deputy director.