Engineering the Acceptance of Climate Change Solutions

Our buildings are filthy—and not just in terms of whether they’re tidied by cleaning crews or not. According to the UN’s Global Status Report for Building and Construction, energy demand and emissions from the building and construction sector make up 20% of global emissions. In 2022, these divisions accounted for 37% of global operational energy and process-related emissions. Energy consumption also reached 132 exajoules, which accounts for more than a third of global demand. 

Its carbon footprint is still growing, too. While a one percent increase from 2021 to 2022 may seem small, that one percent is equal to 10 million more cars circling the Earth’s equator, according to the UN’s report.

Changing how we build things is just one challenge when it comes to addressing a climate-changed world. Not only are some of the most commonly used materials CO2 belchers, but getting people on board with emerging technologies may be an even harder feat than engineering the new solutions.

Concrete itself may be a solid material, but it’s also a lens through which we can view the myriad of challenges facing society’s ability to adapt to climate change.

A Carbon-Heavy, Popular Building Material

In many ways, concrete is an ideal building material. It’s cheap to make, easy to use, durable against intense weather and fire, and can be drummed up just about anywhere. With more than 30 billion tons of concrete consumed each year, it’s one of the world’s most popular building materials for a reason. It just works.

It’s also become an environmental disaster. About 8% of human-caused global CO2 emissions come from concrete production, according to a report from the Royal Institute of International Affairs. Beyond its production, there’s also transportation energy required, as it is often prefabricated off site. And outside of energy concerns, concrete production also takes up an estimated 10% of industrial water use.

Laura Dalton, assistant professor of civil and environmental engineering at Duke, doesn’t like to call concrete “dirty” because, she said, “Technically speaking, it’s extremely sustainable. The issue is that we produce so much of it. Anything produced at that large of a scale is going to have some footprint associated with it.”

Concrete is made by cooking limestone and clay to 1450 degrees Celsius (2640 degrees Fahrenheit), a temperature that requires burning a massive amount of fossil fuels. Building large structures with concrete also usually requires the use of rebar, typically made from steel, to reinforce it. Steel also has a “really terrible CO2 footprint,” Dalton added.

But unlike concrete itself, the ways in which we produce it and the ingredients we use are not set in stone. Progress on these fronts is being made, and if a solution is created—and widely adopted—it could allow our society’s ever-expanding physical footprint to leave behind a much smaller environmental one.

Engineering a Better Concrete Solution

Research into how to cope with concrete-related carbon is moving in several different directions, Dalton said. One is accelerated carbonation. Buildings will naturally sequester carbon over time, but it’s a slow process, and a building may only suck back in about 10% of what was put out to make it. Companies like Mutual Materials have created a process where CO2 is injected back into fresh concrete, where it’s converted into a solid mineral. The process both gets rid of CO2 and makes concrete materials stronger.

Another approach is to make the ingredients used in concrete greener. Research teams are working on making “living cement materials,” where algae creates the limestone used in concrete through a process similar to how coral grows its own limestone-like exoskeleton. Scientists have also been experimenting with other supplementary materials that can be put into concrete, including fly ash, which is a byproduct from burning coal. This line of research is not new, Dalton said, but it has its limits. “You can only replace so many ingredients and still get a useable product,” she said.

While these lines of research are helpful, in her opinion, the most promising work is coming out of two start-ups: Sublime Systems, which started at MIT; and Brimstone, which grew out of Caltech. “They’re getting at the source of the problem,” Dalton said.

They’re doing so by disrupting it. Right now, cement is typically made by mining materials like limestone, clay and gypsum, and then grinding it up in to a fine powder. It’s then heated to 1450 degrees Celcius in a cement kiln to break down the material’s chemical bonds to create new compounds. The new material, called clinker, is then ground down again, mixed with gypsum, and voilà: you have portland cement.

Both Sublime Systems’s and Brimstone’s tactic is to make cement with calcium-rich rocks instead of limestone, which accounts for 60% of the CO2 from making portland cement. This removes the primary source of carbon from the problem. Sublime Systems takes this a step further by using an electric chemical process to break and reform those bonds, skipping the need for a kiln altogether and removing the remaining source of the CO2 problem.

Some new technologies that have been developed to address climate change, like solar panels and electric cars, are becoming commonplace. But better concrete, and other decarbonized building materials, are not yet at that tipping point, said Dalton. Both Sublime Systems and Brimstone are relatively young start-ups and have not yet reached commercial success. “That’s really going to come back to policy and a point where economic considerations will have to give way to environmental ones,” she said.

The Challenge of Implementing Change

Even when an alternative, greener product works, not everyone jumps on board to adopt it. That’s an especially tricky issue with concrete. When something has worked just fine for a long period of time, it’s hard to see a reason to switch things up.

“We as people are used to doing things the way we do them,” said Sara Oliver, director of Duke’s Climate and Sustainability Engineering Master’s Program. When it comes to infrastructure, especially big structures like bridges and buildings, “people are used to seeing them look a certain way.” Why would someone change if it’s been working, especially when it’s what people feel comfortable and safe with?

Part of the problem is that engineers tend to be siloed off into their own entities instead of mixing with and collaborating with other experts—and, in many cases, their end users. One of Oliver’s first jobs as an engineer was working on a highway project being designed using decades-old traffic data. When she pointed this out, she was told that wasn’t her job and to focus on her task only. “For a lot of engineers, the job is just to do the design. You’re not supposed to ask questions. You do your design and you walk away,” she said.

When it comes to climate and sustainability, however, “we can’t operate that way,” Oliver added. The end user, whether it’s a government contractor looking to use decarbonized concrete or an ocean-front community that’s being told the federal government is going to build a seawall, must be part of the conversation. Decarbonized concrete may be as strong or even stronger than what’s being used right now, but that doesn’t mean people will believe statistics in a report; because if the old way works, why take the risk? “You need to bring those people along. You need to understand what their priorities and needs are when determining the risk profile as you’re designing a solution,” she said.

The Stubbornness of Change

Getting large groups of people on board with change will always be a challenge, especially as such issues are often pulled into muddy political waters. When New York banned pollution-spewing natural gas stoves in most new construction homes and buildings, the backlash was so strong that similar projects in other states failed. And other states went even further, passing bans on such ultimatums, including Florida, where 92% of homes already had electric ovens anyway, according to the U.S. Energy Information Administration.

While some of this pushback against climate change solutions is rooted in politics, a lot of it comes from a fundamental fear of change, the unknown and what’s involved in making big moves. “It’s thinking through how many current practices do you have to change to incorporate the new one?” said Rick Larrick, the Hanes Corporate Foundation Professor at the Duke Fuqua School of Business. “If all your current systems are organized to make this way of doing something work, sticking in something new is not as simple as it seems,” he said. “That becomes a very rational reason why people are slow to adopt to what seems to be, on the surface, a really good new way of doing things. But there are real costs of transitioning and integrating.”

Government investment can help, as is happening in building and construction, including in concrete. In the U.S., federal, state and local governments buy about half the concrete cast and poured. “Buy Clean” programs led by the federal government and 12 state governments are designed to use purchasing power to give a boost to cleaner and less carbon-intensive building materials and processes. The 2021 Infrastructure Investment and Jobs Act also earmarked $97 billion in funding to the U.S. Department of Energy to expand its existing pathways while also creating new ones for federal investments in research and development, demonstration, and deployment programs.

Putting money behind these efforts helps, as does redefining what the cost of carbon actually means. European countries have been pushing ahead with concrete alternatives, including 3D printed concrete. In February, a 6,600 sq.-ft, 3D-printed data center opened in Germany, the largest 3D-printed building in Europe so far. That’s possible in part because of how they value—or devalue—carbon, said Larrick. “They put a higher price on carbon,” which makes reducing its production more financially justifiable. “There’s also a basic desire to show that you’re acting on values shared by your voters and consumers,” he added, which is part of the “cost” to speed up a transition.

Incentivizing Community Members to Enact Change

Getting people to accept change, especially when it comes to climate, is difficult, but it has been working in one sector: dams, and the removal of them. What were once usually built for power, sometimes for small mills that no longer exist, are now dangerously falling apart and damaging fish populations and river health.

In 2023, 80 dams came down across the country, according to American Rivers. Overall, 1,160 miles of river have been reconnected for the benefit of river fish and wildlife. That doesn’t mean everyone in these communities just hopped on board. Eric Hutchins, fisheries biologist at the NOAA Restoration Center, has been working on dam removal projects for nearly 40 years. “They all balk,” he said, of every municipality he’s approached about taking down their dam. 

Part of that is inertia. Most often, dam removal wasn’t on a community’s radar. “In most towns, they’re just kind of like a curb on the side of the road,” he said. “Until there’s an issue, it’s not an issue,” like when someone drowns or the dam is due for a costly repair. 

When working with a community, Hutchins starts by striving to understand their feelings about the dam. “I respect that they like a dam socially and functionally in their memory,” he said. “Ecologically, I know that a free-flowing river is nicer, but there’s a lot of value in a pond behind my house.” 

He then looks for common ground in these values and what a dam removal project would mean. “You may have better fishing here in your river, nobody will die anymore due to safety issues, and there won’t be flooding around the dam,” he said. 

As important as this work is, the financial aspect is what usually pushes towns forward when a structure is deemed unsafe and would need millions of dollars to repair and maintain. “I wish I could tell you that of those 80 dams, 80 owners said they wanted to do the right thing for the environment. That’s not the case,” he said. “A high percentage of those 80 dams were removed because of money.”

In his time working for NOAA, he’s seen minds change as the effects of climate change become more apparent, prompting people to try something new, even if it feels uncomfortable—even if it still seems harder to make a change than stand pat.

The combined forces of finance and environmental justice could move the needle for building methods and materials, even if the financial part needs to take a bigger role, as it has for dam removal and the uptick in adoption of other technologies like solar panels, e-bikes and electric cars. Someone who doesn’t “believe” in climate change might make the switch if it’s just cheaper to do so.

“When I define sustainability, it’s a balance among equitable, environmental and economical practices,” said Dalton. “That’s how you really get at solving a global problem.”