If concrete were a country, it would be the third highest in climate emissions globally — that’s how pervasive concrete is as a source of carbon emissions. Large amounts of carbon are emitted in the breaking up of limestone to make cement (a process known as calcination) and the heating up of cement kilns to very high temperatures. At Lendlease, we see not only the problem, but also the opportunity with concrete.
At Lendlease we believe the only way to take on big challenges is to take them on directly. We’ve set the industry leading target of Absolute Zero carbon across all scopes of emissions by 2040, including those related to construction materials like concrete. To meet this target, we’re taking action across a number of fronts, via pilots to reduce the amount of concrete we use and to decarbonize it where possible.
Low-Carbon Concrete Project Pilots
On development projects, where we oversee design and construction, we are working with our structural engineers to reduce the amount of overall concrete designed into our structures. For these projects, we require our concrete providers to give us environmental information before we award contracts to ensure that we are getting both the best carbon performance and that our suppliers can meet our cost plan.
We are also pushing beyond the typical way companies decarbonize concrete by replacing percentages of the cement in concrete with industrial byproducts such as slag and fly ash. Cement is the highest carbon-emitting component of concrete, so tackling cement emissions is critically important. Unfortunately, supplies of slag and fly ash are dwindling globally. Further, the US currently only makes about 79% of the cement it uses, so there is clearly a need for low-carbon, domestically produced cement to replace the traditional cements we use in concrete.
We are also working with new concrete mixes. For example, for a current project in California project, we have used an iterative LCA process to reduce the embodied carbon of the concrete mix design in partnership with our concrete subcontractor. Specifically, we’ve replaced 50% of the cement in the foundation, and 25% of the cement in the post-tension concrete decks with a common industrial byproduct called slag. In addition, we have partnered with ClimateWorks on a potential pour of an innovative ultra low carbon material elsewhere on the project. But, we need to go further.
Decarbonized Concrete Industry
Late-stage concrete startups in the US are creating competitive products to decarbonize concrete, and Lendlease is evaluating these materials. With Climateworks we are also working on additional innovative concrete pours on the West coast this year. As these products scale, we will be ready to use them as our clients demand more decarbonization.
Happily, Lendlease is in good company with our efforts. Many of the biggest buyers of concrete in the US are attempting to solve the same problem and collaboration across the market will accelerate a simple yet ambitious goal: making zero-carbon concrete ubiquitously available in America.
To get these companies to scale, we must prime the pump. These innovative yet proven concrete technologies have a short-term premium, and with cost concerns and no way to predict precise future demand volumes, the forward contracts these companies need to unlock project financing are difficult to execute. The companies need this capital to spin up their production processes to get to market rate, which we think can occur within the next 2-10 years, depending on the specific concrete alternative product.
We are working in coordination with other buyers of concrete to send a strong demand signal, such as spurring the collective use of performance-based specifications to try to help these companies get the financing they need to get to scale. Our hope is that a collective demonstrated demand can help these companies connect with the entities that can invest in that temporary price premium. That will enable the companies to reach the scale they need to fundamentally change how concrete is made in the US in the next ten years and enable us to meet our ambitious mission zero targets.
Future Outlook
We believe in a world where we use concrete to build the homes and hospitals we need without risking the health of our planet. Our customers, investors, and countless project stakeholders have joined our mission to absolute zero. But we can’t operate in isolation. It will take the work of countless construction companies, architects, structural engineers, investors, architects, developers, cement manufacturers, batch processors, and more to transform how concrete is made in the US. Please join us, and USGBC-CA, on our path to absolute zero.
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USGBC-CA NOTE: Please join your colleagues at the California Green Building Conference on May 23rd, which includes a Zero Emission Equipment (construction) panel at 11:15am.
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(posted 5/16/24)
About the Author
Sara Neff is Head of Sustainability for Lendlease America, where she is helping the company meet its ambitious goal of achieving absolute zero carbon across every scope by 2040 while creating $250 million of social value by 2025. In 2022 and 2023, under her leadership Lendlease earned the top residential score in the Americas on GRESB and multiple green leasing awards from the Institute for Market Transformation. Previously, she served as Senior Vice President, Sustainability at Kilroy, where she helped the company achieve carbon neutral operations in 2020.
She has been named a Heart of the Chapter of USGBC-LA, a Los Angeles Woman of Influence by the Los Angeles Business Journal, a 40 under 40 awardee by the Urban Land Institute, a Los Angeles Power Woman in Real Estate by Bisnow, a Women in Sustainability Leader by Green Building & Design magazine, a Woman of Influence by GlobeSt Real Estate Forum, and was the recipient of NAREIT’s 2020 Leader in the Light Leadership Personified award, an award that recognizes achievement in sustainability. She holds a BS from Stanford and an MBA from Columbia Business School. She is a LEED Fellow and holds a BS from Stanford and an MBA from Columbia Business School.
