When it comes to reducing embodied carbon emissions in the real estate sector, developers can’t do it on their own: they must partner with outside stakeholders to influence elements over which they don’t have direct control, including supply chain materials manufacturers.
On September 26, 2023, ULI hosted its second ULI Embodied Carbon Convening, a follow-on to the January 2023 event, this time including developers, construction, concrete, and steel supplier industries at the table. On the concrete and steel side, participants included the American Insitute of Steel Construction, the American Iron and Steel Institute, Brimstone, Carbon Built, CarbonCure, Climate Group, Gerdau, Heidelberg Materials, Holcim US, Master Builders, Nucor, PCA, and Sublime Systems.
This convening intended to build stronger partnerships across the industry in reducing embodied carbon and enable accelerated advancement on sustainability improvements and beyond: forging new connections, identifying ways to cost-effectively reduce embodied carbon in concrete and steel in new developments, and inspiring further action in alignment with the ULI Mission Priority of net zero by 2050 for the building sector. As Ben Myers, senior vice president of sustainability at Boston Properties noted, “We’re moving from a commodity model [with suppliers] to a partnership model.”
Buildings account for an estimated 39 percent of global carbon emissions annually: 28 percent from building operations and 11 percent from building materials and construction. Embodied carbon refers to the greenhouse gas emissions resulting from the manufacturing, transportation, installation, maintenance, and disposal of building materials. While operational carbon has the potential to decrease annually over time with efficiency updates, there is no opportunity to decrease embodied carbon after a building is constructed. Over the lifetime of a building, embodied carbon from materials and construction can account for half of a building’s carbon emissions. This leads to the urgent need to address embodied carbon now, as global building floor area is expected to double by 2060.
The convening started with a level-set to debunk and discuss misconceptions around reducing embodied carbon, specifically regarding concrete and steel. Below are the takeaways from the discussions around each myth.
Myth 1: Stakeholders across the industry don’t know how to design/spec/install/ low carbon steel and concrete.
In some regions this is false, there exist experts across the value chain who know how to get low-carbon steel and concrete in developments. However, in other regions this is sometimes true; education hasn’t yet spread across the country. The US Inflation Reduction Act is releasing funds to address this and help develop Environmental Product Declarations (EPDs) for more products, the backbone of measuring low-carbon materials. An increase in embodied carbon policy and regulatory standards would accelerate actions for low-carbon materials usage. More accessible embodied carbon benchmarks would also help stakeholders understand and adopt low-carbon materials in developments, and the Carbon Leadership Forum (CLF) recently released a new set of material benchmarks to this effect.
Myth 2: Lower carbon concrete and steel materials cost more and always extend construction timelines.
In today’s market, in the U.S. there is not a premium for low-carbon steel; the U.S. currently has the cleanest steel market in the world due to the frequent use of electric arc furnaces for manufacturing, and while offshore steel can be cheaper, it almost always has higher embodied carbon. For concrete, there’s a mindset shift: by targeting a carbon budget instead of certain cement mixes, projects can use the right concrete in the right use cases and meet the timeline on budget. In general, teams must plan for lower carbon concrete from the beginning to factor in the correct cure times into the construction timeline. Also, enhancers and accelerators that reduce cure and reduce the cement in concrete are now available, which reduces the carbon content.
Myth 3: Reducing carbon content in concrete or steel reduces strength, durability, etc.
Steel is purchased based on clear indications of strength and durability requirements, regardless of the embodied carbon of producing the steel. With concrete, it is not an issue if teams are prioritizing quality control. There are also now admixtures and supplemental materials that can increase strength and decrease permeability of low-carbon concrete.
Myth 4: Low carbon materials are the only way to reduce embodied carbon.
Design optimization and smart use of space is also key. There is no need to oversize components like parking that require materials with high embodied carbon to be built. Other low carbon strategies include reusing materials, retrofitting buildings where possible, and designing for disassembly.
Myth 5: Low carbon design is the architect’s responsibility.
While it is partially the architect’s responsibility, stakeholders building the building also have a responsibility. Developers can have influence and lead by setting carbon targets for the architects and engineers to achieve. Life Cycle Assessment consultants can also be crucial partners as they assist with accurate data collection of the embodied carbon of materials and design of a project during its whole life. Urban planners can also make a difference when thinking about the embodied carbon that results from city sprawl, highways, etc.
Myth 6: Steel and concrete suppliers are not measuring the embodied carbon of their products.
More and more, steel and concrete suppliers have EPDs of their projects. However, in certain markets, this challenge is true and not a misconception. Some suppliers also prefer to use industry-average EPDs rather than product-specific EPDs. Even when suppliers do have EPDs, there are flaws in carbon accounting and there isn’t a consistent process for how to derive these numbers. The steel industry offers fewer products than the concrete industry, so better EPD coverage; projects ideally want an EPD per mix for concrete, and there are countless mixes available. Some real estate developers are getting ahead of this by engaging suppliers one year before the procurement RFP is released, to provide advance notice that they’ll be asking for EPDs and give suppliers time to create them.
There’s a huge opportunity for real estate developers/construction firms to partner more with concrete and steel suppliers to build relationships and accelerate decarbonization. Developers are also helping to bridge the education gap with suppliers, and if a supplier knows more than a developer, developers are learning to leverage them. Suppliers now have net zero goals too, and partnerships can help entities across the value chain achieve their respective net zero goals. Real estate is leaning on suppliers to have more product information regarding embodied carbon readily available in pursuit of ambitious goals that involve complete reductions in carbon from portfolios where possible. Research on new, innovative materials is also important to work toward eliminating any remaining cost premium for low carbon materials.
ULI is continuing to build on its existing embodied carbon work through reports, resources, and subsequent convenings, with our next embodied carbon convening planned for mid-2024. ULI will be releasing a report, The Materials Movement: Creating Value with Better Building Materials, which outlines the science behind material impacts on people and planet, makes the business case for better material choices, highlights strategies for reducing embodied carbon and improving material health in development, and showcases projects successfully addressing this issue. Register now for the ULI Materials Movement Webinar on December 1st at 12 pm ET.
