The golden opportunity in ESG may be tangible. Embodied carbon refers to greenhouse gas emissions associated with the manufacture, transportation, installation, maintenance, and disposal of materials. In buildings, there is carbon embodied “up front” during construction, and then carbon during operation, mainly from energy consumption.
Built-in carbon is especially important because it contributes more to climate change emissions during construction than the 30-year operational carbon from a typical newly constructed LEED-certified office building!
It is widely accepted that existing buildings generate about 40% of the world’s annual carbon emissions. Of that total, building operations account for 28% annually, and embodied carbon during construction accounts for a further 11% annually.
Concrete is the most widely used building material, with over 500 million tons produced annually in the United States. In fact, concrete is the most common man-made substance on earth. Therefore, it makes sense to repair the earth with concrete.”
Cement, a component of concrete, is also the single largest source of GHG emissions in buildings. It’s incredibly carbon intensive, just considering that limestone needs to be heated to 2700 degrees Fahrenheit to make Portland Cement clinker.
Translating all this into using it to build buildings is not for the faint of heart, even if someone understands that all this is explained in terms of “global warming potential”. It is also important that more than one-third of his concrete manufacturers are SMEs.
However, there is a very good solution for promoting concrete with a lower carbon content using EPD. An Environmental Product Declaration (EPD) is a way to quantify the environmental impact of a product. This is similar to nutrition labeling on cereal boxes. In the context of buildings, cradle-to-cradle EPD can provide a way to account for the environmental impact of construction materials or products. His EPD for buildings has gained more attention due to its use in green building codes, including LEED.
And this is already starting to happen concretely. Starting March 17, 2022, the U.S. General Services Administration has included requirements for EPD and low-carbon concrete (which reduces global warming potential by 20%) in new federal project requests. Maryland is studying the use of cradle-to-cradle EPDs for concrete and plans to issue a requirement in 2023.
Using an EPD is much preferable to trying a mandatory code language. We blogged the first law-required low-carbon concrete for Marin County statutes in 2020, but the trail has seen little traction in other jurisdictions.
The transition to low-carbon concrete presents potential challenges in terms of workability, especially finishability and pumpability, slow initial strength development, and availability of raw materials, but the industry needs to He says it can be treated with medication. In fact, early trials often report results equal to or better than straight cement mixtures.
Many people say that this is not a big change. Since 2015, the GSA standard states that “concrete ready mixes and site mixes must contain at least 15% fly ash or 25% ground granular blast furnace slag”. Also, in an effort to creatively promote the use of recovered waste (some of which was formerly regulated as a hazardous material), the EPA in January 1983 issued a Federal Register ban on Cement and Concrete Containing Coal Fly Ash, and issued guidelines designed to encourage the use of smelting by-products) have been used in concrete for over 100 years.
Given the incentive, the market will find ways to reduce the carbon footprint of concrete.
To optimize the amount of Portland cement required to meet design specifications, consider the design strength and cure time of the concrete mix. Longer cure times help reduce global warming potential!
Use a whole-building approach to “right size” building designs, reduce concrete use and maximize structural efficiency.
To reduce the carbon footprint of concrete by about 10%, replace traditional Portland cement with a blended cement such as “Portland Limestone Cement” (PLC, or “Type 1L” cement).
Use cementitious supplements such as fly ash, slag, and pozzolans from natural sources or recycled glass to reduce the amount of Portland cement in concrete.
Use admixtures containing carbon nanotube-infused concrete mixtures.
Reduce the clinker content of cement, such as “carbon mineralized concrete,” which uses retained carbon to improve strength and durability.
Select concrete from plants that have an Energy Performance Index (EPI) and meet the ENERGY STAR benchmark for industrial plant energy performance.
New legislation may not be the most effective way to drive change in concrete, but in an industry with a market value of over $400 billion a year (including easily achievable achievements), it will help us become better stewards of our planet. can be ) the carbon reduction strategies described above.
Concrete will never go away. The Romans were the first to build beautiful concrete buildings, some of which are still standing today, including his nearly 2,000-year-old Pantheon and Senate Building. (However, modern rebar-inserted concrete is mostly disposable, and much of it collapses in his fifty years or so.)
Concrete is undoubtedly a great building material that made possible Sydney’s iconic Opera House and the panoramic New River Gorge Bridge. That is why we need to address the negative environmental impacts of specific substances.
With 40 tonnes of concrete per person on the planet, and an additional one tonne per person each year, low-embodiment concrete represents a golden opportunity for ESG. Use it now to fix the world.
