Environmental & Sustainability
Reducing
Embodied
Carbon
embodied carbon footprint–can be specified to replace a portion of the cement volume to create a more environmentally friendly mix. Likewise, similar opportunities exist within the production of steel members, which are fabricated using either a Basic Oxygen Furnace (BOF) or an Electric Arc Furnace (EAF). Of these two processes, the EAF is more environmentally friendly and “significantly reduces the embodied carbon footprint of steel compared to the BOF process,” said Post. According to Lauren Alger, PE, ENV SP, the first step for firms towards reducing their structural embodied carbon footprint involves specifying more sustainable ways to fabricate materials. Alger, the Director of Sustainable Design at STV, further adds, “SE 2050 provides extensive specification guidance for both materials and whole-building processes.” This includes strategies such as a general requirement to submit Environmental Product Declarations (EPDs) to evaluate and compare material footprints, or more specific directives and restrictions related to factors like recycled content or cement usage. More than “new building” approaches to reducing embodied carbon, Alger and Post believe that firms can make a conscious effort to reuse existing buildings or building components when projects allow it. Perhaps the most environmentally friendly option available, reuse projects avert the embodied carbon associated with new building materials as well as the demolition, removal, and post-processing of existing materials. STV is a leading firm in supporting reuse projects, having worked to support renovations and historic preservations of transportation, education, healthcare, justice, corporate, industrial, and other facilities. STV is also leading the way through their involvement in programs like the Structural Engineering Institute’s SE 2050 Challenge, which requires organizations to enact an embodied carbon action plan within
By Luke Carothers
It is no secret that the AEC industry is responsible for a significant portion of greenhouse gas emissions on a yearly basis. Building operations are responsible for 27 percent of the world’s CO2 emissions per year, with an additional 13 percent coming from embodied carbon within construction materials. Representing the emissions generated throughout the full life cycle of a material–including its sourcing, fabrication, installation, maintenance, and end-of-life phases– embodied carbon is a key factor to consider when trying to reduce the industry’s carbon footprint. To help reduce this outsized embodied carbon footprint, AEC firms can utilize material selection and data. When breaking down embodied carbon within new buildings, their structure can account for about 50 percent of their overall embodied carbon footprint. As the two most commonly used structural materials in the building industry, concrete and steel are the two primary embodied carbon contributors. According to Matthew Post, PE, Associate and Structural Engineer at STV , concrete is a significant contributor due to the carbon-intensive production process of its key component: cement. Post further adds that, despite making up only a small portion of concrete mixtures by volume, the manufacturing process of cement can account for up to 90 percent of the embodied carbon footprint of concrete. Steel, on the other hand, carries a large portion of buildings’ embodied carbon footprint due to the processes involved in extracting raw materials and converting them into usable steel. However, Post points out that, despite the high embodied carbon footprint associated with producing these two main materials with which we construct most of our buildings, there are opportunities to improve the environmental impact of these processes. For example, when creating concrete mixtures, fly ash or slag–which are natural byproducts of other manufacturing processes and have a lower
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csengineermag.com
October 2023
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