There is a lot of buzz happening in the structural engineering community around reducing carbon. Engineers are being asked by clients what they are doing to reduce embodied carbon in their structural designs. However, when I speak to structural engineers, many are not clear what their role is to play in reducing carbon. If they deliver a “good” structural design that is efficient and well-coordinated, won’t that do its best at reducing carbon? This is a good question and I wanted to elaborate on this topic in more detail.
But first, let’s review what embodied carbon is and why it is important to the structural engineer.
As a primer for structural engineers exploring the topic, I suggest they read this recent Embodied Carbon Guide published by Hines. Written in partnership with carbon experts from Magnusson Klemencic Associates, it explains what embodied carbon is and related concepts (like GWP and EPD) and why embodied carbon is important to the AEC industry as a whole. It also provides insights into carbon contributors by construction material (steel, concrete, timber, etc.) and methods (material creation vs construction site), which are important for structural engineers to understand.
From a structural perspective, embodied carbon is the carbon released into the atmosphere through the production and construction of the structural materials that are used. As a structural engineer who designs all types of structural systems including concrete and structural steel, it is staggering to see how a typical engineer impacts the global carbon footprint. With a few back-of-the-napkin calculations (see Footnote below), I estimate that structural engineers have a 1000+ fold carbon footprint impact compared to the average global citizen. This is from just the engineering decisions they make around steel and concrete.
Footnote:
*Assumptions: 350,000 structural engineers globally (Zippia, Statistics, US Labor & Bureau Statistics), 8 billion global citizens, 51 Gigatons of annual CO2 emissions (Gates, 2021), 3 Gigatons of CO2 emissions impacted by structural engineers (51 Gigatons * 15% from steel & concrete * 40% of steel and concrete designed by structural engineers)
*Avg global citizen carbon footprint: 51 GT / 8 billion = 6.38 tons per person
In other words, structural design decisions have a much greater impact on carbon emissions compared to making everyday decisions in our personal lives like what type of car we drive to work or how we heat our homes. Therefore, it is important for structural engineers to be educated about what they can do, even if minor. If structural engineers were able to reduce carbon by just 17% on all steel and concrete projects, they could reduce global CO2 emissions by 1%. With great power and influence comes great responsibility and I think structural engineers are able and ready to take this on. Being civil engineers at their core, they are already stewards of our built world, providing safety and resilience for 8 billion+ people and the required infrastructure. Reducing carbon should also be part of that scope, should it not?
Many structural engineers believe so and are taking action. We see several market forces happening in the arena of structural engineering that are important to note:
Industry groups like SEI’s SE2050 climate pledge has nearly 100 structural firms committed to reducing carbon to zero on US projects by 2050. Structural engineers across the globe are making pledges like in the UK and in unison with global engineering associations like FIDIC and CINOV. Also, trade groups are laying out concrete and steel roadmaps to decarbonize their industries by 2050.
Owners and governments are mandating reductions in carbon in construction as well. California has put carbon caps into law this fall for all federal projects as well as New York City’s LECCLA initiative. Owners like Amazon, Microsoft and Google have carbon mandates in place for new construction. The number of carbon reductions in Europe are vast and can’t all be covered in this article.
Technologies that report and reduce carbon are on the ramp up. Investors like Gates backed Breakthrough Energy Ventures, Amazon’s Climate Pledge Fund and Musk’s XPrize for carbon capture are all investing in several tech startups that reduce carbon in construction. This seems especially the case for concrete. Meta is investing in ACI’s new NEU net zero carbon initiative while VCs are investing in concrete startups doing carbon measurement and tracking, carbon capture and design optimization. Figure 1 shows the tech stack landscape in the context of four key areas.
If you digest all these carbon strategies and investments happening across the structural landscape, I see a common thread between them where carbon measurement and design/material efficiencies are very important to decarbonizing the structural sector. These two areas are where structural engineers should focus and ramp up their skill sets in the short term. What is interesting is that firms are already investing in these areas, and that is what we will discuss next.
With all the buzz right now around carbon, structural engineers will need to sift through the noise to determine what is possible and not yet possible in how they design their structures. The first two categories shown in Figure 1 are opportunities for where to start.
Carbon Measurement and Benchmarking - Don Davies, President of MKA and co-founder of the Carbon Leadership Forum, presented at NASCC last year around carbon and stated, “You can’t change what you can’t measure.” Starting with an agreed upon method for measuring carbon impact is the first step. This can mean going through your existing projects to measure what the carbon impact is for the steel and concrete you designed and what was finally installed. This will provide value data to benchmark against, as you design future projects. You are not alone here, and the industry is collecting a lot of data now to benchmark projects. EC3 provided by Building Transparency is an online repository of Environmental Product Declarations (EPD) that structural engineers should get familiar with. It is also becoming a warehouse of data, not just from supplier EPDs but of actual project carbon metrics that the industry can rely on. Other carbon databases exist too around the world like RICS and ICE from the UK. Firms like ARUP have classified carbon on 1000 of their projects and are using that as a benchmark to compare future progress.
Efficiencies in Design and Build - The second area for engineers to focus on is reducing carbon in their structural designs. For concrete, structural engineers are seeing immediate benefits working with the ready-mix suppliers to use low carbon mix designs. Instead of being prescriptive in their specs, engineers should rely on the domain experts here. In Seattle, I’m hearing of 20% CO2 emission reductions on hi-rise construction through use of optimized mix designs (Davies, NASCC 2022). A key part of delivering this efficiency though is having the owners mandate the suppliers to meet carbon mandates and prove how they are measuring and tracking carbon impact.
For steel, optimizations are coming from a range of opportunities:
For all structural system types, including timber, engineers have opportunities to relook at their design strategies using more holistic approaches:
You can see that there are a flurry of opportunities for where engineers can reduce carbon. But where do you get started? Here are some key strategies you can put in place to get the ball rolling:
As more EORs deliver more accurate design deliverables that include “connected steel models,” we are seeing big benefits at reducing carbon. The delivery process is being coined Integrated Steel Delivery (ISD), where engineers integrate structural design with connection engineering and pre-detailing. The impact on reducing carbon comes from these areas of ISD:
Creating the “best” structural design has always been a balancing act, comparing code requirements with cost, constructability, and coordination with the client. So, including carbon into the mix adds an additional factor to consider. I call these insights the “5Cs” that the ISD process integrates to empower engineers to make better engineering decisions (see Figure 2).
There is a lot for the structural engineer to unpack around their role in decarbonizing their structural designs. Make no mistake, the structural engineer plays a key role here as outlined above. The good news is there is a lot of knowledge and proven best practices already in flight that engineers can learn from. I also think it is important for them to engage with the structural supply chains to better understand how to further drive waste and carbon out of their projects. In many of the references cited above, it is the concrete and steel suppliers and fabricators contributing knowledge, expertise and innovations to reduce carbon. We just need to bring that expertise up early into the design phase to truly decarbonize our projects by 2050.
Michael Gustafson is a seasoned business strategist in the AEC tech sector with a focus on structural engineering and fabrication. He practiced as a structural engineer at Ellerbe Becket, holds an MS in Civil Engineering, an MBA from Michael J. Coles College of Business and is a Professional Engineer from California. He is also certified in AI for Business Managers from MIT. Michael is currently Vice President of Strategy and Business Development with Qnect, a service provider of data insights and efficiencies who is unlocking new and sustained value in the construction industry. You can find him on LinkedIn at: https://www.linkedin.com/in/michael-gustafson-2047786/.
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