Embodied Carbon - Why it Matters to the Structural Engineer

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.

Why is carbon reduction 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.

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?

Why Now?

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.

What is possible today for structural engineers to achieve?

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:

  • Specify higher grade steel (grade 65 ksi), especially for columns where the reduced weight and therefore carbon can have a big impact.
  • Rethink how you optimize your framing holistically. Existing rules of thumb around rationalizing your design to create greater simplicity and repetition should be challenged. A recent study in the UK shows that the typical steel frame project is designed around a unity value of 0.50. This means overdesigning the frame by 100%, in addition to what is needed to meet the building code requirements.
  • Optimize procurement, fabrication and erection costs with carbon in mind by bringing those decisions early in design. Leading connection engineers tell me that if engineers provide the beam design forces (vs using UDL), it could improve connection design efficiencies by 300 to 500%. This can have a big impact not only on the cost and speed of erection but also carbon.

For all structural system types, including timber, engineers have opportunities to relook at their design strategies using more holistic approaches:

  • Use performance-based design approaches to better optimize structural designs. This is already being done by engineers designing for fire, wind and seismic and especially in hi-rise structures. Recent recommendations are to apply performance-based design approaches to use lower design loads and therefore carbon (Klemencic, ENR 2022).
  • Adopt “hybrid” structural systems composed of mass timber, steel and concrete that best utilizes each structural system for what they do best. If they are optimized around performance, it generally has a good correlation with reduced carbon.
  • Renovate, reuse or retrofit existing structures where possible. As one engineer told me, “the most sustainable building is the one that isn’t built.”  Designing structures so they can be easily dismantled or repurposed will take a shift in mindset in both universities and engineering offices.  Expect to see debates about this shift soon in the US engineering community as we are seeing in the UK.

So how to get started?

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:

  • Establish standards for reporting:
    • Engage and learn from industry peers and groups
    • Set a company method by benchmarking past projects

  • Pilot carbon measurement on real projects:
    • Include EPDs that are performance based and hold vendors accountable
    • Measure carbon with EPD data at key milestones, not just in early design
    • Share back project data with industry databases like EC3

  • Explore design efficiencies that challenge existing rules of thumb:
    • Challenge existing rationalization strategies that focus on design repetition 
    • Integrate material availability and cost as well as connection constructibility decisions early to best understand carbon impact
    • Assess technologies that help quantify and increase reductions 

  • Share what you learn with industry to foster innovation:
    • Join SE 2050 to learn and network
    • Empower young engineers to lead and innovate
    • Help establish regional benchmarking and reporting standards

EORs are reducing carbon by how they deliver their services

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:

  • Exact steel ordering - Many fabricators order lengths from centerline to centerline vs exact cut lengths. This results in material waste, though recyclable, which generates additional CO2 emissions to make it into new usable steel sections.
  • Reduced weight of bolts, plate and weld - By sharing design forces with the connection engineer, EORs can optimize out overdesign in the steel connections. If the fabricator is involved, it can also optimize connections based on their available inventory which even further reduces carbon. This can all be done in minutes versus days using existing optimization technologies.
  • Value engineering helps assess smart solutions and steel efficiencies in how the frames are designed. This can be from eliminating costly shear doublers or panel zone reinforcement by balancing the frame design selection with connection design.
  • Reduced transportation and erection costs equates to lower carbon. Optimizing the assemblies that maximize fabrication throughput and minimizes erection picks equates to lower carbon.

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.

About the Author

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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