Here you’ll find a variety of resources to assist structural engineers in learning more about embodied carbon. You will find links to some of the leading information. If there is something else you need help on and don’t find it here, please don’t hesitate to contact us and we’ll do our best to direct you to the answer!
Top 10 Things Every Structural Engineer Should Know about Embodied Carbon
- Embodied carbon is the total impact of all greenhouse gases emitted (measured in CO2-equivalent or CO2-e) into the atmosphere by a material, product, or system. For structural materials, embodied carbon is linked to the extraction of the raw material, manufacturing, transportation, construction, maintenance during service life, demolition, and end of life. CO2-equivalent is a unit of measurement based on the relative impact of a given gas on global warming or its Global Warming Potential (GWP). Therefore, embodied carbon and GWP are often used interchangeably.
- Net-zero embodied carbon is when the upfront embodied carbon is reduced to the greatest extent possible. The remaining embodied carbon is then offset so that the emissions over the lifecycle of the building are effectively eliminated. Net-zero embodied carbon is also referred to as neutral embodied carbon.
- Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide. Wood, concrete to some extent, and other renewable materials can be used to sequester and “store” carbon within the material. However, once the structure is demolished, the sequestered carbon can be re-released into the atmosphere. Carbon sequestration (a reduction in embodied carbon) may only be credited to a product if the end of life fate of that carbon is considered in the life cycle assessment. Therefore, the end of life assumptions for structural materials is critical.
- Embodied carbon is essential for structural engineers to address. As buildings’ and infrastructures’ operational emissions work towards achieving net-zero, embodied carbon will become drastically more critical to address and reduce.
- Carbon released during the production of materials and construction of buildings/infrastructure is emitted earlier than carbon released during operation and therefore has a more immediate impact on climate. This is known as the time value of carbon. It is thereby crucial that structural engineers work to reduce the upfront embodied carbon of the structural system to the greatest extent possible.
- A life cycle assessment (LCA) is a method of evaluating the environmental impacts, including embodied carbon, associated with all of the stages of a product or building’s life. The stages include raw material extraction, manufacturing, distribution, construction/assembly, maintenance/repair, and disposal/recycling. Guidelines and standards for LCA’s are ASTM E2921, ISO 14040, and ISO 14044.
- Environmental product declarations (EPDs) are third party verified reports measuring the environmental impacts, including embodied carbon, of a product or material from a life cycle assessment. The typical life cycle stages measured by EPDs include raw material extraction, transportation to processing/manufacture, and manufacturing of the product or material. Notably, most EPDs do not include the product’s end of life considerations. The standard for EPDs is ISO 14025.
- For a holistic view of the embodied carbon of a structural system, it is essential to conduct a whole building LCA (WBLCA). For example, steel and concrete tend to have larger embodied carbon footprints between the stages of raw material extraction to production. However, during design and construction, less of the material can be used due to their inherent strength, and both can be recycled/reused during their end of life. These two factors can greatly reduce the structure’s overall embodied carbon, which can be captured by a whole building LCA.
- The location of a material or product’s extraction and manufacturing can significantly influence the magnitude of its embodied carbon. Producers, manufacturers, and fabricators who source local raw material, use a larger percentage of recycled material, or obtain electricity from a renewable energy source can greatly reduce the embodied carbon of their material or product. Therefore, always try to obtain and compare EPDs from local manufacturers that may supply the projects’ material over using industry averages.
- Some additional strategies structural engineers can use to reduce a structure’s embodied carbon are: using alternative materials like fly ash and slag in concrete, selecting an efficient structural system for the building type and usage, optimizing structural materials, conducting whole building life cycle assessments to inform decision making, and increasing the service life of a building, to list a few.
Specifying Low-Carbon Impact Structural Materials
All structural materials have varying amounts of embodied carbon, so one strategy in reducing the embodied carbon in the structure is to specify structural materials with lesser carbon impacts. However, it is important to understand the effect of using lesser carbon-impact materials on the embodied carbon of the entire building. Structural engineers should be wary of inadvertently shifting the carbon burden to other materials due to use of lesser-carbon materials.
That being said, several industry associations have issued industry-average environmental product declarations (EPDs) for structural materials. For a given material, it may be useful to compare a specific product EPD versus its industry EPD. However, comparing EPD results from different product categories or materials should also be avoided. The following program operator websites list the most-current EPDs:
- ASTM International – https://www.astm.org/CERTIFICATION/EpdAndPCRs.html
- NSF – http://info.nsf.org/Certified/Sustain/listings.asp?ProdCat=EPD
- UL – https://spot.ul.com
Embodied Carbon Resources
- Architecture 2030. https://architecture2030.org/new-buildings-embodied/
- World Green Building Council, 2019. Bringing embodied carbon upfront. Toronto, WGBC. Available online at http://bit.ly/2Hdb2y4
- Urban Land Institute, 2019. Embodied Carbon in Building Materials for Real Estate. https://americas.uli.org/wp-content/uploads/sites/2/ULI-Documents/Greenprint-Embodied-Carbon-Report_FINAL.pdf
- LETI, 2020b. Embodied Carbon Primer. London, LETI. Available online at http://bit.ly/2tJkZ2X
- RIBA, 2019. 2030 Climate Challenge. RIBA, London. Available online at http://bit.ly/2SfeoXK
- Carbon Leadership Forum, 2017. LCA Practice Guide http://www.carbonleadershipforum.org/projects/lca-practice-guide/
- Athena Guide to Whole Building LCA in Green Building Programs https://calculatelca.com/wp-content/uploads/2014/03/Athena_Guide_to_Whole-Building_LCA_in_Green_Building_Programs_March-2014.pdf
- RICS, 2017. Whole life carbon assessment for the built environment, 1st edition. London, RICS. Available online at http://bit.ly/2UGHcK4
BuildingGreen “The Urgency of Embodied Carbon and What You Can Do about It” https://www.buildinggreen.com/feature/urgency-embodied-carbon-and-what-you-can-do-about-it
There are many organizations that have done incredible work in producing online resources, including websites, papers, and studies in the area of embodied carbon. Though we cannot possibly list them all we highly recommend you access the following.
- Architecture 2030 – https://architecture2030.org/new-buildings-embodied/
- ASCE-SEI Sustainability Committee – http://www.seisustainability.org/
- Carbon Leadership Forum (CLF) – pre-eminent industry-academic organization focused on all things embodied carbon. http://www.carbonleadershipforum.org/
- Greenhouse Gas Protocol – The GHG Protocol for Project Accounting is the most comprehensive, policy-neutral accounting tool for quantifying the greenhouse gas benefits of climate change mitigation projects. https://ghgprotocol.org/standards/project-protocol
- World Green Building Council – https://www.worldgbc.org/embodied-carbon
- Embodied Carbon Network (http://carbonleadershipforum.org/embodied-carbon-network/)
- Climate Smart Materials Palette (https://materialspalette.org/)
- Whole Building Life Cycle Assessment: Reference Building Structure and Strategies. https://doi.org/10.1061/9780784415054
- Kathrina Simonen, Barbara X. Rodriguez & Catherine De Wolf. (2017). Benchmarking the Embodied Carbon of Buildings, Technology|Architecture + Design, 1:2, 208-218. https://doi.org/10.1080/24751448.2017.1354623
- RICS Professional Statement: Whole life carbon assessment for the built environment. https://www.rics.org/globalassets/rics-website/media/news/whole-life-carbon-assessment-for-the–built-environment-november-2017.pdf
- Sustainability Guidelines for the Structural Engineer – https://doi.org/10.1061/9780784411193
- Structural Materials and Global Climate – https://doi.org/10.1061/9780784414934
- World Green Building Council: Bringing Embodied Carbon Upfront – https://www.worldgbc.org/news-media/bringing-embodied-carbon-upfront
- The New Carbon Architecture https://ecobuildnetwork.org/projects/new-carbon-architecture
- How to Get to Zero White Paper (coming soon)
LCA software that is used by LCA practitioners requires in-depth knowledge of LCA methods, standards, and practices. This software is often too complex to be useful for structural engineers on a day-to-day basis. Thus, several tools have been developed for estimating the embodied carbon impacts of buildings. Although we don’t endorse any tool, the following are commercially available. Structural engineers are encouraged to understand the underlying assumptions and limitations of each simplified tool.
- Tally (https://choosetally.com/)
- Athena Environmental Impact Estimator (http://www.athenasmi.org/our-software-data/overview/)
- SOM EA Tool (https://somhpd.com/eatool/)
- Thornton-Tomasetti Beacon (https://core-studio.gitbook.io/beacon/)
- One Click LCA (https://www.oneclicklca.com/)
- EC3 (https://www.buildingtransparency.org/en/)