Building operations can always be fine-tuned for optimal performance, but there’s no way to reduce the embodied carbon of the materials used to construct that building once they are installed. This means that there is a finite window of opportunity to lessen the embodied carbon of a new development using typical operations practices. However, the process is getting easier, as suppliers are now offering more sustainable options, including for the two most carbon-intensive materials in building construction: concrete and steel.
Portland cement fabrication accounts for approximately 8% of anthropogenic greenhouse emissions, due to the fossil fuels burned to heat raw limestone to incredible temperatures, as well as the carbon dioxide that off-gasses during this process. After years of research and development, the concrete industry has begun to offer lower-carbon mixes that replace some of that cement with lower-carbon materials. These products perform as well as traditional mixes, if not better, and often there is no increase to a project’s budget.
My firm, Lendlease, is developing The Reed at Southbank, a 440-residence tower that recently topped out in the South Loop neighborhood of Chicago, Illinois. This was our first project to create to meet an embodied carbon reduction target—in this case, 10%. After performing a life cycle cost analysis, we elected to work with our suppliers to reduce the embodied carbon associated with the concrete throughout the project.
Every slab and column in the building uses a proprietary concrete mix procured from McHugh Concrete, which developed the product in partnership with Oremus Material. This lower-carbon alternative substitutes approximately 60% of the Portland cement with ash and slag—manufacturing waste products that would otherwise end up in a landfill.
https://www.usgbc.org/articles/carbon-cutters-reducing-emissions-through-material-selection