A new study by leading structural engineering firm KPFF Consulting Engineers shows that switching to ultra-low carbon concrete masonry units (CMU, or “blocks”) such as those made with CarbonBuilt technology can reduce the embodied carbon of concrete walls by up to 70 percent at comparable costs versus the traditional “tilt-up” construction method. This simple switch will overcome the seemingly intractable problem of massive emissions related to concrete use in these facilities.
It is estimated that concrete contributes nearly 50 percent of the embodied carbon of a typical building. The construction of data centres and logistics facilities will skyrocket in the coming years thanks to the growing use of artificial intelligence (37 percent CAGR) and same-day delivery (24 percent CAGR). This will require the production of millions of tons of concrete in the U.S. alone, which will in turn produce millions of tons of CO2, magnifying climate disruption in the coming years.
But new research from KPFF, conducted for CarbonBuilt, shows there is a way to radically reduce the embodied carbon of concrete used in these facilities through an alternative to the current tilt-up process which is the primary wall construction method. By substituting cast-in-place (or “ready-mix” concrete) with concrete blocks, builders can get to the same end result with up to 70 percent less embodied carbon in its walls at costs comparable to tilt-up.
To reach these conclusions, KPFF compared the use of ultra-low carbon masonry against traditional tilt-up construction for an 87,500 gross square foot industrial warehouse built in 2022 with 38-foot concrete exterior wall panels. KPFF developed a preliminary structural redesign for the same facility using ultra-low carbon concrete blocks to compare cost and constructibility. CarbonBuilt projected the carbon impacts using a life cycle analysis (LCA) for the two different wall types, integrating existing Environmental Product Disclosures (EPDs) for conventional products (including ready-mix concrete, rebar, grout and mortar) and projected EPDs for its blocks.
The study projects embodied carbon reductions of 48 to 70 percent for the walls at a cost increase of only 1 to 2 percent for the total project. The study also noted that there are a number of emerging construction technologies, including robotics, that could further reduce costs, effectively levelling costs with tilt-up construction.
“For a given warehouse or data centre project, there is nothing that would preclude me from considering both tilt-up and CMU on an equal basis,” said Jeff Asher, Managing Principal and Past President-Chairman, KPFF Consulting Engineers, the author of the study. “It’s urgent that the construction industry apply an application-specific lens when selecting concrete methods and materials throughout the building system in line with reducing embodied carbon impacts.”
According to the Infrastructure Masons Climate Accord (ICA) in its publication Greener Concrete for Digital Infrastructure: An Open Letter and Call to Action released in April 2023, “concrete alone makes up 11% of total global emissions. In accordance with [the ICA’s] broader sustainability goals, we recognise the urgency to reduce the embodied carbon of our building materials, specifically through the use of greener concrete.” The Climate Accord and its signatories are a coalition united on carbon reduction in digital infrastructure, with a mandate to achieve global carbon accounting of digital infrastructure and drive the industry to achieve carbon neutrality.
“Our 200+ members include the leading developers and users of data centres worldwide. They’ve driven great advancements in reducing operational CO2 emissions through energy efficiency, renewable power and sustainable materials,” said Miranda Gardiner, Executive Director, iMasons Climate Accord. “Now our industry is focused on reductions to embodied carbon, given the enormous scale of these types of emissions. We welcome companies who are demonstrating how relatively small changes in design and construction methods can yield significant improvements without increased overall costs.”