OVERVIEW We are pleased to release the 2023 update to Turner’s Embodied Carbon Benchmark on the following page. This report reflects emerging trends in the greenhouse gas emissions associated with a sample of our projects’ material footprint. Below is a snapshot of initial conclusions and opportunities for future reduction of embodied carbon in the building materials studied. We hope this benchmarking report will serve as a valuable resource in affecting universal change in the way we build, work, and live in the built environment.
SUMMARY This report corroborates some widely accepted conclusions relating to the embodied carbon footprint of new commercial buildings in the United States In particular, this study indicates:
• Concrete and steel materials remain significant drivers of total embodied carbon footprint in buildings.
• Industry is making incremental improvements in lower embodied carbon material availability though more can, and must, be done.
Future work may explore additional materials such as aluminum, insulation, gypsum board, and acoustic panels to represent a more complete scope of building enclosure and major interiors
TRADE SPECIFIC DETAILS of this Embodied Carbon Baseline include:
CONCRETE:
• For the purpose of this study, concrete includes ready-mixed concrete, precast concrete, concrete masonry units (CMU), aggregate, shotcrete, flowable fill, concrete paving, and cementitious soil treatment
• In this study, concrete materials generated an average of 53% of a building’s embodied carbon footprint.
STRUCTURAL STEEL:
• For the purpose of this study, structural steel includes hot-rolled sections, concrete reinforcing (rebar, wire mesh, and pre- or post- tensioning tendons), metal decks, plate steel, hollow sections, and merchant bar.
• In this study, steel materials generated an average of 33% of a building’s embodied carbon footprint
ASPHALT:
• For the purpose of this study, only asphalt paving materials were included in this category. Roofing and waterproofing products were excluded, though they may be considered in future iterations of the report
• In this study, asphalt materials generated an average of 7% of a building’s embodied carbon footprint.
GLASS:
• For the purpose of this study, glass includes both flat and processed glass panes used in the exterior building façade and in interior storefront applications Mirrors and small door lites have been excluded.
• In this study, glazing materials generated an average of 6% of a building’s embodied carbon footprint
WOOD:
• For the purpose of this study, wood includes prefabricated mass timber elements (CLT, GLT, DLT, NLT), dimensional lumber, and sheet products where quantities are known (e g roof blocking or doors) Miscellaneous in-wall blocking is excluded from this report
• In this study, wood materials generated an average of 2% of a building’s embodied carbon footprint.
FINDINGS METHODOLOGY
WHAT IS IN THIS REPORT? Among the information included in this publication, and of special importance, is the Turner Embodied Carbon Coefficient. This multiplier was determined by analyzing a sample of Turner projects representing more than $ 11B and 17.4M SF in the United States. Sampled projects were modeled in the Embodied Carbon in Construction Calculator (EC3)1 using material quantities for five key materials estimated during preconstruction along with localized industry embodied carbon data.
What’s in a carbon factor? Third-party verified, product-specific and facility-specific Environmental Product Declarations (EPDs) are the gold-standard for tracking material carbon impacts. However, industry baselines must often be used in earlier phases of project development before enough information is available to choose a representative product-specific EPD.
In this study, results using two types of industry data were calculated and compared
1) The Carbon Leadership Forum (CLF)’s 2021 Baselines Report2, and
2) Localized industry averages from EC3 filtered for the likely geographic procurement limits and available performance criteria by material.
16% lower embodied carbon on average was demonstrated across the 37 projects in this study when localized industry averages were used. These results indicate that using this more specific data representative of individual project regions and/or performance requirements yields better results and lower embodied carbon, even in the absence of product-specific EPDs.
Each point on the scatterplot below represents a project from the study. The percent reduction achieved can be seen on the y-axis.
Concrete and steel remain top priorities when considering the overall embodied carbon of buildings and targeting key reduction strategies. The chart below outlines the average relative contributions of each of the five material categories tracked in this study.
Why is steel less of a contributor than last year? In last year’s report, which was limited to only concrete and steel materials, each made up roughly equivalent portions of the total embodied carbon footprint for buildings in the sample set at 49% (concrete) and 51% (steel). By including additional material categories in this year’s update, we would expect to see both concrete and steel contributions decrease.
Instead, we see steel contributions (down 18%) decrease disproportionately to concrete (up 4%). This is likely due to differences in this year’s sample set of projects, which have more projects with primarily concrete structures (7 out of 37 projects) compared to last year’s sample set which was dominated by composite steel structures (only 3 out of 32 primarily concrete projects).
37 projects were modeled for this study with the following criteria:
• Project scope has been awarded to Turner or a Turner-led JV,
• Building is either ground-up/new construction or a renovation/expansion with at least 3 of the 5 tracked materials included in scope, and
• Project is currently in Preconstruction (at the time of selection in Q3 2023). Projects represent one project from each Business Unit (BU) across the U.S. with active precon contracts in 2023 and reflect a variety of market segments totaling more than $ 11B and 17.4M SF.
COMPARING PRODUCT-SPECIFIC DATA TO PUBLISHED INDUSTRY BASELINES
24% lower embodied carbon on average was demonstrated in the six projects which had already begun to collect product-specific EPD data by the time this study was completed. These reductions are in comparison to the CLF 2021 Baselines2
36.92 kg CO2e/SF is the average carbon intensity of the five key materials (concrete, steel, asphalt, glass, and wood) studied in this year’s sample set of projects.
This embodied carbon coefficient can be used to quickly and easily approximate a baseline for the embodied carbon footprint of a project or portfolio.
A project-specific EC3 model using material quantities and EPD data is preferred for accurate benchmarking and reduction tracking, but Turner’s Embodied Carbon Coefficient can be used as an initial approximation or starting point.
For example, the average project size in the study is 471,719 ft2, so the baseline embodied carbon of concrete, steel, asphalt, glass, and wood material for a building of this size would be:
$1,000,000,000.00
$500,000,000.00
This year’s embodied carbon coefficient represents a 4.44% increase over last year’s coefficient which included only two materials concrete and steel. A comparison of just those two materials in isolation showed a 6.67% decrease from 2022 to 2023. While small, this reduction is indicative of a market shift and increase in availability of lower carbon materials.
Projects across 34 different BUs were modeled in this study. Most were primarily new steel composite structures, though a few were primarily concrete or timber, and/or reno/expansion scopes.
Each point on the scatterplot below represents a project from the study. The percent reduction achieved can be seen on the y-axis.
