Case Study


ArcelorMittal and Toyota Pilot Test

RMI collaborated with ArcelorMittal and Toyota to pilot steel product-level greenhouse gas (GHG) data reporting, following RMI's Steel GHG Emissions Reporting Guidance (hereafter “Steel Guidance”).

At A Glance

RMI collaborated with ArcelorMittal and Toyota to pilot steel product-level greenhouse gas (GHG) data reporting, following RMI's Steel GHG Emissions Reporting Guidance (hereafter “Steel Guidance”).

The pilot tested the emissions calculation and data transfer of hot-dip galvanized (HDG) steel produced via two routes: blast furnace-basic oxygen furnace (BF-BOF) and electric arc furnace (EAF), in alignment with the Steel Guidance. This helped pilot partners gain extra transparency into the climate performance of the tested products. The data allowed Toyota to explore potential applications of product-level data to inform low-emissions procurement and shape its sustainability strategy while enabling ArcelorMittal to demonstrate its decarbonization efforts at the product level.

" This pilot provided us with a good opportunity for data exchange dialogue with our supplier. As auto industry has a very broad supply chain, not only steel, so we will enlarge our communication with suppliers of other materials or machinery. Again, this pilot is a good “first-step” for a more complicated purchasing process. "

- Toyota

Targeting Industry Challenges

In the automotive sector, steel buyers face a considerable challenge in defining and achieving scope 3 targets while making informed purchasing decisions. The complexity stems from a lack of clarity on the essential product-level data to collect and the effective application of this data. At the same time, suppliers strive for increased transparency to showcase their efforts in decarbonization. In response to these challenges, ArcelorMittal and Toyota pilot-tested RMI's Steel Guidance, which aims to enhance the transparency of product-level data and apply these insights to facilitate informed business decisions.

Our Objectives

In this pilot, RMI's Steel Guidance was used to:


Enhance the understanding of emissions data at the product level – ArcelorMittal tested the applicability of the guidance in calculating emissions in both BF-BOF and EAF production routes and helped Toyota to gain a better understanding of the benefits of a benchmarking boundary in making product comparisons.


Introduce additional metrics to improve transparency – Empowered ArcelorMittal to showcase their decarbonization efforts more comprehensively and provided Toyota with extra information beyond emission footprints, such as technology label, by-product credit, and primary data share, to support green procurement decision-making.


Standardize the data format for exchange of product carbon footprint information - Enabled pilot participants to transfer data following WBCSD's Partnership for Carbon Transparency (PACT) aligned open source data format with RMI's steel data metrics.

Pilot enabled changes

Pilot Partner
Change Area
Prior Practice
RMI Solutions Applied in Pilot
Data Collection
National/Regional average emission footprint and site-level primary data
Collected product-level specific and primary data from upstream under clear definitions on calculation rules and the boundaries
Calculation process
Internal life cycle assessment (LCA) software and company developed excel tools
Enhanced the functionality of RMI's free, open-source calculation tool, potentially beneficial for companies lacking internal LCA database
Reported metrics
An aggregated for product carbon footprint (PCF) and other life cycle impacts for final product
Reported additional climate info on a product's benchmarking boundary emission, post-consumer scrap fraction, and abatement technology, directly showing alignment with sectoral decarbonization pathways and decarbonization efforts
Data exchange
  • Pdf by email exchange
  • No specific data format required
Reported PACT-aligned data format with RMI’s steel data metrics that enabled pilot partners to understand the importance and potential of standardized data exchange in improving supply chain data transparency and transfer
Supplier data collection
  • Lack of systematic supplier data collection questionnaire/system
  • No product-level specific climate data
  • Obtained crucial insights for future supplier engagement and supply survey development
  • Received key product-level data metrics as per the Steel Guidance, featuring a high primary data share
Use case of product data
  • Limited use of product climate data due to data availability and insufficient coordination between departments
  • Scope 3 emission reduction targets on purchased goods
  • Enhanced coordination between the purchasing and sustainability departments, fostering a shared understanding of product climate data
  • Attained valuable insights into the potential applications of data in Scope 3 emissions reporting, the revision of Scope 3 target setting, internal carbon pricing, and green procurement
Exhibit 1


RMI's steel guidance provides high level comparability between steel products by clearly defining calculation rules and boundaries.

The selected benchmarking boundary for this pilot was to the hot rolling process (one of the two valid options noted in the guidance). This approach streamlining the credit calculation for off-gases utilized as a heat source. The benchmarking boundary emission was also compared to split (by metallic inputs type) decarbonization pathways to better understand real-world emissions reductions associated with the product. This approach - applied across suppliers - can enable buyers to make more informed comparisons of emission footprints between steel products, considering all emission-intensive processes involved (see illustration).

For steel suppliers - incorporating the import/export of intermediate products and considering stockpiling in the emissions calculation inventories is critical to developing an accurate product-level emissions disclosure. During the testing, RMI's calculation tool was improved to consider intermediate products (slabs, hot metal, hot-rolled coil) moving in and out of the integrated steel mill. This ensures accuracy by considering any stockpiling issues that may occur when plants within the same location produce quantities exceeding the site's consumption for an integrated steel mill. Consideration for these elements was incorporated into an improved calculation tool can help steel suppliers that do not have internal existing LCA systems.

Exhibit 2

Both parties recognized the crucial role of a unified data format in facilitating seamless data exchange throughout the supply chain.

Currently lacking dedicated digital software, the pilot employed a CSV-based format for data exchange, with an eye toward potential integration with more scalable digital solutions in the future. Toyota Japan will develop the company’s digital strategy for sustainability data collection in the coming year, leveraging lessons learned from the pilot.

Toyota's enhanced understanding of critical factors affecting product climate performance strengthened collaboration among departments, fostering unified awareness and attitudes toward climate data for informed green procurement.

For Toyota, collecting high quality emissions data and additional metrics such as the technology-label is critical to establishing the confidence required for corporate emissions reductions strategies including green procurement, internal carbon pricing, and target setting.

Regarding green procurement, Toyota recognized the importance of introducing additional metrics to gain a more comprehensive understanding of environmental factors in the procurement process, especially concerning the share of post-consumer scrap to reflect circularity. Separately listing all credits generated only through selling by-products outside the steel boundary helped reveal how emissions are reduced through direct decarbonization actions. A technology label, such as renewable energy or bio-energy, will increasingly signify the direct decarbonization contribution from steelmakers with more adoption of abatement technologies in the sector and will serve as an indicator for investment costs and decarbonization strategies.

Simultaneously, Toyota acknowledged the necessity of establishing a comprehensive supplier survey. Toyota will leverage the guidance to communicate with their suppliers for climate data collection. The aforementioned additional metrics can be collected to provide a deeper understanding of the supplier's environmental efforts.

Remaining Challenges

Achieving harmonization among methodologies remains challenging. RMI's approach diverges from ArcelorMittal's current LCA models, particularly in allocation procedures (e.g., off-gases allocation) and emissions factors for certain raw materials and electricity mixes. These disparities may yield varying emission outcomes and also reflect the needs of harmonization among current existing methodologies in the market. Additionally, the presence of different reporting methodologies and various local reporting requirements makes it difficult for multinational corporation like ArcelorMittal to align methodologies across different sites. Ongoing efforts, such as the Steel Standards Principles, to synchronize methodologies will ease the calculation burden.

Ensuring the accuracy of calculated data results is crucial but challenging for the end-use buyer. While suppliers bear the responsibility for data accuracy, the pilot has identified a need to support buyers in gaining a better understanding of data correctness. Capacity-building or guidance to help buyers on reasonable data metric ranges and verification methods would be beneficial.

"When thinking about transparency and data sharing across supply chains, it's important that any guidance developed focuses on allowing like for like comparison.

In that sense, we welcome RMI's efforts to develop the Steel Emissions Reporting Guidance and we are pleased to have participated in the pilot to test it with our customers.

Through this pilot, we were able to evaluate the feasibility of the proposed data exchange process. We have more than 100 sites operating worldwide, so collecting data will always be a challenging task, and one we look to continuously improve. The guidance itself contributes to determine a suitable level of emissions transparency to address the needs of customers while also ensuring the data exchanged is comparable.”

- ArcelorMittal

The Path Forward


  • Value chain engagement to address supply chain emissions: ArcelorMittal has an ongoing group-level Scope 3 project, with the purpose of identifying value chain emissions hotspots and informing sustainable procurement practices. The pilot has enabled the company to approach value chain engagement through a different lens as it is not only about data sharing, but also identifying collaboration opportunities to drive emission reductions at scale.
  • Aligning to a 1.5C pathway: ArcelorMittal is currently assessing what a science-based target looks like for its global portfolio, using the steel sector specific approach recently published by the Science-Based Target initiative (SBTi) for corporate level reporting.
  • Continue to improve data quality at product level: Currently, data generation is limited to yearly production averages and product averages encompassing a broad range of commercial products. ArcelorMittal aims to enhance granularity by providing more detailed data over shorter time frames, transitioning from average product emissions to capturing emissions specific to individual products.
  • Utilize metrics in steel guidance for product design: When co-designing automotive parts with clients, internal tools are needed to estimate impacts of new technologies and the carbon footprint of several solutions, including competitive alternatives. RMI's metrics can play a role in providing better quality and granularity data.


  • Support internal carbon pricing system development: Toyota is planning the development of internal carbon pricing systems to catalyze a culture of accountability and efficiency, fostering sustainable practices throughout the organization. Better product level data will be critical to ensure the carbon pricing system’s accuracy.
  • Improve alignment with 1.5-degree goal and regulatory advocacy: Recognizing the gap between the company's internal decarbonization targets and the ambitious 1.5-degree goal, Toyota is dedicated to intensifying efforts to bridge this gap. Collecting high quality product-level data will be critical to establishing the scope 3 inventory accuracy necessary to enable Toyota to confidently set emissions reductions targets Furthermore, the acknowledgment of the absence of national regulations governing scope 3 emissions in Japan underscores an opportunity for Toyota to advocate for and contribute to the development of comprehensive regulatory frameworks.