Freight transportation accounts for approximately 7-9% of global greenhouse gas emissions, according to the IPCC's Fourth Assessment Report. Within this footprint, maritime freight, though relatively efficient per tonne-kilometer, generates significant volumes due to the distances covered and quantities transported. In this context, the ability to accurately and standardly quantify CO₂ emissions associated with each transport unit is not only a growing regulatory requirement but also a strategic lever for supply chain optimization.

Historically, carbon measurement in logistics has often lacked uniformity, making comparisons difficult and reduction efforts complex to evaluate. The introduction of international standards such as ISO 14083 and the GLEC v3 framework aims to standardize these practices and provide a common language for the assessment and communication of greenhouse gas (GHG) emissions related to transport and logistics. This alignment is crucial for supply chain directors, transport managers, and CSR officers who must navigate the requirements of the European CSRD and mechanisms like CBAM.

This article will detail the method for calculating carbon per TEU (Twenty-foot Equivalent Unit) container according to these standards, explaining the underlying mechanisms, concrete application steps, necessary data, and pitfalls to avoid. The objective is to provide a solid and operational understanding for proactive management of your logistics operations' carbon footprint.

Why Calculating Carbon per TEU is Essential

The TEU container is the standard unit of measurement for shipping capacity and maritime freight volume. Measuring carbon per TEU allows for direct granularity and comparability of the environmental efficiency of different routes, modes, and operators. This standardization is crucial for strategic supply chain management. For example, a "Triple E" class container ship can carry up to 18,000 TEUs, and the ability to assess CO2 impact per TEU is essential for optimizing loading and vessel selection. It also facilitates compliance with regulations such as the CSRD, which requires large EU companies to report their environmental impact, including Scope 3 emissions related to transport.

Calculation per TEU provides a clear performance baseline that transcends merchandise specifics (weight, density) to focus on the logistics unit itself. It is a key indicator for benchmarking performance and identifying carbon bottlenecks in the supply chain. The European Environment Agency (EEA) regularly highlights the importance of these indicators for developing more sustainable transport policies.

ISO 14083 and GLEC v3 Standards: A Unified Framework

ISO 14083:2023, published in February 2023, finally harmonizes methods for calculating and reporting GHG emissions related to transport and logistics operations. It largely builds on the principles of the Global Logistics Emissions Council (GLEC) v3 framework, developed by the Smart Freight Centre. These standards define clear methodologies for collecting data, calculating emissions by transport mode (maritime, road, rail, air), and attributing these emissions to freight units, such as TEU.

They require the use of methods based on actual fuel consumption whenever possible (level 1 method), prioritizing primary data. If such data is unavailable, secondary data (standardized emission factors by vehicle or vessel type) are used (level 2 method). Finally, default or average sectoral data can be applied (level 3 method), though less precise. ISO 14083 emphasizes data transparency and traceability, fundamental elements for the verifiability of CSRD reports. For example, direct emissions (Scope 1) from a container ship can typically range from 20 to 40 grams of CO2 per tonne-kilometer, depending on its size, speed, and fill rate.

Calculation Methodology: From Consumption to TEU Container

The process of calculating emissions per TEU follows several logical steps, from fuel consumption to final allocation. The general formula relies on the relationship between fuel consumption, fuel emission factors, and transport activity.

Collect fuel consumption data: For a given transport segment (e.g., a maritime journey Shanghai-Rotterdam), collect the total fuel consumption (in liters or tons) for the vessel, train, or truck. In maritime transport, this data often comes from logbooks, bunkering invoices, or vessel monitoring systems (AIS/GPS). For road transport, consumption data comes from truck telematics systems or fuel receipts.
Apply the emission factor: Each fuel type (heavy fuel oil, marine diesel, LNG, gasoline, electricity) has a specific equivalent CO₂ (CO₂e) emission factor, expressed in kg CO₂e per liter or ton of fuel. These factors are generally provided by reference organizations (e.g., EPA in the US, DEFRA in the UK) or international guidelines. For example, heavy fuel oil emits about 3.15 kg CO₂ per liter burned.
Calculate gross emissions for the journey/segment: Emissions (kg CO₂e) = Fuel Consumption (L or T) × Emission Factor (kg CO₂e/L or T).
Determine the "work" performed: Work is measured in tonne-kilometers (tkm) or TEU-kilometers, reflecting the amount of freight transported over a given distance. For a vessel, consider the total TEU capacity loaded on the segment and the distance traveled.
Allocate emissions to freight (TEU): This is the step where the total emissions of the journey are distributed. ISO 14083 suggests two main allocation methods for freight: by merchandise mass (tonne-kilometer) or by volume/loading unit (TEU-kilometer). To calculate an average per TEU, total segment emissions are divided by the total number of TEUs transported on that segment, and sometimes by the distance traveled, to obtain an impact per TEU-kilometer. The most common method for general reporting is to obtain an "average CO₂ per TEU transported" for a given journey.

Attribution can become more complex with partially filled containers or those with varying weights. The standards encourage considering the actual weight of the container and its distance rather than simply dividing by the total available TEUs, to achieve a more accurate footprint.

Operational Implementation of Carbon per TEU Calculation

For a supply chain manager, integrating this calculation involves data structuring and automation. Here are the key steps:

Identify and model transport segments: Break down each port-to-port, port-to-warehouse, or warehouse-to-customer journey into distinct segments (maritime, road, rail). Each segment must be associated with a specific transport mode and distance. Use geospatial data for distance, and technical specifications for vehicles/vessels.
Centralize consumption and activity data: Establish a system to systematically collect primary fuel consumption data (liters, kWh for electric) and activity data (number of TEUs, merchandise weight in tons, distance traveled). This may involve EDI integrations with carriers, access to AIS/GPS data for container ships, or collecting information from internal TMS. For example, a shipper might request MRV (Monitoring, Reporting, Verification) fuel consumption data from their maritime carriers for the journeys concerned. In 2023, MRV allowed collection of data from nearly 12,000 ships, providing a crucial source of information.
Integrate certified emission factors: Use a validated library of CO₂e emission factors compliant with ISO 14083 or GLEC v3. These factors must be regularly updated and cover all fuels and transport modes used. Using dedicated platforms can ensure this compliance.
Develop or use a compliant calculator: Implement a tool that, based on collected data and emission factors, can attribute emissions to each TEU container. This tool must be able to manage different allocation methods (per tkm, per TEU) as recommended by the European Commission for reporting. A typical example would see a 10-ton container traveling 1000 km by truck generating about 800 kg of CO₂, while by sea over 10,000 km, it would produce 300 to 400 kg of CO₂.
Reporting and analysis: Generate TEU emission reports by route, carrier, and period. These reports must be exportable for CSRD/CBAM compliance and allow for comparative analysis to identify optimization levers (choosing less emitting carriers, optimizing container fill rates, alternative transport modes).
Verification and continuous improvement: Have an independent third party verify the calculation methodology and data used, especially in the context of CSRD. Use analyses to set reduction targets and track progress. Continuous improvement is based on increasing the granularity and accuracy of primary data.

Frequently Asked Questions

Q: What's the difference between ISO 14083 and GLEC v3?

A: ISO 14083 is a formal international standard that harmonizes and formalizes methodologies for calculating and reporting GHG emissions in logistics. GLEC v3 is an industry-developed framework by industry experts to provide practical guidance, which served as a major basis and inspiration for the ISO 14083 standard. They are therefore very aligned and complementary.

Q: Is it possible to obtain accurate fuel consumption data from all carriers?

A: This is one of the major challenges. While large maritime and rail carriers often have detailed tracking, access to primary data for road transport (often fragmented) can be more complex. The standards encourage prioritizing primary data (actual consumption) but accept secondary data (emission factors by vehicle/engine type) or tertiary data (sector averages) in the absence of more precise data. EDI integration and the use of connected platforms (BYOK) greatly facilitate this collection.

Q: How to manage the impact of unforeseen events (Suez diversions, strikes) on carbon calculation?

A: Disruptions like detours (Suez, Cape of Good Hope) increase the distance traveled and consequently fuel consumption and associated emissions. A compliant calculator must be able to integrate these changes in route and distance to recalculate emissions. Dynamic tracking of ETAs and actual routes, made possible by AI and AIS/GPS data, is essential to reflect the actual carbon impact of these unplanned events.

Q: Is calculating carbon footprint per TEU sufficient for CSRD compliance?

A: Calculating carbon per TEU is an excellent indicator for logistics and a key element for compliance, as it allows you to break down your Scope 3 (transport) emissions. However, the CSRD requires a broader assessment of all the company's environmental, social, and governance (ESG) impacts. Carbon footprint per TEU will be an essential component of the "Climate" section of your report, but it must be integrated into a more comprehensive CSR approach.

To Go Further

Logistics — Port-to-port orchestration and AI radar for disruption to optimize your routes.
CO² Calculator ISO 14083 — Discover how to precisely assess your maritime, road, and rail emissions.
BYOK — Connect your AIS/GPS/EDI data for increased carbon visibility and calculations based on your primary data.