Carbon dioxide equivalent
An emission estimate quantifies the greenhouse gases emitted into the atmosphere, commonly expressed as CO₂e. The "equivalent" allows for gases other than CO₂ to be converted into CO₂ based on their warming potential.For example, Methane has 28–36 times the warming potential of CO₂. Emitting 1 tonne of methane equates to 28–36 tonnes of CO₂e.To clarify what CO₂e means for your customers, consider a tooltip or hoverable info icon for users:CO₂e includes all greenhouse gases emitted, converted to the warming power of CO₂.
Choosing units for emissions
While emissions are often reported in tonnes, you can use kilograms or grams based on your product or service's scale. For example:- Sea freight (intercontinental): Several tonnes of CO₂e.
- Cloud computing services (small business): Hundreds of kilograms of CO₂e.
- Produce (fruit and vegetables): Hundreds of grams of CO₂e.
Carbon intensity
Carbon intensity quantifies the environmental impact of a product or service by measuring the amount of CO₂e emitted per unit. A higher carbon intensity indicates a greater environmental footprint.In logistics, carbon intensity varies widely depending on the transport method. Even within a single transport mode, factors such as ship size, age, engine type, and fuel type play a significant role. For instance, the carbon intensity of bulk carriers can range from 2.2 to 37.6 gCO₂e/tkm (grams of CO₂e per tonne-kilometre).With increasing regulatory requirements for companies to disclose and reduce emissions, you can support your users by sharing their carbon intensity metrics over time. To encourage sustainable behaviour, consider calculating the carbon intensity range of your products or services (using aggregate data) and communicating this to your customers.For example, when offering shipment transport options, you could define three carbon intensity bands:- Environmental leader (below 200 gCO₂e / tkm)
- Average (between 200 and 400 gCO₂e / tkm)
- Very polluting (above 400 gCO₂e / tkm)
Emission factors
An emission factor (EF) quantifies the amount of CO₂e emitted per unit of activity, such as kilometres travelled, litres of fuel consumed, or items produced. EFs are typically region-specific, tied to a particular year of data, and calculated by scientific organisations, governments, or standard-setting bodies.EFs vary depending on the source, region, and context. For certain products or services, additional variables may influence the EF. For instance, caloric value can impact EFs for petrol, while size is critical for oil tankers.To calculate total emissions, the EF is multiplied by the corresponding activity or expenditure. Some examples of EFs are:| Offering | Additional variables considered | Value | Source | Region | Year |
|---|---|---|---|---|---|
| Paddy rice | NA | 0.4867 kgCO₂e/EUR (kilograms of CO₂e per Euro of paddy rice produced) | EXIOBASE | Portugal | 2021 |
| Oil tanker | Medium sized, heavy fuel oil | 11.9 gCO₂e/tkm (grams of CO₂e per tonne of cargo transported over one kilometre) | GLEC (created by the Smart Freight Centre) | Global | 2024 |
| Petrol | 100% mineral oil blend | 0.24186 kgCO₂e/kWh (kilograms of CO₂e per kilowatt-hour of energy produced) | BEIS (Department for Business, Energy & Industrial Strategy in the UK government) | UK | 2024 |