CO2e, Measuring the Environmental Impact

Every day people make choices that directly or indirectly affect the environment. Manufacturers choose from different materials, suppliers, or production methods. Consumers choose from various products, and packaging available to them. To make more environmentally responsible choices, consumers and manufacturers need reliable information. This is usually related to a life cycle assessment (LCA) which is a widely recognised method of measuring the environmental impact of the various stages of a product’s life by using a value of the carbon dioxide equivalent.

Carbon dioxide equivalent (CO₂e or CO₂eq or CO₂-e) is a unit based on the global warming potential (GWP) of different greenhouse gases. The CO₂e unit measures the environmental impact of one tonne of these greenhouse gases in comparison to the impact of one tonne of CO₂. GWP is the heat absorbed by any greenhouse gas in the atmosphere, as a multiple of the heat that would be absorbed by the same mass of CO₂, therefore GWP is 1 for CO₂. For other gases, GWP depends on the gas and the time frame of the heat absorption.

CO₂e is calculated from GWP and can be measured in weight. For any amount of any gas, the CO₂e value is the amount of CO₂ which would warm the earth, equivalent to the amount of gas released. Thus, it provides a common scale for measuring the climate effects of various gases. For example, if a gas has GWP of 100, two tons of the gas will have a CO₂e of 200 tons, and it also follows that 1 part per million of the gas in the atmosphere has CO₂e of 100 parts per million. The GWP for a mixture of gases can be obtained from the mass-fraction-weighted average of the GWPs of the individual gases. A time horizon of 100 years is commonly used by regulators.

The GWP value depends on how the gas concentration decays over time in the atmosphere. This is often not precisely known and hence the values should not be considered exact. For this reason, when quoting a GWP it is important to give a reference to the calculation.

Benchmark uses highly accurate data inputs to generate overall CO₂e values for each packaging unit. This includes considering the electricity used, materials thickness, colours, substrate, and manufacturer settings & speeds to enable better sustainable choices for both manufacturers and customers alike.

This blog is based on information sourced from P.Muredzi School of Industrial Sciences and Technology, Harare Institute of Technology.