If your company has compared two carbon footprint measurements carried out by different consultancies or tools and obtained different figures, it does not necessarily mean there is a calculation error. When a carbon footprint offers different results, the causes usually lie in the methodology applied, the scope of the study, the defined boundaries, or the sources used to obtain the carbon footprint emission factors.
Measuring an organization’s emissions relies on recognized methodological frameworks but also requires technical decisions during the process. Standards and references such as ISO 14064, ISO 14067, or GHG Protocol establish calculation criteria, although the selection of secondary data, emission factors, and assumptions can influence the final result.
Understanding why my carbon footprint result changes is essential for correctly interpreting the figures, maintaining traceability between different reporting periods, and reducing discrepancies during environmental review or verification processes.
For exhaustive compliance with carbon footprint calculation methodologies, Solid Forest offers its corporate carbon footprint monitoring tool CCMetrics, and Air.e LCA as a Life Cycle Assessment tool for calculating the carbon footprint of products and services.
It is not an error: it is the data source used
To understand the variations when comparing carbon footprints between consultancies, one must first understand the basic formula for calculating emissions. An activity’s carbon footprint is obtained by multiplying activity data by the corresponding emission factor.
Activity data is a direct quantitative variable of your company’s operations, such as the kilowatt-hours (kWh) of electricity consumed in your offices, the liters of diesel refueled by the transport fleet, or the kilograms of raw material purchased from a supplier. For its part, an emission factor is a mathematical coefficient that converts that activity data into tonnes of carbon dioxide equivalent ().
A simple way to understand it is to think of a recipe. The activity data would be the amount of an ingredient used, and the emission factor would be the information that allows for the calculation of its contribution to the final result.
If different reference sources are used to value that same ingredient, the result can also change. Something similar happens in carbon footprint calculation: if two teams use different databases or carbon footprint emission factors, they may obtain different figures even when starting from the same company consumption data.
The most common sources, explained in one sentence each
The origin of the carbon footprint emission factors directly influences the final result of the greenhouse gas inventory. Not all sources collect the same information or have the same level of detail, so choosing one or another can modify the calculation. In technical consultancy, the sources used are usually grouped into three main types:
- Official national data: These come from public bodies such as the Ministry for the Ecological Transition and the Demographic Challenge (MITERD) in Spain, DESNZ (DEFRA) in the United Kingdom, or ADEME in France. They are especially useful when reference values adapted to the national context are needed, for example, for fuel or electricity consumption.
- International reference data: These are sources prepared by organizations such as the Intergovernmental Panel on Climate Change (IPCC) or the International Energy Agency (IEA). They are used when it is necessary to work with international references or with values representative of certain countries, regions, or activities.
- Most comprehensive life cycle databases: These are specialized repositories for Life Cycle Assessment (LCA), such as ecoinvent, which include detailed environmental information on processes, materials, energy sources, and transport. They allow for a higher level of detail and the analysis of emissions associated with different stages of the value chain.
How to know if the result you have been given is reliable
Evaluating the technical quality of a carbon footprint report requires verifying the traceability and methodological consistency used during the calculation process. Not all measurements have the same regulatory robustness or the same level of technical detail.
To confirm if your organization’s calculation is rigorous, it is advisable to review the following key aspects:
- Compliance with international standards: The study must clearly indicate if it has been structured under recognized methodologies such as ISO 14064 or GHG Protocol.
- Breakdown by scopes: The report must differentiate between Scope 1 direct emissions, Scope 2 indirect emissions associated with purchased energy, and Scope 3 indirect value chain emissions, or classified according to the chosen regulation.
- Transparency in emission factors: Each factor applied must include its bibliographic source, the year of publication and validity, and the technical justification for its selection.
- Inclusion of uncertainty: A reliable analysis takes into account the limitations of the secondary data used and clearly explains the boundaries defined for the calculation.
How we work to ensure the data is consistent year after year
At Solid Forest, we work in technical environmental consultancy and environmental technology development. For an organization’s carbon footprint to be compared coherently between different reporting periods, it is essential to maintain consistent methodological criteria, document the sources used, and ensure the traceability of the calculations.
Our organizational carbon footprint calculator, CCMetrics, allows for the structuring of your company’s Scopes 1, 2, and 3 following references such as ISO 14064 and GHG Protocol, in addition to keeping the data and carbon footprint emission factors used in each calculation identified.
For projects with a higher level of detail or product carbon footprint studies based on Life Cycle Assessment, Air.e LCA allows for working with reference databases such as Ecoinvent and modeling different environmental impact categories.
The combination of technical knowledge and tools developed by our own team allows for maintaining data traceability, verifying results with greater clarity, and consistently monitoring the evolution of emissions.
If you need to review how your organization’s carbon footprint is being calculated or want to improve the traceability of your results, contact our team and tell us about your case. We will be happy to help you!
