Carbon accounting measures the greenhouse gas emissions generated by an organization's activity, broken down into scope 1, 2 and 3 under the GHG Protocol. For a single-site company, the exercise stays contained. For a corporate group or a mid-cap company (what the French call an ETI) structured across several subsidiaries, the data is not centralized : each entity has its own energy bills, its own supplier contracts, sometimes its own information system. Consolidating this data into a single, coherent carbon footprint is the obstacle most commonly cited by group sustainability directors.
This guide covers corporate carbon accounting in full : definition, scopes, method and reporting obligations. It then goes deeper into what changes specifically for a multi-entity structure : choosing the organizational boundary, consolidating data across subsidiaries, setting up governance, and the mistakes that distort the consolidated result.
What is corporate carbon accounting?
Corporate carbon accounting is the quantification, expressed in tonnes of CO2 equivalent (tCO2e), of all the greenhouse gas emissions associated with an organization's activity over a given period, usually the fiscal year. The international reference method is the GHG Protocol, which structures these emissions into three scopes : direct emissions (scope 1), indirect emissions from purchased energy (scope 2), and indirect emissions from the upstream and downstream value chain (scope 3).
A carbon accounting exercise is not a product carbon footprint. That falls under life cycle assessment (LCA), a method that measures the environmental impact of a product or service across its entire life cycle. Corporate carbon accounting, by contrast, is measured at the organizational level. See the comparison of both approaches : carbon footprint vs LCA.
For an independent, single-site company, running this exercise means collecting energy consumption data, travel, purchases and waste for a single legal entity. For a corporate group or mid-cap company organized into subsidiaries, the first question is not methodological but organizational : which boundary to consolidate, and under which rule.
Group carbon footprint : what changes with the organizational boundary
Before calculating a single tonne of CO2e, a group must define its organizational boundary, that is, the list of legal entities whose emissions will be included in the consolidated footprint. The GHG Protocol offers three consolidation approaches applicable to a multi-subsidiary group :
The choice of approach is not neutral. A group that holds minority stakes in operating joint ventures will end up with a very different boundary, and therefore a very different total, depending on whether it applies financial control or operational control. The chosen methodology must be documented and applied consistently from one reporting period to the next : this is a traceability requirement, not a technical detail.
Once the organizational boundary is set, the group has to manage the multi-site, multi-entity dimension of data collection : every subsidiary, every production site, every legal entity needs to be able to feed its data into a common structure, without consolidation turning into a manual reconciliation of inconsistent spreadsheets. The guide to conducting a corporate carbon footprint covers the general method ; the sections below focus specifically on the group dimension.
The 3 scopes applied to a multi-entity structure
The GHG Protocol distinguishes three emission scopes. Applied to a multi-entity structure, each one raises its own consolidation challenges.
Scope 1, direct emissions (on-site combustion, company-owned fleet, industrial processes, refrigerant leaks) exist at the level of each subsidiary or site : a plant, a warehouse, a regional fleet. The difficulty is organizational, not methodological : every site needs to report its data at the same level of granularity to allow for consistent aggregation.
Scope 2, indirect emissions from energy (purchased electricity, heat, steam) raise the challenge of contracts that are often negotiated locally, subsidiary by subsidiary, with different suppliers and emission factors depending on the country or pricing zone. Consolidation requires knowing the energy mix behind every contract, which in turn requires an up-to-date emission factors database applicable location by location.
Scope 3, indirect value chain emissions (purchases, upstream and downstream transport, travel, use of sold products, end of life) generally represent the largest share of a group's emissions and the hardest scope to consolidate : purchases are often negotiated centrally for some categories (IT, fleet) and locally for others (raw materials, subcontracting). The guide to scope 3 covers the 15 GHG Protocol categories in detail ; the guide to carbon accounting methods covers the calculation approaches available depending on each subsidiary's maturity.
For a group, the central question is not just "which scope to include" but "at what level of granularity should each subsidiary report, so the aggregation stays usable." A subsidiary that reports its purchases as aggregate monetary data and another that reports detailed physical data will produce an inconsistent consolidated scope 3 unless the method is harmonized upstream.
Consolidating carbon data across subsidiaries
Multi-entity consolidation combines three recurring difficulties : heterogeneous information systems (each subsidiary often has its own ERP, its own invoicing formats, its own units of measurement, which turns consolidation into an error-prone manual reconciliation of spreadsheets), uneven sustainability maturity (a long-standing subsidiary with a dedicated sustainability team collects more granular data than a recently acquired subsidiary with no carbon lead, and the consolidated footprint inherits the weakest level if no common method is imposed), and data governance (who validates what each subsidiary reports, who has the right to change an emission factor used at group level : without a formalized workflow, a local correction can silently break the consistency of the footprint).
Three elements structure reliable data collection at group scale :
Regulatory obligations for corporate groups and mid-cap companies
The most relevant reporting framework at international and European level is the GHG Protocol Corporate Standard for the accounting method itself, and the Corporate Sustainability Reporting Directive (CSRD) for disclosure. At EU level, the CSRD broadens extra-financial reporting, with a climate component aligned on the ESRS standards (including ESRS E1), to a growing scope of companies based on size criteria. The precise timeline and thresholds of the CSRD have been subject to recent revisions at EU level (the "Omnibus" package) that were not settled at the time of writing : do not rely on an unverified figure without checking an up-to-date official source. For a group, the CSRD adds a structuring constraint : reporting must cover the value chain, which ties directly into the multi-entity consolidation challenge described above.
Two obligations described below are French national requirements, not international ones, and apply only to entities operating under French law. Groups with no French subsidiary can skip this section ; groups with a French entity should treat it as a local layer on top of the international and EU frameworks above.
In France, the mandatory Bilan d'émissions de gaz à effet de serre (BEGES), the French GHG emissions report set out in Article L.229-25 of the French Environmental Code, applies to private-law companies with more than 500 employees in mainland France (more than 250 in French overseas regions and departments), as well as to the State, regions, departments, metropolitan authorities, communities of municipalities with more than 50,000 inhabitants, and other public-law bodies employing more than 250 people. The report is public and updated every 4 years for private-law entities, every 3 years for the State, local authorities and other public-law bodies. Since the regulatory method was updated (method V5), a transition plan must be attached to the report. Including significant indirect emissions beyond scope 2 (part of scope 3) is mandatory only for private-law entities that are also subject to the French Déclaration de Performance Extra-Financière (DPEF, the French non-financial performance statement) ; other private-law entities covered by the BEGES only need to include scope 2 at a minimum, with broader coverage recommended but not required. The BEGES V5 method is detailed in the "BEGES V5 regulatory method" resource listed below (French-language source, since the BEGES is a French regulation).
For a French group with subsidiaries, one question comes up immediately : does the obligation apply subsidiary by subsidiary, or at the consolidated group level? The answer depends on the legal structure and the organizational boundary chosen (see above) : a subsidiary that, on its own, does not reach the regulatory threshold may still need to be included in the report if the group consolidates at the level of financial or operational control. This point deserves a case-by-case check against the texts in force : thresholds and assessment rules can change, and this summary does not replace a dedicated regulatory analysis.
One principle stays stable regardless of the applicable framework : the quality of the underlying data, its traceability, granularity and consistency of method across subsidiaries, determines the reliability of the final report.
Method : building a consolidated carbon footprint step by step
Common mistakes in a multi-entity carbon footprint
How Kabaun supports corporate groups and mid-cap companies
Kabaun is a carbon management platform built for multi-entity structures. Data management natively supports a multi-entity, multi-site dimension, structuring data collection by subsidiary and by site without losing the ability to consolidate at group level. The calculation engine applies the GHG Protocol across scope 1, 2 and 3, including the 15 scope 3 categories, and relies on a database of more than 270,000 emission factors sourced from 8 public databases, which can be customized whenever a subsidiary has more precise data.
Data collection is streamlined through CSV/Excel import with AI-assisted mapping, manual entry for one-off data, and API connectors to subsidiaries' information systems. Validation workflows track who entered and who approved each data point, at both entity and group level, and delegated access lets external auditors work inside the tool without exposing the full boundary. On the reporting side, an interactive dashboard and PDF/Excel reports present consolidated results alongside the subsidiary-level detail, with tracking of reduction targets over time. The Klem conversational assistant builds on this architecture to help group sustainability teams analyze emission sources and simulate decarbonization scenarios, without replacing the audit trail or human validation of the data.
FAQ · Frequently asked questions about corporate carbon accounting
What is a consolidated corporate carbon footprint for a group?
It is the aggregation, following a defined organizational boundary rule (equity share, financial control or operational control), of the greenhouse gas emissions of all the subsidiaries and sites of a group into a single scope 1, 2 and 3 inventory, expressed in tonnes of CO2 equivalent.
Which consolidation approach should a multi-entity group choose?
The choice depends on the group's governance. The financial control approach generally follows the boundary already used for financial consolidation, which makes data consistency easier. The operational control approach is relevant when the group directly manages the operations of minority-owned sites. Whichever approach is chosen, it must be documented and applied consistently.
Does a group need a carbon footprint per subsidiary or a single group footprint?
The two are complementary. Each subsidiary needs a detailed footprint to steer its own reduction actions, while the group needs a consolidated footprint for regulatory reporting and strategic planning. Structuring the data by entity while enabling aggregation avoids duplicating collection work.
Is scope 3 mandatory in a group carbon footprint?
Scope 3 generally represents the majority of a group's emissions. Under the French BEGES regulatory method (V5), including it is mandatory only for private-law entities that are also subject to the French DPEF non-financial performance statement ; other entities covered by the BEGES only need to include scope 2 at a minimum, with scope 3 recommended but not required. It is, however, central to any reporting aligned with the ESRS standards under the CSRD, which covers the upstream and downstream value chain.
How do you avoid double counting emissions between subsidiaries of the same group?
Double counting happens with intra-group transactions recorded as scope 3 by both entities involved. It is corrected by documenting intra-group flows and applying an elimination rule consistent with the chosen consolidation method.
Does a group carbon footprint replace local regulatory reports for each subsidiary?
Not necessarily. Some subsidiaries can be individually subject to a local obligation (such as the French BEGES, if they exceed the applicable threshold) independently of the group's consolidated reporting. Each obligation should be checked both subsidiary by subsidiary and at group level.
What is the difference between corporate carbon accounting and product carbon footprint (LCA)?
Corporate carbon accounting measures emissions at the organizational level over a given period. Product carbon footprint, calculated through life cycle assessment (LCA), measures a product's impact across its entire life cycle, from raw material extraction to end of life. A group may need both approaches.
Additional resources
From the Kabaun blog : conducting a corporate carbon footprint, carbon accounting, carbon accounting methods, emission factors explained, scope 3 : upstream and downstream emissions, carbon footprint vs LCA, decarbonization strategy guide.
Conclusion
For a corporate group or a multi-entity mid-cap company, carbon accounting hinges above all on defining the organizational boundary and on the ability to get consistent data from every subsidiary. The scope-based method stays the same as for a single-site company ; what changes is the scale of data governance.
The first concrete action : document in writing the consolidation rule chosen (equity share, financial control or operational control) before launching the data collection campaign, so next year's footprint stays comparable.
Kabaun helps you consolidate your group carbon footprint → kabaun.com/contact
