A gas boiler, a delivery truck, a refrigerant leak from a chiller unit: these three sources share one thing in common, they all fall under Scope 1, the direct greenhouse gas emissions of an organization.

This article defines Scope 1 under the GHG Protocol Corporate Standard, details the four source categories to track, explains the activity data × emission factor formula, and draws the exact boundary with Scope 2 on the cases that most often cause confusion (purchased heat, electric vehicles, cogeneration).

Table of contents

  • What is Scope 1
  • Organizational boundary, the first decision to make
  • The four source categories of Scope 1
  • The calculation formula and the role of GWP
  • Two worked examples
  • Collecting Scope 1 data
  • The boundary between Scope 1 and Scope 2
  • The case of biogenic CO2
  • Scope 1 and reporting standards: GHG Protocol, ISO 14064-1, ESRS
  • Common mistakes
  • How Kabaun automates Scope 1 calculation
  • FAQ
  • Sources

What is Scope 1

The GHG Protocol Corporate Standard, the methodological reference published by the World Resources Institute and the World Business Council for Sustainable Development, defines Scope 1 as the direct greenhouse gas emissions from sources owned or controlled by the reporting organization. This standard structures the whole carbon footprint into three complementary scopes, described in our reference guide to Scopes 1, 2 and 3.

If the organization itself burns the fuel, operates the vehicle, or owns the equipment that leaks, the emission is direct and belongs to Scope 1. If the emission happens at a third party, an energy supplier for instance, it becomes indirect and falls under Scope 2 or Scope 3. The GHG Protocol remains the common reference framework across the three scopes.

Organizational boundary, the first decision to make

Before tracking a single emission source, a company managing several subsidiaries, joint ventures or sites must set its organizational boundary: which entities to consolidate, and under what rule. The GHG Protocol offers three approaches, which do not produce the same result on a multi-entity group.

  • Operational control: consolidate 100% of the activities where the organization has the authority to introduce and implement operating policies, even as a minority shareholder.
  • Financial control: consolidate 100% of the activities under financial control, even without day-to-day operational management.
  • Equity share: consolidate only the share of emissions matching the organization's ownership stake, a 40%-owned subsidiary counted at 40%.

A fleet or a boiler operated by a subsidiary owned at 30% will therefore show up at 100% of the group's Scope 1 under operational or financial control, against only 30% under the equity share approach. Whichever method is chosen must stay consistent from one reporting year to the next.

The four source categories of Scope 1

The GHG Protocol Corporate Standard groups direct emissions into four categories.

  • Stationary combustion: boilers, industrial furnaces, backup generators, production burners. Activity data: volume of fuel consumed on site (natural gas in m³ or kWh, heating oil in liters, coal in tons).
  • Mobile combustion: vehicles and equipment owned or held under long-term lease (company car fleet, trucks, construction equipment, combustion-engine forklifts). Activity data: fuel consumed in liters, or distance traveled combined with an average consumption per vehicle type.
  • Process emissions: emissions from a physical or chemical transformation independent of combustion (calcination in cement production, industrial chemical reactions, on-site waste treatment), each process requiring its own quantification method.
  • Fugitive emissions: refrigerant leaks from air conditioning, refrigeration and heat pumps, methane leaks on gas networks, SF6 releases from certain electrical equipment. HFC refrigerants have a global warming potential far higher than CO2: a leak of a few kilograms can outweigh, in tons of CO2 equivalent, the combustion of several thousand liters of fuel.

The calculation formula and the role of GWP

Calculating a Scope 1 emission follows a logic common to the whole GHG Protocol:

Emissions (in kg or tons of CO2e) = Activity data × Emission factor

Activity data measures a physical quantity consumed or produced: liters of diesel, m³ of natural gas, kilograms of refrigerant topped up. The emission factor converts this physical unit into CO2 equivalent. Every factor should state its source (a national emission factor database, DEFRA, EPA, IPCC) and its publication year, since these values are updated regularly.

When a gas other than CO2 is involved, fugitive methane or a refrigerant, the calculation applies the global warming potential (GWP), which expresses how many times a gas warms the atmosphere more than CO2 over a 100-year horizon. GWP is not a fixed constant: the IPCC revises it with every assessment report. The IPCC's fifth assessment report (AR5, 2013) put the 100-year GWP at 28 for non-fossil methane and 30 for fossil methane, and at 265 for nitrous oxide (N2O). According to the US Environmental Protection Agency (EPA), which uses the IPCC's sixth assessment report (AR6) values, these figures shift to 27-30 for methane depending on its fossil or non-fossil origin, and to 273 for N2O. A national or sector-specific database generally states which IPCC assessment report its values come from: it is better to keep the GWP tied to the chosen factor than to mix GWPs from different reports in the same calculation.

Two worked examples

Stationary combustion. An industrial site consumes 50,000 m³ of natural gas over the reporting year. With an illustrative emission factor of 2 kg CO2e/m³, the resulting emission is 50,000 × 2 = 100,000 kg CO2e, or 100 tons CO2e. The exact factor depends on the composition of the gas delivered and should be checked in an up-to-date database rather than reused from one year to the next.

Fugitive emission. A chiller unit loses 2 kg of R-410A refrigerant over the year, detected during a mandatory leak check. With an illustrative GWP of 2,000 for this refrigerant, the resulting emission is 2 × 2,000 = 4,000 kg CO2e, or 4 tons CO2e, for only 2 kg of physical mass released: fugitive emissions should never be overlooked in favor of combustion sources alone.

Both examples are deliberately illustrative: the real factor and GWP must always be checked against the database the company actually uses.

Collecting Scope 1 data

Three data sources cover most of Scope 1:

  • Energy invoices (natural gas, heating oil, propane): consumption in kWh or liters, to be compared against a reference database where needed.
  • Fuel records: fleet fuel cards, diesel delivery notes for backup generators, meters on construction equipment.
  • Regulatory refrigerant logs: in the EU, the F-Gas Regulation requires tracking refrigerant charges and top-ups on equipment above certain thresholds, a log directly usable to quantify fugitive emissions.

These three sources reconstruct most of Scope 1, provided the documents are centralized throughout the year rather than at the end of the reporting cycle, an approach more reliable than a spend-based estimate, which should stay reserved for secondary items.

The boundary between Scope 1 and Scope 2

Three concrete cases regularly cause classification errors.

Purchased heat or steam. A site that buys heat or steam produced by a district heating network or a third-party boiler plant does not count this energy in Scope 1: the combustion happens at the supplier's premises. This consumption belongs to Scope 2, just like purchased electricity.

Electric fleet vehicles. An electric vehicle generates no on-board combustion, so it has no Scope 1 emission at all. The electricity used to charge it falls under Scope 2. Only a combustion-engine or hybrid vehicle, which burns onboard fuel, stays in Scope 1.

On-site cogeneration. A cogeneration unit (simultaneous production of electricity and heat from the same fuel) burned on site stays entirely in Scope 1 for the full fuel consumed, including the share used to produce electricity exported to the grid.

The case of biogenic CO2

CO2 from biomass combustion (wood energy, biogas, biofuels) is treated separately under the GHG Protocol Corporate Standard: reported on a distinct line, outside the total of the three scopes, rather than added to direct emissions, because this carbon was captured by the biomass shortly before combustion. This separate treatment does not exempt a company from measuring and disclosing these emissions.

Scope 1 and reporting standards: GHG Protocol, ISO 14064-1, ESRS

The GHG Protocol Corporate Standard remains the global reference for quantifying Scope 1. Companies that want their inventory aligned with an international standard, often ahead of third-party verification, can also rely on ISO 14064-1, the standard that sets out specifications for the quantification and reporting of greenhouse gas emissions and removals at the organization level.

In the European Union, companies within the scope of the CSRD directive must disclose their emissions by scope under the ESRS E1 standard on climate change, developed by EFRAG. Its Disclosure Requirement E1-6 specifically calls for gross Scope 1, Scope 2 and Scope 3 emissions and their total, with the underlying calculation methodology. In France, the mandatory BEGES inventory places direct emissions, the equivalent of Scope 1, in its category 1, and since its 2022 methodology update it also requires significant indirect emissions.

Common mistakes

  • Forgetting fugitive emissions, by tracking only energy and fuel invoices.
  • Classifying purchased heat as Scope 1, a frequent mix-up on sites connected to a district heating network.
  • Mixing GWP values from different IPCC assessment reports without documenting it, which makes results incomparable.
  • Changing the organizational boundary without documenting it, which makes year-over-year comparisons misleading.
  • Using a generic emission factor without checking its source or date, which makes the calculation impossible to audit.

How Kabaun automates Scope 1 calculation

Kabaun is a carbon management platform built on the GHG Protocol:

  • Calculation engine compliant with the GHG Protocol Corporate Standard, with 270,000 emission factors from 8 public databases (ADEME Base Carbone, DEFRA, EPA, Exiobase, Agribalyse, GLEC, Miteco, OpenCEDA).
  • Native coverage of Scopes 1, 2 and 3, with an explicit choice of which scopes to include.
  • Custom emission factors (a specific refrigerant, a fuel not covered by standard databases), with administrator validation and full traceability.
  • Tamper-proof audit trail, with supporting evidence attached to every emission line.

FAQ

What is the difference between Scope 1 and Scope 2? Scope 1 covers direct emissions from a source the organization owns or controls: its own boiler, its own vehicles, its own refrigerant leaks. Scope 2 covers indirect emissions from purchased energy (electricity, heat, steam) produced by a third party, even when consumed on the organization's own site. An electric fleet vehicle, for instance, burns no fuel on board: the electricity used to charge it is counted in Scope 2.

Why do refrigerant leaks weigh so much in the calculation? Because these gases have a global warming potential far higher than CO2: a few leaked kilograms can represent several tons of CO2 equivalent. Ignoring this source often significantly understates the real Scope 1 of an air-conditioned or refrigerated site.

Does Scope 1 depend on the organizational boundary chosen? Yes. Depending on whether a company consolidates through operational control, financial control or equity share, the same boiler or fleet can show up at 100% or at only a fraction of the group's Scope 1. This methodological choice must be documented and applied consistently.

How is CO2 from biomass combustion treated? The GHG Protocol requires this biogenic CO2 to be reported separately from the total of the three scopes, on a distinct line, rather than added to fossil emissions. It must still be measured and disclosed, not ignored.

What is the basic formula for calculating a Scope 1 emission? Emissions in CO2e equal activity data (the quantity of fuel consumed or refrigerant leaked) multiplied by an emission factor from a documented database (a national factor database, DEFRA, EPA). For a gas other than CO2, the factor incorporates that gas's global warming potential.

Conclusion

Scope 1 covers the emissions an organization directly controls: stationary combustion, mobile combustion, industrial processes and fugitive emissions. Calculating it relies on verifiable activity data multiplied by a sourced emission factor, with a documented GWP whenever a gas other than CO2 is involved. Rigor comes down to three points: a stable organizational boundary from one year to the next, a clear line with Scope 2 on ambiguous cases such as purchased heat or electric vehicles, and systematic tracking of refrigerant leaks.

Kabaun automates your Scope 1 calculation under the GHG Protocol → www.kabaun.com/en/contact

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