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Scope 1, 2 and 3 emissions: what they are and how they are calculated

A guide to the different types of emissions, including differences, practical examples and tools for managing them in a company.

Talking about Scope 1, 2 and 3 emissions has become an almost essential step for anyone dealing with corporate sustainability, regardless of the size of the company. The topic stems from a specific need: understanding where the greenhouse gas emissions generated by an organisation come from and how they can be reduced effectively.

The classification into three areas, defined by the GHG Protocol, makes it possible to interpret a complex phenomenon in a structured way. In this guide, we look at what distinguishes the three Scopes, why it is useful to measure them and where to start in order to do so correctly.

What are Scope 1, 2 and 3 emissions?

Scope 1, 2 and 3 emissions are the international classification used by the GHG Protocol (Greenhouse Gas Protocol) to describe the greenhouse gas emissions generated by an organisation, based on their origin and the degree of control the company has over them.

The logic behind this classification is simple: to distinguish between the emissions a company produces directly and those it generates indirectly, through the Energy it purchases or through the activities of its value chain. This distinction is the starting point for any credible sustainability report or ESG report.

The standard was developed by the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD) and is now the most widely used reference for setting effective decarbonisation strategies and building an emissions inventory that can be compared over time and across different companies.

The differences between Scope 1, Scope 2 and Scope 3, with practical examples

Understanding the differences between the three Scopes is essential to avoid confusing responsibilities and intervention priorities.

Scope 1

Scope 2

Scope 3

Scope 1 includes direct emissions, i.e. those produced by sources owned or controlled by the company. This category includes:

the combustion of natural gas in boilers or internal production plants;
the fuel consumed by company-owned or leased vehicles;
emissions resulting from industrial processes managed directly by the company.

Scope 2 concerns indirect emissions related to electricity, heat or steam purchased and consumed by the company. Although the emission physically occurs at the Energy supplier’s facilities, the accounting responsibility falls on the party consuming that Energy.

Scope 3, the broadest and often the most complex to quantify, includes all other indirect emissions generated along the value chain, both upstream and downstream of the company’s activities. Some examples include:

goods and services purchased from external suppliers;
the transport and distribution of goods not managed directly by the company;
employees’ business travel and commuting;
the use and end-of-life of products sold.

For many companies, especially those with extensive supply chains, Scope 3 represents the most significant share of the overall carbon footprint, although it remains the most difficult to measure accurately.

Why is it worthwhile for companies to measure emissions?

Measuring their emissions is no longer just an exercise in voluntary transparency: it is increasingly a requirement coming from the market. Large companies subject to sustainability reporting obligations ask their suppliers, including small and medium-sized enterprises, for reliable emissions data in order to complete their Scope 3 inventory.

In this context, the European regulatory framework is evolving: the Omnibus I simplification package has raised the size thresholds for the direct CSRD reporting obligation, reducing the number of companies directly involved. However, this does not mean that the issue is becoming less relevant: emissions measurement remains an increasingly frequent requirement across supply chains, in relationships with the banking system and in credit and investment assessments.

Beyond the regulatory dimension, there are concrete reasons related to competitiveness. A company that knows its carbon footprint can identify efficiency opportunities, reduce Energy waste and communicate its commitment to sustainability with solid data. Adopting an Energy management system such as the one provided for by ISO 50001 certification helps structure the collection of the data needed to calculate Scope 1 and 2 emissions, integrating Energy monitoring into a continuous improvement process rather than an occasional measurement.

How they are calculated: method and tools

The calculation of Scope 1, 2 and 3 emissions follows a methodology defined by the GHG Protocol, structured into a number of main steps:

define the organisational and operational boundaries of the inventory, i.e. which activities and sites to include;

collect consumption data relating to fuels, electricity and value chain activities;

apply the appropriate emission factors to convert consumption into quantities of CO2 equivalent;

distinguish, for Scope 2, between the location-based approach, based on the average factor of the national power grid, and the market-based approach, which takes into account the specific Energy mix of the chosen supplier.

The main critical issue for most companies concerns Scope 3: it requires data from external parties, such as suppliers and customers, who are often not yet accustomed to providing this type of information in a structured way. For this reason, many organisations choose to proceed in stages, starting with Scope 1 and 2, which are easier to quantify using internal data, and then gradually expanding the scope to Scope 3 according to the categories most relevant to their sector.

Where to start: Enel's role in Energy consulting

Starting an emissions measurement process requires specific technical expertise, especially in the initial phase of defining boundaries and collecting data. For companies approaching this process for the first time, relying on an Energy consultant can greatly simplify the work: from analysing consumption to choosing the correct emission factors, through to setting up a continuous monitoring system over time.

As an Energy partner, Enel supports companies with tailored decarbonisation pathways, built on scientifically validated methodologies and aligned with the emission reduction targets defined by the GHG Protocol.

The proposed solutions ensure compliance with the main European regulations, such as the Green Deal and the Fit for 55 package, the CSRD and the EU Taxonomy, as well as with the most widely recognised international standards, including ISO 14064, ISO 50001, the Science Based Targets initiative (SBTi) and the TCFD framework for climate risk management.

This type of support helps avoid the most common errors in an initial measurement, such as unclear organisational boundaries or incomplete Scope 3 data, and makes it possible to build a gradual and Sustainable pathway aligned with the company’s resources and priorities.

The stages of the decarbonisation pathway

The decarbonisation pathway develops through progressive stages, each with specific objectives and dedicated tools.

Calculation of the company’s carbon footprint, including Scope 1, 2 and 3 emissions, and completion of an Energy audit compliant with European Directive 2012/27; this phase makes it possible to identify the main sources of emissions and the Energy consumption areas requiring intervention.

Definition of an action roadmap based on future scenarios and scientifically validated objectives, integrating a portfolio of solutions such as Energy efficiency, Photovoltaic, process Electrification and circular economy.

Translation of the strategy into concrete actions, managed through a detailed schedule and performance indicators (KPIs) that make it possible to monitor progress over time.

Adoption of Energy management systems and digital reporting platforms that make it possible to verify results in real time, update the strategy and ensure continuous improvement in environmental performance.

Each phase builds on the previous one, ensuring a consistent and measurable pathway towards climate neutrality.

Why choose an Energy consultant?

In summary, turning to an Energy consultant means: transforming a cost into a strategic lever, simplifying Energy management, accessing specialist expertise, adopting tailor-made solutions and building long-term stability.

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Frequently Asked Questions

The carbon footprint is the overall amount of an organisation’s emissions, expressed in CO2 equivalent. The Scope 1, 2 and 3 classification, on the other hand, is the method used to break down and organise this figure by source, making it possible to understand which levers can be acted on to reduce it.

Following the entry into force of the Omnibus I package, the direct reporting obligation applies only to companies with more than 1,000 employees and more than €450 million in annual net turnover. SMEs are therefore not subject to the direct obligation, but are increasingly involved indirectly when they are part of the supply chain of companies subject to reporting requirements.

For companies subject to reporting obligations, a form of assurance with a limited level of assurance is required. For companies that are not subject to these obligations, however, formal external verification is not required, although a review by an independent professional increases the reliability and credibility of the data communicated to customers, banks or investors.

In the initial phase, the following are generally required: electricity and gas bills and supply contracts, fuel consumption data for the company fleet, invoices relating to business travel and transport, and any information provided by the main suppliers on purchased goods and services.

No, it is not a mandatory requirement. It is a voluntary Energy management system which, if adopted, makes the collection of the Energy data required for the calculation more structured and continuous, but emissions can also be calculated without formal certification.

Because it is divided into fifteen different categories and requires data that the company does not directly control, but must obtain from suppliers, customers and other parties in the value chain, who are often not yet accustomed to providing this type of information in a standardised way.