Scope 1, 2 and 3 emissions — explained in plain English
Every corporate carbon footprint is split into three scopes under the GHG Protocol: direct emissions a company owns (Scope 1), emissions from the energy it buys (Scope 2), and everything else across its value chain (Scope 3). Here is what each one means, worked examples, and how SECR and UK SRS S2 each use them.
Scope 1, 2 and 3 — one framework, three boundaries
The GHG Protocol Corporate Standard splits a company's greenhouse gas emissions into three scopes based on where control and ownership sit, not on how large the emission is.
One classification, one global standard
Scope 1 (direct), Scope 2 (purchased energy) and Scope 3 (everything else in the value chain) come from the GHG Protocol Corporate Accounting and Reporting Standard, first published in 2001 and revised in 2004.
Every major carbon-reporting framework in use in the UK today — SECR, UK SRS S2, CDP — reports emissions using this same three-scope structure, which is what makes company-to-company comparison possible.
The scope boundaries follow operational control and ownership, not the size of the emission or how far away it happens. A large emission from a supplier’s factory is Scope 3 even though it may dwarf the reporting company’s own Scope 1 total 1. This is deliberate: the three-scope split prevents double counting when many companies in a value chain report emissions, because each company’s Scope 1 is, by definition, some other company’s Scope 3.
In the UK, SECR has required Scope 1 and Scope 2 disclosure from large companies since 2019. UK SRS S2 goes further, requiring all three scopes — with Scope 3 carrying transitional relief. The rest of this page works through each scope in turn, then covers how the two UK regimes differ.
Scope 1: emissions the company causes directly
Scope 1 covers greenhouse gases released from sources the reporting company owns or controls — combustion, fleet vehicles and fugitive gas leaks.
- Stationary combustionScope 1
- Fuel burned on-site to produce heat, steam or power — gas boilers, furnaces, generators and combined heat and power (CHP) plant that the company owns or controls.
- Mobile combustionScope 1
- Fuel burned in company-owned or company-leased vehicles, forklifts, plant and machinery — diesel vans, company cars, HGVs and construction equipment.
- Process emissionsScope 1
- Emissions released by an industrial process itself, independent of fuel combustion — for example CO₂ released during cement manufacture or chemical reactions in industrial processes.
- Fugitive emissionsScope 1
- Unintentional releases such as refrigerant or air-conditioning gas leaks, and methane leaks from gas infrastructure the company controls. Often overlooked, but can be a material share of Scope 1 for companies with large refrigeration or cooling estates.
A retailer’s Scope 1 emissions are typically dominated by gas heating in owned stores and diesel in an owned delivery fleet. A manufacturer’s Scope 1 emissions often include process emissions from the manufacturing line itself, on top of combustion. Companies that operate few owned buildings or vehicles — for example a software business renting office space and using no company vehicles — can have a very small Scope 1 footprint, even though their total footprint (once Scope 2 and Scope 3 are added) may still be substantial.
Scope 2: emissions from the electricity, steam, heat and cooling you buy
Scope 2 covers indirect emissions from generating the electricity, steam, heat or cooling a company purchases and consumes — reported two ways under the GHG Protocol Scope 2 Guidance.
Location-based and market-based reporting
The GHG Protocol Scope 2 Guidance requires companies that report Scope 2 to disclose it two ways.
The location-based figure applies an average emissions factor for the grid the company draws power from — in the UK, the DESNZ grid electricity factor.
The market-based figure reflects the specific electricity contracts a company has in place, including renewable energy certificates, power purchase agreements and green tariffs.
The two figures can diverge significantly for companies that have purchased renewable electricity contracts.
Scope 2 typically arises from grid electricity used to power lighting, IT equipment, machinery and HVAC systems in offices, warehouses and factories. It also covers purchased steam or heat from a district heating network, and purchased cooling from a shared chilled-water system. A company with an all-electric vehicle fleet shifts what would otherwise be Scope 1 fuel combustion into Scope 2 electricity consumption — one reason the two scopes are best read together rather than in isolation. Companies should always use the current-year DESNZ conversion factors 7 for the location-based figure; out-of-date factors are a common reporting error.
Scope 1 vs Scope 2 — the difference in practice
Both scopes cover energy-related emissions inside the company's own operations. The dividing line is ownership: who burns the fuel, and who generates the power.
Scope 1 is what you burn. Scope 2 is what you buy. Scope 3 is everything you touch without owning.
A common shorthand for the three-scope boundary
Scope 3, in summary — the full guide is a click away
Scope 3 covers 15 categories of indirect emissions across the value chain, upstream and downstream of the reporting company's own operations.
SECR covers Scope 1 and 2 — UK SRS S2 covers all three
The two UK carbon-reporting regimes ask for different scope coverage. Knowing which applies to a given company is the first step in any compliance programme.
| Regime | Scopes required | Who it applies to |
|---|---|---|
| SECR (SI 2018/1155) | Scope 1 and 2 (plus a narrow grey-fleet Scope 3 element for unquoted companies/LLPs) | Quoted companies (any size); large unquoted companies and large LLPs — turnover ≥£36m, balance sheet ≥£18m or 250+ employees (2 of 3) |
| UK SRS S2 (proposed mandatory) | Scope 1, 2 and 3 (Scope 3 comply-or-explain from FY beginning 1 Jan 2028) | ~515 UK-listed companies across UKLR 6, 14, 15, 16 and 22 (FCA CP26/5) |
SECR, in force under SI 2018/1155 4 for financial years beginning on or after 1 April 2019, requires quoted companies to disclose global Scope 1 and Scope 2 emissions, and large unquoted companies and large LLPs to disclose UK energy use and associated Scope 1 and Scope 2 emissions (plus a limited Scope 3 element for grey-fleet business travel). SECR was not built to require a full Scope 3 inventory, and the DESNZ post-implementation review published 26 May 2026 recommended retaining SECR broadly unchanged alongside UK SRS.
UK SRS S2 5 is the standard that closes that gap: it requires disclosure of gross Scope 1, Scope 2 and Scope 3 emissions, all calculated using the GHG Protocol Corporate Standard 1. The FCA’s CP26/5 consultation 6proposes UK SRS S2 as mandatory for in-scope listed companies for financial years beginning on or after 1 January 2027, with Scope 3 given one further year of comply-or-explain relief. A company already reporting Scope 1 and 2 under SECR has a head start: the same activity data and DESNZ conversion factors carry over directly into UK SRS S2’s Scope 1 and 2 figures, leaving Scope 3 as the genuinely new build.
Scope 1, 2 and 3 — frequently asked
The definitions and distinctions readers ask about most, with the difference between Scope 1 and Scope 2 answered directly.
What are Scope 1, 2 and 3 emissions?
Scope 1, 2 and 3 are the three categories the GHG Protocol Corporate Standard 1 uses to classify a company’s greenhouse gas emissions. Scope 1 is direct emissions from sources the company owns or controls. Scope 2 is indirect emissions from purchased electricity, steam, heat or cooling. Scope 3is every other indirect emission across the value chain, both upstream (suppliers) and downstream (customers) — usually the largest share of a company’s total footprint.
What is a Scope 1 emission, with an example?
A Scope 1 emission is a direct emission from a source the reporting company owns or controls 1. Examples: gas burned in an on-site boiler, diesel burned in company-owned delivery vans, and refrigerant gas leaking from an owned air-conditioning unit (a fugitive emission).
What is a Scope 2 emission, with an example?
A Scope 2 emission is an indirect emission from the generation of purchased electricity, steam, heat or cooling that the company consumes 1. Example: the emissions associated with the grid electricity used to power an office building’s lighting and computers. The GHG Protocol Scope 2 Guidance 2requires dual reporting — a location-based figure (grid average) and a market-based figure (reflecting any renewable-electricity contracts).
What is the difference between Scope 1 and Scope 2 emissions?
Scope 1 is direct — the company burns the fuel or releases the gas itself, from equipment it owns or controls. Scope 2 is indirect — the emissions happen at a power station or heat network the company does not own, but the company caused them by purchasing that electricity, steam, heat or cooling 1. A company with an all-electric fleet and no gas boilers can have near-zero Scope 1 emissions while still carrying a substantial Scope 2 figure from the electricity it buys.
What are Scope 3 emissions, briefly?
Scope 3 covers all other indirect emissions in the value chain — 15 categories defined by the GHG Protocol Corporate Value Chain (Scope 3) Standard 3, from purchased goods and business travel to the use and disposal of sold products. For most companies it is the largest scope by volume. See the full Scope 3 emissions guide for all 15 categories with examples.
Does UK SECR require Scope 1, 2 and 3 reporting?
SECR, under SI 2018/1155 4, is built around Scope 1 and Scope 2. Quoted companies must disclose global Scope 1 and Scope 2 emissions; large unquoted companies and large LLPs disclose UK energy use and associated Scope 1 and Scope 2 emissions, plus a narrow Scope 3 element covering business travel in employee-owned vehicles used for work (“grey fleet”). SECR does not require a full Scope 3 inventory — that is a UK SRS S2 requirement, not a SECR one.
Does UK SRS S2 require all three scopes?
Yes. UK SRS S2 5 requires disclosure of gross Scope 1, Scope 2 and Scope 3 emissions, calculated using the GHG Protocol Corporate Standard. Scope 3 carries a one-year transitional relief on a comply-or-explain basis, biting for financial years beginning on or after 1 January 2028 6. Scope 1 and Scope 2 have no such relief once UK SRS S2 becomes mandatory.
Emissions reporting — the wider UK stack
From the GHG Protocol foundations through to UK SRS S2 implementation and Scope 3 data quality.
Scope 3 emissions: all 15 categories
Every GHG Protocol Scope 3 category with a real-world example, measurement routes, and UK SRS S2 timing.
StandardsThe GHG Protocol explained
What the GHG Protocol is, its authority, and the corporate-suite revision underway to 2027.
FoundationSECR reporting guide
The Scope 1 and 2 statutory disclosure regime in force since 2019, and how it feeds into UK SRS S2.
ImplementationCarbon accounting in the UK
How UK companies build emissions inventories in practice, including DESNZ conversion factors.
Related guides & references
Scope 3 Emissions: All 15 Categories Explained
Every GHG Protocol Scope 3 category with a real-world example, the three measurement routes, and UK SRS S2 timing.
The GHG Protocol: the standard behind UK SRS emissions
What the GHG Protocol is, how it works, and the revision currently underway.
UK SRS Scope 3 Reporting Guide
Data quality hierarchy, financed emissions and the comply-or-explain timeline for UK SRS S2 Scope 3.
SECR Reporting Guide
The Scope 1 and Scope 2 statutory disclosure regime that predates and underpins UK SRS S2.
Carbon Reporting Software
Platforms that calculate and track Scope 1, 2 and 3 emissions using current-year DESNZ conversion factors.
Complete Scope 3 Emissions Inventory
Step-by-step guide to building a Scope 3 inventory across all 15 categories, with calculation examples.