Scope 1 emissions — definition, examples and calculation

What are scope 1 emissions?

Scope 1 emissions are the direct greenhouse gas emissions from sources your business owns or controls. If an asset you own or control physically burns fuel or releases gas — a boiler, a van, a leaking chiller — the emission is yours, and it is a scope 1 emission. The GHG Protocol Corporate Standard, the global standard for carbon accounting, sets the definition that UK SECR reporting follows.

The GHG Protocol classifies greenhouse gas emissions into three scopes — scopes 1, 2 and 3. Scope 1 emissions are direct emissions; scope 2 covers indirect emissions from purchased energy; scope 3 covers all other indirect, value chain emissions. Scope 1 is the only one of the three scopes where the emissions occur directly from your own equipment, which makes it the easiest of scopes 1, 2 and 3 to measure accurately.

The "owned or controlled" test almost always uses the operational control boundary: you account for scope 1 emissions from any site where you have authority to set operating policies. That is the default boundary for SECR, and the same boundary you use across scopes 1, 2 and 3.

The four categories of scope 1 emissions

Under the GHG Protocol, scope 1 emissions sources fall into four buckets:

Stationary and mobile combustion are emissions from fuels you burn directly. Fugitive emissions come from refrigerant losses and are the most commonly missed, because top-ups are billed through facilities management rather than energy. Process emissions come from chemical reactions rather than combustion and affect only a few industries — but where they apply, they are often the single largest source of emissions.

What is not included in scope 1

Scope 1 does not include emissions from purchased electricity (scope 2) or emissions generated up and down your value chain (scope 3). Three things look like scope 1 but are not — and double-counting them is the most common error:

• Purchased electricity — the generation happens at the power station, so it falls under scope 2, not scope 1.
• Purchased heat and steam — bought-in energy, so it is also scope 2.
• Grey-fleet mileage — staff using their own cars for business is scope 3, because you do not own those vehicles. Owned and leased fleet vehicles stay in scope 1.

Scope 1 emissions examples by industry

Where your biggest scope 1 emissions sources sit depends on your sector:

• Logistics and transport — diesel fleet dominates, often 80%+ of total emissions; plus LPG warehouse heating and F-gas from refrigerated units.
• Manufacturing — natural gas for process and space heating; diesel forklifts; F-gas from chillers; process CO₂ in cement, lime, steel, glass and fertiliser.
• Retail — F-gas from refrigeration display units (often the largest single source); store heating gas; van fleet.
• Property and real estate — gas for heating and hot water; back-up generators; F-gas from air-conditioning; LPG at off-grid sites.
• Hospitality — kitchen and hot-water gas; F-gas from air-conditioning and walk-in fridges.
• Healthcare — heating and sterilisation gas; medical gas losses (high-GWP nitrous oxide); building cooling F-gas; patient-transport fleet.
• Professional services — usually small: office gas, any pool cars, server-room cooling.

How to calculate scope 1 emissions

Calculating scope 1 emissions uses one formula for every source: activity data × emission factor = tCO₂e.

Step 1 — Collect 12 months of activity data

Step 2 — Match each source to the correct DEFRA emission factor

The DEFRA conversion factors give a separate emission factor for every fuel, vehicle and refrigerant. The factor year must match the data year: calendar-year 2026 data uses the 2026 factors (published June 2026).

Step 3 — Multiply and sum

For each source, activity data × emission factor = kgCO₂e. Divide by 1,000 for tCO₂e, then total across all sources to get your scope 1 emissions.

Worked example — small office and small fleet

The emission factors below are illustrative — always use the current published DEFRA values for your data year.

Run the same calculation in minutes with the free SECR carbon calculator.

Five pitfalls when calculating scope 1

1. Gross vs net calorific value. UK gas invoices are usually gross; DEFRA publishes both. Pick one and document it.
2. Forgetting refrigerants. Get the F-gas register — top-ups are easy to miss.
3. Grey-fleet confusion. Grey-fleet is scope 3, not scope 1. Do not double-count.
4. Mixing GWPs. Refrigerant CO₂e uses the Global Warming Potential values DEFRA references each year; restate consistently if you compare years.
5. Overlooking process emissions. In cement, lime, steel, glass, ammonia or fertiliser, these are often your largest single scope 1 source.

Scopes 1, 2 and 3 emissions explained

Companies report greenhouse gas (GHG) emissions across three scopes, so that every tonne of emissions is counted once and only once. Understanding scopes 1, 2 and 3 together shows why scope 1 is only part of the picture:

• Scope 1 emissions are direct emissions from owned or controlled sources.
• Scope 2 covers indirect emissions from the generation of purchased energy — see the scope 2 guide.
• Scope 3 covers all other indirect, value chain emissions — see the scope 3 guide.

The difference between scope 1 and scope 2 is where the fuel burns: scope 1 emissions occur on your own equipment, whereas scope 2 emissions occur at the power station that supplies your electricity. For most UK companies, scope 1 and 2 together are only 5–20% of the total carbon footprint — scope 3 emissions make up the rest — which is why measuring all three scopes of emissions gives the true carbon footprint.

Under SECR, scope 1 and 2 are mandatory and scope 3 is largely voluntary for unquoted companies, so most SECR reports focus on scope 1 and 2 emissions. As CSRD-aligned reporting spreads, full scopes 1, 2 and 3 reporting is becoming the norm.

How scope 1 fits in SECR

Scope 1 emissions are mandatory under SECR for every qualifying UK organisation. What you disclose depends on company type:

SECR applies to large UK companies and LLPs meeting at least two of three thresholds: turnover of £36m or more, balance sheet total of £18m or more, or 250 or more employees. The April 2025 Companies Act uplift raised the general "large" definition to £54m and £27m, but the SECR thresholds did not move — so a company now classed as "medium" can still be in scope. Confirm yours with the free eligibility checker.

In the report, scope 1 emissions usually appear as a single line in the emissions table, with optional sub-source detail in a footnote. The SECR report template shows the standard layout.

How to reduce scope 1 emissions

Once you have measured it, the highest-impact ways to reduce scope 1 emissions are:

• Heat pumps instead of gas boilers — shifts scope 1 gas into scope 2 electricity, which keeps falling as the grid decarbonises.
• Electric vehicles instead of diesel fleet — cuts your largest mobile-combustion source.
• F-gas management — low-GWP refrigerants and tighter leak detection to cut fugitive emissions.
• Process efficiency — heat recovery and combustion tuning.
• Behavioural measures — driver training and switch-off protocols.

These emissions reduction actions are exactly what belongs in the SECR energy-efficiency narrative, so measuring scope 1 well makes your report stronger and supports any emissions reduction targets you set. For a fuller plan, see net-zero strategy.

Get a specialist to build your scope 1 inventory

Scope 1 is mathematically simple but operationally fiddly — fuel cards, gas bills, F-gas registers and refrigerant contracts usually live in different parts of the business, and pulling them together is where most of the time goes. A vetted, IEMA-qualified specialist can assemble a complete scope 1 and scope 2 emissions inventory and calculate your emissions on the current DEFRA factors. Check your eligibility, then we will introduce you to the right specialist — free and with no obligation.