Scope 1, 2 and 3 Emissions Explained: UK SECR Guide

Written by Calvin Lo, Founder of Aphelios Software | August 2026 | 7 min read

"Scope 1, Scope 2, Scope 3" gets thrown around in every carbon conversation, but the definitions are surprisingly simple once you think about where the emissions physically happen. The scopes exist to stop the same emissions being counted twice: if every company counted everything, the same tonne of CO2 would appear in dozens of reports.

Aphelios uses the scope definitions exactly as printed by the UK Government’s DESNZ conversion factor publication, so your disclosure matches the official methodology. This guide explains each scope with practical examples, and what you actually need to record for SECR.

Scope 1: Direct Emissions

Scope 1 covers emissions from sources your company owns or controls. If the fuel is burned on your premises or in your vehicles, it is Scope 1. Common examples:

• Natural gas burned in boilers and ovens
• Petrol, diesel or LPG in company vehicles
• Fuel for generators and site machinery
• Refrigerant and process emissions

Under SECR, Scope 1 emissions must be reported for UK sources, with the energy use recorded in kilowatt-hours (kWh) alongside the associated CO2e.

Scope 2: Energy-Indirect Emissions

Scope 2 covers emissions from the energy you purchase, most commonly electricity. You do not physically burn the fuel - the power station does - but your electricity consumption is attributed to you using the official grid factor for the reporting year.

Under SECR, electricity used for lighting, refrigeration, IT and equipment is the classic Scope 2 example, and it is mandatory to report with the energy use recorded in kWh.

Scope 3: Other Indirect Emissions

Scope 3 is everything else in your value chain: emissions that happen because of your business, but outside your operational control. Examples include:

• Business travel in rented cars, trains, flights and taxis
• Delivery and logistics emissions
• Purchased goods and services (supply chain)
• Employee commuting and home working

Under SECR, Scope 3 reporting is voluntary. That said, supply-chain questionnaires and ESG frameworks increasingly ask for it, and many companies track Scope 3 travel at a minimum because the data is easy to capture.

Which Scopes Does SECR Actually Require?

In every SECR report you also need an intensity ratio and, for in-scope companies, an energy-efficiency narrative - covered in our intensity ratio guide.

How to Record Activities Correctly

For each activity you record, you need three things:

1. The activity data - e.g. 12,400 kWh of electricity, 800 litres of diesel, 2,300 miles of business travel
2. The matching conversion factor - chosen from the official DESNZ factor set for the right year
3. A methodology note - how the figure was obtained (meter reading, invoice, estimate), which SECR requires for transparency

In Aphelios emissions, each activity stores its data-source type and methodology note, lets you attach evidence such as energy bills, and calculates the CO2e automatically using the correct official DESNZ factor. Energy use in kWh is captured at the same time - required for Scope 1 and 2 under SECR.

Biogenic CO2 - Reported Separately

One detail that catches companies out: CO2 from biomass and bioenergy (biogenic CO2) is reported separately and excluded from the gross totals, per the SECR guidelines. Aphelios tracks biogenic emissions separately so your totals stay methodologically correct.

Scope FAQ

This guide is a planning aide, not legal advice. Confirm your reporting approach with your accountant before filing.