Why does it matter?
Understanding and reporting emissions by scope is fundamental to credible carbon management. Without this categorisation, organisations cannot identify where their emissions come from, set meaningful reduction targets, or report transparently to stakeholders. Scope classification is required by virtually every major emissions reporting framework, including the UK government's Carbon Reduction Plan requirements for public procurement.
Key details
Scope 1: Direct emissions
Scope 1 emissions come from sources that the organisation directly owns or controls. This includes emissions from burning fuel on-site (such as gas boilers), company-owned vehicles, industrial processes, and fugitive emissions (such as refrigerant leaks). These are typically the most straightforward emissions to measure and reduce.
Scope 2: Indirect emissions from energy
Scope 2 emissions result from the generation of purchased electricity, heat, steam, or cooling consumed by the organisation. Although the emissions physically occur at the power station or energy facility, they are attributed to the organisation that purchases and uses the energy. Switching to renewable energy tariffs or generating on-site renewable energy are common approaches to reducing Scope 2 emissions.
Scope 3: Value chain emissions
Scope 3 is the broadest and most complex category, covering all other indirect emissions in the organisation's value chain. The GHG Protocol defines 15 categories of Scope 3 emissions, split into upstream activities (such as purchased goods and services, business travel, employee commuting, and waste generated in operations) and downstream activities (such as the use and end-of-life treatment of sold products).
For most organisations, Scope 3 represents the largest share of total emissions, often 70–90% or more. It is also the most challenging to measure accurately, as it relies on data from suppliers, customers, and other third parties.
Reporting requirements
UK government Carbon Reduction Plans (as required by PPN 006 / PPN 06/21) mandate reporting of Scope 1 and 2 emissions and a specified subset of Scope 3 categories. The GHG Protocol provides detailed guidance on calculation methodologies for all three scopes, and the UK government publishes annual conversion factors through DEFRA to support accurate emissions calculations.
UK & public sector context
For suppliers to the UK public sector, the ability to measure and report Scope 1, 2, and 3 emissions is now a compliance requirement for major contracts. PPN 006 (the successor to PPN 06/21 under the Procurement Act 2023) requires a published Carbon Reduction Plan covering all three scopes for contracts above £5 million per year. The NHS has extended carbon reduction plan requirements to all procurements regardless of value.
Beyond mandatory compliance, many contracting authorities are beginning to evaluate suppliers' carbon performance as part of broader social value assessments, rewarding those who can demonstrate measurable progress on emissions reduction across all scopes.