A Guide to Scope 1 Emissions for UK Businesses

Scope 1 is the part of a carbon footprint a business has the most direct control over, and the least room to misreport. There’s no supplier data to chase and no certificate market to navigate. If the fuel was burned in something the business owns or operates, it counts, and the reporting obligations around it are tightening rather than easing.

This guide covers what Scope 1 emissions are, the four categories they fall into under the GHG Protocol, how they’re calculated using UK government conversion factors, what large businesses are currently required to report, and which reduction levers genuinely eliminate Scope 1 emissions rather than simply moving them elsewhere. 

For the broader picture of how Scope 1 fits alongside Scope 2 and Scope 3, see our guide to reducing Scope 1-3 emissions.

What Are Scope 1 Emissions?

The GHG Protocol defines Scope 1 as direct greenhouse gas emissions from sources a business owns or controls. The defining test is operational control, not physical location: a gas boiler in a leased unit still counts if the business runs it, while electricity drawn from the grid does not, even though it’s consumed on-site.

This is what separates Scope 1 from Scope 2, which covers emissions from purchased electricity, heat, steam, or cooling generated elsewhere. It’s also distinct from Scope 3, which covers everything else across the value chain, including emissions a business’s suppliers and customers produce. 

Scope 1 sits in between: the emissions a business is most directly responsible for, and consequently the ones with the clearest line back to a specific piece of equipment or fleet.

For industrial businesses, Scope 1 is rarely the largest of the three scopes (that’s usually Scope 3), but it’s typically the most measurable, since the data already exists in fuel invoices, vehicle logs, and meter readings rather than needing to be estimated or requested from a third party.

The Four Categories of Scope 1 Emissions

Most guidance on Scope 1 stops at “company vehicles and boilers.” That covers two of the four categories the GHG Protocol actually defines, and misses the one most likely to catch food and beverage, pharmaceutical, and chemicals businesses off guard.

Fugitive emissions are the category most often left out of generic Scope 1 guidance, and the one with the highest potential to surprise a business that assumes Scope 1 begins and ends with fuel. Many common refrigerants have a global warming potential many times that of CO2, so even a relatively small leak from an ageing refrigeration system can represent a disproportionate share of a site’s Scope 1 footprint.

How Scope 1 Emissions Are Calculated

The standard method is activity-based. Take a quantity of fuel consumed (litres of diesel, cubic metres of natural gas, kilograms of refrigerant lost) and multiply it by the relevant emission factor to produce a figure in kgCO2e.

In the UK, those emission factors come from DESNZ’s annual government conversion factors, published each year alongside a methodology report explaining how they’re derived. A business burning 10,000 litres of diesel in its fleet over a year applies that year’s diesel combustion factor to the volume consumed to arrive at a Scope 1 figure for that fuel source. The same logic applies to natural gas used in stationary boilers, with a separate factor for that fuel type.

Fugitive emissions are calculated differently. Rather than activity data on fuel burned, the relevant figure is the quantity of refrigerant lost, multiplied by that specific gas’s global warming potential, which varies considerably between refrigerant types. Process emissions, where they apply, typically follow factors specific to the chemical reaction or industrial process involved, set out in more specialised parts of the GHG Protocol’s guidance rather than the general conversion factors used for fuel.

Because conversion factors are updated annually to reflect changes in fuel composition and the broader energy mix, the GHG Protocol’s own guidance is to apply the factor set published for the year in which the emissions actually occurred, rather than the most recently published set, when calculating a historical reporting period.

What UK Businesses Are Required to Report

Scope 1 sits at the centre of the UK’s current mandatory carbon reporting regime. Under Streamlined Energy and Carbon Reporting (SECR), large UK companies, those meeting two of three thresholds covering employee numbers above 250, turnover above £36 million, or balance sheet total above £18 million, must report Scope 1 and Scope 2 emissions in their annual Directors’ Report. Unlike Scope 3, there’s no voluntary carve-out; if a business meets the SECR thresholds, Scope 1 disclosure isn’t optional.

That obligation is also where the regulatory direction is heading next. The UK Sustainability Reporting Standards (UK SRS), published in final form by the Department for Business and Trade on 25 February 2026, are currently available for voluntary use, but the Financial Conduct Authority is consulting on making UK SRS S2 climate disclosures, which require GHG emissions reporting across all three scopes, mandatory for listed companies from accounting periods beginning on or after 1 January 2027. The government has also signalled it will consult separately during 2026 on extending requirements to large private companies.

The practical implication for Scope 1 specifically is that it isn’t a category waiting for future regulation to make it matter. It’s already a hard requirement under SECR for any qualifying business, and the standards arriving behind it build on the same foundation rather than relaxing it.

Why Some Scope 1 Emissions Are Easier to Eliminate Than Others

Not all Scope 1 sources respond to the same kind of effort. Some can be reduced through better operation of the same equipment: tuning a boiler, training drivers in more efficient habits, fixing a slow refrigerant leak before it becomes a large one. These are genuine reductions, achieved without changing what the equipment runs on.

Others can’t be meaningfully reduced that way. A gas boiler running efficiently is still a Scope 1 source for as long as it burns gas. A diesel HGV driven well still burns diesel. For this second group, the only way to actually eliminate the Scope 1 emissions, rather than trim them at the margins, is to change the energy input itself. For instance, replacing the gas boiler with an electric heat pump, or replacing diesel vehicles with electric ones where duty cycles allow.

That substitution doesn’t make the emissions disappear. It moves them. A heat pump or an electric van still requires energy, just in the form of purchased electricity rather than combusted fuel, which means the emissions that were Scope 1 become Scope 2 instead. Whether that’s genuine progress depends entirely on what’s powering the electricity that replaces the fuel.

Practical Levers for Reducing Scope 1 Emissions

Most credible Scope 1 strategies work through three layers, starting with what requires the least operational change.

Efficiency comes first, since it reduces fuel use without altering what equipment runs on. Common starting points include:

• Servicing and tuning boilers, furnaces, and combustion equipment to manufacturer specification
• Training drivers in fuel-efficient habits and optimising delivery routes to cut unnecessary mileage
• Installing leak detection systems on refrigeration and cooling equipment to catch fugitive emissions early
• Sub-metering fuel use by site or process to identify where consumption is highest

Substitution is the second step, and the one that actually removes a source from Scope 1 rather than reducing its output. This includes electrifying company vehicles where charging infrastructure and duty cycles make it practical, replacing gas-fired heating with electric heat pumps, and, where the process allows, electrifying parts of on-site heat demand that previously relied on combustion. Not every Scope 1 source has a viable substitution path yet; some heavy mobile plant and certain process emissions remain genuinely hard to abate with current technology.

Monitoring is the third step, underpinning both of the others. Accurate fuel and refrigerant data, collected consistently, is what makes it possible to demonstrate reductions credibly under SECR and the emerging UK SRS framework, rather than relying on estimates.

Why Reducing Scope 1 Often Means Strengthening Your Scope 2 Strategy

The substitution layer above creates a specific dependency worth being honest about. When a fleet is electrified or a gas boiler is replaced with a heat pump, the Scope 1 emissions disappear, but new electricity demand appears in their place, and that demand lands in Scope 2. If the grid electricity meeting that new demand carries a high carbon intensity, the business has shifted emissions from one scope to another rather than reduced its overall footprint.

This is where on-site solar generation becomes beneficial to a Scope 1 reduction strategy, even though it doesn’t address Scope 1 directly. A Solar PPA gives a business access to electricity generated on its own site, typically at a fixed rate below current grid cost, without the capital outlay of installing the system outright. 

For a business electrifying its fleet or its heating, that on-site generation lowers the carbon intensity of the Scope 2 load absorbing what used to be Scope 1 fuel use, which is what turns an electrification programme into a genuine net reduction rather than a reshuffle between scopes.

The two strategies work in sequence rather than in competition: electrify the Scope 1 sources that can be electrified, then decarbonise the electricity meeting that new demand. A Solar PPA addresses the second half of that sequence. It doesn’t replace the first.

Explore Solar PPA Solutions

If your business is weighing up fleet or heating electrification and wants a clearer picture of what on-site generation could mean for the resulting electricity demand, the Commercial Solar PPA Calculator gives an indicative view based on your site profile. For a fuller look at how the funded model works, our Solar PPA solutions page sets out the structure end to end.

FAQs

What is the difference between Scope 1 and Scope 2 emissions?

Scope 1 covers direct emissions from sources a business owns or controls, such as fuel burned in company vehicles or gas used in on-site boilers. Scope 2 covers indirect emissions from electricity, heat, steam, or cooling that a business purchases and consumes, where the emissions physically occur at the generation source rather than on-site.

What are examples of Scope 1 emissions?

Scope 1 examples fall into four categories: stationary combustion (boilers, furnaces, on-site generators), mobile combustion (company vehicles, forklifts, mobile plant), process emissions (gases released directly by certain manufacturing or chemical processes), and fugitive emissions (refrigerant leaks from cooling and refrigeration systems).

Is Scope 1 reporting mandatory in the UK?

Yes, for large UK businesses. Under SECR, companies meeting two of three size criteria (over 250 employees, turnover above £36 million, or balance sheet above £18 million) must report Scope 1 and Scope 2 emissions in their annual Directors’ Report, with no voluntary exemption. The UK Sustainability Reporting Standards, published in February 2026, build on this requirement and are expected to extend mandatory climate disclosure further from 2027.

Can a Solar PPA reduce Scope 1 emissions?

Not directly. A Solar PPA provides on-site renewable electricity, which reduces Scope 2 emissions, not Scope 1. It becomes relevant to a Scope 1 strategy when a business electrifies fleet or heating that was previously a Scope 1 fuel source, since those emissions move into Scope 2, where a Solar PPA can lower the carbon intensity of the electricity meeting that new demand.