Scope 1 in Practice: Where Emissions Come From and How to Calculate Them
Scope 1 is often the easiest part of the calculation, because the data lives in the company’s own systems. Yet this is precisely where the most common technical mistakes occur: refrigerant leaks are forgotten, a leased vehicle is assigned to the wrong scope, or machinery is left out of the boundary entirely. This article walks through what Scope 1 actually covers in practice, where to find the numbers, and how the formula works.
What Scope 1 Covers: Four Emission Sources
The GHG Protocol divides Scope 1 into four source categories.
Stationary combustion. Heating boilers, steam generators, and other fixed combustion equipment. Typically light fuel oil, natural gas, propane, biogas, or wood pellets.
Mobile combustion. Vehicles and machinery owned or under long-term control of the company: vans, trucks, passenger cars, tractors, excavators, forklifts. Fuel is typically diesel, petrol, or renewable diesel (HVO).
Process emissions. Emissions arising from production processes that do not come from energy use. Examples include calcination in cement manufacturing, metal smelting, and chemical industry reactions. Most service and retail companies have none of these.
Fugitive emissions. Leaks of refrigerants and other gases. The most important source for most companies is refrigerant top-ups in cooling equipment and heat pumps. R410A, R134a, and R404A are common, with GWP values ranging from 1,300 to 4,000. The F-gas regulation is driving a shift toward lower-GWP refrigerants, but the transition is still under way and older gases remain in use.
In practice, most SMEs have Scope 1 concentrated in two or three sources. Fuel for property heating is the largest factor when heating is self-supplied. Mobile fuels are decisive when the company operates its own fleet. Refrigerants become significant in buildings with large cooling systems, such as food warehouses and data centres.
What Scope 1 Does NOT Cover: Common Misconceptions
Leased vehicles. Under the operational control approach, long-term operating leases fall under Scope 1 if the company controls use and fuel choice. Short-term rental cars and an employee’s personal vehicle belong in Scope 3 (category 6 or 7).
Purchased heat and electricity. District heating, purchased electricity, and steam belong in Scope 2, even when consumed on company premises. More detail in the Scope 2 article.
Employee commuting in personal cars. These are Scope 3 category 7 (employee commuting), not Scope 1, even when the employer reimburses mileage.
Business travel by air or rail. Scope 3 category 6 (business travel).
Supplier deliveries in their own vehicles. Even when goods arrive at company premises, they are counted as Scope 3 category 4 (upstream transportation and distribution), because the vehicle is not under the company’s control.
District heating and cooling emissions. Even though the energy is consumed on company premises, the emissions occur at the supplier’s plant and belong in Scope 2.
Data Collection: Where to Find the Numbers
Scope 1 data typically comes from three sources.
Finance system. Request fuel and gas purchases for the financial year, broken down by supplier and expressed in litres or cubic metres. This single report often covers 80–90% of Scope 1.
Vehicle register or fuel card system. For passenger cars and vans, fuel card data gives litres directly. Alternatively, mileage and average consumption can be used, but this increases uncertainty.
Maintenance reports. Refrigerant top-ups are recorded in service company reports. Request a list of all top-ups during the financial year: equipment name, refrigerant type, and quantity in kilograms.
Practical tip: request the data at the start of the financial year, not at year-end. Fuel purchase data is available within one or two days, but gathering maintenance reports can take weeks.
Calculation in Practice: The Formula and Emission Factors
The formula is straightforward:
Activity data × emission factor = emissions (kg CO2e)
Examples.
Light fuel oil for heating: 10,000 litres × 2.66 kg CO2e/litre = 26,600 kg CO2e (≈ 26.6 tCO2e).
Diesel van: 4,500 litres × 2.67 kg CO2e/litre = 12,015 kg CO2e (≈ 12 tCO2e). The emission factor includes CO2, CH4, and N2O in CO2-equivalent terms.
Refrigerant R410A: 2.5 kg top-up × GWP 2,088 = 5,220 kg CO2e (≈ 5.2 tCO2e). GWP values come from the IPCC AR6 report.
Factors are sourced from recognised references: Lipasto (VTT) for Finnish transport, DEFRA UK GHG Reporting Conversion Factors for general use, and IPCC AR6 for GWP values. More on this in the article Emission Factors and Data Sources.
Every choice is documented: the source of the factor, the publication year, and the version. This is the first thing a verifier will check.
The Most Common Mistakes in Scope 1
Confusing fuel types. Diesel and light fuel oil are different products for tax purposes but nearly identical in combustion terms. Their emission factors differ slightly, and mixing them up can lead to a systematic error.
Forgetting machinery. Forklifts, excavators, snow ploughs, and other off-road equipment are often left out because they are not registered as road vehicles. Fuel purchase data will reveal them.
Underestimating refrigerant leaks. Many companies exclude refrigerants from Scope 1 on the grounds that “the systems have been serviced and nothing has leaked.” In practice, small top-ups occur regularly, and their GWP impact is significant.
Incorrectly zeroing out biofuel emissions. CO2 from biogenic fuel is reported separately as biogenic, but CH4 and N2O are counted normally in Scope 1. Simply setting the bio-fraction to zero without the proper split leads to underreporting.
HVO and blends. Renewable diesel (HVO) and blended fuels (e.g. B7, B30) require separate calculation. The bio-fraction must be checked on the fuel purchase receipt, and factors sourced separately for the bio component and the fossil component.
Multiple sites merged together. If fuel purchases arrive on a single invoice covering several sites, the split is worth clarifying separately. This also supports site-level reporting and targeted reduction measures.
Prioritising Scope 1 Reduction Measures
Once the calculation is complete, Scope 1 is typically the easiest area to act on, because the company has direct control over the emission sources. Typical reduction measures and their impact:
Switching heating systems. Replacing oil heating with a heat pump or district heating shifts emissions from Scope 1 to Scope 2, or eliminates them entirely if the energy source is renewable.
Electrifying the vehicle fleet. Moving from combustion engines to electric vehicles removes Scope 1 emissions and shifts them to Scope 2 (electricity for charging). The net emission impact depends on the electricity emission factor.
HVO transition for machinery. Suitable when electrification is not yet feasible (e.g. heavy machinery). Typically reduces CO2 emissions by 60–90%, though a price premium over fossil diesel remains.
Reducing refrigerant leaks. Regular servicing and replacing older R410A and R404A systems with low-GWP alternatives (R32, R290) delivers significant emission reductions in one step.
When prioritising reductions, it is worth looking at both the tonnage and the payback period of each measure. The business case for investment is often stronger when energy savings and the long-term cost advantage of electrification are factored in alongside the carbon numbers.
Frequently Asked Questions
Do leased vehicles belong in Scope 1?
Under the operational control approach, yes, if the lease is long-term and the company decides on use and fuel. Short-term rentals and an employee’s personal car belong in Scope 3.
Where do I get emission factors for fuels?
Finnish transport factors from VTT Lipasto. For general use, DEFRA UK GHG Reporting Conversion Factors is updated annually.
How are refrigerant emissions calculated?
Quantity of refrigerant added (kg) × GWP of the refrigerant. GWP values are available in the IPCC AR6 report. Request a top-up report for the financial year from your service company.
Is the emission from biofuel zero?
The CO2 fraction is reported separately as biogenic, but CH4 and N2O are counted normally. Simply recording “zero” is not compliant with the standard.
Must machinery be included?
Yes, if it is owned by the company or under long-term control. Fuel purchase data is usually the signal that reveals machinery in the calculation.
Scope 1 data scattered across different systems?
We collect your fuel, vehicle, and maintenance data on your behalf and perform the calculation in accordance with the GHG Protocol. We act as coordinator: your role is access to the systems and brief answers to follow-up questions.
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