How to Calculate Scope 1 Emissions for a Small Business (With Examples)

What Are Scope 1 Emissions and Why Do They Matter?

Scope 1 emissions are direct greenhouse gas emissions from sources that your company owns or controls. They are the emissions you create by burning fuel, operating vehicles, and leaking refrigerant — not emissions embedded in the electricity you buy (that's Scope 2) or in your supply chain (that's Scope 3).

For most European SMEs, Scope 1 comes from four sources: natural gas for heating, diesel and petrol for company vehicles, LPG for forklifts or catering equipment, and refrigerant gases leaking from air conditioning or cold storage systems.

Getting Scope 1 right matters because it directly feeds into your Carbon Passport — which is what your enterprise clients use for their own Scope 3 Category 1 reporting under CSRD.

How Do You Calculate Natural Gas Emissions?

Natural gas is measured in cubic metres (m³) or kilowatt-hours (kWh) on your utility bills. The DEFRA 2023 emission factor is 2.204 kgCO2e per m³ (or 0.203 kgCO2e per kWh if your bills use kWh).

Worked example — manufacturing unit: Annual gas consumption: 12,000 m³ 12,000 × 2.204 = 26,448 kgCO2e = 26.4 tCO2e

UK bills in kWh: 130,000 kWh × 0.203 = 26,390 kgCO2e ≈ same figure.

Note: some gas bills quote "calorific value" in MJ or therms. Convert first: 1 therm = 29.3 kWh; 1 MJ = 0.278 kWh. Then apply the kWh factor.

How Do You Calculate Diesel and Petrol Emissions?

Use your fuel card statements or mileage records to find annual consumption in litres. Key DEFRA 2023 factors:

Worked example — delivery fleet: Annual diesel consumption: 8,500 litres 8,500 × 2.683 = 22,805 kgCO2e = 22.8 tCO2e

If you have mileage records only: DEFRA also provides distance-based factors. Average diesel car = 0.154 kgCO2e/km; diesel HGV = 0.617 kgCO2e/km (articulated, fully loaded).

How Do You Account for Refrigerant Leaks?

This is the most commonly missed Scope 1 source. Refrigerant gases have Global Warming Potentials (GWP) hundreds of times higher than CO2 — a small leak can equal several tonnes of CO2 equivalent.

How to find the data: ask your HVAC/refrigeration maintenance contractor for the annual service records showing how much refrigerant was topped up. That quantity approximates what leaked.

DEFRA 2023 GWP values:

Worked example: 3 kg of R-410A topped up during annual service. 3 × 2,088 = 6,264 kgCO2e = 6.3 tCO2e — more than many companies' entire gas heating emissions.

What If You Don't Have Exact Records?

DEFRA guidance allows reasonable estimation. Acceptable approaches:

• For vehicles with mileage logs but no fuel records, use distance-based factors
• For LPG use without records, estimate from the number of gas bottles purchased (one standard 47 kg propane bottle ≈ 0.064 tCO2e)
• For refrigerants with no maintenance records, a nil return is acceptable with a written note explaining why
• For a new business without 12 months of data, extrapolate from partial records and state the assumption

Always document your assumptions. DeCarbonOPS records your inputs and methodology, so you can explain your calculation to any auditor without digging back through spreadsheets.

How Does Scope 1 Relate to Your Overall Carbon Footprint?

Scope 1 is the foundation. For most SMEs, the breakdown looks like this:

The largest Scope 1 reduction opportunity for most businesses is switching from a gas boiler to a heat pump (moves the emission from Scope 1 to Scope 2, which can then be zeroed with renewable electricity) and replacing diesel fleet vehicles with EVs.