How Are Scope 1 Direct Emissions Calculated?

Calculating Scope 1 emissions aims to determine the greenhouse gas emissions arising from an organisation's direct activities. These emissions generally come from the following sources:

• Combustion of fossil fuels: Direct combustion of fossil fuels (coal, oil, natural gas, etc.) at sources such as factories, offices or vehicles.

• Industrial processes: Chemical reactions used in production processes or industrial activities (for example, cement production or metalworking).

• Vehicles and equipment owned by the organisation: Emissions produced by the company's vehicles, generators or other equipment.

• Fugitive emissions: Unintentional releases such as refrigerant leaks from refrigeration and air-conditioning systems.

Steps for calculating Scope 1 emissions

1. Identifying emission sources

• First, all direct emission sources that cause greenhouse gas emissions during the company's activities must be identified. These include fuel consumption (vehicles, machinery, factories, etc.), industrial processes (such as chemical reactions), fugitive emissions, waste management and other emission sources.

2. Monitoring fuel consumption

• Fossil fuel consumption: All quantities of fossil fuel used by the company (for example, natural gas, coal, petrol, diesel, etc.) should be recorded. This applies to all fuel consumption, such as vehicles, machinery, heating systems or electricity generation.

• Fuel type and energy content per unit: The type of fuel used should be identified, and the energy content per unit of each fuel (such as MJ/litre or MJ/kg) and its emission factors (kg CO₂e/m³, kg CO₂e/litre) should be obtained.

3. Using emission factors

• Emission calculations use specific emission factors for each fuel type. These factors determine the quantity of greenhouse gases emitted (usually CO₂, CH₄ and N₂O) per quantity of fuel used. Emission factors may vary between countries and sectors. For example (approximate values):

  • Emission factor for petrol: 2.31 kg CO₂/litre

  • Emission factor for diesel: 2.68 kg CO₂/litre

  • Emission factor for natural gas: 1.96 kg CO₂/m³

4. Calculation formula

Emissions from each source can be calculated using the following formula:

Emissions = Fuel quantity × Emission factor

Example:

• If a vehicle consumed 1,000 litres of petrol and the emission factor for petrol is 2.31 kg CO₂/litre, the CO₂ emitted by this vehicle is: 1,000 litres × 2.31 kg CO₂/litre = 2,310 kg CO₂

5. Calculating total emissions

• Once the calculations for all direct emission sources have been added together, total Scope 1 emissions have been calculated. These calculations are usually performed on an annual basis.

Example calculation

A factory uses a natural gas boiler and a work vehicle. Emissions can be calculated with the following data:

• Natural gas consumption: 50,000 m³

• Emission factor (natural gas): 1.96 kg CO₂/m³

• Fuel consumption (vehicle): 1,000 litres of petrol

• Emission factor (petrol): 2.31 kg CO₂/litre

Calculation:

• Natural gas emissions: 50,000 m³ × 1.96 kg CO₂/m³ = 98,000 kg CO₂

• Vehicle emissions: 1,000 litres × 2.31 kg CO₂/litre = 2,310 kg CO₂

• Total Scope 1 emissions: 98,000 kg CO₂ + 2,310 kg CO₂ = 100,310 kg CO₂

The Scope 1 emissions from this factory will therefore be 100,310 kg CO₂ (approximately 100.3 tonnes of CO₂).

This calculation is an important step for organisations to monitor and report their direct emissions, because accurate data is needed to reduce greenhouse gas emissions.