Collecting Activity Data for a Greenhouse Gas Inventory

Greenhouse gas inventory process

1. Review the organisation and define the inventory objectives and boundaries.

2. Identify emission-generating activities and collect the information, documents and records needed for quantification.

3. Quantify emissions.

4. Establish and document the base-year inventory.

5. Prepare the greenhouse gas inventory report.

Identifying and collecting activity data

Identify the greenhouse gas emission sources

ISO 14064-1:2018 groups organisational GHG reporting into six categories:

• Category 1: Direct GHG emissions and removals.
• Category 2: Indirect GHG emissions from imported energy.
• Category 3: Indirect GHG emissions from transportation.
• Category 4: Indirect GHG emissions from products used by the organisation.
• Category 5: Indirect GHG emissions associated with the use of products from the organisation.
• Category 6: Indirect GHG emissions from other sources.

Calculating and measuring greenhouse gas emissions

Illustrative activity-data calculations; the Scope 1–3 terminology below follows the GHG Protocol

Scope 1: Direct GHG emissions

Stationary fuel combustion

Emissions by gas = quantity of fuel consumed × the applicable fuel emission factor.

Total fuel-combustion emissions = the sum of emissions for each fuel and gas, with the required GWP conversion to CO₂e.

Road transport within the organisation’s direct-emissions boundary

Emissions = Σ(fuel consumed for fuel a × the corresponding emission factor), with the relevant gas and CO₂e conversions.

Scope 2: Indirect emissions from purchased energy

Electricity emissions = electricity consumed × the applicable grid or supplier emission factor, using the required reporting method.

Scope 3: Other indirect GHG emissions

Emissions = activity data × the applicable emission factor; apply GWP where the factor is expressed as the mass of an individual gas rather than CO₂e.

Activity data quantify the activities that generate emissions or removals during a defined period.

An emission factor relates an amount of emissions to a unit of activity. Appropriate factors depend on the source, geography, technology, fuel, reporting period and calculation method; removal factors are selected separately where relevant.

How to collect activity data

The key question is how to obtain data that are sufficiently accurate, reliable and complete. Data are not always readily available: the organisation may need to establish a collection and recording process.

Examples for common activity-data types:

1. Energy consumption: electricity, petrol, diesel, gas, coal and other fuels

• Identify which energy users consume each energy type and how often they operate.
• Separate significant uses where practical. For example, a workshop with five cutting machines and one copper-melting furnace can monitor the furnace separately from the cutting machines. Submetering by production stage can improve analysis; the appropriate arrangement depends on the inventory and management needs.
• Maintain consumption records, with daily tracking where useful and monthly and annual summaries, reconciled against invoices, meter readings and stock records as applicable.

2. Industrial processes

• Identify the main industrial processes and the applicable sector or IPCC guidance. Collect the activity data required by the selected method for each relevant process.

3. Wastewater and solid waste

• Identify the sources and production stages. Use appropriate meters, weighing records or other documented methods before streams are combined where practical.
• Separate relevant waste types, such as municipal, industrial and hazardous waste, and record the quantities and treatment routes needed by the calculation method.
• For wastewater, collect flow or volume and the relevant organic-load data, such as BOD or COD from representative test results, according to the selected method.
• Compile monthly wastewater and waste quantities from continuous readings or collection records; these activity quantities are inputs to, rather than themselves the calculated GHG emissions.
• Maintain activity-data records by day or collection event as appropriate, with monthly and annual summaries.

4. Fertiliser

• Identify the fertiliser type and chemical composition.
• Record each application and compile monthly and annual consumption totals.

5. Trees and vegetation

• Collect the species, number, age and other required measurements, such as tree dimensions, land area or stock change, according to the selected removal-accounting method. Tree counts alone do not quantify annual removals.
• Keep a vegetation-data register and update changes at an appropriate frequency.

6. Other emission sources

• Plan collection for each source. Prefer reliable source-specific data where available. Documented estimates, mass balances, models or secondary data may be appropriate under the selected method when direct data are unavailable; record assumptions, limitations and uncertainty rather than rejecting all indirect methods.
• Maintain activity-data records and periodic reports.

These examples support the planning of activity-data collection. For specialist sources, follow the applicable sector guidance and selected inventory method so that all necessary inputs are available.

After planning, collect and review the data and assess uncertainty. Investigate anomalies promptly. For example, if electricity consumption doubles without a comparable production change, check operating conditions, records and meter performance instead of automatically assuming the meter is faulty.

Related articles

Organisational GHG inventories under ISO 14064-1

Product carbon footprinting under ISO 14067

Calculating GHG emissions from electricity use

References

GHG Protocol — calculation methods and data

GHG Protocol — Scope 3 calculation guidance