Step 4: Identify your emission sources
On This Page (9 sections)
This is step 4 of 7 in Build your GHG inventory. Previous: Step 3: Set your operational boundaries. Next: Step 5: Collect activity data.
An emission source is a specific activity, process or piece of equipment that releases greenhouse gases, such as a boiler, a delivery van or an electricity meter. In this step you make a list of all sources inside your boundary. Steps 5 and 6 then collect data and calculate emissions for each source on the list.
Types of source
| Scope | Type | Examples |
|---|---|---|
| Scope 1 | Stationary combustion | Gas boilers, diesel generators, kilns, ovens |
| Scope 1 | Mobile combustion | Company cars, lorries, vans, forklifts, boats |
| Scope 1 | Process emissions | Cement clinker, chemical reactions, wastewater treatment |
| Scope 1 | Fugitive emissions | Refrigerant leaks, fire extinguishers, gas pipe leaks |
| Scope 2 | Purchased energy | Grid electricity, chilled water from a district cooling plant, purchased steam |
| Scope 3 | Value chain activities | Purchased materials, freight, waste, business travel, commuting |
Two points often cause errors:
- Vehicles. A company-owned or leased car that you run is Scope 1. A taxi or a flight is Scope 3 business travel. A staff member's own car used to get to work is Scope 3 employee commuting.
- Generators. Diesel burned in your own generator is Scope 1. Electricity that you buy from the grid is Scope 2. Do not count the generator's electricity again in Scope 2.
How to find your sources
- Walk through each facility. Look for anything that burns fuel, uses electricity, holds refrigerant or treats waste. Facilities and maintenance staff know where these are.
- Read your invoices. Fuel, electricity, gas, refrigerant service and waste invoices each point to a source.
- Check your asset register. It lists vehicles, generators, chillers and other equipment.
- Use your Scope 3 screening. For each category that you included in step 3, list the activities that cause its emissions.
- Ask each department. Logistics, procurement, human resources and production often know about sources that others do not.
Record each source
For each source, write down:
| Field | Example |
|---|---|
| Facility | Shah Alam factory |
| Source | Boiler 2 |
| Scope and category | Scope 1, stationary combustion |
| Gas or fuel | Natural gas |
| Activity data | m³ of gas per month |
| Data source | Gas supplier invoice |
| Data owner | Facilities manager |
This source list becomes your data collection plan in step 5.
Example source list
A manufacturer with one factory and one office could have this list:
| Facility | Source | Scope | Activity data |
|---|---|---|---|
| Factory | Natural gas boilers | 1 | m³ |
| Factory | Backup diesel generator | 1 | litres |
| Factory | Delivery lorries | 1 | litres of diesel |
| Factory | Chillers (refrigerant top-ups) | 1 | kg of refrigerant |
| Factory | Grid electricity | 2 | kWh |
| Office | Grid electricity | 2 | kWh |
| Office | Split air conditioners (refrigerant top-ups) | 1 | kg of refrigerant |
| Group | Raw materials and packaging | 3, category 1 | tonnes or RM spent |
| Group | Inbound freight | 3, category 4 | tonne-km |
| Factory | Waste to landfill | 3, category 5 | tonnes |
| Group | Business flights | 3, category 6 | passenger-km |
| Group | Employee commuting | 3, category 7 | survey results |
Small sources
Include small sources where you can. The GHG Protocol warns that a fixed size limit for leaving sources out can bias the inventory. If you leave a source out, write down which one, why, and your estimate of its size. Make sure that the excluded sources together stay small, so that they do not change the result.
Changes during the year
Sites and equipment change. If a site opens, closes or is sold during the year, include its sources only for the months it was inside your boundary. If you replace equipment, for example a diesel generator with a solar system, keep both on the list for the year of the change. Review the source list at the start of each reporting period.
Check your progress
Before you go to step 5, make sure that you have:
- A source list for every facility in your boundary
- A scope and category for each source
- The activity data, data source and owner for each source
In Carbon GPT
Each type of source becomes a predefined measure: a reusable template with its emission factor, grouped by scope and category. Set them up in Predefined Measures. Your activity records then become Measures based on these templates.
Sources
- GHG Protocol Corporate Standard, chapters 1, 4 and 6
- GHG Protocol Scope 2 Guidance
- GHG Protocol Corporate Value Chain (Scope 3) Standard, chapter 5
