Build your GHG inventory
On This Page (8 sections)
A greenhouse gas (GHG) inventory is a list of your emission sources and their emissions for one year. This guide splits the work into 7 steps. Each step follows the GHG Protocol Corporate Standard, which IFRS S2 and Bursa Malaysia's reporting rules use.
If the 3 scopes are new to you, read The GHG Protocol and the 3 scopes first.
The 7 steps
| Step | What you decide or do | What you have at the end |
|---|---|---|
| 1. What is a GHG inventory? | Why you need the inventory, who will use it, and who will help | A purpose, a reporting period and a team |
| 2. Set your organisational boundaries | Which companies and sites the inventory covers | A list of facilities and one consolidation approach |
| 3. Set your operational boundaries | Which scopes and Scope 3 categories you include | A list of included categories, with reasons for each exclusion |
| 4. Identify your emission sources | Which activities cause emissions at each site | A source list by facility, scope and category |
| 5. Collect activity data | Where each number comes from and who provides it | A data collection plan and the data itself |
| 6. Calculate your emissions | Which emission factors you use | Emissions per source, in tCO₂e |
| 7. Report and verify | What you disclose and how it is checked | A report that is ready for review or assurance |
Where to start
If this is your first inventory, start with Scope 1 and Scope 2. The data is usually in your own records: fuel invoices, refrigerant logs and electricity bills. Then add the Scope 3 categories that your reporting rules require, for example business travel and employee commuting for Bursa Malaysia. Add other Scope 3 categories in order of size, starting with the largest. Step 3 explains how to find which categories are large for your business.
How long it takes
The first inventory takes the longest, because you make most decisions once and write them down. In later years, you repeat steps 5 to 7 and review steps 2 to 4 for changes, such as a new site or an acquisition.
Time depends on the number of sites and on how easy the data is to find. Electricity bills and fuel records are usually quick to collect. Scope 3 data from suppliers usually takes the longest.
Decisions to write down
Each step involves choices. Record each choice, the reason for it and the date, in one place. An assurance provider will ask for this record, and next year's team will need it. The most important decisions are:
- The consolidation approach in step 2 (equity share, financial control or operational control)
- The Scope 3 categories that you include and exclude in step 3, and why
- Any source that you leave out, and why
- The base year, if you set a reduction target
- The emission factors and global warming potentials (GWPs) that you use, with their source and year
Who does what
Carbon accounting needs people from several parts of the business:
| Team | What they usually provide |
|---|---|
| Finance | The group structure, ownership shares, spend data and invoices |
| Facilities or operations | Electricity bills, fuel records, refrigerant maintenance logs |
| Procurement | Supplier lists and purchase data for Scope 3 |
| Human resources | Staff numbers and data for employee commuting surveys |
| Logistics | Freight volumes, distances and transport modes |
| Sustainability or finance lead | The decisions, the calculation and the report |
Common mistakes to prevent
- Changing methods every year. If you change a method, explain the change and its effect on the numbers.
- Mixing up units. A mistake between kWh and MWh changes a result by a factor of 1,000.
- Counting the same emissions twice. For example, do not count fuel for a generator in Scope 1 and the electricity it produces in Scope 2.
- Subtracting carbon credits. Report gross emissions. Report credits separately.
The 7 steps in Carbon GPT
Each step page links to the matching part of the Carbon GPT Platform guides. For example, your boundary becomes a list of facilities, your sources become predefined measures, and your activity data becomes measures.
