Carbon accounting, explained from the ground up
A plain-English introduction to how emissions are measured, and why data and evidence quality matter.
The three scopes
Under the GHG Protocol, emissions are grouped into three scopes. Scope 1 covers direct emissions from sources you own or control. Scope 2 covers purchased energy. Scope 3 covers all other indirect emissions across your value chain, and is usually the largest.
Direct emissions
Sources you own or control, such as company vehicles and on-site fuel combustion.
Purchased energy
Indirect emissions from the electricity, steam, heating, and cooling you buy.
Value chain
All other indirect emissions across 15 categories, upstream and downstream. Usually the largest.
What is carbon accounting?
Carbon accounting is the process of measuring the greenhouse gas emissions linked to an organisation's activities, expressed in tonnes of carbon dioxide equivalent (tCO2e). It gives you a baseline to understand your footprint and act on it.
Activity data
Activity data is the underlying information about activities that generate emissions, such as energy use, fuel, business travel, and purchased goods. Good carbon accounting starts with collecting this data reliably and knowing where it came from.
Emission factors
Emission factors convert activity data into emissions. For example, a factor turns litres of fuel or kilowatt hours of electricity into tCO2e. Using recognised, up-to-date factors keeps your figures credible.
tCO2e
Different greenhouse gases have different warming effects, so emissions are expressed in a common unit: tonnes of carbon dioxide equivalent. This lets you add up and compare emissions across sources.
Why evidence matters
Reporting only helps if people believe the figures. Keeping evidence connected to each number, with a clear method and owner, means you can answer questions from auditors, customers, and investors with confidence.
Why data quality matters
The quality of your footprint depends on the quality of your data. Validation, clear ownership, and consistent methods reduce errors and make reporting repeatable year after year.
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