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A carbon footprint is the total greenhouse gas emissions caused by an organisation, event, product, or person over a defined period or life cycle. It is expressed in tCO₂e, meaning tonnes of CO₂-equivalent, or in kg CO₂e. The “e” matters: different gases trap different amounts of heat, so each is converted into the equivalent impact of carbon dioxide. That conversion is what lets one number describe everything at once.

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The three questions

Every footprint answers the same three:
  1. What are we measuring? An organisation, an event, a product.
  2. Over what period or scope? Which emissions, which dates, which life cycle stages.
  3. How do we convert activity into CO₂e? Activity data plus emission factors.
Get those three stated clearly and you have a footprint. Leave any of them vague and you have a number nobody can check.

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Footprint vs emissions

The two words get used interchangeably, but there is a useful distinction:
  • Emissions are the actual release of greenhouse gases: fuel burned, electricity used, waste decomposing.
  • A carbon footprint is the quantified, documented total of those emissions for a defined subject and boundary.
The footprint is the measured result, with its boundary attached.

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What goes into one

Most footprints combine:
  • Energy: electricity, gas, fuels, onsite generation
  • Travel and transport: flights, vehicles, commuting, freight
  • Purchases and services: goods, services, and materials used to operate
  • Waste and materials: disposal, recycling, packaging, construction
  • Other sources: refrigerants, process emissions, land use change
The mix depends on what you are measuring and how wide you draw the boundary.

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Three common types

Covers emissions from running an organisation over a period, usually a year: energy across all sites, employee travel and commuting, purchased goods and services, operational waste.This is what most people mean by “our annual carbon footprint.” In Salvidia it is an Organisation assessment.

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Why CO₂e, and what a GWP is

Not all greenhouse gases are equal. Methane traps far more heat per kilogram than carbon dioxide does. To compare them, each gas has a global warming potential: CO₂ is the baseline at 1, methane and nitrous oxide are considerably higher. Multiply the quantity of a gas by its GWP and you get its CO₂e. One tonne of methane at a GWP of 28 becomes 28 tCO₂e. You will rarely calculate this yourself. Published emission factors already have GWPs built in. It is worth knowing why the unit exists, because it explains how refrigerant leaks can matter more than they look.

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Boundaries decide what counts

The boundary is the most consequential decision in any footprint, and the one most often left implicit:
  • Organisational boundary: which entities, sites, and operations are included
  • Operational boundary: which scopes and activities are included
An organisation might include all owned and controlled Australian sites, Scope 1 and 2, plus material Scope 3 categories, while excluding a minor overseas subsidiary for now. That is a legitimate boundary as long as it is stated. Aim to be transparent, include everything material, and keep it consistent year on year. See Organisational boundaries.

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How it is calculated

A footprint is built from many individual lines:
  • 10,000 kWh of electricity × factor
  • 25,000 km of car travel × factor
  • 3 tonnes of landfill waste × factor
  • $5,000 of marketing spend × factor
Each line gets its own CO₂e value. Lines group into categories and scopes, and those roll up into totals and breakdowns. No adjustment happens in between, which is why any total can be traced back to the entries underneath it.

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What a carbon footprint is not

  • It is not just your electricity use.
  • It is not just Scope 1 and 2.
  • It is not a purchase of offsets.
A credible footprint is broader than energy, grounded in a stated methodology, and used as the basis for reduction rather than compensation.

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What you do with it

Find your hotspots

See which sites, activities, or categories drive most of your emissions, so effort lands where it counts.

Track progress

Compare years, events, or product variants to see whether what you changed actually worked.

Report and win work

Feed real numbers into reports, tenders, frameworks, and customer conversations.

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Where to go next