tCO2e

Businesses release several greenhouse gases, not just carbon dioxide. Burning fuel releases small amounts of methane and nitrous oxide too, and air conditioning can leak refrigerants. Each gas traps a different amount of heat. tCO2e converts them all into the amount of CO2 that would cause the same warming, so you can add them up and compare them.

What it means for a small business

You will see tCO2e at the bottom of almost every carbon footprint, carbon reduction plan and supplier questionnaire. One tonne is 1,000 kg. Small figures are often written in kg CO2e instead.

You do not need to do the gas conversions yourself. The UK government’s conversion factors are already expressed in kg CO2e, so multiplying your activity (kWh, litres, miles) by the factor gives you CO2e directly.

To put it in context, a small office-based business typically has a footprint of a few tonnes to a few tens of tonnes a year. Businesses with vehicles or premises tend to sit higher.

An example

An office uses 12,000 kWh of electricity and 20,000 kWh of gas in a year.

• Electricity: 12,000 × about 0.13 kg = roughly 1,570 kg CO2e
• Gas: 20,000 × about 0.18 kg = roughly 3,600 kg CO2e
• Total: about 5,200 kg, or 5.2 tCO2e

The factors are approximate, from recent UK government sets. Our guide to what tCO2e means has more examples.

How ESG Now handles it

The ESG Now report shows every line of your footprint in kg CO2e, with the activity, the factor used and the result, then totals each scope and the whole footprint in tCO2e. That way anyone reading it can follow the working. See the methodology for the factor sets used.