Carbon Footprint
Emissions from energy use and an emission factor.
Formula
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Example
1000 kWh × 0.4 = 400 kg CO₂
How it works
This formula estimates the amount of carbon dioxide produced when you use energy or burn fuel. You multiply the quantity of energy or fuel used by an emission factor, which tells you how much CO₂ is released per unit of that energy or fuel. It works because different fuels and electricity sources have different carbon intensities, so the factor converts usage into emissions.
When to use it
Use this when estimating emissions from electricity bills, vehicle fuel use, heating, or other activities that consume energy. It is a common first-step calculation in carbon accounting, sustainability reports, and basic environmental impact comparisons.
Worked example, step by step
Natural gas used = 50 therms Emission factor = 5.3 kg CO₂ per therm CO₂ = E × f CO₂ = 50 × 5.3 CO₂ = 265 kg CO₂
Common mistakes to avoid
- Using the wrong emission factor for the fuel or electricity source
- Forgetting to match units, such as mixing kWh with an emission factor given per MWh
- Treating the result as total greenhouse gases instead of just CO₂
Did You Know?
Emission factors depend heavily on the energy source.
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