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Carbon footprint calculator

A footprint is a sum of activity times emission factor. The factors carry real uncertainty; the arithmetic does not.

kWh/year
g/kWh
kWh/year
g/km
t CO2e/year

About 2.5 for a high-meat diet, 1.7 average, 1.1 vegetarian, 0.9 vegan.

Annual footprint
9.55t CO2e
= Exact Household carbon footprint
Per person
4.77 t CO2e Below the global average
From heating gas
2196
From electricity
675
From driving
1800
From flying
874
From food
4000
Mature trees to absorb it in a year At about 21 kg of CO2 per tree per year.
455
Show the working
  1. Electricity = 2700
  2. Grid intensity = 250
  3. Gas = 12 000
  4. Car distance = 12 000
  5. Car emissions = 150
  6. Flying distance = 4000
  7. Diet footprint = 2
  8. People in the household = 2
  9. From electricity = 2700 * 250 / 1000 = 675
  10. From heating gas = 12 000 * 0.183 = 2196
  11. From driving = 12 000 * 150 / 1000 = 1800
  12. From flying = 4000 * 0.115 * 1.9 = 874
  13. From food = 2 * 1000 * 2 = 4000
  14. total_kg = 675 + 2196 + 1800 + 874 + 4000 = 9545
  15. Annual footprint = 9545 / 1000 = 9.545
  16. Per person = 2 > 0 ? 9.545 / 2 : 0 = 4.7725
  17. Mature trees to absorb it in a year = 9545 / 21 = 454.524

Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.

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    The formula

    • footprint = sum of activity x emission factor

    Natural gas emits about 183 g of CO2 per kWh delivered. Grid electricity varies hugely by country and by hour.

    Emission factors carry real uncertainty, especially for aviation and food. Treat the total as an order of magnitude.

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