Nicole—the maths
Home » Magazine » Good, issue 10 » 10:10 » Nicole—the mathsHere’s how Nicole can cut her carbon footprint 10% in 2010.
Nicole’s total annual emissions for electricity, transport and meat are 3,258.93kg CO2e + 1197 (meat) = 4,455.93kg = 4.45 tonnes
10:10 reduction goal = 0.45 tonnes
Assumptions
- average amount electricity per year = 2,908 kWh (EECA)
- average beef consumption 34.2kg per year (Beef NZ) × 35kg CO2e = 840kg
- lives 6km from work
- Honda Civic (2000) Hatchback, 5 seats, 1668cc petrol engine, 4-gear automatic, 4WD = 7.1l/100km
- drives average 14,000km/year, at 7.1l/100km = 994 litres petrol/year
- one 6kg rubbish bag/week
Calculations
Correctly inflate tyres (and check every month) = 0.12
- 14,000km/year, at 7.1l/100km = 994 litres petrol/year
- If a car’s tyres are under-inflated, there is more ‘rolling resistance’. This means more energy is needed for the wheel to roll – just as a soft soccer ball will not roll as easily as a properly inflated one = 5% more fuel (via FuelSaver)
- save 5% fuel = 49.7 litres
- 49.7 × 2.33 kg CO2e = 116 kg CO2e
Get her vehicle tuned = 0.12
- 14,000km/year, at 7.1l/100km = 994 litres petrol/year
- A vehicle that is out of tune will not burn fuel as efficiently as it is designed to = 5% more fuel (via FuelSaver)
- 5% of 994 = 49.7 litres
- 49.7 litres × 2.33 kg CO2e/litre = 116 kg CO2e
Compost all food and garden waste = 0.1
- 52 × 6kg bags rubbish
- CarboNZero calculator = 106kg CO2e
Open the car window instead of using air con = 0.06
- Assume need air con for half of all journeys (warmer months) = 7,000km
- Open window/sunroof (at speeds under 80 km/h; the higher the speed, the more wind resistance and therefore the more fuel the car uses) = save 5% fuel (via FuelSaver)
- 0.071 litres/km × 7000 = 497 litres
- 5% of 497 = 24.85 litres
- 24.85 litres × 2.33 kg CO2e/litre = 58 kg CO2e
Replace one 100W bulb with 20W eco-bulb = 0.03
- Assume bulbs on for five hours a day
- 100W bulb × 5 hours × 365 = 182,500 = 182.5kWh
- 20W bulb × 5 × 365 = 36,500 = 36.5kWh
- 182.5 – 36.5 = 146 kWh saved per bulb
- 146 × 0.21 EEF = 31 kg CO2e
Wash your clothes on cold washes rather than warm = 0.02
- Median electricity consumption for a top loader 312.5 kWh, based on 250 kWh average for medium top loader (warm wash 27c / cold wash 3c per load) and 375 kWh average for large top loader (warm wash 40c / cold wash 4c per load), from Consumer NZ Appliance Running Costs report (updated 2 Jul 2009), converted back to kWh using quoted electricity cost of 20 c/kWh; assumes 4 loads a week
- 312.5 kWh × 0.21 EEF = 65.6 kg CO2e
- divided by 3 (number people in household) = 22 kg
Halve beef consumption = 0.6
- 34.2kg beef per year average consumption × 50% = 17.1kg
- 17.1kg beef × 35kg CO2e per kilo beef = 599kg CO2e
Slow down, brake earlier and more gently = 0.47
- 0.071 litres/km × 14,000 = 994 litres
- Fast driving, heavy acceleration and braking uses more energy (and therefore more fuel) than traveling at a constant speed = 25% more fuel (via FuelSaver)
- We decided to use a more conservative estimate = save 20% fuel
- 20% × 994 litres = 198.8 litres
- 198.8 litres × 2.33 kg CO2e/litre = 469.35 kg CO2e
Car-pool to work with 2 others = 0.48
- 6km twice/day, five days/week, 48 weeks/year = 2,880km
- 0.071 litres/km) = 204.48 litres
- 204.48 litres × 2.33 kg CO2e/litre = 476 kg CO2e
