What the Numbers Mean

With the defaults (300 kWh/mo electricity, 50 therms/mo gas, 1,000 mi/month at 25 mpg, 3 flights/year), the footprint is 9.5 tons CO2e per year — classified Average, just under the 10-ton threshold. Home energy (4.6t) and driving (4.2t) dominate; flights add 0.7t.

Emission Factors

Electricity uses a 0.4 kg/kWh average grid mix — your local grid may be cleaner (renewables) or dirtier (coal). Gas is 5.3 kg/therm, heating oil 10.1 kg/gal, gasoline 8.8 kg/gal, and flights 150/400/1,200 kg per short/medium/long round trip, based on EPA and Carbon Trust averages.