What the Numbers Mean

With the defaults (900 kWh/mo electricity, 60 therms/mo gas), the home emits 8.14 tons CO2e per year — 4.32 t from electricity and 3.82 t from gas, about 53% vs 47%. That's roughly 407 trees' worth of annual absorption capacity.

Where the Emissions Come From

Electricity uses a 0.4 kg/kWh US-average grid factor (higher in coal regions, near zero with renewables), gas 5.3 kg/therm, heating oil 10.1 kg/gal, and propane 5.7 kg/gal. Heating and cooling dominate most homes — efficiency upgrades cut every line in this table regardless of fuel.