Calculating you Homes Carbon Footprint
Except for nuclear energy, all other types of energy come from the sun. So when we convert these sources back into energy for our homes one of the byproducts made is carbon dioxide (CO2) which is a greenhouse gas that is released into our atmosphere.
Start by getting together all of your electric and gas bills for the last year. Making a spreadsheet helps to visualize the numbers and do the math for you. Write down the month, KWH or Therms and cost. If you are totally electric you will have a large usage in the summer and winter with a smaller usage in April and October. These two months will have a usage that reflects your base load. The base load is the energy needed to run you're house except for the seasonal heating and cooling loads. Similarly, if you have gas you should be able to separate the heating cost from the base load for your water heater and stove.
For the electrical total up your kilowatt hours (KWh) and multiple times 1.9 lbs/KWh to get lbs of CO2. My house used 24,873 KWh * 1.9 lbs/KWh = 47,258 lbs of CO2 per year.
With gas, add up your therms and multiply by 12lbs/therm. An average home in the South with gas heat might use 536 therms * 12 lbs/therm = 6,432 lbs of CO2 per year.
If you're using a different heating fuel multiply a number from the table below.
| Type | CO2/unit | CO2/therm |
| Natural gas | 12 lbs/therm | 12 lbs |
| Propane | 13 lbs/gal | 14 lbs |
| Fuel oil | 26 lbs/gal | 19 lbs |
| Wood | 5000 lbs/cord | 21 lbs |
| Electricity from gas | 1.3 lbs/KWh | 39 lbs |
| Electricity from oil | 2.2 lbs/KWh | 63 lbs |
| Electricity from coal | 2.4 lbs/KWh | 69 lbs |
| Average Electricity | 1.5 lbs/KWh | 45 lbs |
| From the Energy Information Administration | ||
Average electricity factors in national sources including hydro that produces very little Carbon Dioxide. In the South we get the majority of our energy from coal so numbers for us average from 1.8 to 2.0 lbs/KWh and 54 to 60 lbs.