How do I calculate my own carbon footprint?
Here is some handy information for the DIY energy analyst.
It may be quite enlightening to analyze the carbon footprint of your house or building. The information is easily calculated: natural gas bills show consumption in MCF (thousand cubic feet), heating oil is bought by the gallon, and electricity is billed by kWh. The carbon dioxide footprint analysis is accomplished using the CO2 coefficients listed in the table below. The table also shows BTU conversion factors by energy source, which allows the calculation of the total energy consumption supplied by various energy sources. The following simple scenario shows how to arrive at a fairly accurate analysis. The analysis should mainly be used to calculate the impact of home modifications such as adding spray foam insulation or replacing windows. Required conversion factors for energy and related carbon emissions are listed in the table below.
Scenario 1: single family home with heater, dryer and hot water boiler powered by natural gas. Air conditioning, stove, appliances and lights are powered by electricity.
Example: Gas bill for the last 12 months: 200 MCF. Average monthly MCF during the summer months: 5. The 5 MCF would be the natural gas consumed by the hot water boiler and gas dryer only, since the heating system is turned off.
Using the table below, you can calculate the following:
Total CO2 emissions related to natural gas: 200 MCF/year x 120.593 lbs/MCF = 24,118.6 lbs/year.
Heating only: 200 MCF/year - ( 12 months x 5 MCF ) = 140 MCF. The heating related CO2 emissions are calculated as 140 MCF/year x 120.593 lbs/MCF = 16,883.02 lbs./year. If you were to insulate your existing attic with spray foam, you could see a year later how you have reduced your CO2 emissions. Likewise, if you switch the energy source, the impact in terms of efficiency is easily calculated by multiplying the energy consumption in units by the BTU.
| Energy Source | Unit | BTU | CO2 lbs/Unit |
|---|---|---|---|
| Natural Gas | MCF (1000 ft3 | 1,020,000 | 120.593 |
| Fuel oil #2 | Gal | 139,000 | 22.384 |
| Fuel oil #4 | Gal | 145,000 | 22.384 |
| Fuel oil $6 | Gal | 150,000 | 26.033 |
| Electricity2 | KWh | 3,413 | 1.34 |
| Gasoline (mid grade) | Gal | 125,000 | 19.564 |
| Refrigeration | Ton/hr | 12,000 | |
| Coal - anthracite | Ton3 | 15,200,000 | 5685 |
| Wood (50% moisture) | Ton3 | 9,000,000 | 3812 |