Commentary

The EnergyRace calculator strikes a balance between ease of use and the precision that would come from asking you to provide 12 months of energy consumption information.  The purpose of the calculation is to give you an estimate without requiring you to enter large amounts of data.

Home Heating

Oil, natural gas and propane produce different amounts of CO2 and have different average consumption rates.  When you tell us which you use, we plug in the national consumption average for that fuel and the CO2 that comes from a gallon or cubic foot of that fuel.  The data comes from the US DOE and EPA.

State Residence

The amount of CO2 produced to create electricity varies dramatically from state to state.  The difference comes from how electricity is created in that state.  Like them or hate them, nuclear and hydro-electric power plants do not generate CO2.  Among the fossil fuel-fired power plants, the natural gas ones generate less CO2 than the coal-fired plants.

EnergyRace takes the EPA's 2004 electricity and CO2 emissions data by power plant, by state, and calculates the amount of CO2 produced to generate a kilowatt hour of electricity in that state.

Electricity Use

Carbon footprint calculators on the web often will ask you what your average monthly electric bill is.  EnergyRace takes a different approach.  We use the US EIA and DOE data on average residential megawatt hours of electricity used by households in each state.

Home Type/Size Adjustment

Since EnergyRace is dealing with household averages for electricity and heating costs, we use the home type and number of people living in the home to adjust the average numbers up or down.

For Apartments we take 70% of the average, townhouses are 80%, small houses are 90%, medium houses 100% and large houses 130%.

Family Size Adjustment

If you live by yourself, you probably don't use as much electricity and heating as you would if you live with a family of 6.  More people, appliances used more frequently, more hot water used, etc..

Here are the adjustments we make to the state averages made for the number of people in the home:

1 . . 90%
2 . . 95%
3 . . 100%
4 . . 105%
5 . . 110%
6 . . 115%
7 . . 120%
8 . . 123%
9 . . 126%
10 . 130%

Air Miles

The amount of CO2 generated by air travel varies somewhat based on whether you take a short trip or a long trip.  But as a streamlining of the process, we just ask total air miles and multiply by .45 lbs of CO2 per air mile.  The average miles per year per flying American comes from data provided by the Bureau of Transportation Statistics.

Cars

For gasoline use, you specify your car and how many miles you drive it per year and we use the EPA combined city/highway miles per gallon data for that car.  The EPA's mileage testing tends to overestimate the miles per gallon that a car will get in actual driving conditions so this number is a conservative one.

Notes

The resulting estimated carbon emissions is in US tons.  CO2 emissions are reported internationally in metric tons. 

One big downside to our using US state electricity data is that it makes it very hard for our international visitors to use the tool.  This is a shortcoming that we will eventually address. 

If you live with 3 other people, the estimate includes the electricity and heating for all 4 of you.