Carbon Footprint Formula

Household Energy

Equations for household energy category courtesy of the EPA Household Greenhouse Gas Calculator.

Electricity
CO₂ emissions in pounds = (average amount of electric bill per month ÷ price per kwh) × electricity emissions factor × months in a year
Price per kwh average for Connecticut = $0.20
Electricity emissions factor = 1.37

Natural Gas
CO₂ emissions in pounds = (average amount of natural gas bill per month ÷ price per thousand cubic feet) × natural gas emissions factor × months in a year
Price per thousand cubic feet average for Connecticut = $14.14
Electricity emissions factor = 120.61

Fuel Oil
CO₂ emissions in pounds = (average amount of fuel oil bill per month ÷ price per gallon) × fuel oil emissions factor × months in a year
Price per gallon average for Connecticut = $2.88
Fuel oil emissions factor = 22.37

Propane
CO₂ emissions in pounds = (average amount of propane bill per month ÷ price per gallon) × propane emissions factor × months in a year
Price per gallon average for Connecticut = $2.76
Propane emissions factor = 12.17

Transportation

Equations for vehicle emissions category courtesy of the EPA Household Greenhouse Gas Calculator.

Equations for public transportation and air travel categories courtesy of the The Berkely Institute Of The Environment.

Vehicles
CO₂ emissions in pounds = ((number of miles driven per week × weeks in a year) ÷ fuel efficiency per vehicle) × pounds of CO₂ emitted per gallon × emissions of greenhouse gases other than CO₂
Pounds of CO₂ emitted per gallon = 19.4
Emissions of greenhouse gases other than CO₂ = 100 ÷ 95

Public Transportation
CO₂ emissions in pounds = (miles traveled per year × public transportation direct emissions) + (public transportation direct emissions × indirect emissions multiplication factor) × gram to pound conversion
Pounds of CO₂ emitted per gallon = 19.4
Emissions of greenhouse gases other than CO₂ = 100 ÷ 95
Gram to pound conversion = .0022

Air Travel
CO₂ emissions in pounds = air miles traveled per year × (average direct emissions per air mile × indirect well-to-pump factor × indirect atmospheric radiative forcing factor) × gram to pound conversion
Average emissions per mile = 223
Indirect well-to-pump factor = 1.2
Indirect atmospheric radiative forcing factor = 1.9
Gram to pound conversion = .0022

Diet and Eating Habits

Equations for diet and eating habits category courtesy of the The Berkely Institute Of The Environment.

Food
CO₂ emissions in pounds = Sum of food categories [ (dollars spent on each category per month × emissions factor for each category × months in a year) × gram to pound conversion ]
Meat, fish, & eggs emissions factor = 1452
Cereals & Bakery Products emissions factor = 741
Dairy emissions factor = 1911
Fruits & vegetables emissions factor = 1176
Eating out emissions factor = 368
Other foods emissions factor = 467
Gram to pound conversion = .0022

Services and Goods

Equations for goods and services category courtesy of the The Berkely Institute Of The Environment.

Services and Goods
CO₂ emissions in pounds = Sum of services and goods categories [ (dollars spent on each category per month × emissions factor for each category × months in a year) × gram to pound conversion ]
Clothing emissions factor = 436
Furnishing & household items emissions factor = 459
Other goods emissions factor = 338
Services emissions factor = 178
Gram to pound conversion = .0022