DRIVING

**Total Tons of CO2 Produced =
Driving Miles Traveled / Miles per Gallon * CO2 Produced per Gallon Burned**

**Driving Miles Traveled**

First, we calculate the distance between the ‘from’ and ‘to’ locations you entered. Then, we add a 15% mileage factor to account for the non-linear nature of roads. Or, if you entered an ‘actual mileage’, we use that number.

**Miles per Gallon**

If you selected a car size, the following fuel efficiency values are used in calculations:

**• Small/medium car: **22.4 mpg based on 2006 average US passenger car fuel efficiency [U.S. Department of Transportation, Federal Highway Administration, Highway Statistics (Washington, DC: Annual issues), table VM-1]

**• Large car: **18.0 mpg based on 2006 average other 2-axle, 4-tire vehicles [U.S. Department of Transportation, Federal Highway Administration, Highway Statistics (Washington, DC: Annual issues), table VM-1]

Or, if you entered an ‘actual economy’ (mpg), we use that number.

**CO2 Produced per Gallon Burned**

19.56 pounds of CO2 are produced for each gallon of gasoline burned [GHG Protocol Direct Emissions Tool v1.0]

FLIGHTS

**Total Tons of CO2 Produced =
Flight Miles Traveled * Flight Emissions Factor * Radiative Forcing Index (RFI)**

**Flight Miles Traveled**

We calculate the distance between the ‘from’ and ‘to’ locations you entered to determine miles traveled. Or, if you entered an ‘actual mileage’, we use that number.

**Flight Emissions Factor**

Depending on whether your travel segments fit into the short, medium or long haul category (i.e., the length of your flight, we apply a CO2 emissions factor of 0.64, 0.44 or 0.40 lbs of CO2 per passenger mile, respectively. This gives us the direct CO2 emissions from your flight. [These factors are from the GHG Protocol Commuting Emissions Tool v 1.2]

**Radiative Forcing Index (RFI)**

We apply an RFI of 2.0 to the direct CO2 emissions from air travel, resulting in total CO2 equivalent emission factors of 1.28, 0.88 or 0.8 for short, medium and long haul flight segments, respectively. By doubling the direct CO2 emissions, our goal is to account for the overall global warming impact of air travel for all air emissions. [Intergovernmental Panel on Climate Change (IPCC)1999].

RAIL

**Total Tons of CO2 Produced = Rail Miles Traveled * Rail Emissions Factor**

**Rail Miles Traveled**

We calculate the distance between the ‘from’ and ‘to’ locations you entered to determine miles traveled. Or, if you entered an ‘actual mileage’, we use that number.

**Rail Emissions Factor**

Depending on whether your rail travel is local or intercity, we apply a CO2 emissions factor of 0.35 lbs or 0.42 lbs of CO2 per passenger mile, respectively. This gives us the direct CO2 emissions from your rail travel. [These factors are from the GHG Protocol Commuting Emissions Tool v 1.2]

BUS

**Total Tons of CO2 Produced = Bus Miles Traveled * Bus Emissions Factor**

**Bus Miles Traveled**

We calculate the distance between the ‘from’ and ‘to’ locations you entered to determine miles traveled. Or, if you entered an ‘actual mileage’, we use that number.

**Bus Emissions Factor**

Depending on whether your bus travel is local or intercity, we apply a CO2 emissions factor of 0.0172 lbs or 0.66 lbs of CO2 per passenger mile, respectively. This gives us the direct CO2 emissions from your bus travel. [These factors are from the GHG Protocol Commuting Emissions Tool v 1.2]

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