HOW WE CALCULATE YOUR EMISSIONS

 

Driving

The basic equation to determine the amount of emissions that result from driving is:

(Gallons of gas used)  x  (emission factor for CO2)  x  (factor to account for other greenhouse gases (110/95))  =  Amount of CO2e released into the atmosphere.

Gallons of gas used can be determined by entering the miles driven and dividing that by the fuel efficiency of a car (miles per gallon).  Fuel Efficiency can be determined by measuring the gas consumed per mile by the car owner or can be collected from EPA average determinations by car type.  Approximations can be made by general car class as well (ghg protocol).

The emission factor for CO2 is a number for how much CO2 is released per gallon of gas.  This was sourced from the ghg protocol website.  The emission factor for gas is 8.87 kg of CO2 per gallon, and for diesel is 10.15 kg CO2 per gallon.

The emission factor for other greenhouse gases was sourced from the EPA website.  They suggest multiplying by 100/95 to represent the 5% of emissions that are created by other greenhouse gases like methane, nitrous oxide, and HFCs.

The US national averages for fuel efficiency and miles driven per year were sourced from the EPA website.

http://www.ghgprotocol.org/calculation-tools

http://www.epa.gov/OMS/climate/420f05004.htm 

Flying

The basic equation to determine the amount of emissions that result from flying is:

Short flights (less than 500 km):  (distance traveled + extra to account for rerouting)  x (emissions factor) x (business class if selected) =  The approximate amount of CO2e released by a person traveling on this flight.

Medium and long flights (more than 500 km): (distance traveled + extra to account for rerouting)  x  (emission factor)  x  (radiative forcing index)  x  (business class if selected) =  The approximate amount of CO2e released by a person traveling on this flight.

The distances are calculated using the ‘great circle distances’.  An extra 50 km is added per flight. This is the average deviation from the great circle distance on a flight.

The emission factor for a flight is a number that estimates how much CO2e is released per passenger on a flight.   This accounts for the type of planes used for each distance category, the flight characteristics of each distance category (short flights have higher ratio of climbing to cruising and thus use more fuel per km and the longest flights are heavier due to the large amount of fuel they must carry and therefore are less efficient than medium flights), the average number of passengers on the planes, and taxiing and holding pattern averages.  These were sourced from the UK’s DEFRA website (Department for Environment, Food and Rural Affairs).

·      Short Flights (less than 500 km) = 0.1753 kg of CO2e per passenger km.

·      Medium Flights (500-1600 km) = 0.0983 kg of CO2e per passenger km

·      Long Flights (greater than 1600 km) = 0.1106 kg of CO2e per passenger km

Radiative forcing index.  When airplanes emit greenhouse gases they do so at considerable altitude.  This leads to a pronounced affect of the pollution called radiative forcing.  The science of radiative forcing is still being understood but there is considerable agreement that it should be accounted for on long and medium length flights.  Shorter flights do not reach the altitudes that cause radiative forcing.  We have chosen to use the conservative figure of 1.9 for our radiative forcing index.  This is consistent with some of the latest science and is supported by UK’s DEFRA.

If the business class button is selected the emissions are multiplied by 1.5.  This accounts for the amount of space being used by the business class seats.  Approximately 1.5 people in coach could sit in the space used by a business class seat.  The more people on the plane the fewer emissions each is responsible for.

Average distances of each flight distance category were determined to be:

·      Short: 400 km (250 miles)

·      Medium: 1050 km (650 miles)

·      Long: 4300 km (2670 miles)

·      Extended: 10500 km (6500 miles)

This was the mean distance in each category with the shortest flight estimated to be 300km and the longest flight estimated to be 14,000 km.

http://www.defra.gov.uk/environment/business/envrp/pdf/passenger-transport.pdf

http://www.ghgprotocol.org/calculation-tools

https://www.atmosfair.de/fileadmin/user_upload/Medienecke/Downloadmaterial/Rund_um_atmosfair/Documentation_Calculator_EN_2008.pdf

Housing

Electricity

The basic equation to determine the amount of emissions that result from home electricity use is:

(Annual electricity usage)  x  (emission factor) – (% of renewable energy used)  = amount of CO2 released per year.

Annual electricity usage can be either entered directly by user or determined by monthly average.  An estimate of monthly average electricity use (in kilowatt hours) can be entered and then multiplied by 12 months to determine the yearly total.  If the electricity use is not known, the average monthly bill can be entered and the usage can be determined by dividing that by the national average energy rate ($0.10 per kwh).

The emission factor is determined by entering a zip code and using the eGrid statistics to determine how ‘dirty’ the grid is.  If a grid is supplied by a large percentage of coal burning power plants, then more CO2 is released for every kwh of electricity used.

If someone enters that a percentage of her home electricity comes from a renewable source then that percentage is subtracted from the total energy consumed.

National average energy use and CO2 emissions were sourced from the EPA website and are from 2004.

http://www.eia.doe.gov/cneaf/electricity/epa/epat7p4.html

http://www.eia.doe.gov/cneaf/electricity/epm/table5_6_a.html

http://www.epa.gov/climatechange/emissions/downloads/emissionsfactorsbrochure2004.pdf 

Natural Gas

The basic equation to determine the amount of emissions that result from the use of natural gas in the home is:

(annual use of natural gas in cubic feet) x (emission factor) = annual emissions of CO2 from natural gas.

Annual use of natural gas can be entered or determined by the monthly average use multiplied by 12 months.  If use is not known it can be determined by entering average monthly bill and dividing by average price of gas ($0.013 per cubic foot, from EIA website).

The emission factor for natural gas is 0.054 kg per cubic foot (EIA website)

The average national emissions from natural gas use is 4.9895 metric tons of CO2 (2004, EIA).

http://www.eia.doe.gov/oil_gas/natural_gas/data_publications/natural_gas_annual/nga.html

EIA U.S. Energy Information Administration 2004. A Look at Residential Energy Consumption in 2001

 

Heating Oil

The basic equation to determine the amount of emissions that result from heating oil use in the home is:

(annual use of heating oil in gallons) x (emission factor) = annual emissions of CO2 from heating oil use.

Annual use of heating oil can be entered or determined using monthly average use and multiplying by 12 months.  If monthly average use is not known it can be determined by entering average monthly heating oil bill and dividing by average price per gallon ($3.77 per gallon, EIA website 2008).

The emission factor for heating oil is 10.11 kg of CO2 per gallon (EPA)

US ‘typical’ annual CO2 emissions from heating oil use was 6.577 metric tons of CO2 in 2004, based on national average monthly consumption of 55 gallons of oil (EIA, 2004).

http://tonto.eia.doe.gov/dnav/pet/pet_sum_mkt_dcu_nus_m.htm

U.S. Energy Information Administration 2004. A Look at Residential Energy Consumption in 2001.

 

Propane

The basic equation to determine the amount of emissions that result from propane use in the home is:

(annual use of propane in gallons) x (emission factor) = annual emissions of CO2 from heating oil use.

Annual use of propane can be entered or determined using monthly average use and multiplying by 12 months.  If monthly average use is not known it can be determined by entering average monthly propane bill and dividing by average price per gallon ($2.56 per gallon, EIA website 2008).

The emission factor for propane is 5.747 kg of CO2 per gallon (EIA)

http://tonto.eia.doe.gov/dnav/pet/hist/mprreus4m.htm

http://www.eia.doe.gov/oiaf/1605/coefficients.html 

 

Waste and Recycling

The EPA estimates that the average person in the US is responsible for 1018 pounds of CO2e emissions from our annual waste.  They also estimate that everything that is recycled reduces that amount by the amounts below:

·      Newspaper – 83.4 kg (184 pounds)

·      Magazines – 21.6 kg (47.7 pounds)

·      Glass – 11.6 kg (25.6 pounds)

·      Plastic –  21.1 kg (46.6 pounds)

·      Metal – 75.2 kg (165.8 pounds)

http://www.epa.gov/climatechange/emissions/ind_assumptions.html 

 

National Averages

The EPA estimates these national average emissions:

·      Driving and Flying – 11 metric tons (Berkeley Institute of the Environment)

·      Home energy –10.4 metric tons (EPA)

·      National Average – 21.4 metric tons (the two above added together)

·      Developed countries – 9.7 tons (UNFCCC)

·      World Average – 5.4 tons (UNFCCC)

(UNFCCC)://mdgs.un.org/unsd/mdg/Data.aspx

http://www.epa.gov/climatechange/emissions/ind_assumptions.html

 

 If you have any further questions please email us at info@bigtreeclimatefund.com