Carbon Footprint
A carbon footprint is a measure of the impact our activities have on the environment, and in particular climate change. It relates to the amount of greenhouse gases produced in our day-to-day lives through burning fossil fuels for electricity, heating and transportation etc.
The carbon footprint is a measurement of all greenhouse gases we individually produce and has units of tonnes (or kg) of carbon dioxide equivalent.
The pie chart above shows the main elements which
make up the total of an typical person's carbon footprint in the developed world.
A carbon footprint is made up of the sum of two parts, the primary footprint (shown by the green slices of the pie chart) and the secondary footprint (shown as the yellow slices).
1. The primary footprint is a measure of our direct emissions of CO2 from the burning of fossil fuels including domestic energy consumption and transportation (e.g. car and plane). We have direct control of these.
2. The secondary footprint is a measure of the indirect CO2 emissions from the whole lifecycle of products we use - those associated with their manufacture and eventual breakdown. To put it very simply – the more we buy the more emissions will be caused on our behalf.
How We Calculate
Carbonfund.org's Carbon Calculators use information from the U.S. Department of Energy's Energy Information Administration and other leading sources to develop an accurate assessment of carbon dioxide emissions emitted per energy type or use.
Residential
Electricity
We calculate emissions from electricity generation based off of state-based figures from Department of Energy’s Energy Information Administration. On average, electricity sources emit 1.297 lbs CO2 per kWh (0.0005883 metric tons CO2 per kWh). State CO2 emissions per kWh may vary greatly in accordance with the amount of clean energy in the energy supply (Vermont, Idaho: .03 lbs/kWh; North Dakota: 2.24 lbs/kWh).
Natural Gas
There are 12.0593 pounds CO2 per CCF of natural gas. We multiply 12.0593 by the number of CCF consumed annually and divide by 2,205 to get metric tons of CO2 (Source: US DOE 1605(b) Voluntary Reporting of Greenhouse Gases Program.)
US avg.: In 2005 62.5 million households used natural gas. Collectively, they used 4,838 billion cubic feet of natural gas annually, or 774.08 CCF (approximately 812 therms) per household or 296.58 CCF (approximately 311 therms) per person per household using natural gas. (Source: Energy Information Agency, US Census Bureau.)
Heating Oil
There are 22.384 pounds of CO2 per gallon of heating oil (diesel fuel). We multiply 22.384 by the number of gallons of heating oil consumed annually and divide by 2,205 to get metric tons of CO2 per gallon. (Source: US DOE 1605(b) Voluntary Reporting of Greenhouse Gases Program.)
US avg.: In 2004, 5,997 million gallons of heating oil were consumed by 8.1 million households, resulting in an average of 740.37 gallons per household or 283.67 gallons per person per household using heating oil. (Source: Energy Information Agency. Volume; Households.)
Transportation
Vehicles
Unleaded gasoline has 8.87 kg (19.56 lbs) of CO2 per gallon. By dividing number of miles driven by miles per gallon, we get the number of gallons of gasoline consumed annually. We multiply this by 8.87 and divide by 1,000 to get metric tons of CO2 (Source: US DOE 1605(b) Voluntary Reporting of Greenhouse Gases Program.)
US avg.: Automobiles fuel efficiency (MPG) varies widely. It is useful for you to have an idea of your own car’s fuel economy. The average fuel economy for cars sold in 2005 is about 25.2 MPG (Source: National Highway Traffic Safety Administration.)
The Department of Transportation's MOBILE 6.2 model, used by regional governments to model air quality, uses a fleet average (all cars, old and new) of 20.3 mpg. (Source: EPA)
Metric users: To convert liters per 100 km, the metric standard, to CO2, do the following: kilometers per year * 0.62 and enter it in the miles driven per year box. There are 3.79 liters per gallon. Hint: 7.58 l/100km = 30mpg.
British users: Take your MPG and multiply by .83 to get US MPG (Source: Digital Dutch web converter.) In 2001, the average distance driven by US drivers was 13,785 miles (Source: Federal Highway Administration, page 41.)
Air Travel
CO2 emissions in air travel vary by length of flight--ranging from .24 kg CO2 per passenger mile for short flights down to .18 kg CO2 per passenger mile for long flights. Our calculator allows the user to take the issue of radiative forcing into account. (Sources: Emissions factor based on 2006 data collected in the United Kingdom available from the The World Resources Institute. For more information on air travel-related radiative forcing, please see this IPCC document.)
Rail Travel
The CO2 emissions for rail travel vary by distance of the trip. On average, commuter rail and subway trains emit 0.35 lbs CO2 per passenger mile, and long distance trains emit 0.42 lbs CO2 per passenger mile (Source WRI: Employee commuting spreadsheet.) For rail trips under 20 miles we calculate your emissions at 0.35 lbs CO2 per passenger mile, and over 20 miles we calculate at 0.42 lbs CO2 per passenger mile. Transportation conditions vary in real life beyond what can be estimated. To ensure that our rail calculators fully covers your trip, we add 10% to the total mileage of your trip to account for potential detours, stop-overs, and other issues that may arise on your trip.
Bus Travel
The CO2 emission associated with bus travel vary by distance of trip. Inner city commuting buses emit 0.66 lbs CO2 per passenger mile, and long distance bus trips emit 0.18 lbs CO2 per passenger mile (Source WRI: Employee commuting spreadsheet.) For bus trips under 20 miles we calculate your emissions at 0.66lbs CO2 per passenger mile and for long distance bus trips we calculate at 0.18 lbs CO2 per passenger mile. Road and transportation conditions vary in real life beyond what can be estimated. To ensure that our bus calculator fully covers your trip, we added 10% to the total mileage of your trip to account for potential traffic jams, detours, and pit-stops that may arise on your trip.
Total US CO2-equivalent Emissions
Based on established total US emissions of 7,122 million metric tons CO2-equivalent, the figure is divided by the US population to yield CO2-equivalent per person. (Source: Energy Information Agency, US Census Bureau.)
Hospitality
Meals
The average person's diet contributes 455.41 kg CO2e to the atmosphere each year. By dividing by 365, it is deduced that a person emits, on average, 1.25 kg CO2e a day from their meals. This calculation is based on a non-vegetarian diet. The emissions for food preparation are not included in this calculation. (Source: Wired Magazine.)
Hotel Rooms
Emissions associated with a one night stay in a hotel room are calculated at 29.53 kg CO2 per room day for an average hotel. For upscale hotels, emissions are calculated at 33.38 kg CO2 per room day. (Source: Environmental Protection Agency.) CHP Potential in the Hotel and Casino Market Sectors, prepared by Energy and Environmental Analysis, Inc. for EPA.
Business Calculator
Office Emissions
All emissions factors in the “Office Emissions” category are based on annual (12 month) emissions. Emissions factors for energy (kWh) are based on state based figures from the Department of Energy’s Energy Information Administration
Natural Gas
Emissions factors for natural gas by your monthly bill are based on state based figures from the Department of Energy’s Energy Information Administration. These figures include the average natural gas prices by state. We calculate the emissions of natural gas to be 116.376 lbs per 1,000 cubic feet, or 0.12 lbs per sq. ft. (source: EIA DOE)
Electricity
Emissions factors for electricity by your monthly bill are based on state based figures from the Department of Energy’s Energy Information Administration to get the state-by-state prices for energy, and the emissions factors are generated from the Department of Energy’s Energy Information Administration.
Heating Oil
Emissions factors for heating oil calculated by your monthly bill are based on the national average price for heating oil ($2.22 per gallon) from the Department of Energy (courtesy of NPGA.org). We calculate the emissions of heating oil to be 22.384 lbs CO2 per gallon (source DOE EIA)
Propane
Emissions factors for propane calculated by your monthly bill are based on the national average price for propane ($1.87 per gallon) from the Department of Energy (courtesy of NPGA.org). We calculate the emissions of propane to be 12.17 lbs CO2 per gallon (source DOE EIA).
Building Type
Emissions factors by building type are calculated using assumptions from the EIA DOE. The figures provide the kWh used per sq foot of building type, then we multiply the energy needed for a particular space by state based emissions factors.
Number of Employees
Emissions factors calculated by number of employees is calculated with the average sq ft needed per employees, 225 sq ft (based on industry assumptions that a typical office will require between 175 – 250 sq ft per employee). We then calculate the total sq ft by average emissions for office buildings by sq ft (Source: Energy Star). Then we multiply the energy needed for the total space by state based emissions factors.
Servers
Server emissions are calculated assuming an average 251 watt server (source: Energy Star) with 95% up time. The energy usage of each server is then multiplied by state based emissions factors.
Fleet
Fleet emissions cars assume the national average of 25.2 mpg and the emissions factor of 19.564 lbs CO2 per gallon of gasoline consumed. Fleet emissions deliver vans and trucks assume an average of 7.8 mpg (Source: EERE) and the emissions factor of 22.384 lbs CO2 per gallon of diesel consumed. Fleet emissions big rigs assume an average of 5.3 mpg and the emissions factor of 22.384 lbs CO2 per gallon of diesel consumed.
Employee Travel
All travel emissions factors sourced from WRI.
• Short flights are calculated to be 500 miles round-trip with emissions of 0.53 lbs CO2 per passenger mile
• Medium flights are calculated to be 1,500 miles round-trip with emissions of 0.42 lbs CO2 per passenger mile
• Long flights are calculated to be 4,000 miles round-trip with emissions of 0.397 lbs CO2 per passenger mile
• Train trips are calculated 0.35 lbs CO2 per passenger mile
• Bus trips are calculated at 0.18 lbs CO2 per passenger mile
Employee Commute
All emissions figures from WRI.
• Commute by Car – assumes 25.2 mpg fuel efficiency for the vehicle, 19.564 lbs CO2 per gallon of gas consumed and a two way commute 245 days a year.
• Commute by Transit – assumes a two way commute 245 days a year, with 0.37 lbs CO2 emitted per mile.
Shipping Calculator
Carbonfund.org’s shipping calculator utilizes three user generated inputs to determine a unit called a ‘ton-mile’ (e.g. a ton of freight traveling 1 mile, or a half ton of freight traveling two miles, or 1/1000th of a ton traveling 1,000 miles… you get the point):
• Total number of shipments
• Avg Weight of Shipment (lbs)
• Avg Shipping Distance (mi)
From this information we determine the shipment(s) ‘ton-miles’. So if you have 50 shipments (A) of 100 lbs (B) each traveling an average distance of 500 miles(C), you multiply A*B*C, 50*100*500 to get 2,500,000 lbs-miles – to get to ton-miles, divide by 2204 to get 1,134.3 ton-miles. Once you have that figure, multiply it by the appropriate emissions factor depending on how you are shipping the package. So 1134.3 ton-miles being shipped by truck (0.3725 lbs CO2 per ton-mile) gives you a total emissions of 422.52 lbs CO2. Shipping Emissions Factors:
• Air cargo - 1.7739 lbs CO2 per Ton-Mile
• Truck - 0.3725 lbs CO2 per Ton-Mile
• Train - 0.2306 lbs CO2 per Ton-Mile
• Sea freight - 0.0887 lbs CO2 per Ton-Mile
• Zeppelin - 0.1951 lbs CO2 per Ton-Mile
(Source: Timeforchange.org who in turn sourced from http://fluglaerm.de/hamburg/klima.htm).
Conversions
• 1 Renewable Energy Certificate = 1 Megawatt Hour (MWh) = 1,000 Kilowatt Hours (KWh)
• 1 Kilowatt Hour = 3,413 British Thermal Units (BTUs)
• 1 Metric Tonne = 2,204.6 Pounds
• 1 Pound = 0.00045 Metric Tons
• 1 Short Ton = 2,000 Pounds
• 1 Short Ton = 0.90719 Metric Tons
• 1 Therm = 100 Cubic Feet
Carbon Footprint function Generally
A carbon footprint is the total set of greenhouse gases (GHG) emissions caused by an organization, event or product. For simplicity of reporting, it is often expressed in terms of the amount of carbon dioxcide, or its equivalent of other GHGs, emitted.
The concept name of the carbon footprint originates from ecological footprint discussion. The carbon footprint is a subset of the ecological footprint and of the more comprehensive Life Cycle Assessment (LCA).
An individual, nation, or organization's carbon footprint can be measured by undertaking a GHG emissions assessment. Once the size of a carbon footprint is known, a strategy can be devised to reduce it, e.g. by technological developments, better process and product management, changed Green Public or Private Procurement (GPP), Carbon capture, consumption strategies, and others.
The mitigation of carbon footprints through the development of alternative projects, such as solar or wind energy or reforestation, represents one way of reducing a carbon footprint and is often known as Carbon offsetting.
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