This page includes references and calculations for the 2017 and 2018 version of emission factors. These references and emission factors are out of date, but we continue to provide them for historic documentation.
To see the most current references associated with the 2020 version of emission factors, see the Carbon References Page and Nitrogen References Page.
The references are organized by scope. We will be adding references for each section as they become available. If you see the hyperlink, then the references are ready. If you have any questions about the references below or about any references not yet documented here, please contact us here.
Scope 1:
- Stationary fuels
- Transport fuels
- Fertilizer and animals
- Refrigerants & Chemicals
Scope 2:
- Utility consumption
- Renewable energy
Scope 3:
- Commuting, Business travel & study abroad, and Student travel to/from home
- Food
- Paper
- Waste & Wastewater
Sinks and offsets:
- Compost, non-additional sequestration, and offsets
Campus Carbon Calculator
In the table below, please find the list of references used in the Excel-based Campus Carbon Calculator. Some of these references are out of date, but it will give you an idea of the types of references we are using in SIMAP. Please contact us at unh@simap.org if you have any questions about the references.
| Reference Number | Web Site | Citation | Notes |
|---|---|---|---|
| 1 | https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks | Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2005 (April 2007) EPA 430-R-07-002; Annex 6.1 Table A-228 | Values are taken from the IPCC 3rd assessment report and assume a 100 year atmospheric lifetime period. |
| 2 | GREET Model 1.5a, Argonne National Laboratory, US Department of Energy | Gasoline vehicles are from GREET 1.5a Near-Term Results Table 3.1 "Per-Mile Fuel Consumption and Emissions of Vehicle Operations." Cars and Light Duty Trucks (LDT-1) were selected to represent the commuter fleet. Factors were converted from g/mile to g/gallon using the fuel efficiency. Diesel vehicle emission factors are from heavy duty vehicles (trucks, buses, etc) and are located in the EF Emissions Factors table. | |
| 3 |
http://www.bts.gov/publications/national_transportation_statistics/2005/ |
U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics 2005. BTS05-08 | Fleet composition (% cars) was derived from total registered vehicles in the US for each year (Table 1-11) and includes passenger cars, light trucks and motorcycles. Average fuel efficiency is from Table 4-11 and includes passenger cars, light trucks and motorcycles. |
| 4 | Annual Energy Review 2004. Energy Information Administration, U.S. Department of Energy. Appendix A | Heating values for liquid fuels were changed from MMBtu / Barrel to MMBtu / gallon using 42 gallons / barrel. The heating value for coal is "Commercial Coal." Natural Gas HHV is based on total consumption including electric end use. LPG and Motor Gasoline also are based on total consumption data. All factors are Higher Heating Values, as used by the US EPA. | |
| 5 |
http://www.bts.gov/publications/national_transportation_statistics/2002/ |
U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics 2002. BTS02-08 (4-20) | Airline efficiency (Btu/Passenger Mile) from table 4-20. Factors for Domestic Travel were used, assuming that the vast majority of travel would be within country. |
| 6 | https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks | Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2006. February 2008. Annex 2, page A-43, Table A-32. | Values are carbon content coefficients used in the U.S. EPA Emissions Inventory, expressed as Tg Carbon / Qbtu. |
| 7 | https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks | Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2006. February 2008. Annex 3, page A-98, Table A-70. | Factors are for CH4 and N2O emissions from commercial fuel combustion, expressed in g / GJ. These were obtained from the 2006 IPCC Guidelines for National Greenhouse Gas Inventories. Factors were converted from g / GJ to kg / MMBtu as follows: (g / GJ) * (1 kg / 1000 g) * (1 GJ / 1.055056 MMBtu) |
| 8 | https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks | Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2001 (April 2003) EPA 430-R-03-004; Annex E | CH4 and N2O emission factors from table E-15. Factors were converted from "g gas / kg fuel" to "kg gas / gallon" using 7.93 barrels jet fuel/metric tonne (from Annex Y - reference 8), 42 gallons/barrel, and 1000 g / kg. |
| 9 | Updated State-level Greenhouse Gas Emission Coefficients for Electricity Generation 1998-2000. Energy Information Administration, Office of Integrated Analysis and Forecasting, Energy Information Administration, U.S. Department of Energy, April 2002 | CO2 from wood and waste are calculated and reported separately as "biogenic" emissions. See Intergovernmental Panel on Climate Change, Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories, Reference Manual (Volume 3), 1996, p. 6.28 (http://www.ipcc-nggip.iges.or.jp/public/gl/invs6a.htm). The CH4 and N2O coefficient for wood is taken from EPA’s AP-42 (using their assumed 4500 Btu/lb and their coefficients of 0.1 lb CH /ton and 0.04 lb N O/ton). Coefficients for refuse assumed to be the same as for wood. CH4 and N2O emissions from wood are included becuase they would not have been released during the natural decomposition of the material. Heating value was converted as follows: (4500 Btu/lb ) x (2,000 lbs / Short Ton) x ( MMBtu / 1,000,000 Btu) = 9.0 MMBtu / Short Ton | |
| 10 | https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks | Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2001 (April 2003) EPA 430-R-03-004; Annex L & M | Emission factors for cattle (dairy and beef) were derived from national data by dividing total emissions (Table L-11) by total population of animals (Table M-1). This was done to simplify the calculations as much needed data would be hard to estimate at the university scale. |
| 11 |
http://www.epa.gov/cleanenergy/energy-resources/egrid/archive.html |
Emissions and Generated Resource Integrated Database (eGRID), Data Years 1996-2000, Version 2.01. US EPA Office of Atmospheric Programs. Prepared by E.H. Pechan & Associates, Inc. | CO2 Emission factors the average from 1998 - 2000, because data was only available at the subregion scale for those years. Using constant electric emission factors will not capture changing emission due to changes in fuel source. However, it will result in more transparent final emission estimates for the university because all changes in emissions will be due to changes at the university. Factors were converted from Short Tons/MWh to kg/kWh using the conversions on the EF_Constants sheet. Energy efficiency (MMBtu fuel / kWh) is also averaged from 1998 to 2000 and is derived by dividing total heat input by net electricity generation. |
| 12 |
http://www.epa.gov/cleanenergy/energy-resources/egrid/index.html |
Emissions and Generated Resource Integrated Database (eGRID2010), Data Year 2007, Version 1.1. US EPA Office of Atmospheric Programs. | CO2 Emission factors are from the year 2007, the most recent available. Factors were converted from pounds/MWh to kg/kWh using the conversions on the EF_Constants sheet. Energy efficiency (MMBtu fuel input / kWh) is from 2007 and is derived by dividing total heat input by net electricity generation. |
| 13 | Updated State-level Greenhouse Gas Emission Coefficients for Electricity Generation 1998-2000. Energy Information Administration, Office of Integrated Analysis and Forecasting, Energy Information Administration, U.S. Department of Energy, April 2002 | Emission factors for CH4 and N2O are averages for 1998-2000. Values are only available by state, and were converted from Short Tons/MWh or lbs/MWh to kg/kWh using the conversions on the EF_Constants sheet. | |
| 14 | https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=60000AVO.TXT | Solid Waste Management And Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks. 3rd EDITION, September 2006. Section 5, page 70, exhibit 5-1. | Factor is for gross CO2 emissions from combustion of the nonbiomass portion of mixed municipal solid waste, expressed as MTCE / Wet Short Ton. It assumes no transportation emissions because combustion is on campus. It does not include potentially avoided landfill CH4 emissions. This source converted CO2 emissions to MTCE using 44 MT CO2 / 22 MTCE, so these values should be used to convert the emissions factors from MTCE to MT CO2. |
| 15 | https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks | Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2001 (April 2003) EPA 430-R-03-004; Annex N | |
| 16 |
https://www.nist.gov/sites/default/files/documents/pml/wmd/metric/SP1038.pdf |
Energy Tips #15, Office of Industrial Technologies, U.S. Department of Energy | Production efficiencies from Table 2. |
| 17 | https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=60000AVO.TXT | Solid Waste Management And Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks, 3rd EDITION, September 2006, Section 4 | Factor is for composted "yard trimmings" from exhibit 4-6. The factor estimates the carbon sink from increased humus formation and soil carbon restoration. It includes emissions for transportation and turning the compost pile. The factor is multiplied by 2.1 to convert from MTCE per wet ton of yard trimmings to MTCE per wet ton of compost. |
| 18 | United States Department of Commerce, National Institute of Standards and Technology, Guide for the Use of the International System of Units (SI) | Official conversion factors. | |
| 19 | U.S. Bureau of Economic Analysis, National Income and Product Accounts Tables, Table 1.1.9 Implicit Price Deflators for Gross Domestic Product | Historical record of US GDP Price deflators. Used for years 1990 - 2006 on the Input_InflAdj sheet. | |
| 20 | U.S. Energy Information Administration, Annual Energy Outlook 2007, Year-by-Year Reference Case Tables, Table 19 Macroeconomic Indicators | Projected US GDP Price deflators for 2007 - 2030. Used for years 2007 - 2030 on the Input_InflAdj sheet. | |
| 21 | U.S. Data projections. Industrial sector national forecasted energy prices. US Department of Energy, Energy Information Administration, Annual Energy Outlook, 2007, Supplemental Tables, Table 3. (Values for 2000-2003 are taken from AEOs 2003-2006) | As the price for a given fuel in a given year varies between annual reports (even after converting to chained 2005$), prices for past years are taken from the most recent report which includes data for that year (i.e. the prices for fuels in 2000 are taken from the 2003 report, the prices for fuels in 2001 from the 2004 report, and so on). | |
| 22 | Updated State-level Greenhouse Gas Emission Coefficients for Electricity Generation 1998-2000. Energy Information Administration, Office of Integrated Analysis and Forecasting, Energy Information Administration, U.S. Department of Energy, April 2002 | From Table 3. Lbs/MMBTU converted to g/MMBTU by multiplying by 454. (See EF_Constants: 1lb=.454 kgx1000=454 grams) | |
| 23 | Annual Energy Review 2005. Energy Information Administration, U.S. Department of Energy. | Average transmission and distribution losses of 9% are indicated on P42 (section 2) | |
| 24 | IRS Business Milage Reimbursement Rate | This is a rate used by many businesses and College Campusses to reimburse program-related travel. This directly financed travel, despite being conducted in personal cars, lies further within the university's control than voluntary travel not reimbursed by the university. | |
| 25 | U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Alternative Fuel Price Reports, May 2000 - October 2007 | The alternative fuel report is published at varying intervals and does not always report national averages or data for all fuels. Thus these values are the average (weighted by number of stations reporting if national average was not reported) of all reported values for a given year, converted to 2005$, and scaled by the percent difference between the price for E85 as reported by the alternative fuel report and the Annual Energy Outlook reports. | |
| 26 | U.S. Department of Energy, Energy Information Administration, Annual Energy Review, Table 8.2.b - Electricity Net Generation: Electric Power Sector, 1949-2006 | ||
| 27 | U.S. Department of Energy, Energy Information Administration, Annual Energy Review, Table 8.4.b - Consumption for Electricity Generation by Energy Source: Electric Power Sector, 1949-2006 | ||
| 28 | https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=60000AVO.TXT | Solid Waste Management And Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks. 3rd EDITION, September 2006. Section 5, page 70, exhibit 5-1. | Factor is for gross N2O emissions from combustion of mixed municipal solid waste, expressed as MTCE / Wet Short Ton. CH4 emissions are not mentioned so they are assumed to be zero. The factor assumes no transportation emissions because combustion is on campus. This source converted N2O emissions to MTCE using 44 MT CO2 / 22 MTCE and GWP N2O = 310, so these values should be used to convert the emissions factors from MTCE to MT CH4. |
| 29 | https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks | Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2005 (April 2007) USEPA #430-R-07-002; Annex 5, A-279 | Although hydroelectricity producion may result in increased CH4 emissions from decaying organic matter in reservoirs and wetlands, there is currently no established scientific methedology to estimate these emissions and so they are ignored. |
| 30 | Historical Climatological Series 5-1 and 5-2: State-population weighted heating and cooling degree days (base 65 Deg F) | Heating degree days before FY1993 and after FY2007 are averages of FY1993-FY2007. Cooling degree days before FY1995 and after FY2007 are averages of FY1995-FY2007. | |
| 31 | Alaska Climate Research Center | All values are average for Anchorage International Airport from 1971-2000 | |
| 32 | Hawaii State Climate Office | All values are average for Honolulu Airport from 1949-2002 | |
| 33 | https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks | Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2006 (February 2008); Section 8.2, p8-8 - 8-9 | All wastewater is assumed to be domestic wastewater, rather than industrial wastewater. Per capita wastewater production was calculated by dividing wastewater flow to publicly owned treatment works (100 gallons / person / day) by the % of all wastewater that is processed by these facilities (79%). kg BOD / gallon wastewater was calculated by dividing per capita BOD production (0.09 kg / person / day) by per capita wastewater production (127 gallons / person / day). |
| 34 | https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks | Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2006 (February 2008); Section 8.2, p8-13 - 8-14 | The N2O emissions factor for effluent discharged to aquatic environments was calculated using the 2006 U.S. population (303 million) and per capita protein consumption (41.9 kg / person), 0.16 kg N / kg protein, and a factor of 1.4 to adjust for non-consumed protein added to domestic wastewater. It excludes industrial and commercial co-discharged protein, assumes that 7.4% of the sewage-N is removed as sludge, assumes 0.005 kg N2O-N per kg sewage-N, and assumes 127 gallons wastewater / person / day (see note for reference 36). This gives a factor of 1.48*10^-6 kg N2O / gallon. All waste treatment plants are assumed to use intentional nitrification and denitrification, which adds an additional 1.51*10-7 kg N2O / gallon for a total of 1.63*10^-6 kg N2O / gallon. |
| 35 | |||
| 36 | https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=60000AVO.TXT | Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks, 2nd EDICTION, EPA530-R-02-006, May 2002 | Landfilling (from Exhibit 7-6): Factor includes the emissions associated with transporting the waste to the landfill and CH4 from biogenic sources, but not CO2 resulting from the combustion of biogenic CH4, following the U.S. EPA guidelines. For combustion of landfill gas with electric generation, the factor takes into account Utility CO2 emissions avoided by biogas electric generation. When food discards, yard trimmings, paper, and wood are landfilled, anaerobic bacteria degrade the materials, producing CH4 and CO2. CH4 is counted as an anthropogenic GHG, because even though it is derived from sustainably harvested biogenic sources, degradation would not result in CH4 emissions if not for deposition in landfills. The CO2 is not counted as a GHG in this context because if it were not emitted from landfills, it would be produced through natural decomposition. Because metals do not contain carbon, they do not generate CH4 when landfilled. Landfill emissions factors do not account for net carbon storage of some of the embodied emissions contained in the solid waste, since those embodied emissions are not included elsewhere in the inventory. See source for more details. |
| 37 | https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=60000AVO.TXT | Solid Waste Management and Greenhouse Gases: A Life-Cycle Assessment of Emissions and Sinks, 2nd EDICTION, EPA530-R-02-006, May 2002 | Waste Combustion (from Exhibit 6-6): Factors include emissions from combustion of waste but not from biogenic sources following the U.S. EPA guidelines. Factor takes into account Utility CO2 emissions avoided by biogas electric generation. Factor does not include avoided CO2 emissions due to steel recovery and recycling, as few universities will dispose of great amounts of steel. Factors are negative because energy generation from waste results in fewer emissions than would have been emitted by standard utility generation. These factors do not account for other harmful effects of waste combustion. |
| 38 |
Environmental Defense Fund Paper Calculator. Online at http://www.edf.org/papercalculator/ accessed 4/26/2008 Definitions for the types of paper: Paper-Types.pdf [12/7/2018]
|
All values were calculated by using the Environmental Defense Fund Paper Calculator to determine the eCO2 emissions (in lbs) for paper of each paper type containing 0%, 50%, and 100% recycled content. The eCO2 emissions in lbs were then converted to metric tons using the conversion factors on the EF_Constants sheet. A linear regression was applied to the 3 data points for each paper type. In every case this regression had an r^2 value of 1, indicating that eCO2 emissions are a linear function of paper % recycled content. The slope and y-intercept of the linear regression were calculated, and then converted to MT eCO2 / lb using the conversion factors on the EF_Constants sheet. | |
| 39 | The Climate Registry, General Reporting Protocol, v1.1 Accessed 11/08 | Heating values and carbon content for all biogenic emissions assumed to be the same as for "wood and wood waste" in Table 12.2 "U.S. Default Factors for Calculating CO2 Emissions from Non-Fossil Fuel" p.75. This document in turn references the EPA Climate Leaders 2007 emissions factors. | |
| 40 | The Climate Registry, General Reporting Protocol, v1.1 Accessed 11/08 | Table 13.1 U.S. Default CO2 Emission Factors for Transport Fuels, used to calculate biogenic emissions from B100, B20 and B5 (by taking 20% and 5%, respectively, of the two latter sources, multiplying it by the total gallons of fuel, and then multiplying by the B100 emissions factor.) | |
| 41 |
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch2s2-10-2.html |
IPCC 4th Assessment Report | Values are taken from the IPCC 4th assessment report and assume a 100 year atmospheric lifetime period. |
| 42 |
https://www.statista.com/statistics/655381/passenger-yield-of-commercial-airlines-worldwide/ |
For 1990-2013 used the Annual Round-Trip Fares and Fees: (Domestic, International) chart. Years between 2005 and 2017, from Statistica. |
Values taken from these two websites and combined to create a price per mile, which is used to convert dollars spent to miles traveled. |