GHG Emissions Inventory

GHG Emissions Inventory

GHG Emissions Inventory

References

Worked Examples

Inventory (every quantity carries its own unit select; the unit-system radio above does not change anything in this tool)

Scope 1: stationary combustion (boilers, furnaces, generators; an energy unit uses the factors per mmBtu, a mass or volume unit the factors per unit of fuel)

Scope 1: mobile combustion (CO2 from the fuel; CH4 and N2O from the distance and model year for on-road vehicles, from the fuel for non-road equipment)

Scope 1: refrigerants and other gases released (the mass lost in the year: recharge or top-up records, or charge times annual leak rate)

Scope 2: purchased electricity (location-based from the grid rate; market-based from contractual instruments and a supplier rate)

Scope 2: purchased steam, heat and cooling energy

Scope 3: transport, business travel and commuting by distance (hub Tables 8 and 10)

Scope 3: waste generated in operations (hub Table 9, metric tons CO2e per short ton by material and treatment)

Intensity metrics (optional: a blank denominator is left out)

Base year and target (optional: metric tons CO2e of the base-year inventory; blank fields are left out)

Reduction scenarios (optional what-if on the entered rows; zero or blank leaves a measure out)

Scopes

One row

Stationary combustion

Mobile combustion

Refrigerants and other gases

Global warming potentials

Purchased electricity: two totals

Scope 3 rows

Intensity, base year and target

Reduction scenarios

Uncertainty

What the tool does not do

Tools › Environmental › Emissions and Climate › GHG Emissions Inventory

A scope 1, scope 2 and selected scope 3 greenhouse gas inventory by the activity data times emission factor method of the EPA Center for Corporate Climate Leadership guidance. Rows of stationary combustion (63 fuels in energy, mass or volume units), mobile combustion (CO2 from the fuel, CH4 and N2O from the distance and model year of on-road vehicles or the fuel of non-road equipment), refrigerant and other gas releases (32 gases, 30 blends or an entered GWP), purchased electricity by eGRID subregion or an entered factor with the location-based and market-based totals, purchased steam and heat, distance-based scope 3 transport, business travel and commuting, and waste by material and treatment are multiplied by the factors of the EPA GHG Emission Factors Hub (15 January 2025), which the tool carries cell for cell, and weighted by the 100-year global warming potentials of the IPCC Fourth, Fifth or Sixth Assessment Report. The results are CO2, CH4, N2O and CO2e per row, totals by scope, category and gas with biogenic CO2 reported separately, intensity per revenue, employee, floor area and unit of output, the change against a base year with a linear target path, a what-if table of efficiency, fuel switching and renewable electricity, the uncertainty of the totals from entered activity-data ranges, and a CSV export. The first default row is the natural gas boiler example of the EPA stationary combustion guidance (326.7 metric tons CO2e).

Scope 1: stationary and mobile combustion and refrigerant releases; scope 2: electricity (location-based and market-based) and steam; scope 3: transport, travel, commuting and waste
EPA GHG Emission Factors Hub 2025 Tables 1 to 12 and the eGRID2023 subregion rates shipped as data; units chosen per row
AR4, AR5 or AR6 global warming potentials, or entered values; biogenic CO2 kept outside the scopes
Totals by scope, category and gas; intensity metrics; base-year change and target path; reduction scenarios; uncertainty; CSV export

Unit System: SI / USCS

Equation Display:

Organization
Reporting Year
GWP Values
GWP of CH4
GWP of N2O
eGRID Data

	Source	Fuel ℹ️Fuels of EPA Emission Factors Hub Table 1 (40 CFR Part 98 Tables C-1 and C-2). Solid fuels take a mass or an energy unit, gases and liquids a volume or an energy unit. The CO2 of a biomass fuel is reported as biogenic, outside the scopes; its CH4 and N2O count in scope 1.	Quantity	Unit	Range ± % ℹ️Half-range of the row's activity data in percent (for example 5 for ± 5 %). Blank = no range. Only the activity data is ranged; the emission factors are taken as exact.
1
2
3

	Source	Vehicle ℹ️Vehicle and fuel of hub Tables 3 (on-road gasoline), 4 (on-road diesel and alternative fuel) and 5 (non-road). The fuel of the choice sets the CO2 factor of Table 2. Enter a blend such as E85 or B20 as two rows, one per component.	Fuel	Fuel Unit	Distance ℹ️On-road vehicles only: the CH4 and N2O factors are per vehicle-mile. Blank = CH4 and N2O not calculated for the row.	Distance Unit	Model Year ℹ️On-road gasoline and diesel vehicles: the factors of Tables 3 and 4 are listed by model year (to 2022). Blank = the newest listed year.	Range ± % ℹ️Half-range of the row's activity data in percent (for example 5 for ± 5 %). Blank = no range. Only the activity data is ranged; the emission factors are taken as exact.
1
2

	Source	Gas ℹ️Pure gases of hub Table 11 and blends of Table 12. For a gas that is not listed choose Other gas and enter its GWP. Refrigerants regulated under the Montreal Protocol (CFCs, HCFCs such as R-22) are outside the inventory scopes and carry no GWP here, as in Table 12.	Mass	Unit	GWP Entered ℹ️Optional: overrides the table value of the row. Required for Other gas.	Range ± % ℹ️Half-range of the row's activity data in percent (for example 5 for ± 5 %). Blank = no range. Only the activity data is ranged; the emission factors are taken as exact.
1
2

	Site	Grid ℹ️eGRID subregion of the site (total output emission rates), the U.S. average, or Entered factor for a site outside the United States or a utility-specific rate.	Quantity	Unit	Entered kg/MWh ℹ️Location-based factor for the Entered factor choice, in kg CO2e per MWh (the same number as g per kWh).	Market kg/MWh ℹ️Supplier-specific or contract emission rate for the market-based total, kg CO2e per MWh. Blank = the grid rate of the row (no residual-mix rates are published for the United States).	Instruments % ℹ️Percent of the row covered by zero-emission contractual instruments (renewable energy certificates, a power purchase agreement, a green tariff). It lowers the market-based total only.	Range ± % ℹ️Half-range of the row's activity data in percent (for example 5 for ± 5 %). Blank = no range. Only the activity data is ranged; the emission factors are taken as exact.
1
2

	Source	Quantity	Unit	Entered kg/mmBtu ℹ️Supplier factor. Blank = hub Table 7 (66.33 kg CO2, 1.25 g CH4, 0.125 g N2O per mmBtu: natural gas at 80 % boiler efficiency).	Range ± % ℹ️Half-range of the row's activity data in percent (for example 5 for ± 5 %). Blank = no range. Only the activity data is ranged; the emission factors are taken as exact.
1

	Stream	Material	Treatment ℹ️Not every material has a factor for every treatment (the table prints NA); the row is then reported as an input message.	Mass	Unit	Range ± % ℹ️Half-range of the row's activity data in percent (for example 5 for ± 5 %). Blank = no range. Only the activity data is ranged; the emission factors are taken as exact.
1
2

Revenue, millions
Employees
Floor Area
Area Unit
Units of Output
Output Name

Base Year
Scope 1
Scope 2, location
Scope 2, market
Scope 3
Target Cut, %
Target Year

Stationary Fuel Cut, %
Mobile Fuel Cut, %
Electricity Cut, %
Switch From
Switch To
Share Switched, %
Energy Ratio
Renewable Electricity, %

Scopes, Emission Factors, GWP Sets, Market-Based Scope 2, Scenarios and Uncertainty | Method page

A greenhouse gas inventory adds up what an organization emitted in a year. Each line of it is a measured or billed quantity (the activity data: therms of gas, gallons of fuel, kilowatt hours, kilograms of refrigerant topped up) multiplied by an emission factor. This tool carries the factor tables of the EPA GHG Emission Factors Hub of 15 January 2025 cell for cell, follows the calculation steps of the EPA Center for Corporate Climate Leadership guidance documents, and reports the result in the scopes of the GHG Protocol.

Scope 1 is what the organization emits itself: fuel burned in its boilers, furnaces and generators (stationary combustion), fuel burned in its vehicles and equipment (mobile combustion), and refrigerants and other gases that escape from its equipment. Scope 2 is the emission at the power plant or district plant for the electricity, steam, heat or cooling it buys. Scope 3 is everything else in the value chain; the tool covers the categories for which the hub prints factors: transportation and distribution by distance (categories 4 and 9), waste generated in operations (5), business travel (6) and employee commuting (7). The scope 3 total is therefore the total of the entered categories, not a complete scope 3 inventory.

For every gas, emissions = activity × emission factor. The three combustion gases are carbon dioxide, methane and nitrous oxide, and the row total is expressed as carbon dioxide equivalent,

CO₂e = CO₂ + GWP_CH4 · CH₄ + GWP_N2O · N₂O + Σ GWP_i · m_i

where the last term is the mass of each other gas released times its global warming potential. The first default row is the worked example of the EPA stationary combustion guidance: 61,500 therms of natural gas are 6,150 mmBtu, times 53.06 kg CO₂, 1.0 g CH₄ and 0.10 g N₂O per mmBtu gives 326.3 t CO₂, 6.15 kg CH₄ and 0.615 kg N₂O, and with GWPs of 28 and 265 the row is 326.7 metric tons CO₂e, as the guidance prints.

Hub Table 1 (from 40 CFR Part 98, Tables C-1 and C-2) lists 63 fuels with a default higher heating value and two sets of factors: per mmBtu, and per unit of fuel (short ton of a solid, standard cubic foot of a gas, gallon of a liquid). A quantity entered in an energy unit takes the per-mmBtu factors (the guidance's Equation 2, the preferred form when the bill states energy); a quantity in a mass or volume unit takes the per-unit factors (Equation 1). The per-unit columns are the per-mmBtu factors times the default heating value, rounded as printed, so the two routes can differ in the third or fourth figure. The kraft pulping liquors have per-mmBtu factors only.

Unit conversions use the exact definitions of NIST SP 811: 1 Btu_IT = 1055.05585262 J (so 1 mmBtu = 1.05505585 GJ = 293.071 kWh), 1 lb = 0.45359237 kg, 1 short ton = 907.18474 kg, 1 gal = 3.785411784 L, 1 ft³ = 0.028316846592 m³, 1 barrel = 42 gal, 1 mile = 1.609344 km. The therm is 100,000 Btu, 0.1 mmBtu, as in the EPA guidance. Gas volumes are converted as volumes; a cubic metre at other reference conditions than the standard cubic foot's should be corrected before it is entered.

Biomass. The CO₂ from burning a biomass fuel (wood, agricultural residues, landfill gas, biodiesel, ethanol, pulping liquor) is reported as biogenic CO₂, separately and outside the scopes; its CH₄ and N₂O count in scope 1. The tool follows that rule for the stationary fuels of the biomass groups of Table 1 and for biodiesel and ethanol in vehicles.

CO₂ comes from the fuel: gallons (or standard cubic feet of CNG) times the factor of hub Table 2. CH₄ and N₂O depend on the engine and its emission controls rather than on the fuel alone. For on-road vehicles Tables 3 and 4 give grams per vehicle-mile by vehicle type, fuel and model year, so those two gases come from the distance; for non-road equipment (ships, locomotives, aircraft, construction, agricultural and other equipment) Table 5 gives grams per gallon, so they come from the fuel. A row with fuel but no distance reports CO₂ only, and says so. A model year after the last one listed (2022) takes the last row. Methanol vehicles are left out because Table 2 has no CO₂ factor for methanol; electric vehicles belong in the electricity table.

The row is the mass released in the year times the gas's GWP. The mass is what was added to the equipment to bring it back to full charge, or the charge times an annual leak rate (the EPA guidance's screening method: capacity × leak rate × fraction of the year in use), entered as a mass. Hub Table 11 lists 32 gases and Table 12 thirty blends; a blend's GWP counts only its HFC and PFC constituents, so blends of HCFCs alone show zero, as in the table. Any other gas can be entered with its own GWP.

A GWP is the warming of a kilogram of a gas over 100 years relative to a kilogram of CO₂. The values have been revised in each IPCC assessment, and an inventory must state which set it uses and keep to it across the years it compares.

Set	CH₄	N₂O	HFC-134a	SF₆	Source of the values in the tool
AR4 (2007)	25	298	1,430	22,800	EPA hub of 2023, Table 11; 40 CFR Part 98 Table A-1 (2024 edition)
AR5 (2013)	28	265	1,300	23,500	EPA hub of 2025, Table 11
AR6 (2021)	29.8 / 27.0	273	1,530	24,300	IPCC AR6 Working Group I, Tables 7.15 and 7.SM.7

AR6 gives methane two values: 29.8 for methane of fossil origin and 27.0 for non-fossil methane. The tool applies 27.0 to the methane of biomass fuels and biofuels and 29.8 to all other methane. Under AR4 and AR6 a blend's GWP is the composition-weighted sum of its constituents' values; under AR5 it is the value printed in Table 12. The Entered choice replaces the CH₄ and N₂O values and leaves the other gases at AR5. The waste factors of Table 9 and the entered electricity, steam and market factors are already in CO₂e and are not re-weighted.

Location-based: megawatt hours times the average emission rate of the grid region. For the United States those are the eGRID subregion total output rates in lb per MWh for each gas (1 lb = 0.45359237 kg). The hub's Table 6 prints eGRID2023 as first released in January 2025; EPA revised the eGRID2023 summary tables afterwards (revision 2, June 2025), and several subregions changed by a few percent. The tool defaults to revision 2 and offers the hub's printing as the other choice. The non-baseload rates in the same table are for estimating the effect of a change in consumption, not for an inventory, and are not used. For a site elsewhere choose Entered factor and give the grid's rate in kg CO₂e per MWh.

Market-based: the same megawatt hours priced by what the organization has contracted for. The share covered by zero-emission instruments (renewable energy certificates, a power purchase agreement, a utility green tariff) is taken out, and the rest is multiplied by the supplier or contract rate if one is entered, otherwise by the grid rate, since no residual-mix rates are published for the United States:

market-based = MWh · (1 − instruments) · (supplier rate, or the grid rate)

Both totals are reported side by side, as the GHG Protocol's scope 2 guidance requires of an organization with any contractual instruments. Purchased steam and heat take hub Table 7 (natural gas burned at 80 percent efficiency) or a supplier factor.

Tables 8 and 10 give factors per vehicle-mile, passenger-mile or short ton-mile; the kilometre basis converts with 1 mile = 1.609344 km and 1 short ton-mile = 1.459972 tonne-km. Table 9 gives metric tons CO₂e per short ton of each of 61 materials for each treatment (recycled, landfilled, combusted, composted, anaerobically digested); the table prints NA where a treatment does not apply to a material, and the tool reports such a row instead of inventing a factor.

Intensity is a total divided by a measure of activity: revenue, employees, floor area, or units of output. The base-year table shows the change, the percent change, and the compound annual rate (E / E₀)^1/n − 1 over the n years between the two inventories. The target check draws a straight line from the base-year emissions to the target-year emissions E₀(1 − cut) and compares this year's scope 1 + 2 with the point on the line. A base year is only comparable when it was calculated with the same boundaries, the same GWP set and consistent factors; when the organization or the method changes materially, the base year is recalculated.

The what-if table reruns the whole inventory with changed activity data. Efficiency scales the stationary fuel rows, the mobile rows (fuel and distance) and the electricity rows by the entered cuts. Fuel switching removes a share of one stationary fuel's energy and supplies it with another fuel or with electricity: new energy = displaced energy × energy ratio, where the ratio is the old equipment's efficiency over the new one's efficiency or COP (0.8 / 3 ≈ 0.27 for a boiler replaced by a heat pump, 1 for a like-for-like fuel change). Electricity added by a switch is bought at the terms of the first electricity row. Renewable electricity raises the contractual-instrument share of every electricity row to the entered percentage, which lowers the market-based total and leaves the location-based total where the grid puts it. The combined line applies the three in that order, so its saving is less than the sum of the separate savings.

If a row's activity is known to ± u percent, its emissions are known to ± u percent, a half-range h = u E. For a total of rows whose errors are independent the half-ranges add in quadrature, H = √(Σ h²); if every row erred in the same direction they would add directly, H = Σ h. The tool prints both. Only the activity data is ranged. Emission factors carry their own uncertainty (small for the CO₂ of a commercial fuel, large for CH₄ and N₂O factors, waste and travel factors) and GWPs theirs; neither is included.

It does not set the organizational boundary (equity share or control), does not cover process emissions, fugitive methane from gas systems, or the scope 3 categories without a hub factor (purchased goods and services, capital goods, fuel- and energy-related activities including transmission losses, leased assets, use of sold products, investments), and does not verify data. The factors are those of the United States; for sites elsewhere the fuel factors are a reasonable first estimate and the electricity factor must be entered.

U.S. Environmental Protection Agency (2025). Emission Factors for Greenhouse Gas Inventories. GHG Emission Factors Hub, 15 January 2025.

U.S. Environmental Protection Agency (2023). Emission Factors for Greenhouse Gas Inventories. GHG Emission Factors Hub, 2023 edition.

U.S. Environmental Protection Agency (2023). Greenhouse Gas Inventory Guidance: Direct Emissions from Stationary Combustion Sources. Center for Corporate Climate Leadership, December 2023.

U.S. Environmental Protection Agency (2023). Greenhouse Gas Inventory Guidance: Direct Emissions from Mobile Combustion Sources. Center for Corporate Climate Leadership, December 2023.

U.S. Environmental Protection Agency (2023). Greenhouse Gas Inventory Guidance: Direct Fugitive Emissions from Refrigeration, Air Conditioning, Fire Suppression, and Industrial Gases. Center for Corporate Climate Leadership, December 2023.

U.S. Environmental Protection Agency (2023). Greenhouse Gas Inventory Guidance: Indirect Emissions from Purchased Electricity. Center for Corporate Climate Leadership, December 2023.

U.S. Environmental Protection Agency (2025). eGRID Summary Tables 2023. Emissions and Generation Resource Integrated Database, revision 2.

U.S. Environmental Protection Agency (2024). Mandatory Greenhouse Gas Reporting. 40 CFR Part 98, Subparts A and C, Code of Federal Regulations, revised as of 1 July 2024.

U.S. Environmental Protection Agency (2024). Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2022. Annexes. Washington, DC.

Forster, P., Storelvmo, T., Armour, K., Collins, W., Dufresne, J.-L., Frame, D., Lunt, D. J., Mauritsen, T., Palmer, M. D., Watanabe, M., Wild, M., and Zhang, H. (2021). "The Earth's Energy Budget, Climate Feedbacks, and Climate Sensitivity." In Masson-Delmotte, V., et al. (eds.), Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, pp. 923–1054.

Smith, C., Nicholls, Z. R. J., Armour, K., Collins, W., Forster, P., Meinshausen, M., Palmer, M. D., and Watanabe, M. (2021). "The Earth's Energy Budget, Climate Feedbacks, and Climate Sensitivity Supplementary Material." In Masson-Delmotte, V., et al. (eds.), Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change.

Thompson, A., and Taylor, B. N. (2008). Guide for the Use of the International System of Units (SI). NIST Special Publication 811, 2008 ed. National Institute of Standards and Technology, Gaithersburg, MD.

World Resources Institute and World Business Council for Sustainable Development (2004). The Greenhouse Gas Protocol: A Corporate Accounting and Reporting Standard, revised ed. WRI and WBCSD, Washington, DC, and Geneva.

World Resources Institute (2015). GHG Protocol Scope 2 Guidance: An Amendment to the GHG Protocol Corporate Standard. WRI, Washington, DC.

World Resources Institute and World Business Council for Sustainable Development (2011). Corporate Value Chain (Scope 3) Accounting and Reporting Standard. WRI and WBCSD, Washington, DC, and Geneva.

Mode ℹ️The unit in parentheses is what the quantity counts: vehicle-miles, passenger-miles or short ton-miles (the kilometre basis counts vehicle-km, passenger-km or tonne-km).

Range ± % ℹ️Half-range of the row's activity data in percent (for example 5 for ± 5 %). Blank = no range. Only the activity data is ranged; the emission factors are taken as exact.

Published examples this tool reproduces; each page lists the inputs to enter and the printed answers.

Natural gas boiler billed in therms: CO2, CH4, N2O and CO2e (EPA inventory guidance example) inside a scope 1, 2 and 3 inventory (the tool's default inputs)

All worked examples

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