This page lists the variables used in each Inputs Verifier Tool (IVT) equation in subpart C. This information is intended primarily for XML uploaders to enable them to understand how each IVT equation is calculated and to identify sources for the constants, default values, and lookup values needed to solve the equations.
Click the links for the equations below to view the variables used in the IVT calculations:
 Equation C1: Annual CO_{2} Mass Emissions for the Specific Fuel Type for Tier 1
 Equation C1a: Annual CO_{2} Mass Emissions from Natural Gas Combustion for Tier 1  Therms
 Equation C1b: Annual CO_{2} Mass Emissions from Natural Gas Combustion for Tier 1  MMBtu
 Equation C2a: Annual CO_{2} mass emissions for a specific fuel type for Tier 2
 Equation C2b: Weighted Annual Average High Heat Value of the Fuel
 Equation C2c: Annual CO_{2} Mass Emissions from MSW or Solid Fuel Combustion
 Equation C3: Annual CO_{2} Mass Emissions from the Combustion of the Specific Solid Fuel for Tier 3
 Equation C4: Annual CO_{2} Mass Emissions from the Combustion of the Specific Liquid Fuel for Tier 3
 Equation C5: Annual CO_{2} Mass Emissions from the Combustion of the Specific Gaseous Fuel for Tier 3
Equation C8: Annual CH_{4} or N_{2}O Emissions from the Combustion of a Particular Type of Fuel for which Tier 1 or Tier 3 Is Used to Calculate CO_{2} Emissions
 Equation C8a: Annual CH_{4} or N_{2}O Emissions from the Combustion of Natural Gas  Therms
 Equation C8b: Annual CH_{4} or N_{2}O Emissions from the Combustion of Natural Gas  mmBtu
 Equation C13: Annual Volume of CO_{2} Emitted from Combustion of a Particular Fossil Fuel
Equation C1: Annual CO_{2} Mass Emissions for the Specific Fuel Type for Tier 1
Equation C1 calculates annual CO2 mass emissions for the specific fuel type for Tier 1
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CO_{2}  Annual CO_{2} mass emissions for the specific fuel type  metric tons  Output 
Fuel  Mass or volume of fuel combusted per year, from company records as defined in §98.6  short tons for solid fuel volume in standard cubic feet for gaseous fuel volume in gallons for liquid fuel  User input 
HHV  Default high heat value of the fuel, from Table C1 of this subpart  mmBtu per mass or mmBtu per volume, as applicable  
EF  Fuelspecific default CO_{2} emission factor, from Table C1 of this subpart  kg CO_{2}/mmBtu  
1 × 10^{−3}  Conversion factor from kilograms to metric tons    0.001 
Equation C1a: Annual CO_{2} Mass Emissions from Natural Gas Combustion for Tier 1  Therms
Equation C1a calculates annual CO_{2} mass emissions from natural gas combustion when natural gas consumption in billing records is expressed in therms.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CO_{2}  Annual CO_{2} mass emissions from natural gas combustion  metric tons  Output 
Gas  Annual natural gas usage, from billing records  therms  User input 
EF  Fuelspecific default CO_{2} emission factor for natural gas, from Table C1 of this subpart  kg CO_{2}/mmBtu  
0.1  Conversion factor from therms to mmBtu  mmBtu/therm  0.1 
1 × 10^{−3}  Conversion factor from kilograms to metric tons    0.001 
Equation C1b: Annual CO_{2} Mass Emissions from Natural Gas Combustion for Tier 1  mmBtu
Equation C1b calculates annual CO_{2} mass emissions from natural gas combustion when natural gas consumption in billing records is expressed in mmBtu.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CO_{2}  Annual CO_{2} mass emissions from natural gas combustion  metric tons  Output 
Gas  Annual natural gas usage, from billing records  mmBtu  User input 
EF  Fuelspecific default CO_{2} emission factor for natural gas, from Table C1 of this subpart  kg CO_{2}/mmBtu  
1 × 10^{−3}  Conversion factor from kilograms to metric tons    0.001 
Equation C2a: Annual CO_{2} mass emissions for a specific fuel type for Tier 2
Equation C2a calculates annual CO_{2} mass emissions for a specific fuel type for Tier 2.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CO_{2}  Annual CO_{2} mass emissions for a specific fuel type  metric tons  Output 
Fuel  Mass or volume of the fuel combusted during the year, from company records as defined in §98.6  short tons for solid fuel volume in standard cubic feet for gaseous fuel volume in gallons for liquid fuel  User input 
HHV  Annual average high heat value of the fuel  mmBtu per mass or volume. The average HHV shall be calculated according to the requirements of paragraph (a)(2)(ii) of this section  User input 
EF  Fuelspecific default CO_{2 }emission factor, from Table C1 of this subpart  kg CO_{2}/mmBtu  
1 × 10−3  Conversion factor from kilograms to metric tons    0.001 
Equation C2b: Weighted Annual Average High Heat Value of the Fuel
Equation C2b calculates the weighted annual average high heat value of the fuel.
The table below defines the parameters in this equation. Equation C2b does not include constants, default values, or lookup values.
Parameter  Description  Units of Measure  Value or Source 

(HHV)_{annual}  Weighted annual average high heat value of the fuel  mmBtu per mass or volume  Output 
(HHV)_{I}  Measured high heat value of the fuel, for month “i” (which may be the arithmetic average of multiple determinations), or, if applicable, an appropriate substitute data value  mmBtu per mass or volume  User input 
(Fuel)_{I}  Mass or volume of the fuel combusted during month “i,” from company records  short tons for solid fuel volume in standard cubic feet for gaseous fuel volume in gallons for liquid fuel  User input 
n  Number of months in the year that the fuel is burned in the unit    112 
Equation C2c: Annual CO2 Mass Emissions from MSW or Solid Fuel Combustion
Equation C2c calculates annual CO_{2} mass emissions from MSW or solid fuel combustion.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CO_{2}  Annual CO_{2} mass emissions from MSW or solid fuel combustion  metric tons  Output 
Steam  Total mass of steam generated by MSW or solid fuel combustion during the reporting year  lb steam  User input 
B  Ratio of the boiler's maximum rated heat input capacity to its design rated steam output capacity  mmBtu/lb steam  User input 
EF  Fuelspecific default CO_{2} emission factor, from Table C1 of this subpart  kg CO_{2}/mmBtu  
1 × 10−3  Conversion factor from kilograms to metric tons    0.001 
Equation C3: Annual CO_{2} Mass Emissions from the Combustion of the Specific Solid Fuel for Tier 3
Equation C3 calculates annual CO_{2} mass emissions from the combustion of the specific solid fuel.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CO_{2}  Annual CO_{2} mass emissions from the combustion of the specific solid fuel  metric tons  Output 
Fuel  Annual mass of the solid fuel combusted, from company records as defined in §98.6  short tons  User input 
CC  Annual average carbon content of the solid fuel  percent by weight, expressed as a decimal fraction, e.g., 95% = 0.95  User input

44/12  Ratio of molecular weights, CO_{2} to carbon    44/12 
0.91  Conversion factor from short tons to metric tons    0.91 
Equation C4: Annual CO_{2} Mass Emissions from the Combustion of the Specific Liquid Fuel for Tier 3
Equation C4 calculates annual CO_{2} mass emissions from the combustion of the specific liquid fuel.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CO_{2}  Annual CO_{2} mass emissions from the combustion of the specific liquid fuel  metric tons  Output 
Fuel  Annual volume of the liquid fuel combusted  gallons  User input 
CC  Annual average carbon content of the liquid fuel  kg C per gallon of fuel  User input 
44/12  Ratio of molecular weights, CO_{2} to carbon    44/12 
0.001  Conversion factor from kg to metric tons    0.001 
Equation C5: Annual CO_{2} Mass Emissions from the Combustion of the Specific Gaseous Fuel for Tier 3
Equation C5 calculates annual CO_{2} mass emissions from combustion of the specific gaseous fuel.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CO_{2}  Annual CO_{2} mass emissions from combustion of the specific gaseous fuel  metric tons  Output 
Fuel  Annual volume of the gaseous fuel combusted  scf  User input 
CC  Annual average carbon content of the gaseous fuel  kg C per kg of fuel  User input 
MW  Annual average molecular weight of the gaseous fuel  kg/kgmole  User input 
MVC  Molar volume conversion factor at standard conditions, as defined in §98.6  scf per kg mole  849.5 @ 68°F, or 836.6 @ 60 °F 
44/12  Ratio of molecular weights, CO_{2} to carbon    44/12 
0.001  Conversion factor from kg to metric tons    0.001 
Equation C8: Annual CH_{4} or N_{2}O Emissions from the Combustion of a Particular Type of Fuel for which Tier 1 or Tier 3 Is Used to Calculate CO_{2} Emissions
Equation C8 calculates annual CH_{4} or N_{2}O emissions from the combustion of a particular type of fuel for which Tier 1 or Tier 3 Is Used to Calculate CO_{2} Emissions
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CH_{4} or N_{2}O  Annual CH_{4} or N_{2}O emissions from the combustion of a particular type of fuel  metric tons  Output 
Fuel  Mass or volume of the fuel combusted, either from company records or directly measured by a fuel flow meter, as applicable  mass or volume per year  User Input 
HHV  Default high heat value of the fuel from Table C1 of this subpart; alternatively, for Tier 3, if actual HHV data are available for the reporting year, you may average these data using the procedures specified in paragraph (a)(2)(ii) of this section, and use the average value in Equation C8  mmBtu per mass or volume  Table C1 or calculated per §98.33(a)(2)(ii) 
EF  Fuelspecific default emission factor for CH_{4} or N_{2}O, from Table C2 of this subpart  kg CH_{4} or N_{2}O per mmBtu  
1 × 10^{−3}  Conversion factor from kilograms to metric tons    0.001 
Equation C8a: Annual CH_{4} or N_{2}O Emissions from the Combustion of Natural Gas  Therms
Equation C8a calculates the annual CH_{4} or N_{2}O emissions from the combustion of natural gas when natural gas consumption in billing records is expressed in therms.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CH_{4} or N_{2}O  Annual CH_{4} or N_{2}O emissions from the combustion of natural gas  metric tons  Output 
Fuel  Annual natural gas usage, from gas billing records  therms  User input 
EF  Fuelspecific default emission factor for CH_{4} or N_{2}O, from Table C2 of this subpart  kg CH_{4} or N_{2}O per mmBtu  
0.1  Conversion factor from therms to mmBtu    0.1 
1 × 10^{−3}  Conversion factor from kilograms to metric tons    0.001 
Equation C8b: Annual CH_{4} or N_{2}O Emissions from the Combustion of Natural Gas  mmBtu
Equation C8b calculates the annual CH_{4} or N_{2}O emissions from the combustion of natural gas when natural gas consumption in billing records is expressed in mmBtu.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CH_{4} or N_{2}O  Annual CH_{4} or N_{2}O emissions from the combustion of natural gas  metric tons  Output 
Fuel  Annual natural gas usage, from gas billing records  mmBtu  User input 
EF  Fuelspecific default emission factor for CH_{4} or N_{2}O, from Table C2 of this subpart  kg CH_{4} or N_{2}O per mmBtu  
1 × 10^{−3}  Conversion factor from kilograms to metric tons    0.001 
Equation C9a: Annual CH_{4} or N_{2}O Emissions from the Combustion of a Particular Type of Fuel for which Tier 2 Is Used to Calculate CO_{2} Emissions
Equation C9a calculates annual CH_{4} or N_{2}O emissions from the combustion of a particular type of fuel for which Tier 2 is used to calculate CO_{2} emissions.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CH_{4} or N_{2}O  Annual CH_{4} or N_{2}O emissions from the combustion of a particular type of fuel  metric tons  Output 
Fuel  Mass or volume of the fuel combusted during the reporting year  short tons for solid fuel volume in standard cubic feet for gaseous fuel volume in gallons for liquid fuel  User input 
HHV  High heat value of the fuel, averaged for all valid measurements for the reporting year  mmBtu per mass or volume  User input 
EF  Fuelspecific default emission factor for CH_{4} or N_{2}O, from Table C2 of this subpart  kg CH_{4} or N_{2}O per mmBtu  
1 × 10^{−3}  Conversion factor from kilograms to metric tons    0.001 
Equation C9b: Annual CH_{4} or N_{2}O emissions from the combustion of a solid fuel for which Equation C2b Is Used to Calculate CO_{2} Emissions
Equation C9b calculates annual CH_{4} or N_{2}O emissions from the combustion of a solid fuel for which Equation C2b Is Used to Calculate CO_{2} Emissions.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 
CH_{4} or N_{2}O  Annual CH_{4} or N_{2}O emissions from the combustion of a solid fuel  metric tons  Output 
Steam  Total mass of steam generated by solid fuel combustion during the reporting year  lb steam  User input 
B  Ratio of the boiler's maximum rated heat input capacity to its design rated steam output  mmBtu/lb steam  User input 
EF  Fuelspecific emission factor for CH_{4} or N_{2}O, from Table C2 of this subpart  kg CH_{4} or N_{2}O per mmBtu  
1 × 10−3  Conversion factor from kilograms to metric tons    0.001 
Equation C10: Annual CH_{4} or N_{2}O Emissions from the Combustion of a Particular Type of Fuel for which Tier 4 Is Used to Calculate CO_{2} Emissions
Equation C10 calculates annual CH_{4} or N_{2}O emissions from the combustion of a particular type of fuel for which Tier 4 is used to calculate CO_{2} emissions.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

CH_{4} or N_{2}O  Annual CH_{4} or N_{2}O emissions from the combustion of a particular type of fuel  metric tons 

(HI)_{A}  Cumulative annual heat input from combustion of the fuel  mmBtu 

EF  Fuelspecific emission factor for CH_{4} or N_{2}O, from Table C2 of this section  kg CH_{4} or N_{2}O per mmBtu) 

0.001  Conversion factor from kg to metric tons   

Equation C13: Annual Volume of CO_{2} Emitted from Combustion of a Particular Fossil Fuel
Equation C13 calculates annual volume of CO_{2} emitted from combustion of a particular fossil fuel.
The table below defines the parameters in this equation and provides the values or sources of any constants, default values, and lookup values.
Parameter  Description  Units of Measure  Value or Source 

V_{ff}  Annual volume of CO_{2} emitted from combustion of a particular fossil fuel  scf  Output 
Fuel  Total quantity of the fossil fuel combusted in the reporting year, from company records, as defined in §98.6  lb for solid fuel gallons for liquid fuel scf for gaseous fuel  User input 
F_{c}  Fuelspecific carbon based Ffactor, either a default value from Table 1 in section 3.3.5 of appendix F to 40 CFR part 75, or a sitespecific value determined under section 3.3.6 of appendix F to 40 CFR part 75  scf CO_{2}/mmBtu  Table 1 in Appendix F in 40 CFR 75 or 
HHV  Annual average high heat value of the fossil fuel, from fuel sampling and analysis (Sampled as specified (e.g., monthly, quarterly, semiannually, or by lot in §98.34(a)(2). The average HHV shall be calculated according to the requirements of paragraph (a)(2)(ii) of this section.)  Btu/lb for solid fuel Btu/gal for liquid fuel Btu/scf for gaseous fuel  User input

10^{6}  Conversion factor, Btu per mmBtu    1000000 