Subpart C IVT Equation Inputs Summary

CO₂

Annual CO₂ 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 C-1 of this subpart

mmBtu per mass or 
mmBtu per volume, 
as applicable

Table C-1

EF

Fuel-specific default CO₂ emission 
factor, from Table C-1 of this subpart

kg CO₂/mmBtu

Table C-1

1 × 10⁻³

Conversion factor from kilograms 
to metric tons

- 

 0.001

CO₂

Annual CO₂ mass emissions from natural gas combustion

metric tons

 Output

Gas

Annual natural gas usage, from billing records

therms

 User input

EF

Fuel-specific default CO₂ emission factor for natural gas, from Table C-1 of this subpart

kg CO₂/mmBtu

Table C-1

0.1

Conversion factor from therms to mmBtu

mmBtu/therm

 0.1

1 × 10⁻³

Conversion factor from kilograms to metric tons

-

 0.001

CO₂

Annual CO₂ mass emissions from natural gas combustion

metric tons

 Output

Gas

Annual natural gas usage, from billing records

mmBtu

 User input

EF

Fuel-specific default CO₂ emission factor for natural gas, from Table C-1 of this subpart

kg CO₂/mmBtu

Table C-1

1 × 10⁻³

Conversion factor from kilograms to metric tons

-

 0.001

CO₂

Annual CO₂ 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

Fuel-specific default CO₂ emission factor, from 
Table C-1 of this subpart

kg CO₂/mmBtu

Table C-1 

1 × 10−3

Conversion factor from kilograms to metric tons

 -

0.001

(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

-

1-12 

CO₂

Annual CO₂ 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

Fuel-specific default CO₂ emission factor, from 
Table C-1 of this subpart

kg CO₂/mmBtu

Table C-1 

1 × 10−3

Conversion factor from kilograms to metric tons

-

 0.001

CO₂

Annual CO₂ 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, CO₂ to carbon

- 

 44/12

0.91

Conversion factor from short tons to metric tons

- 

 0.91

CO₂

Annual CO₂ 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, CO₂ to carbon

- 

44/12 

0.001

Conversion factor from kg to metric tons

- 

0.001 

CO₂

Annual CO₂ 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/kg-mole

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, CO₂ to carbon

- 

44/12 

0.001

Conversion factor from kg to metric tons

- 

0.001 

CH₄ or N₂O

Annual CH₄ or N₂O 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 C-1 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 C-8

mmBtu per mass or volume

Table C-1 or 
calculated per 
§98.33(a)(2)(ii)

EF

Fuel-specific default emission factor for CH₄ or N₂O, 
from Table C-2 of this subpart

kg CH₄ or N₂O per mmBtu

Table C-2 

1 × 10⁻³

Conversion factor from kilograms to metric tons

-

 0.001

CH₄ or N₂O

Annual CH₄ or N₂O emissions from the combustion of natural gas

metric tons

Output 

Fuel

Annual natural gas usage, from gas billing records

therms

User input

EF

Fuel-specific default emission factor for CH₄ or N₂O, 
from Table C-2 of this subpart

kg CH₄ or N₂O per mmBtu

Table C-2 

0.1

Conversion factor from therms to mmBtu

-

 0.1

1 × 10⁻³

Conversion factor from kilograms to metric tons

-

 0.001

CH₄ or N₂O

Annual CH₄ or N₂O emissions from the combustion of natural gas

metric tons

Output 

Fuel

Annual natural gas usage, from gas billing records

mmBtu

User input

EF

Fuel-specific default emission factor for CH₄ or N₂O, 
from Table C-2 of this subpart

kg CH₄ or N₂O per mmBtu

Table C-2 

1 × 10⁻³

Conversion factor from kilograms to metric tons

-

 0.001

CH₄ or N₂O

Annual CH₄ or N₂O 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

Fuel-specific default emission factor for CH₄ or N₂O, 
from Table C-2 of this subpart

kg CH₄ or N₂O per mmBtu

Table C-2  

1 × 10⁻³

Conversion factor from kilograms to metric tons

-

0.001 

CH₄ or N₂O

Annual CH₄ or N₂O 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

Fuel-specific emission factor for CH₄ or N₂O, from Table C-2 of this section

kg CH₄ or N₂O per mmBtu)

0.001

Conversion factor from kg to metric tons

-

V_ff

Annual volume of CO₂ 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

Fuel-specific carbon based F-factor, either a default 
value from Table 1 in section 3.3.5 of 
appendix F to 40 CFR part 75, or a 
site-specific value determined under section 3.3.6 
of appendix F to 40 CFR part 75

scf CO₂/mmBtu

Table 1 in Appendix F in 
40 CFR 75

or

Section 3.3.6 of Appendix 
F to 40 CFR 75

HHV

Annual average high heat value of the fossil fuel, from 
fuel sampling and analysis (Sampled as specified 
(e.g., monthly, quarterly, semi-annually, 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

10⁶

Conversion factor, Btu per mmBtu

-

 1000000