What are extra calculation in EEOI? Which fuel calculations are excluded in EEDI? What exactly is excluded in Boiler Calculation?

Answer

1. What “extra calculation” is there in EEOI?

EEOI is based on actual operational fuel consumed, not theoretical/design consumption:

EEOI=∑(FCj×CFj) / (mcargo×D))))

The important “extra” compared with EEDI is that EEOI counts practically all actual fuel consumed for the voyage/period, including:

Main engine fuel
Auxiliary engine/DG fuel
Boiler fuel
Incinerator fuel
Fuel consumed at sea and in port

IMO MEPC.1/Circ.684 specifically defines EEOI fuel consumption as all fuel consumed at sea and in port by main and auxiliary engines, including boilers and incinerators.

2. Which fuel/power consumption is excluded from EEDI?

EEDI auxiliary power PAEPAE represents the power necessary for normal maximum sea load associated with propulsion machinery and normal living/navigation requirements.

It excludes power that is not associated with normal propulsion operation, particularly:

Bow/stern thrusters
Cargo pumps
Cargo gear
Ballast pumps
Power required for maintaining cargo
- Reefer containers/refrigeration
- Cargo hold ventilation fans, etc.
Cargo-handling related loads

The IMO EEDI power-plant diagram shows these loads outside the normal PAEPAE boundary, and the guidelines describe PAEPAE as normal sea load for propulsion systems and accommodation.

Why?

Because EEDI is intended to compare the energy efficiency of transporting the ship/cargo through the water, rather than penalizing one ship simply because its cargo requires special heating, cooling, pumping or handling.

3. Exact Exclusions in Boiler Calculations: Boilers serve two primary purposes on board: service/auxiliary load (heating HFO, hotel load) and cargo load (cargo discharge pumps, cargo heating).

Regulatory Index	Boiler Fuel Status	Exclusions & Exemption Rationale
EEDI (Design Index)	Completely Excluded (with minor exception for passenger/Ro-Ro ships)	Fuel for oil-fired auxiliary boilers is excluded from the standard EEDI formula because cargo heating/discharge pumps do not contribute to normal underway propulsion/transit efficiency. (Note: For passenger and Ro-Pax vessels where steam is required for HVAC/catering during transit, an estimated auxiliary power PAE term accounts for electric/steam load without explicitly logging operational boiler fuel).
EEOI (Operational Index)	Fully Included	Zero Exclusions. All fuel burned in oil-fired boilers during sea transit, anchorage, and port operations (including cargo discharge and heating) must be logged and included in the operational CO2 numerator.
CII / IMO DCS Framework	Deductible via Correction Factors (MEPC.355(78))	Under operational CII rules, fuel consumed by oil-fired boilers for cargo heating and cargo discharge on tankers (FCboiler) can be explicitly measured (via dedicated flowmeters) and deducted from the total CO2 emissions under verified IMO G5 correction factor guidelines.

Regulatory Index

Boiler Fuel Status

Exclusions & Exemption Rationale

EEDI (Design Index)

Completely Excluded (with minor exception for passenger/Ro-Ro ships)

Fuel for oil-fired auxiliary boilers is excluded from the standard EEDI formula because cargo heating/discharge pumps do not contribute to normal underway propulsion/transit efficiency.

(Note: For passenger and Ro-Pax vessels where steam is required for HVAC/catering during transit, an estimated auxiliary power PAE term accounts for electric/steam load without explicitly logging operational boiler fuel).

EEOI (Operational Index)

Fully Included

Zero Exclusions. All fuel burned in oil-fired boilers during sea transit, anchorage, and port operations (including cargo discharge and heating) must be logged and included in the operational CO2 numerator.

CII / IMO DCS Framework

Deductible via Correction Factors (MEPC.355(78))

Under operational CII rules, fuel consumed by oil-fired boilers for cargo heating and cargo discharge on tankers (FCboiler) can be explicitly measured (via dedicated flowmeters) and deducted from the total CO2 emissions under verified IMO G5 correction factor guidelines.