Reefer correction

How reefer-container CO₂ is stripped from CII per IMO MEPC.355(78).

Container ships and reefer vessels carrying refrigerated containers consume extra fuel to keep cargo cold. IMO MEPC.355(78) recognises this is cargo-related rather than propulsion-related, and lets operators strip those emissions from the Attained CII calculation.

Formula

Reefer fuel (tonnes) = Cx × SFOC × Reefer-Hours / 1,000,000
Reefer CO₂ (tonnes)  = Reefer fuel × CF
Corrected Attained CII = (Total CO₂ − Reefer CO₂) × 10⁶ / (Capacity × Distance NM)

IMO default constants

The platform uses the MEPC.355(78) defaults:

Constant	Value	Notes
Cx (default reefer power)	2.75 kW	Per active reefer
SFOC (2-stroke engines)	175 g/kWh	Default for container ships
SFOC (4-stroke engines)	200 g/kWh	Alternate, configurable
CF (HFO)	3.114 t CO₂ / t fuel	Default
CF (MGO/MDO)	3.206 t CO₂ / t fuel	Alternative

Inputs from the consumption log

The platform sums activeReefers × period across every report in the year to compute total reefer-hours. From there, fuel and CO₂ follow directly.

What you see

On the vessel detail page, two CII numbers are shown side by side:

• Database CII — what’s reported in the consumption logs (operator-supplied, may or may not include reefer correction depending on source)
• Corrected CII — the reefer-corrected figure computed by the platform

A link opens the full MEPC.355(78) PDF in an in-app slide-out for reference.

Implementation

src/lib/utils/ciiCalculator.ts — exports calculateReeferCorrection and calculateCIIWithReeferCorrection.

Reference

• IMO MEPC.355(78) — 2022 Interim Guidelines on correction factors and voyage adjustments for CII calculations
• IMO MEPC.364(79) — CO₂ emission factors (Cf) for HFO and MGO