ISO 8861 Airflow Logic, Combustion Air, Machinery Heat Rejection & Fan Capacity

Ship Engine Room Ventilation, Combustion Air, Heat Load & Fan Sizing Tool

Build an engine-room air balance from diesel combustion demand and machinery heat emission, identify whether thermal load or the combustion-air minimum controls the design, size supply and extraction fans with reserve capacity, estimate intake free area, air changes, fan electrical power and annual operating cost, and expose retrofit bottlenecks before the ventilation package is specified.

Currency
Currency selector changes display only. No exchange-rate conversion is performed.

Engine Room Design Conditions

ISO 8861:1998 remains the current published ISO engine-room ventilation standard. Its standard design basis uses 35°C outside air and a maximum 12.5 K rise from intake air to air leaving the engine room. Keep these editable when the project or class basis requires different conditions.

m³
°C
K
kg/m³
kJ/kg·K
%
1.50 represents the ISO 8861 total-airflow minimum of combustion airflow plus 50%.
%
Used in the heat-evacuation screening term. Keep aligned with the calculation basis adopted by the project.
%

Main Propulsion Diesel Engines

kW
kg/kW·s
Manufacturer value preferred. ISO guidance value shown for the selected engine type.
kW total
%

Diesel Generator Engines

kW
kg/kW·s
kW total
%

Boiler & Other Combustion Air

m³/s
Enter manufacturer or boiler heat-balance airflow at the simultaneous normal-sea design condition.
m³/s
kW
kW

Additional Machinery-Space Heat Load

kW
kW
kW
kW
kW
kW

Machinery & Heat-Source Register

Add the machinery that is simultaneously operating in the design condition. Diesel rows calculate combustion airflow from kW × air requirement unless direct combustion airflow is entered. Heat emission remains an explicit manufacturer / project input.

Equipment Type Qty Power each kW Air kg/kW·s Direct combustion m³/s Heat emission kW Sim % Inside ER?

Supply Fan Bank

m³/s
Pa
%
%
m³/s
Optional comparison against an existing vessel before retrofit.
m/s

Extraction Fan Bank

m³/s
Pa
%
%
m/s
h/year

Retrofit Cost & Fan Energy

$ / kWh
$
$
$
$
$
%
kWh/year
Optional. Used only to compare annual fan electricity after retrofit.

Ventilation System Readiness

Ventilation screening only: This tool is not a class-approved HVAC design, CFD air-distribution analysis, duct-network calculation, fan acoustic study, fire-damper design, hazardous-area ventilation study or equipment-temperature guarantee. Manufacturer combustion-air and heat-emission data should take precedence over generic guidance values. Final fan duty also requires the real duct, louver, damper, filter, silencer and weather-protection pressure losses.
Reference basis: ISO 8861:1998, Shipbuilding - Engine-room ventilation in diesel-engined ships - Design requirements and basis of calculations, remains the current published ISO edition and was confirmed in 2022. The standard uses simultaneous machinery operation under the design condition, manufacturer data where possible, combustion-air calculations and machinery heat emission to establish engine-room ventilation demand. Confirm the applicable class, flag, fire-safety and project requirements for the vessel.
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