Ship HVAC Cooling Load, Chiller Capacity & Airflow Tool

Accommodation Cooling Load • Moist-Air Ventilation Load • Chiller Duty • N+1 Capacity • Supply Airflow • AHU Capacity • Chilled Water Flow • Ambient Sensitivity

Ship HVAC Cooling Load, Chiller Capacity & Airflow Tool

Size and stress-test shipboard accommodation HVAC from the cooling load outward. Simple mode gives a fast summer capacity and airflow screen. Advanced decomposes each zone into transmission, solar, occupants, lighting, equipment, ventilation, infiltration and latent load, then checks chillers, AHUs, N+1 redundancy, chilled-water flow, condenser heat rejection and hot-weather sensitivity.

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Fast accommodation HVAC screen.The default summer basis uses ISO 7547:2022 values of 35°C / 70% RH outdoors, 25°C indoors and 8 L/s-person outdoor air. Adjust the inputs for the vessel specification, route and project design basis.

CoolingSensible + latent design load

AirflowSupply and outdoor-air demand

PlantChiller margin and CHW flow

Summer Design Case

Conditioned floor aream² of accommodation / conditioned spaces.

Average clear heightm.

Outdoor dry-bulb temperature°C.

Outdoor relative humidity% RH.

Indoor design temperature°C. Simple mode assumes 55% indoor RH.

Design occupancypersons.

Outdoor air per personL/s-person. ISO 7547:2022 default basis is 8.

Envelope + solar + internal sensible factorW/m² planning factor. Advanced mode decomposes this.

Supply air temperature°C leaving AHU / design supply air.

Available chiller cooling capacitykW available at the entered design condition.

Plant Design Basis

Outdoor dry-bulb°C.

Outdoor RH%.

Occupant sensible heatW/person, project input.

Occupant latent heatW/person, project input.

Ventilation sensible heat recovery% effective. Enter zero if none.

Ventilation latent heat recovery% effective.

Plant diversity factor% applied to summed zone load. Project-specific.

Cooling reserve% added after diversity.

N+1 capacity target% of design requirement after loss of largest unit.

Chilled water supply°C.

Chilled water return°C.

Condenser seawater riseK, for indicative heat-rejection flow.

Fan power added as cooling load% of estimated supply fan input reaching conditioned air.

Conditioned Zone Register

Boundary temperature can represent outside structure or a hotter adjacent space such as an engine room. Outdoor air is the greater of occupancy ventilation and exhaust make-up. Total supply airflow is the greater of sensible-load airflow, outdoor-air demand and entered minimum supply ACH.

Use	Zone	Area m²	Height m	People	Indoor °C	RH %	Boundary area m²	Boundary °C	U W/m²K	Solar area m²	Solar W/m²	Shading %	Lights W/m²	Equipment W/m²	Outdoor air L/s-p	Exhaust L/s	Infiltration ACH	Supply °C	Min supply ACH

Chiller Register

Enter usable cooling capacity at the relevant evaporating/condensing design point or apply a user-entered derate. N+1 removes the largest available effective unit.

Use	Available?	Unit	Design capacity kW	Derate %	Max duty %	Rated input kW

AHU / Supply Fan Register

Fan input is estimated from airflow × static pressure ÷ fan and motor efficiency. Available airflow is derated and limited by the entered maximum duty percentage.

Use	Available?	AHU / Fan	Supply m³/s	Derate %	Max duty %	External static Pa	Fan eff %	Motor eff %

Engineering boundary: this is a load, airflow and plant-capacity planning tool. Vessel specification, flag/class requirements, fire-zone and smoke-control arrangements, equipment manufacturer selection data, duct pressure calculations, noise limits, hazardous-area requirements and commissioning measurements remain controlling.

Technical basis: ISO 7547:2022 is the current international standard for air-conditioning and ventilation design conditions and calculation basis for accommodation and other enclosed compartments on seagoing merchant ships. Its standard summer basis includes 35°C / 70% RH outdoor air, 25°C / 55% RH indoor air and at least 0.008 m³/s outdoor air per person unless the project basis states otherwise. ASHRAE shipboard guidance identifies solar radiation, transmission, occupants, lights and ventilation air as principal cooling-load components. The tool uses moist-air enthalpy for outdoor-air and infiltration loads, user-entered project factors for equipment-specific derating, and does not claim class or statutory approval.

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