ISO 8933-1:2024

Ships and marine technology - Energy efficiency - Part 1: Energy efficiency of individual maritime components

This document specifies generic measuring and calculation methods to evaluate the energy efficiency of individual maritime components installed on board ships, vessels for inland navigation or offshore structures. This document only covers energy consuming components for which a “unit output” can be clearly defined and which require energy to function. This document only covers the major energy consuming components of a typical ship. It does not cover the propulsion component of the ship (e.g. the propeller).

Navires et technologie maritime — Éfficacité énergétique — Partie 1: Efficacité énergétique des éléments maritimes individuels

General Information

• Status: Published
• Publication Date: 21-Nov-2024
• ICS: 47.020.01 - General standards related to shipbuilding and marine structures
• Technical Committee: ISO/TC 8 - Ships and marine technology
• Drafting Committee: ISO/TC 8 - Ships and marine technology
• Current Stage: 6060 - International Standard published
• Start Date: 22-Nov-2024
• Due Date: 20-Jul-2025
• Completion Date: 22-Nov-2024

Overview

ISO 8933-1:2024 - Ships and marine technology - Energy efficiency - Part 1: Energy efficiency of individual maritime components defines standardized, generic measuring and calculation methods to evaluate the energy efficiency of major, energy‑consuming shipboard components. The standard applies to components with a clearly defined “unit output” (e.g., pumps, fans, gearboxes, heat exchangers, centrifuges) installed on ships, inland vessels or offshore structures. It explicitly excludes propulsion components (for example, propellers).

Keywords: ISO 8933-1:2024, energy efficiency, maritime components, ships, measuring methods, calculation methods, marine technology.

Key topics and technical requirements

• Scope and definitions: Clear definitions of input, output, component, and energy efficiency (aligned with ISO/IEC terminology).
• Methodology (Clause 5): Generic method to evaluate component efficiency using representative operational boundaries and process windows that match expected onboard use.
• Measuring conditions: Requirements to define test and measurement conditions so results reflect normal operational patterns, accounting for ambient and operational variability.
• Component‑specific clauses:
  • Pumps (Clause 6): inputs/outputs, boundary definitions, calculation and measuring methods.
  • Fans (Clause 7): performance metrics, flow and pressure considerations, test procedures.
  • Mechanical power transmission / Gearboxes (Clause 8): input/output definitions, calculation and measurement procedures.
  • Heat exchanging (Clause 9): thermal energy flows, electrical heaters, calculation and measurement techniques.
  • Centrifuges (Clause 10): defining unit output, measuring and calculation approaches.
• Symbols and units: Standardized symbols (E, P, Q, qV, ṁ, η, ρ, etc.) and units for consistent reporting.
• Objective comparison: Standardized outputs enable objective comparisons between different components for retrofit or newbuild decisions.

Practical applications

• Selecting energy‑efficient components during newbuild or retrofit procurement.
• Performing ship energy audits and component-level benchmarking.
• Enabling manufacturers to validate component performance under ship-representative conditions.
• Supporting compliance efforts tied to ship energy management (e.g., IMO SEEMP) and corporate sustainability targets.
• Informing life‑cycle cost and carbon-emission reduction analyses.

Who should use this standard

• Shipowners and operators evaluating retrofit options
• Shipyards and naval architects integrating systems during design and installation
• Maritime equipment manufacturers and test labs
• Classification societies, regulators, and energy managers conducting performance verification

Related standards and references

• ISO/IEC term definitions (referenced for energy efficiency terminology)
• IMO SEEMP (context and motivation for energy efficiency measures)
• ISO/TC 8 (technical committee responsible for ships and marine technology)

ISO 8933-1:2024 provides a practical, standardized basis for measuring and reporting the energy efficiency of individual maritime components to improve operational energy performance and support informed procurement and regulatory decisions.

Standards Content (Sample)

International
Standard
ISO 8933-1
First edition
Ships and marine technology —
2024-11
Energy efficiency —
Part 1:
Energy efficiency of individual
maritime components
Navires et technologie maritime — Éfficacité énergétique —
Partie 1: Efficacité énergétique des éléments maritimes
individuels
Reference number
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 2
5 Method to evaluate the energy efficiency of individual maritime components . 2
5.1 General .2
5.2 Measuring conditions .3
6 Pumps . 3
6.1 General .3
6.2 Definition of input and output .3
6.3 Definitions of boundaries and media .4
6.4 Calculation method.4
6.5 Measuring method .5
7 Fans . 6
7.1 General .6
7.2 Definition of input and output .6
7.3 Definitions of boundaries and media .7
7.4 Calculation method.7
7.5 Measuring method .8
8 Mechanical power transmission . 9
8.1 Gearboxes .9
8.1.1 General .9
8.1.2 Definition of input and output .10
8.1.3 Definitions of boundaries and media .10
8.1.4 Calculation method .10
8.1.5 Measuring method . 13
9 Heat exchanging .15
9.1 General . 15
9.2 Definition of input and output .16
9.3 Definitions of boundaries and media .16
9.4 Calculation method.17
9.4.1 General .17
9.4.2 Electrical heaters .17
9.5 Measuring method .19
10 Centrifuges .20
10.1 General . 20
10.2 Definition of input and output . 20
10.3 Definitions of boundaries and media . 20
10.4 Calculation method.21
10.5 Measuring method .21
Bibliography .23

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 8, Ship and marine technology.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
Environmental concerns, emission regulations, fuel prices, and emission taxes are increasing the demand for
greater energy efficiency in shipping. In 2013, the International Maritime Organization (IMO) adopted the
[1]
Ship Energy Efficiency Management Plan (SEEMP) to significantly decrease the amount of carbon dioxide
(CO ) emissions by 10 % to 50 % per transport work in international shipping. This strategy refers to a
[14]
pathway of CO emissions reduction which is consistent with the goals of the Paris Agreement, alongside
[15]
the United Nations 2030 Agenda for Sustainable Development.
Standardizing methods to evaluate energy efficiency in the maritime sector interface is valuable for a range
of different stakeholders, including:
— shipowners who are looking to buy maritime systems to comply with IMO SEEMP initiatives;
— maritime equipment and engine manufacturers who are responsible for the design and production of
ship systems;
— governments that are committed to environmental regulations and environmental targets such as the
“levels of ambition” adopted by IMO.
The purpose of this document is to improve energy efficiency in ships by providing more energy efficient
options that can be considered when replacing malfunctioning components throughout the ship lifetime.
This document allows shipowners and shipyard workers to objectively identify the most energy-efficient
components for retrofits, as well as newbuilds.
The document provides a method for comparing energy performance on an objective basis to prevent energy
loss and to improve cost-efficiency and environmental conditions during maritime transport. This document
makes it possible for users to compare the energy efficiency of different individual maritime components
based on a standardized method to measure and calculate the values.
It is a widely established that the usual combination of best efficient single systems on board do not lead
in sum to the most efficient ship. It is common practice that owners instruct shipyards to meet the criteria
for an optimized operating point of the respective ship system during the design phase (new build or
reconstruction).
Accordingly, a shipyard checks before installation that each single system or component meets good energy
efficiency values. It is not possible to calculate the ship's overall efficiency if the operating conditions are not
standardized.
An example of a system or component where the efficiency depends on the operational conditions is an
engine room ventilation without a given fan speed control system. If fan is designed and optimized for the
tropical zone and the ship is operated under North Atlantic conditions, less power is necessary during winter
times. Owing to the absence of a controller, the fan rotation speed cannot be adjusted. In sum, every single
fan can operate efficiently on a test bed. An efficient performance is questionable if the ship sails under
different operational conditions than what it is designed for.
To raise the overall operational energy efficiency of a ship in different operational conditions, the overall
ship-individual combined system efficiency check should be performed. In addition, manufacturers, and
operators should take into account the possible variations between test bed conditions and onboard test
conditions when developing individual components and systems.

v
International Standard ISO 8933-1:2024(en)
Ships and marine technology — Energy efficiency —
Part 1:
Energy efficiency of individual maritime components
1 Scope
This document specifies generic measuring and calculation methods to evaluate the energy efficiency
of individual maritime components installed on board ships, vessels for inland navigation or offshore
structures. This document only covers energy consuming components for which a “unit output” can be
clearly defined and which require energy to function.
This document only covers the major energy consuming components of a typical ship. It does not cover the
propulsion component of the ship (e.g. the propeller).
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
energy efficiency
ratio or other quantitative relationship between an output (3.4) of performance, service, goods or energy,
and an input (3.3) of energy
EXAMPLE Efficiency conversion energy; energy required/energy used; output/input; theoretical energy used to
operate/energy used to operate.
Note 1 to entry: Both input and output shall be clearly specified in quantity and be measurable.
[SOURCE: ISO/IEC 13273-1:2015, 3.4.1]
3.2
component
element performing only one function whose efficiency is defined by the ratio between input (3.3)and
output (3.4)
EXAMPLE Electric motor, water pump.
3.3
input
product, material or energy flow that enters a component (3.2)
Note 1 to entry: Products and materials include raw materials, intermediate products and co-products.

3.4
output
product, material or energy flow that leaves a component (3.2)
Note 1 to entry: Products and materials include raw materials, intermediate products, co-products and releases.
4 Symbols and abbreviated terms
The following symbols are used throughout the document:
EER energy efficiency ratio used in the heating/cooling industry non-dimensionless
E energy consumption J
P power consumption W
Q thermal energy J
T temperature K or °C
V volume m
q volume flow rate m /s
V
q mass flow rate kg/s
m
c specific heat capacity at constant pressure J/kg K
p
c specific heat capacity at constant volume J/kg K
V
H enthalpy J/kg
η efficiency ratio dimensionless
ρ density of water kg/m
τ torque N·m
5 Method to evaluate the energy efficiency of individual maritime components
5.1 General
This document focuses on the components responsible for the major energy consumption of a typical ship.
The component types are categorized into the following groups:
— pumps (Clause 6);
— fans (Clause 7);
— gearboxes (mechanical power transmission) (Clause 8);
— heat exchanging (Clause 9);
— centrifuges (Clause 10).
The energy efficiency of the component is evaluated based on its expected operational purpose on board
the ship and during its expected process operating window. This means that the boundary conditions on
which the component is evaluated are defined to represent the normal operational pattern. This operational
pattern can include the variations in ambient conditions or variations in the ship's operational pattern. This
will be defined for each of the components.

The basic terminology of a maritime component is illustrated in Figure 5.1.
Key
B boundary
1 component
I input (energy, temperature, pressure, flow, concentration, force, velocity, torque, electricity)
O output (energy, temperature, pressure, flow, concentration, force, velocity, torque, electricity)
Figure 5.1 — Basic terminology of a maritime component
In relation to this document in the pursuit of simplifying the energy efficiency consideration of components,
it is acknowledged that some influencing parameters are ignored, however such parameters will only have a
minor impact on the result and are, hence, considered negligible unless otherwise addressed.
5.2 Measuring conditions
The actual conditions, such as ambient air temperature and shaft speed, etc. shall be recorded on the
measuring report when the parameters for the energy efficiency are measured.
The parameters shall be measured by appropriately calibrated measuring instruments.
6 Pumps
6.1 General
Pumps have a wide variety of functions on a ship. For each purpose, several pump types can be used.
This document covers the energy efficiency for the following pump types.
— Positive displacement pumps:
— reciprocating pump (piston pumps, plunger pumps etc.);
— rotary pump (gear pump, screw pump, vane pump, lobe pump etc.).
— Dynamic pressure pumps:
— centrifugal pump.
6.2 Definition of input and output
The definitions of the inputs and outputs are made generic for all the pump types. Each pump type has its
own set of properties that affect the efficiency, but these are not accounted for in this document.
Clause 6 does not consider the efficiency of power production, such as electrical power, pneumatic power or
hydraulic power.
The input and output of a pump component consists of the following:
— input: liquid inlet (inlet pressure and flow), pump shaft power;
— output: liquid outlet (outlet pressure and flow).
6.3 Definitions of boundaries and media
The boundary of a pump is set to exclude the motor and any gear. These components form a complete working
pump unit, and all of these elements are necessary for a functional pump unit. Any auxiliary devices, such as
mechanical seal barrier systems, are also excluded from the energy efficiency consideration.
The pump component and its boundaries are shown in Figure 6.1.
Key
B boundary
I1 liquid inlet (pump suction)
I2 pump shaft power
1 pump
O1 liquid outlet (pump discharge)
Figure 6.1 — Boundaries of a pump component
6.4 Calculation method
The general formula for pump efficiency, valid for all pump types, is shown in Formula (6.1):
qp ⋅ Δ
V
η = (6.1)
pump
P
pump
where
q is the liquid flow of the pump, expressed in m /s;
V
Δp is the differential pressure – liquid outlet pressure minus liquid inlet pressure – of the pump,
expressed in Pa;
P is the pump shaft power, expressed in W.
pump
A pump can state a liquid head (or column) height expressed in metres.
The relation between liquid head and pressure is shown in Formula (6.2):
pg=⋅ρ  ⋅h (6.2)
where
p is the pressure, expressed in Pa;
ρ is the density of the liquid, expressed in kg/m ;
g is the gravity constant 9,81 m/s ;
h is the liquid head, expressed in m.
Combining Formulae (6.1) and (6.2), the formula for efficiency of a pump can be written as Formula (6.3):
qg ⋅⋅ρ  ⋅ Δh
V
η = (6.3)
pump
P
pump
where
q is the liquid flow of the pump, expressed in m /s;
V
Δh is the differential head – liquid outlet head minus liquid inlet head – of the pump, expressed in m;
ρ is the density of the liquid, expressed in kg/m ;
g is the gravity constant 9,81 m/s ;
P is the pump shaft power, expressed in W.
pump
6.5 Measuring method
To measure the pump efficiency, it is most useful to use Formula (6.1), rather than Formula (6.3), as it is
easier to measure the pressure instead of head. Formula (6.1) is suitable for any pump type.
As it is difficult to measure the pump shaft power directly, the motor power should be measured and
adjusted for the motor efficiency η . This relation is shown in Formula (6.4)
motor
PP=⋅ η (6.4)
pump motormotor
[13]
If shaft power is used as input, the efficiency can be found in IEC 60034-2-1 .
Combining Formulae (6.1) and (6.4) gives an expression for pump efficiency that is easy to measure, as
shown in Formula (6.5):
qp ⋅ Δ
V
η = (6.5)
pump
P ⋅η
motormotor
The measuring method is illustrated in Figure 6.2.

Key
B boundary
I1 liquid inlet (pump suction)
I2 pump shaft power
I3 motor power in
1 motor
2 pump
O1 liquid outlet (pump discharge)
Figure 6.2 — Measuring method for pump energy efficiency
The process for determining the pump efficiency is:
a) measure the liquid flow in m /s;
b) measure the differential pressure, at the pump flanges, in Pa;
c) measure the motor input power in W;
d) determine η relating to the type of motor and the operational profile;
motor
e) use Formula (6.5) to calculate the pump efficiency.
7 Fans
7.1 General
Fans have different functions on a ship and for each purpose, a number of fan types can be used.
This document covers the energy efficiency for the following fan types:
— positive displacement fans.
— dynamic pressure fans:
— centrifugal fans.
7.2 Definition of input and output
The definitions of the inputs and outputs are made generic for all fan types. Each fan type has its own set of
properties that affect the efficiency, but these are not accounted for in this document.

Clause 7 in this document also does not take into account the efficiency of power production, such as
electrical power, pneumatic power or hydraulic power.
The input and output of a pump component consists of the following:
— input: gas inlet (inlet pressure and flow), fan shaft power;
— output: gas outlet (outlet pressure and flow).
7.3 Definitions of boundaries and media
The boundary of a fan is set to exclude the motor and eventual gear. These components form a complete
working fan unit, and all of these elements are necessary for a functional fan unit.
The fan component and its boundaries are shown in Figure 7.1
Key
B boundary
I1 gas inlet (fan suction)
I2 fan shaft power
1 fan
O1 gas outlet (fan discharge)
Figure 7.1 — Boundaries of a fan component
7.4 Calculation method
The general formula for fan efficiency, valid for all fan types, is shown in Formula (7.1):
qp ⋅ Δ
V
η = (7.1)
fan
P
fan
where
q is the gas flow of the fan, expressed in m /s;
v
Δp is the differential pressure – discharge pressure minus suction pressure – of the fan, expressed
in Pa;
P is the fan shaft power – fan, expressed in W.
fan
A centrifugal fan can state a head (or column) height expressed in metres.

The relation between head and pressure is shown in Formula (7.2):
pg=⋅ρ  ⋅h (7.2)
where
p is the pressure, expressed in Pa;
ρ is the density of the gas, expressed in kg/m ;
g is the gravity constant 9,81 m/s ;
h is the head, expressed in m.
Combining Formulae (7.1) and (7.2), the formula for efficiency of a centrifugal fan can be written as shown
in Formula (7.3):
qg ⋅⋅ρ  ⋅ Δh
V
η = (7.3)
fan
P
fan
where
q is the flow of the fan, expressed in m /s;
v
Δh is the differential head – gas outlet head minus gas inlet head – of the fan, expressed in m;
ρ is the density of the gas, expressed in kg/m ;
g is the gravity constant 9,81 m/s ;
P is the fan shaft power in, expressed in W.
fan
Formula 7.3 is useful to relate the calculation of fan efficiency to the centrifugal fan curve, which in most
cases is expressed with head and not pressure.
7.5 Measuring method
To measure the fan efficiency, it is most useful to use Formula (7.1), rather than Formula (7.3), as it is easier
to measure the pressure instead of head. Formula (7.1) is
...