IEC 63402-1:2025

IEC 63402-1 ®
Edition 1.0 2025-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
GROUP ENERGY EFFICIENCY PUBLICATION
PUBLICATION GROUPÉE SUR L'EFFICACITÉ ÉNERGÉTIQUE
Energy efficiency - Customer energy management systems -
Part 1: General requirements and architecture

Efficacité énergétique - Système de gestion d'énergie client -
Partie 1: Exigences générales et architecture
ICS 03.100.70, 27.015, 29.020 ISBN 978-2-8327-0498-1

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CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms, definitions and abbreviated terms . 6
3.1 Terms and definitions . 6
3.2 Abbreviated terms. 9
4 Design considerations . 9
4.1 General . 9
4.2 Data security and privacy design guidelines . 10
4.2.1 General. 10
4.2.2 Data security and privacy on the Smart Grid side . 10
4.2.3 Data security and privacy on premises side . 10
4.2.4 Customer Energy Manager system security . 10
4.3 Device type agnostic energy management . 10
4.4 Clock alignment . 10
4.5 Energy management system resilience . 11
5 Background . 11
6 Smart Grid premises architecture . 14
6.1 Single CEM energy management architecture . 14
6.1.1 General. 14
6.1.2 Interface S0 . 17
6.1.3 Energy Management Gateway (EMG) . 17
6.1.4 Interface S1 . 17
6.1.5 Customer Energy Manager (CEM) . 17
6.1.6 Interface S2 . 18
6.1.7 Interface M1 . 19
6.1.8 Resource manager . 19
6.1.9 HBES, SASS and smart devices . 19
6.1.10 Single CEM energy management architecture including EV . 19
6.1.11 Single CEM energy management architecture with increased resilience. 21
6.2 Cascaded CEM energy management architecture . 21
6.2.1 General. 21
6.2.2 Interface S0 . 22
6.2.3 Energy Management Gateway . 22
6.2.4 Interface S1 . 22
6.2.5 Interface S3 . 22
6.2.6 Interface M1 . 22
6.2.7 BEM . 23
6.2.8 PCC monitor . 23
6.2.9 CEM . 24
6.2.10 S2 Interface . 24
6.2.11 Resource manager . 24
6.2.12 Cascaded CEM energy management architecture with EV . 24
7 User stories and use cases . 25
7.1 Requirements for interoperability . 25
7.2 Determining the requirements for interface S2 . 25
7.3 Extensibility of interface S2 use cases . 25
Annex A (informative) Use case example . 26
Annex B (informative) Some CEM energy management architecture examples with
different loads / generators . 28
B.1 CEM energy management architecture with PV . 28
B.2 CEM energy management architecture with battery . 29
B.3 CEM energy management architecture with CHP . 29
B.4 Cascaded CEM energy management architecture . 30
Bibliography . 31

Figure 1 – Future electricity network . 12
Figure 2 – Abstract view of Future Electricity Network described by the Smart Grid
Reference Architecture (SGAM) Model . 13
Figure 3 – Graphical representation of a Premises Smart Grid system . 14
Figure 4 – Single CEM energy management architecture . 15
Figure 5 – Single CEM energy management architecture with a divided Actor B . 16
Figure 6 – IEC TC69 Information document (69/927/INF): "Overview of E-Mobility High-
level Communication Protocols" . 20
Figure 7 – Single CEM energy management architecture including an EV . 20
Figure 8 – Single CEM energy management architecture with increased resilience . 21
Figure 9 – Cascaded CEM energy management architecture . 22
Figure 10 – Cascaded CEM energy management architecture with EV . 24
Figure A.1 – Sequence diagrams of the example use case . 27
Figure B.1 – CEM energy management architecture with PV . 28
Figure B.2 – CEM energy management architecture with battery . 29
Figure B.3 – CEM energy management architecture with CHP . 29
Figure B.4 – Cascaded CEM energy management architecture . 30

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Energy efficiency - Customer energy management systems -
Part 1: General requirements and architecture

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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IEC 63402-1 has been prepared by subcommittee 23K: Electrical energy efficiency products, of
IEC technical committee 23: Electrical accessories. It is an International Standard.
It has the status of a group energy efficiency publication in accordance with IEC Guide 118.
The text of this International Standard is based on the following documents:
Draft Report on voting
23K/120/FDIS 23K/126/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 63402 series, published under the general title Energy efficiency –
Customer energy management systems, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
INTRODUCTION
In traditional electricity networks, energy flows in one direction and communications from the
generator to the consumer is generally done via the transmission and distribution systems.
Although there is some monitoring and control of equipment in the transmission and distribution
systems, there is no communication with, or control of, consumer equipment. In particular, there
is no means of requesting short-term control of consumer equipment to match either the
prevailing generation, or transmission and distribution grid conditions, or both. Generation
equipment is controlled to match the open-ended (uncontrolled) demand of the consumer.
Today the world is faced with an increase of energy consumption, which is directly linked to an
increase of CO production. The increased CO density in the atmosphere supports the climate
2 2
warming of the earth.
One significant way to cope with the increased energy consumption without increasing the CO
production is to use more renewable energy resources.
Unfortunately, the available renewable energy supply is not aligned with the energy demand.
To increase efficiency, the energy demand should be aligned as much as possible with the
available energy supply. The future grid will become generation led rather than demand led as
it is today. In order to reach this goal, communications between the various equipment and
systems of the stakeholders within the energy field is necessary. This new form of grid which
exchanges information and energy between producers, consumers, distributors and metering
is known as the "Smart Grid".
The IEC 63402 series describes aspects of this Smart Grid that relate specifically to the
premises (home or building) part of the Smart Grid, including the common interface between
equipment in the premises and the Smart Grid.

1 Scope
This part of IEC 63402 specifies general requirements and the architecture between the Point
of Common Coupling (PCC) and smart devices (SD) operating within the Smart Grid premises-
side system (i.e. residential or commercial but not industrial premises).
This document does not include requirements for:
– safety
– electromagnetic compatibility (EMC);
– data security, as it is assumed that the underlying protocols will take the data security aspect
into account
NOTE Although data security is not within the scope of this document, Clause 4 provides some high-level
design guidelines for data security.
– special equipment (e.g. legacy heat pumps) with a direct physical connection to the grid, as
such equipment bypasses the customer energy manager (CEM) and is not HBES/BACS
enabled (covered by other standards than the IEC 63402 series).
This group EE publication is primarily intended to be used as an EE standard for the products
mentioned in the scope, but is also intended to be used by TCs in the preparation of publications
for products which are included in the boundary mentioned in the scope of this document.
2 Normative references
There are no normative references in this document.
3 Terms, definitions and abbreviated terms
For the purposes of this document, the following terms, definitions and abbreviated terms apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/
3.1 Terms and definitions
3.1.1
Customer Energy Manager
CEM
internal automation function for optimizing the energy consumption, production and storage
within the premises according to the preferences of the customer using internal flexibilities and
typically based on external information received through the Energy Management Gateway and
possibly other data sources
3.1.2
Customer Energy Manager system
CEM system
system that allows the management of energy consumption, production and storage within the
premises, consisting of a CEM connected to one or more resource managers (RMs) which
themselves act as gateways to HBES/BACS, either SASS or smart appliances, or both
Note 1 to entry: In other standards this is often referred to as an Energy Management Systems (EMS).
3.1.3
Energy Management Gateway
EMG
access point (functional entity) sending and receiving smart grid related information and
commands between an actor in the grid and the CEM, letting the CEM decide how to process
the events
Note 1 to entry: The communication is often ensured through an internet connection.
3.1.4
Building Energy Management
BEM
internal automation function for observing the PCC, to avoid an overload of the PCC and share
the available energy between the different subsystems which are represented by the connected
CEMs
Note 1 to entry: BEM is also called sometimes facility energy manager (FEM).
Note 2 to entry: The BEM gets additional information (voltage, frequency, cos phi) from a grid observer which allows
to support the grid even in the case the internet protocol (IP) communication is broken.
3.1.5
Head End System
HES
system that receives metering data in the advanced metering infrastructure
3.1.6
Home and Building Electronic System/Building Automation Control System
HBES/BACS
logical group of devices which uses a multi-application communication system where the
functions are distributed and linked through a common communication process
Note 1 to entry: HBES/BACS is used in homes and buildings plus their surroundings. Functions of the system are,
for example: switching, open loop controlling, closed loop controlling, monitoring and supervising.
Note 2 to entry: In literature, HBES or BACS can be referred also as "home control system or network", "home
electronic systems", "building automation systems", etc.
EXAMPLE Management of lighting, heating, energy, water, fire alarms, blinds, different forms of security, etc. See
introduction of EN 50491-4-1.
3.1.7
schema
abstract model that documents and organizes the data required in a defined way, so it can be
used for different purposes such as exchanging and / or storing information
3.1.8
Meter Data Management
MDM
software system that performs long-term data storage and management for the vast quantities
of data delivered by smart metering systems
3.1.9
resource manager
RM
function that exclusively represents a logical group of devices or a single smart device, and is
responsible for sending unambiguous instructions to the logical group of devices or to a single
device, typically using a device-specific protocol
Note 1 to entry: In the context of this document the resource manager manages the energy flexibility of a logical
group of devices or a single smart device.
Note 2 to entry: The resource manager can be implemented in a special device, in the smart device itself or outside
of the device.
3.1.10
premises
public or private building/home where energy is used or produced, or both
3.1.11
smart appliance
device that consumes energy that can be controlled by a resource manager
EXAMPLE Washing machines, freezers, dishwashers, etc.
3.1.12
smart device
SD
device that can consume, produce or store energy (or a combination thereof) and that can be
controlled by a resource manager for the purpose of energy management
EXAMPLE lighting controllers, electric vehicles, smart appliances, renewable power sources, energy storage
systems, etc.
3.1.13
Single Application Smart System
SASS
group of devices having a communication interface for a single application such as heating or
lighting, that consume, produce or store energy (or a combination thereof) and that can be
controlled by a resource manager for the purpose of energy management
3.1.14
aggregator
party which contracts with a number of other network users (e.g. energy consumers) in order to
combine the effect of smaller loads or distributed energy resources for actions such as demand
response or for ancillary services
3.1.15
Point of Common Coupling
PCC
point in an electric power system, electrically nearest to a particular load, at which other loads,
can be, connected
Note 1 to entry: These loads can be either devices, equipment or systems, or distinct network users' installations.
Note 2 to entry: Point of Common Coupling is equal to grid connection point.
3.1.16
Point of Common Coupling monitor
PCC monitor
device that measures the voltage, frequency, current at the PCC and sends this information to
the BEM
3.1.17
energy metering service provider
party providing energy metering services
3.1.18
distribution system operator
DSO
component that securely operates and develops an active distribution system comprising
networks, demand, generation and other flexible distributed energy resources
3.1.19
energy service provider
party providing energy (utility) or energy services (aggregator, e-mobility service provider, etc.)
3.2 Abbreviated terms
BACS Building Automation Control Systems
BEM Building Energy Manager (sometimes also called FEM)
CEM Customer Energy Manager
CHP Combined Heat and Power
CSC Charging Station Controller, as defined in the IEC 63110 series
CSMS Charging System Management Systems, as defined in the IEC 63110 series
DER Distributed Energy Resources
DSO Distribution System Operator
EMG Energy Management Gateway
EMS Energy Management System
EV Electrical Vehicle Energy
EV Electrical Vehicle
EVSE Electric Vehicle Supply Equipment, as defined in IEC 63110
FEM Facility Energy Manager
H1 Local connection to simple external consumer display
H2 Connection between the SMG and EMG
HES Head End System
HBES Home and Building Electronic System
MDM Meter Data Management
MDU Multi dwelling unit
MCF Meter Communication Function
PCC Point of common coupling
RM Resource manager
SASS Single Application Smart System
SD Smart Device
SGAM Smart Grid Architecture Model
SGCG Smart Grid Co-ordination Group, reporting to CEN-CENELEC-ETSI and in charge
of answering the M/490 mandate
SMG Smart Meter Gateway
S0 Interface between DSO and Energy management gateway
S1 Interface between Energy management gateway and CEM
S2 Interface between CEM and Resource Manager
4 Design considerations
4.1 General
When designing a system such as a Smart Grid, some general design considerations have to
be taken into account. One important requirement for the Smart Grid is data security and data
privacy.
4.2 Data security and privacy design guidelines
4.2.1 General
Data security and privacy shall protect the system and keep the data private as much as
possible.
Data security and privacy shall make a distinction between the data security and privacy related
to the Smart Grid side and the data security and privacy within the premises side. The risk level
and the required security can be derived from a risk assessment according to the IEC 62443
series for the communication channels.
4.2.2 Data security and privacy on the Smart Grid side
The risk of a possible attack and impair data should be minimized by applying relevant
standards. Data privacy can be achieved by only permitting the exchange of aggregated energy
management related data and or private data for which the customer has given permission to
be used by a third party.
4.2.3 Data security and privacy on premises side
Data security and privacy on the premises side shall ensure that the data can only be read by
authorized persons and cannot be manipulated. Depending on the implementation of the system,
this can be reached with different methods, for example:
– data encryption and decryption.
– constructive design (avoid that no one except authorized persons can gain access to the
devices and communication channels).
4.2.4 Customer Energy Manager system security
The security of the Customer Energy Manager system is linked to the number of connections
between the Customer Energy Manager system and the neighbourhood network. Every
connection attempt between the Customer Energy Manager system and the neighbourhood
network shall be vetted to avoid unauthorized access to the Customer Energy Manager system.
The more connections are between the two networks then the more effort shall be spent for
configuring of the different Firewalls and the higher is the risk of security holes. Therefore, it is
recommended to limit the connection points between the Customer Energy Manager system
and the neighbourhood network as much as possible. Ideally there is only one connection
between the Customer Energy Manager system and the neighbourhood network.
4.3 Device type agnostic energy management
While today there is a set of common devices and appliances (e.g. freezers, TV sets, electric
bikes, etc.), the data structures of the interface between the CEM and a resource manager
should be designed in such a way that even future device types can be correctly managed
without the need to update the communication standard.
4.4 Clock alignment
The main task for a CEM is to manage energy, which basically is variations of (average) power
over time. One of the key CEM data structures is therefore a power profile and it makes "time"
a central and very important aspect.
"Time" seems like a trivial concept. Humans tend to think of "absolute" time in the form of a
"date" plus a "24 h clock" information. But on a technical level it is not that trivial at all, because
there are aspects like time zones, different calendars, daylight saving time, leap seconds,
hardware clock drift and the overall question of how to actually synchronize multiple clocks to
a desired type and precision of alignment.
This is why the CEM architecture shall incorporate a concept of clock alignment with a well-
defined master clock and time synchronization rules and procedures.
4.5 Energy management system resilience
The CEM is a logical function which relies on communication to other actors. Therefore, the
resilience of the entire energy management system is primarily linked to cybersecurity
requirements.
The system's resilience can be improved if the physical aspects are also taken into account.
Observing the PCC by measuring the frequency, voltage and current provides additional
information. Frequency provides information about the global power balance in the
interconnection, voltage provides information about the local power balance of the relevant
distribution network, and current provides information about the power balance of the customer
cell in the premises. It also allows to estimate the ratio of loads and generators which are
controllable or observable by resource managers (RMs) to those which are unmanaged in the
premises.
This information enables validation of the digital representation (model) to check if it matches
the physical reality (measurement). Discrepancies allow the detection of potential system
malfunctions or breaches of cybersecurity techniques.
Furthermore, the correct delivery of grid supporting functions (ancillary services) – which ensure
the resilience of upstream networks – will require the CEM to be aware of the measurements
at the PCC and the electrical dynamics of the premises' electrical power system. A CEM which
is aware of the grid state is more resilient in situations of disrupted communication to upstream
actors because the physical information allows adjustments of its optimization strategies (e.g.
activation of stabilization measures).
5 Background
The traditional model of the grid will lead to increased inefficiencies as electricity energy
consumption and the connection of distributed (renewable) energy resource equipment is
increased.
In order to address these issues, the architecture of traditional grids is being extended to include
remote control of distributed loads and energy resources, requiring bi-directional
communication. This is the "Smart Grid" (see Figure 1):
Smart grids rely on flexibility in energy production or consumption, or both, to compensate for
imbalance and congestion in the grid, for example caused by:
– increasing electricity demand by electric vehicle charging.
– increasing numbers of renewable energy sources that are far less predictable or controllable
than traditional power plants.
The use of devices and equipment in homes and buildings that are able to control their energy
consumption or generation (either locally or remotely) greatly enhances the flexibility capability
of a Smart Grid.
Energy flexibility can be defined as the ability to willingly deviate from either the normal energy
production or consumption or both pattern(s), either over time or by power level, or both. This
flexibility can be used by third parties to help alleviate imbalance or congestion.
Third parties will use different incentive schemes to unlock the flexibility potential, such as time
of day pricing, real time pricing, feed-in tariffs and variable grid tariffs. These incentives should
be mapped in some way to the capabilities of smart devices in order to deliver energy flexibility.
Figure 1 – Future electricity network
The Smart Grid Architecture Model (SGAM) was developed by the CEN-CENELEC-ETSI Smart
Grid Coordination Group in order to provide a general representation of the architecture of a
Smart Grid. It is used here in order to show the scope of this specification within the general
context of the Smart Grid.
The SGAM incorporates the main elements of the electricity energy supply system as a set of
domains. Each domain is further split into hierarchical levels of power system management,
referred to as zones, ranging from process to market (see Figure 2). Finally, five interoperable
layers are mapped over the domains and zones. More information can be found in CEN-
CENELEC-ETSI Smart Grid Coordination – Group Smart Grid Reference Architecture
(November 2012). This document relates to the customer premises domain, the process to field
zones and communication, information and function interoperability layers.
Figure 2 – Abstract view of Future Electricity Network described by
the Smart Grid Reference Architecture (SGAM) Model
Figure 3 – Graphical representation of a Premises Smart Grid system
In a Smart Grid environment, devices in the home and building environment are considered as
either loads, generators, storage or a combination of all three (see Figure 3). Some devices are
able to communicate with each other and external bodies for energy management purposes.
These are referred to as smart devices and can include space and water heating systems, white
and brown goods ("appliances"), plug-in electric vehicles, micro generation equipment
(photovoltaic, combined heat power, wind turbine, hydroelectric, fuel cell, etc.), domestic
storage batteries, lighting systems and so on.
6 Smart Grid premises architecture
6.1 Single CEM energy management architecture
6.1.1 General
The Smart Grid can control or influence the operation of smart devices, according to its
requirements. For instance, the Smart Grid can request that the energy consumption or
production of a building is increased or decreased or shifted in time. This control can be directed
to specific smart devices or to the property in general. In the latter case, a range of options for
smart device control can result in the same aggregated outcome for the property.
The consumer is likely to have their own set of preferences for the operation of their smart
devices. These preferences include time of use, cost, level of comfort (e.g. heating or lighting
or both) etc. Unless expressed explicitly in legally binding documents (i.e. a contract) the
consumer's preference shall always take precedence over those of the Smart Grid. However,
the consumer can be presented with a set of options (i.e. from a control entity) from which to
choose and can modify their preferences at any time.
Figure 4 – Single CEM energy management architecture
In Figure 4, Actor A is called the "aggregator/supplier/DSO" which makes the energy available.
Actor B is called the metering actor and/or the distribution system operator (DSO). Both actors
are very different. Premises can have only one DSO, but multiple metering actors. Latest in
multifamily premises, it shall be taken into account that there could be many different metering
service providers.
Both actors have different requirements for the communication channel. The metering actor
needs precise energy values with a timestamp (the duration of the data exchange is not so
important, because the measured value is linked with a timestamp). The DSO needs fast power
measurements to prevent an overload of the PCC. A current spike which exceeds the limits for
some seconds could cause the fuse cut-out to operate at the PCC, although it is not visible in
the metering communication.
These different requirements make it advisable to divide Actor B into an energy metering service
provider and a distribution system operator.
The single CEM energy management architecture where Actor B is divided into the energy
metering service provider role and the energy service provider role is shown in Figure 5.
The energy service provider generates the energy for a CEM energy-managed architecture. A
CEM energy-managed architecture can have different service providers which deliver energy
for different applications (e.g. an e-mobility provider produces the energy for the electrical
vehicle (EV) and a utility produces the energy for the premises). The energy service provider is
mostly interested in kWh and is linked to the market aspect of the energy exchange.
The DSO distributes the energy and delivers it to the PCC of the CEM energy-managed
architecture. In contrast to the energy service provider, a CEM energy-managed architecture
can have only one DSO. In case a building has more than one PPC, every PPC is linked to an
independent energy consuming/producing net and could therefore be seen as an individual
CEM energy-managed area, although the areas are in the same building. The DSO requires
knowledge about the physical aspects of the energy exchange at the PCC (power, current,
voltage, frequency). The energy metering service provider meters the energy which is delivered
or produced by the CEM energy-managed architecture, the response time is less important
because the measured values have a timestamp.

Figure 5 – Single CEM energy management architecture with a divided Actor B
The entity providing the logical connection between the Smart Grid and the smart devices in
the home/building is known as the Customer Energy Manager (CEM). It is expected that CEMs
will be made available with a range of features, from the very simple to the highly sophisticated.
Although this document does not specify the operation of the CEM, several assumptions are
made on the basic operation of every CEM.
In essence, the CEM at least multiplexes or de-multiplexes or both communication between the
Smart Grid and the smart devices in the home and building although it can also provide other
services including forecasting and scheduling.
As of yet there is however no standardized interface to describe and control the energy flexibility
of smart devices. Such an interface (S2), defined in the IEC 63402 series, allows generic,
interoperable communication for energy flexibility between smart devices and energy
management applications.
Different types of smart devices in the home and building are likely to use different
communication protocols and different data or function models. In addition, it is likely that Smart
Grid entities use a different set of protocols from the home and building smart devices.
There are a limited number of protocols available for communication from the Smart Grid to the
home and building. However, within the home and building space many protocols are available
today and more are likely to become available in the future. In order to avoid the requirement
to support an open-ended range of protocols, it is useful to define a "neutral" or common
data/function model, message structures and message sequencing rules to be used between
the CEM and the various HBES or SASS to which the smart devices are attached.
6.1.2 Interface S0
S0 is the link between the outer Smart Grid world (i.e. the distribution network) and the Smart
Grid premises side. S0 can have different functions depending on the local Smart Grid
implementation. Usually, the communications protocols used by the S0 will only vary at the
lower layers; the information models and protocol are expected to be unchanged. Information
coming in from the grid is terminated at the CEM.
6.1.3 Energy Management Gateway (EMG)
The EMG com
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