SIST ISO 18523-2:2020

INTERNATIONAL ISO
STANDARD 18523-2
First edition
2018-02
Energy performance of buildings —
Schedule and condition of building,
zone and space usage for energy
calculation —
Part 2:
Residential buildings
Performance énergétique des bâtiments — Plan et conditions
d'utilisation des espaces, zones et bâtiments pour le calcul
d'énergie —
Partie 2: Bâtiments résidentiels
Reference number
ISO 18523-2:2018(E)
©
ISO 2018

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ISO 18523-2:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
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, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

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ISO 18523-2:2018(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Space . 2
3.2 Schedule . 3
3.3 Parameters for conditions of building, zone and space usage . 4
3.4 Descriptions for daily schedule . 5
4 Framework of the schedule and condition for building energy calculation .7
4.1 Indispensable schedules . 7
4.2 Daily schedule . 7
4.3 Division of year and daily, weekly, monthly, seasonal and annual allocations of
daily schedules . 9
5 Conditions for energy calculation included in the schedule and condition of zone
and space usage .11
5.1 Energy needs and uses .11
5.2 Condition .11
5.2.1 Occupancy or occupancy density .11
5.2.2 Operation of technical building systems and requirement for their services .12
5.2.3 Internal heat gains .14
5.2.4 Operation of movable fittings .15
5.3 Process for determining schedule and condition in housing units .15
5.3.1 Family structure .15
5.3.2 Time use of daily life of family member(s) .15
5.3.3 Schedule and area for space heating and cooling .16
5.3.4 Schedule and area of overall ventilation .16
5.3.5 Schedule and area of local exhaust ventilation .17
5.3.6 Amount of domestic hot water usage .17
5.3.7 Possession and usage of appliances .17
6 Category of residential building, zone and space .17
6.1 General .17
6.2 Category of space or zone .18
6.2.1 Categories of space or zone inside housing unit .18
6.2.2 Categories of space or zone outside housing unit .18
Annex A (informative) Examples of time use as daily life of family .19
Annex B (informative) Format of annual schedule by daily allocation of daily schedules .23
Annex C (informative) Examples of schedules for space heating and cooling .24
Annex D (informative) Example of schedule and area for local ventilation .25
Annex E (informative) Examples of schedule and condition for domestic hot water .26
Annex F (informative) Example of schedule and condition for usage of electric appliances .27
Annex G (informative) Examples of categories of space and zone of residential buildings .31
Bibliography .32
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ISO 18523-2:2018(E)

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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use
in the built environment.
A list of all parts in the ISO 18523 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved

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ISO 18523-2:2018(E)

Introduction
There is a strong need to improve the environment to make the evaluation of energy performance of
buildings more reliable and practical, so that energy efficiency of buildings is improved by referring
to the evaluation results. There have been no international standards prescribing building use in this
area. This document prescribes the indispensable information on the conditions for zone and space
usage in energy calculations for residential buildings.
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INTERNATIONAL STANDARD ISO 18523-2:2018(E)
Energy performance of buildings — Schedule and
condition of building, zone and space usage for energy
calculation —
Part 2:
Residential buildings
1 Scope
This document specifies the formats to present the schedule and conditions of zone and space usage
(referred to as input data of energy calculations) for residential buildings.
The schedule and conditions include schedules of occupancy, operation of technical building systems,
ventilation rates, hot water usage, usage of appliances and internal heat gains due to occupancy, lighting
and appliances. The schedule and conditions for lighting are applicable to fixed installed lighting
fixtures.
This document also gives categories of residential building, zone and space according to differentiating
schedule and condition. For residential buildings or its housing units which contain any category of
space or zone of non-residential buildings, ISO 18523-1 applies.
Depending on necessary minuteness of the energy calculation, different levels of schedule and condition
from the view point of time and space averaging are specified.
The values and categories for the schedule and condition are included informatively.
NOTE The schedule and condition in this document is basically different from assumptions in order to
determine the size of technical building systems in the process of design, where possible largest or smallest values
are assumed. Instead, most usual and average values, which are assumed for the building energy calculation, are
dealt with in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 18523-1, Energy performance of buildings — Schedule and condition of building, zone and space usage
for energy calculation — Part 1: Non-residential buildings
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
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ISO 18523-2:2018(E)

3.1 Space
3.1.1
apartment block
building (3.1.2), which contains multiple housing units (3.1.8)
3.1.2
building
construction as a whole, including its envelope and all technical building systems (3.3.13), where energy
is used to condition the indoor environment, to provide domestic hot water and illumination and other
services related to the use of the building
3.1.3
building zone
zone
part of a building consisting of (part of) one or more spaces with assumed uniform properties related
to a specific service or service component, or (in absence of a service) assumed uniform indoor
environmental conditions
3.1.4
common space
indoor or outdoor space, which is commonly used by residents
3.1.5
thermally conditioned space
thermally conditioned zone
heated and/or cooled space (zone)
3.1.6
elementary space
space
part of a room, a room or group of adjacent rooms with assumed uniform properties for all considered
types of zones
3.1.7
habitable room
room that is continuously used for living, working, meeting, amusement and other purposes similar
thereto
Note 1 to entry: Spaces such as bathroom, washroom, toilet, entrance hall or corridor are excluded.
3.1.8
housing unit
single-family house (3.1.9) or apartment (flat or maisonette) of apartment blocks (3.1.1)
3.1.9
single-family house
detached house
independent residential building, where a family lives
3.1.10
thermally unconditioned space
thermally unconditioned zone
space (zone) that is not heated nor cooled
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ISO 18523-2:2018(E)

3.2 Schedule
3.2.1
annual operation hours
operation hours
total length of hours in a standard year (3.2.11) when a technical building system (3.3.13) can be operated
depending on necessity
3.2.2
annual schedule
allocation of daily schedule(s) (3.2.4) for one year
Note 1 to entry: Division of the year can be selected from 365 days, 53 weeks, 12 months, seasons or no division
(a set of daily schedules is uniformly applied throughout the year).
3.2.3
daily operating hours
hours when a service system is operated, or the length of the hours
3.2.4
daily schedule
conditions of occupancy, service system operations, requirement for the functions of the service
systems and internal heat gains at each time of a day
3.2.5
daily schedule with hourly conditions
set of hourly conditions of occupancy, service system operations, requirement for the functions of the
service systems and internal heat gains in a day
3.2.6
monthly schedule
allocation of daily schedule(s) (3.2.4) for each month of the year
3.2.7
seasonal schedule
allocation of daily schedule(s) (3.2.4) to each season of the year
3.2.8
schedule
information on condition(s) of building, zone or space usage throughout a cycle of period, such as day,
week, month, season and year
3.2.9
set of daily schedules
complete set of daily schedules representing usage of a category of building, zone or space in one year
3.2.10
standard year
selected year, of which the number of days has to be 365 and arrangement of weekdays, weekends and
holidays are referred in weekly, monthly, seasonal and annual schedules
3.2.11
weekly schedule
allocation of daily schedule(s) (3.2.4) to each week of the year
3.2.12
whole set of annual schedules
complete set of annual schedules (3.2.2) representing usage of all types of building, zone and space, as
objects of energy calculation
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ISO 18523-2:2018(E)

3.2.13
whole set of seasonal schedules
complete set of seasonal schedules (3.2.7) representing usage of all types of building, zone and space, as
objects of energy calculation
3.2.14
whole set of monthly schedules
complete set of monthly schedules (3.2.6) representing usage of all types of building, zone and space, as
objects of energy calculation
3.3 Parameters for conditions of building, zone and space usage
3.3.1
appliances
consumer electronics and machines for housekeeping
3.3.2
condition
status of occupancy (3.3.9), operation of service systems, requirement for the functions of the technical
building systems (3.3.13) and internal heat gains
3.3.3
demand control ventilation
ventilation with a rate controlled according to the necessity of the ventilation, such as the emission rate
of target pollutant
3.3.4
local exhaust ventilation
mechanical exhaust ventilation for eliminating contaminants, such as odour, combustion gases, water
vapour and oil mist, from nearby sources
3.3.5
height of the working plane
height of the plane on which the assumed visual task is carried out, from the floor
Note 1 to entry: Height of the working plane is expressed in metres, m.
3.3.6
height of the specified surface
height of the plane on which the requirement for the ambient lighting is assumed, from the floor
Note 1 to entry: Height of the specified surface is expressed in metres, m.
3.3.7
luminaire
apparatus which distributes, filters or transforms the light transmitted from one or more lamps and which
includes, except the lamps themselves, all the parts necessary for fixing and protecting the lamps and,
where necessary, circuit auxiliaries together with the means for connecting them to the electric supply
3.3.8
maintained average illuminance
value below which the average illuminance over the specified surface is not allowed to fall
Note 1 to entry: Maintained average illuminance is expressed in lux.
3.3.9
occupancy
presence of users in building, zone or space
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ISO 18523-2:2018(E)

3.3.10
occupancy density
number of present users in building, zone or room per unit floor area of the space
Note 1 to entry: Occupancy density is used mainly for the calculations for space heating/cooling and ventilation.
3.3.11
overall ventilation
ventilation for supplying outdoor air into indoor spaces to dilute general contaminants, such as
formaldehyde, CO and water vapour
2
3.3.12
simultaneous usage ratio
ratio of the number of zones or spaces which belong to a group of zones and spaces and
are occupied or used at the time, to the total number of zones or spaces in the group
Note 1 to entry: This concept is applied to a group of zones or spaces of the same category, such as a group of
guest rooms in hotels, a series of personal office rooms in office buildings, etc.
3.3.13
technical building system
all energy-using or -distributing components in a building that are operated to support the occupant
or process functions housed therein (including HVAC, domestic hot water, illumination, transportation,
laundering or similar functions)
3.3.14
movable fitting
movable part of openings, which is used for the purposes of, for example, solar shading, adding
insulation, ventilation and security
3.4 Descriptions for daily schedule
3.4.1
hourly ratio
ratio of hourly value of parameters to their reference value
Note 1 to entry: Multiplying hourly ratios by the reference value, hourly values of the parameter is calculated.
This shall be calculated in accordance with ISO 18523-1.
3.4.2
reference domestic hot water usage
maximum hourly service hot water usage by users of the space or zone
Note 1 to entry: Measured in volume flow rate per person, in volume flow rate per unit floor area or in volume
flow rate per bed.
Note 2 to entry: The volume flow rate is calculated with the assumption on hot water temperature.
3.4.3
reference heat gain due to appliances
maximum hourly total (sensible and latent) heat gain due to appliances inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, heat gain due to appliances at the time can be calculated.
3.4.4
reference heat gain due to person
maximum hourly total (sensible and latent) heat gain due to person inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
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ISO 18523-2:2018(E)

Note 2 to entry: To be multiplied by hourly ratio, heat gain due to person at the time can be calculated.
3.4.5
reference heat gain due to lighting
maximum hourly sensible heat gain due to lighting inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, heat gain due to lighting at the time can be calculated.
3.4.6
reference latent heat gain due to appliances
maximum hourly latent heat gain due to appliances inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, latent heat gain due to appliances at the time can be calculated.
3.4.7
reference latent heat gain due to person
maximum hourly latent heat gain due to person inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, latent heat gain due to person at the time can be calculated.
3.4.8
reference occupancy density
maximum hourly occupancy density of the space or zone
Note 1 to entry: Measured in person per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, occupancy density at the time can be calculated.
3.4.9
reference sensible heat gain due to appliances
maximum hourly sensible heat gain due to appliances inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, sensible heat gain due to appliances at the time can be
calculated.
3.4.10
reference sensible heat gain due to person
maximum hourly sensible heat gain due to person inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratio, sensible heat gain due to person at the time can be calculated.
3.4.11
reference ventilation requirement
most probable estimation of outdoor air supply (in volume flow rate per unit floor area or in air change
per hour) to the space or zone
3.4.12
total daily usage of domestic hot water
total volume of service hot water usage in one day
Note 1 to entry: Measured in volume per person, in volume per unit floor area, in volume per bed or in volume per
household (housing unit).
Note 2 to entry: The volume is calculated with the assumption of hot water temperature.
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ISO 18523-2:2018(E)

4 Framework of the schedule and condition for building energy calculation
4.1 Indispensable schedules
The energy calculations for residential buildings are characterized by the division number of the
year, the calculation period or the calculation interval. Each calculation method has its appropriate
calculation interval according to characteristics of the target physical phenomenon (for example,
unsteadiness) and minuteness of the calculation responding to changes of climatic condition, occupants’
behaviour, status of service systems and so on.
Due to the variety of calculation method, there is a variety of form of the schedule and condition of
zone and space usage. Nevertheless, there is a fundamental unit of form, daily schedule, which shall be
included in forms for the schedule and condition. The daily schedule corresponds to the minimum cycle
of zone and space usage, and also of climatic and solar condition.
Some nations adopt so called “monthly calculation” for space heating and cooling energy needs and
uses, taking monthly variation of outdoor temperature and solar irradiance into consideration. One
daily schedule for workday and the number of the workdays is given to each month for each type of zone
and space. Monthly means of outdoor air condition (for example, temperature) and solar irradiance for
different orientations and inclinations are given for the calculation. The expression of the daily schedule
varies from detailed expression with hourly values to simplified expression such as daily mean values
and the like. Additional schedule for holiday can be given in a simplified way such as only with daily
mean values.
Similarly, in so called “seasonal calculation”, one daily schedule for workday and the number of the
workdays for each season are given to each season for each type of zone and room, and the calculation
is done with seasonal mean values for climatic condition.
For the calculation of more steady phenomena, so called “annual calculation” can work if seasonal
change of solar condition is integrated throughout the year and condensed in specific coefficients.
Nevertheless, one daily schedule for a workday and the number of annual workdays are necessary.
Additional daily schedules for holiday can be given.
For the calculation of lighting, monthly or yearly calculation is mainly used, even though unsteady
aspects of lighting still have to be dealt with. In the calculation for lighting, when input parameters
such as operating hours with and without daylight are prescribed, a daily schedule as described in
column (2) of Table 1 and annual schedule by monthly allocation of daily schedules (Table 5) or annual
schedule without division of the year (Table 7) should be explicitly given, so that the operating hours
for light are well harmonized with those for other technical systems.
Therefore, for each category of zone and space, a necessary number of daily schedules (e.g., two daily
schedules for workday and holiday), and one of annual, seasonal, monthly and weekly schedules shall
be given in order that the daily schedules are allocated for the year.
4.2 Daily schedule
The daily schedule shall contain hourly values of conditions for one day, or shall contain condensed or
simplified information on conditions for the day. With some assumptions, the hourly detailed values can
be generated from the condensed or simplified information and used even for detailed calculation. If
necessary, multiple daily schedules representing different daily patterns of usage should be given such
as for workdays, holidays and going-out days. The number of daily schedules depends on minuteness of
the schedule and conditions as well as on the category of zone and space under consideration.
The conditions described in the daily schedule are grouped into five categories:
a) General information on occupancy and usage of zone and space;
b) Operation of technical building systems and requirement for their services;
c) Usage of appliances;
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ISO 18523-2:2018(E)

d) Internal heat gains;
e) Operation of movable fittings.
The basic structure of a daily schedule is shown in Table 1.
Table 1 — Framework of daily schedule for zone and space
(1)  Description by hourly (2) Condensed or simplified
values for 0–24 h description
a)  General Occupancy or occu- Hourly occupancy or occupancy Times of start and end of occupancy
information on pancy density density or total hours of occupancy, and
occupancy and average occupancy or occupancy
usage density during usage
Simultaneous Hourly simultaneous usage ratio Mean simultaneous usage ratio
usage ratio of a set during usage
of rooms
b)  Operation Space heating and/ Hourly status of space heating Times of start and end of operation,
of technical or cooling and/or cooling system (in or out or total hours of operation
building systems of operation)
and requirement
for their building
services
Hourly set-points of room temper- Set-point temperature and/or
ature and/or humidity humidity during operation, and/or
information on set-back operation
Ventilation for gen- Hourly status of ventilation Times of start and end of operation,
eral contaminants system (in or out of operation) or total hours of operation
(overall ventilation)
Lighting Hourly status of lighting system Times of start and end of operation,
(in or out of operation) or total hours of operation
Maintained average illuminance Maintained average illuminance
and heigh
...

SLOVENSKI STANDARD
oSIST ISO 18523-2:2020
01-marec-2020
Energetska učinkovitost stavb - Načrt in pogoji uporabe prostorov, con in stavb za
izračun energije - 2. del: Stanovanjske stavbe
Energy performance of buildings -- Schedule and condition of building, zone and space
usage for energy calculation -- Part 2: Residential buildings
Performance énergétique des bâtiments -- Plan et conditions d'utilisation des espaces,
zones et bâtiments pour le calcul d'énergie -- Partie 2: Bâtiments résidentiels
Ta slovenski standard je istoveten z: ISO 18523-2:2018
ICS:
91.040.30 Stanovanjske stavbe Residential buildings
91.120.10 Toplotna izolacija stavb Thermal insulation of
buildings
oSIST ISO 18523-2:2020 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST ISO 18523-2:2020

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oSIST ISO 18523-2:2020
INTERNATIONAL ISO
STANDARD 18523-2
First edition
2018-02
Energy performance of buildings —
Schedule and condition of building,
zone and space usage for energy
calculation —
Part 2:
Residential buildings
Performance énergétique des bâtiments — Plan et conditions
d'utilisation des espaces, zones et bâtiments pour le calcul
d'énergie —
Partie 2: Bâtiments résidentiels
Reference number
ISO 18523-2:2018(E)
©
ISO 2018

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oSIST ISO 18523-2:2020
ISO 18523-2:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2018
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, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

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oSIST ISO 18523-2:2020
ISO 18523-2:2018(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Space . 2
3.2 Schedule . 3
3.3 Parameters for conditions of building, zone and space usage . 4
3.4 Descriptions for daily schedule . 5
4 Framework of the schedule and condition for building energy calculation .7
4.1 Indispensable schedules . 7
4.2 Daily schedule . 7
4.3 Division of year and daily, weekly, monthly, seasonal and annual allocations of
daily schedules . 9
5 Conditions for energy calculation included in the schedule and condition of zone
and space usage .11
5.1 Energy needs and uses .11
5.2 Condition .11
5.2.1 Occupancy or occupancy density .11
5.2.2 Operation of technical building systems and requirement for their services .12
5.2.3 Internal heat gains .14
5.2.4 Operation of movable fittings .15
5.3 Process for determining schedule and condition in housing units .15
5.3.1 Family structure .15
5.3.2 Time use of daily life of family member(s) .15
5.3.3 Schedule and area for space heating and cooling .16
5.3.4 Schedule and area of overall ventilation .16
5.3.5 Schedule and area of local exhaust ventilation .17
5.3.6 Amount of domestic hot water usage .17
5.3.7 Possession and usage of appliances .17
6 Category of residential building, zone and space .17
6.1 General .17
6.2 Category of space or zone .18
6.2.1 Categories of space or zone inside housing unit .18
6.2.2 Categories of space or zone outside housing unit .18
Annex A (informative) Examples of time use as daily life of family .19
Annex B (informative) Format of annual schedule by daily allocation of daily schedules .23
Annex C (informative) Examples of schedules for space heating and cooling .24
Annex D (informative) Example of schedule and area for local ventilation .25
Annex E (informative) Examples of schedule and condition for domestic hot water .26
Annex F (informative) Example of schedule and condition for usage of electric appliances .27
Annex G (informative) Examples of categories of space and zone of residential buildings .31
Bibliography .32
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oSIST ISO 18523-2:2020
ISO 18523-2:2018(E)

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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on 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 the following
URL: www .iso .org/ iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use
in the built environment.
A list of all parts in the ISO 18523 series can be found on the ISO website.
iv © ISO 2018 – All rights reserved

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oSIST ISO 18523-2:2020
ISO 18523-2:2018(E)

Introduction
There is a strong need to improve the environment to make the evaluation of energy performance of
buildings more reliable and practical, so that energy efficiency of buildings is improved by referring
to the evaluation results. There have been no international standards prescribing building use in this
area. This document prescribes the indispensable information on the conditions for zone and space
usage in energy calculations for residential buildings.
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oSIST ISO 18523-2:2020

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oSIST ISO 18523-2:2020
INTERNATIONAL STANDARD ISO 18523-2:2018(E)
Energy performance of buildings — Schedule and
condition of building, zone and space usage for energy
calculation —
Part 2:
Residential buildings
1 Scope
This document specifies the formats to present the schedule and conditions of zone and space usage
(referred to as input data of energy calculations) for residential buildings.
The schedule and conditions include schedules of occupancy, operation of technical building systems,
ventilation rates, hot water usage, usage of appliances and internal heat gains due to occupancy, lighting
and appliances. The schedule and conditions for lighting are applicable to fixed installed lighting
fixtures.
This document also gives categories of residential building, zone and space according to differentiating
schedule and condition. For residential buildings or its housing units which contain any category of
space or zone of non-residential buildings, ISO 18523-1 applies.
Depending on necessary minuteness of the energy calculation, different levels of schedule and condition
from the view point of time and space averaging are specified.
The values and categories for the schedule and condition are included informatively.
NOTE The schedule and condition in this document is basically different from assumptions in order to
determine the size of technical building systems in the process of design, where possible largest or smallest values
are assumed. Instead, most usual and average values, which are assumed for the building energy calculation, are
dealt with in this document.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 18523-1, Energy performance of buildings — Schedule and condition of building, zone and space usage
for energy calculation — Part 1: Non-residential buildings
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
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oSIST ISO 18523-2:2020
ISO 18523-2:2018(E)

3.1 Space
3.1.1
apartment block
building (3.1.2), which contains multiple housing units (3.1.8)
3.1.2
building
construction as a whole, including its envelope and all technical building systems (3.3.13), where energy
is used to condition the indoor environment, to provide domestic hot water and illumination and other
services related to the use of the building
3.1.3
building zone
zone
part of a building consisting of (part of) one or more spaces with assumed uniform properties related
to a specific service or service component, or (in absence of a service) assumed uniform indoor
environmental conditions
3.1.4
common space
indoor or outdoor space, which is commonly used by residents
3.1.5
thermally conditioned space
thermally conditioned zone
heated and/or cooled space (zone)
3.1.6
elementary space
space
part of a room, a room or group of adjacent rooms with assumed uniform properties for all considered
types of zones
3.1.7
habitable room
room that is continuously used for living, working, meeting, amusement and other purposes similar
thereto
Note 1 to entry: Spaces such as bathroom, washroom, toilet, entrance hall or corridor are excluded.
3.1.8
housing unit
single-family house (3.1.9) or apartment (flat or maisonette) of apartment blocks (3.1.1)
3.1.9
single-family house
detached house
independent residential building, where a family lives
3.1.10
thermally unconditioned space
thermally unconditioned zone
space (zone) that is not heated nor cooled
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oSIST ISO 18523-2:2020
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3.2 Schedule
3.2.1
annual operation hours
operation hours
total length of hours in a standard year (3.2.11) when a technical building system (3.3.13) can be operated
depending on necessity
3.2.2
annual schedule
allocation of daily schedule(s) (3.2.4) for one year
Note 1 to entry: Division of the year can be selected from 365 days, 53 weeks, 12 months, seasons or no division
(a set of daily schedules is uniformly applied throughout the year).
3.2.3
daily operating hours
hours when a service system is operated, or the length of the hours
3.2.4
daily schedule
conditions of occupancy, service system operations, requirement for the functions of the service
systems and internal heat gains at each time of a day
3.2.5
daily schedule with hourly conditions
set of hourly conditions of occupancy, service system operations, requirement for the functions of the
service systems and internal heat gains in a day
3.2.6
monthly schedule
allocation of daily schedule(s) (3.2.4) for each month of the year
3.2.7
seasonal schedule
allocation of daily schedule(s) (3.2.4) to each season of the year
3.2.8
schedule
information on condition(s) of building, zone or space usage throughout a cycle of period, such as day,
week, month, season and year
3.2.9
set of daily schedules
complete set of daily schedules representing usage of a category of building, zone or space in one year
3.2.10
standard year
selected year, of which the number of days has to be 365 and arrangement of weekdays, weekends and
holidays are referred in weekly, monthly, seasonal and annual schedules
3.2.11
weekly schedule
allocation of daily schedule(s) (3.2.4) to each week of the year
3.2.12
whole set of annual schedules
complete set of annual schedules (3.2.2) representing usage of all types of building, zone and space, as
objects of energy calculation
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3.2.13
whole set of seasonal schedules
complete set of seasonal schedules (3.2.7) representing usage of all types of building, zone and space, as
objects of energy calculation
3.2.14
whole set of monthly schedules
complete set of monthly schedules (3.2.6) representing usage of all types of building, zone and space, as
objects of energy calculation
3.3 Parameters for conditions of building, zone and space usage
3.3.1
appliances
consumer electronics and machines for housekeeping
3.3.2
condition
status of occupancy (3.3.9), operation of service systems, requirement for the functions of the technical
building systems (3.3.13) and internal heat gains
3.3.3
demand control ventilation
ventilation with a rate controlled according to the necessity of the ventilation, such as the emission rate
of target pollutant
3.3.4
local exhaust ventilation
mechanical exhaust ventilation for eliminating contaminants, such as odour, combustion gases, water
vapour and oil mist, from nearby sources
3.3.5
height of the working plane
height of the plane on which the assumed visual task is carried out, from the floor
Note 1 to entry: Height of the working plane is expressed in metres, m.
3.3.6
height of the specified surface
height of the plane on which the requirement for the ambient lighting is assumed, from the floor
Note 1 to entry: Height of the specified surface is expressed in metres, m.
3.3.7
luminaire
apparatus which distributes, filters or transforms the light transmitted from one or more lamps and which
includes, except the lamps themselves, all the parts necessary for fixing and protecting the lamps and,
where necessary, circuit auxiliaries together with the means for connecting them to the electric supply
3.3.8
maintained average illuminance
value below which the average illuminance over the specified surface is not allowed to fall
Note 1 to entry: Maintained average illuminance is expressed in lux.
3.3.9
occupancy
presence of users in building, zone or space
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3.3.10
occupancy density
number of present users in building, zone or room per unit floor area of the space
Note 1 to entry: Occupancy density is used mainly for the calculations for space heating/cooling and ventilation.
3.3.11
overall ventilation
ventilation for supplying outdoor air into indoor spaces to dilute general contaminants, such as
formaldehyde, CO and water vapour
2
3.3.12
simultaneous usage ratio
ratio of the number of zones or spaces which belong to a group of zones and spaces and
are occupied or used at the time, to the total number of zones or spaces in the group
Note 1 to entry: This concept is applied to a group of zones or spaces of the same category, such as a group of
guest rooms in hotels, a series of personal office rooms in office buildings, etc.
3.3.13
technical building system
all energy-using or -distributing components in a building that are operated to support the occupant
or process functions housed therein (including HVAC, domestic hot water, illumination, transportation,
laundering or similar functions)
3.3.14
movable fitting
movable part of openings, which is used for the purposes of, for example, solar shading, adding
insulation, ventilation and security
3.4 Descriptions for daily schedule
3.4.1
hourly ratio
ratio of hourly value of parameters to their reference value
Note 1 to entry: Multiplying hourly ratios by the reference value, hourly values of the parameter is calculated.
This shall be calculated in accordance with ISO 18523-1.
3.4.2
reference domestic hot water usage
maximum hourly service hot water usage by users of the space or zone
Note 1 to entry: Measured in volume flow rate per person, in volume flow rate per unit floor area or in volume
flow rate per bed.
Note 2 to entry: The volume flow rate is calculated with the assumption on hot water temperature.
3.4.3
reference heat gain due to appliances
maximum hourly total (sensible and latent) heat gain due to appliances inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, heat gain due to appliances at the time can be calculated.
3.4.4
reference heat gain due to person
maximum hourly total (sensible and latent) heat gain due to person inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
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Note 2 to entry: To be multiplied by hourly ratio, heat gain due to person at the time can be calculated.
3.4.5
reference heat gain due to lighting
maximum hourly sensible heat gain due to lighting inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, heat gain due to lighting at the time can be calculated.
3.4.6
reference latent heat gain due to appliances
maximum hourly latent heat gain due to appliances inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, latent heat gain due to appliances at the time can be calculated.
3.4.7
reference latent heat gain due to person
maximum hourly latent heat gain due to person inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, latent heat gain due to person at the time can be calculated.
3.4.8
reference occupancy density
maximum hourly occupancy density of the space or zone
Note 1 to entry: Measured in person per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, occupancy density at the time can be calculated.
3.4.9
reference sensible heat gain due to appliances
maximum hourly sensible heat gain due to appliances inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratios, sensible heat gain due to appliances at the time can be
calculated.
3.4.10
reference sensible heat gain due to person
maximum hourly sensible heat gain due to person inside the room or zone
Note 1 to entry: Measured in watt per unit floor area.
Note 2 to entry: To be multiplied by hourly ratio, sensible heat gain due to person at the time can be calculated.
3.4.11
reference ventilation requirement
most probable estimation of outdoor air supply (in volume flow rate per unit floor area or in air change
per hour) to the space or zone
3.4.12
total daily usage of domestic hot water
total volume of service hot water usage in one day
Note 1 to entry: Measured in volume per person, in volume per unit floor area, in volume per bed or in volume per
household (housing unit).
Note 2 to entry: The volume is calculated with the assumption of hot water temperature.
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oSIST ISO 18523-2:2020
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4 Framework of the schedule and condition for building energy calculation
4.1 Indispensable schedules
The energy calculations for residential buildings are characterized by the division number of the
year, the calculation period or the calculation interval. Each calculation method has its appropriate
calculation interval according to characteristics of the target physical phenomenon (for example,
unsteadiness) and minuteness of the calculation responding to changes of climatic condition, occupants’
behaviour, status of service systems and so on.
Due to the variety of calculation method, there is a variety of form of the schedule and condition of
zone and space usage. Nevertheless, there is a fundamental unit of form, daily schedule, which shall be
included in forms for the schedule and condition. The daily schedule corresponds to the minimum cycle
of zone and space usage, and also of climatic and solar condition.
Some nations adopt so called “monthly calculation” for space heating and cooling energy needs and
uses, taking monthly variation of outdoor temperature and solar irradiance into consideration. One
daily schedule for workday and the number of the workdays is given to each month for each type of zone
and space. Monthly means of outdoor air condition (for example, temperature) and solar irradiance for
different orientations and inclinations are given for the calculation. The expression of the daily schedule
varies from detailed expression with hourly values to simplified expression such as daily mean values
and the like. Additional schedule for holiday can be given in a simplified way such as only with daily
mean values.
Similarly, in so called “seasonal calculation”, one daily schedule for workday and the number of the
workdays for each season are given to each season for each type of zone and room, and the calculation
is done with seasonal mean values for climatic condition.
For the calculation of more steady phenomena, so called “annual calculation” can work if seasonal
change of solar condition is integrated throughout the year and condensed in specific coefficients.
Nevertheless, one daily schedule for a workday and the number of annual workdays are necessary.
Additional daily schedules for holiday can be given.
For the calculation of lighting, monthly or yearly calculation is mainly used, even though unsteady
aspects of lighting still have to be dealt with. In the calculation for lighting, when input parameters
such as operating hours with and without daylight are prescribed, a daily schedule as described in
column (2) of Table 1 and annual schedule by monthly allocation of daily schedules (Table 5) or annual
schedule without division of the year (Table 7) should be explicitly given, so that the operating hours
for light are well harmonized with those for other technical systems.
Therefore, for each category of zone and space, a necessary number of daily schedules (e.g., two daily
schedules for workday and holiday), and one of annual, seasonal, monthly and weekly schedules shall
be given in order that the daily schedules are allocated for the year.
4.2 Daily schedule
The daily schedule shall contain hourly values of conditions for one day, or shall contain condensed or
simplified information on conditions for the day. With some assumptions, the hourly detailed values can
be generated from the condensed or simplified information and used even for detailed calculation. If
necessary, multiple daily schedules representing different daily patterns of usage should be given such
as for workdays, holidays and going-out days. The number of daily schedules depends on minuteness of
the schedule and conditions as well as on the category of zone and space under consideration.
The conditions described in the daily schedule are grouped into five categories:
a) General information on occupancy and usage of zone and space;
b) Operation of technical building systems and requirement for their services;
c) Usage of appliances;
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d) Internal heat gains;
e) Operation of movable fittings.
The basic structure of a daily schedule
...