ISO 52018-1:2017

INTERNATIONAL ISO
STANDARD 52018-1
First edition
2017-06
Energy performance of buildings —
Indicators for partial EPB
requirements related to thermal
energy balance and fabric features —
Part 1:
Overview of options
Performance énergétique des bâtiments — Indicateurs pour
des exigences PEB partielles liées aux caractéristiques du bilan
énergétique thermique et du bâti —
Partie 1: Aperçu des options
Reference number
©
ISO 2017
© ISO 2017, Published in Switzerland
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ii © ISO 2017 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
3.1 Building . 2
3.2 Indoor and outdoor conditions. 5
3.3 Technical building systems . 6
3.4 Energy . 7
3.5 Energy performance . 7
3.6 Building heat transfer, heat gains and recoverable system thermal losses . 8
4 Symbols and subscripts .10
4.1 Symbols .10
4.2 Subscripts .10
5 Description of this document .11
5.1 General .11
5.2 Brief overview of this document .12
5.3 Selection criteria between the possible options .12
5.4 Input and output data .12
6 Mix of EPB features with requirements .13
7 Summer thermal comfort .13
8 Winter thermal comfort .14
9 Energy need for heating or variants .14
10 Energy need for cooling, or variants .15
11 Combination of “needs” .15
12 Overall thermal insulation of the thermal envelope .15
13 Thermal insulation of individual elements of the thermal envelope .15
14 Thermal bridges .16
15 Window energy performances.17
16 Airtightness of the thermal envelope .17
17 Solar control .18
18 Other requirements .18
19 Quality control .18
20 Compliance check .18
Annex A (normative) Input and method selection data sheet — Template .20
Annex B (informative) Input and method selection data sheet — Default choices .29
Annex C (normative) Regional references in line with ISO Global Relevance Policy .42
Bibliography .43
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: w w w . i s o .org/ iso/ foreword .html.
ISO 52018-1 was prepared by ISO Technical Committee ISO/TC 163, Thermal performance and energy
use in the built environment, Subcommittee SC 2, Calculation methods, in collaboration with the European
Committee for Standardization (CEN) Technical Committee CEN/TC 89, Thermal performance of
buildings and building components, in accordance with the Agreement on technical cooperation between
ISO and CEN (Vienna Agreement).
A list of all parts in the ISO 52018 series can be found on the ISO website.
iv © ISO 2017 – All rights reserved

Introduction
This document is part of a series aimed at the international harmonization of the methodology for
assessing the energy performance of buildings. Throughout, this series is referred to as a “set of EPB
standards”.
All EPB standards follow specific rules to ensure overall consistency, unambiguity and transparency.
All EPB standards provide a certain flexibility with regard to the methods, the required input data and
references to other EPB standards, by the introduction of a normative template in Annex A and Annex B
with informative default choices.
For the correct use of this document, a normative template is given in Annex A to specify these choices.
Informative default choices are provided in Annex B.
The main target groups for this document are architects, engineers and regulators.
Use by or for regulators: In case the document is used in the context of national or regional legal
requirements, mandatory choices may be given at national or regional level for such specific
applications. These choices (either the informative default choices from Annex B or choices adapted to
national/regional needs, but in any case following the template of Annex A) can be made available as
national annex or as separate (e.g. legal) document (national data sheet).
NOTE 1 So in this case:
— the regulators will specify the choices;
— the individual user will apply the document to assess the energy performance of a building, and thereby use
the choices made by the regulators.
Topics addressed in this document can be subject to public regulation. Public regulation on the same
topics can override the default values in Annex B. Public regulation on the same topics can even, for
certain applications, override the use of this document. Legal requirements and choices are in general
not published in standards but in legal documents. In order to avoid double publications and difficult
updating of double documents, a national annex may refer to the legal texts where national choices
have been made by public authorities. Different national annexes or national data sheets are possible,
for different applications.
It is expected, if the default values, choices and references to other EPB standards in Annex B are not
followed due to national regulations, policy or traditions, that:
— national or regional authorities prepare data sheets containing the choices and national or regional
values, according to the model in Annex A. In this case a national annex (e.g. NA) is recommended,
containing a reference to these data sheets;
— or, by default, the national standards body will consider the possibility to add or include a national
annex in agreement with the template of Annex A, in accordance to the legal documents that give
national or regional values and choices.
Further target groups are parties wanting to motivate their assumptions by classifying the building
energy performance for a dedicated building stock.
[7]
More information is provided in the technical report (ISO/TR 52018-2) accompanying this document.
The subset of EPB standards prepared under the responsibility of ISO/TC 163/SC 2 cover inter alia:
— calculation procedures on the overall energy use and energy performance of buildings;
— calculation procedures on the indoor temperature in buildings (e.g. in case of no space heating or
cooling);
— indicators for partial EPB requirements related to thermal energy balance and fabric features;
— calculation methods covering the performance and thermal, hygrothermal, solar and visual
characteristics of specific parts of the building and specific building elements and components, such
as opaque envelope elements, ground floor, windows and facades.
ISO/TC 163/SC 2 cooperates with other technical committees for the details on, for example, appliances,
technical building systems and indoor environment.
The overall and partial EPB indicators, i.e. the quantitative output of EPB assessments, can be used for
different purposes.
a) Requirements: To set public or private requirements regarding the energy performance of
buildings.
b) Decisions: To facilitate decisions or actions in the private or public domain.
c) Information and communication: For building designers, owners, operators, users, policymakers
and citizens (as sellers or renters, as prospective buyers or tenants).
ISO 52003-1 and ISO 52003-2 discuss in a general manner the post-processing of the outputs of the EPB
standards. They describe the concepts of EPB features and EPB indicators and deal with the principles
of requirements, ratings and certificates. They also briefly deal in a more practical manner with the
overall EPB requirements.
This document deals on a practical level with the requirements related to the fabric and related to
the thermal balance of the building. Thermal balance aspects concern both the heating and cooling
needs and the free floating temperatures, especially with respect to overheating or too cold indoor
temperatures.
Most of the EPB features falling within this scope are succinctly enumerated and for each of them, many
possible indicators are listed. Annex A provides standardized tables to report the choices that are made
by regulators. Annex B gives motivated default choices.
As ISO 52003-1, this document does not provide any EPB assessment method (calculation, measurement
of inspection). Instead, they refer to other EPB and non-EPB standards for the determination of EPB
indicators.
ISO/TR 52018-2 is the technical report corresponding to this document. It provides extensive
background information to help with making well-considered choices. For best understanding, the
reader is advised to read this document and ISO/TR 52018-2 in parallel, clause by clause.
EPB indicators that can possibly be used for setting requirements to technical building systems are in
principle covered in the corresponding EPB documents (which are until now mostly CEN standards).
Table 1 shows the relative position of this document within the set of EPB standards in the context of
the modular structure as set out in ISO 52000-1.
NOTE 2 In ISO/TR 52000-2, the same table can be found, with, for each module, the numbers of the relevant
EPB standards and accompanying technical reports that are published or in preparation.
NOTE 3 The modules represent EPB standards, although one EPB standard could cover more
than one module and one module could be covered by more than one EPB standard, for instance, a
simplified and a detailed method, respectively. See also Clause 2 and Tables A.1 and B.1.
vi © ISO 2017 – All rights reserved

Table 1 — Position of this document (in casu M2–4) within the modular structure of the set of
EPB standards
Building
Overarching Technical Building Systems
(as such)
Building
Ven- Dehu- PV,
Sub- Descrip- Descrip- Descrip- Heat- Cool- Humid- Domestic automa-
tila- midifi- Lighting wind,
module tions tions tions ing ing ification hot water tion and
tion cation .
control
sub1 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11
1 General General General
Common
terms and
definitions; Building en-
a
2 Needs
symbols, ergy needs
units and
subscripts
(Free)
indoor Maximum
3 Applications conditions load and
without power
systems
Ways to
Ways to
Ways to ex- ISO express
express
4 press energy 52018- energy
energy per-
performance 1 perfor-
formance
mance
Building Heat
Emission
categories transfer by
5 and con-
and building transmis-
trol
boundaries sion
Building oc- Heat trans-
Distribu-
cupancy and fer by infil-
6 tion and
operating tration and
control
conditions ventilation
Aggregation
of energy Storage
Internal
7 services and con-
heat gains
and energy trol
carriers
Genera-
Building Solar heat
8 tion and
zoning gains
control
Load
Building
Calculated dispatch-
dynamics
9 energy per- ing and
(thermal
formance operating
mass)
conditions
Measured
Measured Measured
energy
10 energy per- energy per-
perfor-
formance formance
mance
11 Inspection Inspection Inspection
Ways to ex-
12 press indoor BMS
comfort
External
13 environment
conditions
Economic
calculation
a
The shaded modules are not applicable.
INTERNATIONAL STANDARD ISO 52018-1:2017(E)
Energy performance of buildings — Indicators for partial
EPB requirements related to thermal energy balance and
fabric features —
Part 1:
Overview of options
1 Scope
The set of EPB assessment standards produces a great number of overall and partial EPB indicators as
outputs, which can be used for different purposes. This document deals with the use as requirement of
partial EPB indicators related to the fabric and related to the thermal balance of the building. Thermal
balance aspects concern both the heating and cooling needs and the free floating temperatures,
especially with respect to overheating or too cold indoor temperatures. This document can support
both private parties and public regulators (and all stakeholders involved in the regulatory process)
with the “post-processing” of these outputs.
This document provides standardized tables for reporting, in a structured and transparent manner,
the choices that are to be made with respect to the partial EPB requirements covered by this document.
The tables are non-restrictive, thus allowing for full regulatory flexibility.
NOTE Table 1 in the Introduction shows the relative position of this document within the set of EPB
standards in the context of the modular structure as set out in ISO 52000-1.
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.
NOTE 1 In addition, Annex C contains specific parallel routes in referencing standards, in order to take into
account existing national and/or regional regulations and/or legal environments while maintaining global
relevance.
NOTE 2 Default references to EPB standards other than ISO 52000-1 are identified by the EPB module code
number and given in Annex A (normative template) and Annex B (informative default choice).
EXAMPLE EPB module code number: M5–5, or M5–5.1 (if module M5–5 is subdivided), or M5–5/1 (if reference to
a specific clause of the standard covering M5–5).
ISO 7345, Thermal insulation — Physical quantities and definitions
ISO 9050, Glass in building — Determination of light transmittance, solar direct transmittance, total solar
energy transmittance, ultraviolet transmittance and related glazing factors
ISO 9972:2015, Thermal performance of buildings — Determination of air permeability of buildings — Fan
pressurization method
ISO 10291, Glass in building — Determination of steady-state U values (thermal transmittance) of multiple
glazing — Guarded hot plate method
ISO 10292, Glass in building — Calculation of steady-state U values (thermal transmittance) of multiple
glazing
ISO 10293, Glass in building — Determination of steady-state U values (thermal transmittance) of multiple
glazing — Heat flow meter method
ISO 13788, Hygrothermal performance of building components and building elements — Internal surface
temperature to avoid critical surface humidity and interstitial condensation — Calculation methods
ISO 15099, Thermal performance of windows, doors and shading devices — Detailed calculations
ISO 18292, Energy performance of fenestration systems for residential buildings — Calculation procedure
ISO 52000-1:2017, Energy performance of buildings — Overarching EPB assessment — Part 1: General
framework and procedures
EN 410, Glass in building — Determination of luminous and solar characteristics of glazing
EN 673, Glass in building — Determination of thermal transmittance (U value) — Calculation method
EN 674, Glass in building — Determination of thermal transmittance (U value) — Guarded hot plate method
EN 675, Glass in building — Determination of thermal transmittance (U value) — Heat flow meter method
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7345 and ISO 52000-1 and the
following 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
3.1 Building
3.1.1
assessed object
building, part of a building or portfolio of buildings that is the object of the energy performance
assessment
Note 1 to entry: The assessed object comprises all spaces and technical systems which may contribute to or
influence the energy performance assessment.
Note 2 to entry: The assessed object may include one or several building units, if these are not individually object
of the energy performance assessment.
Note 3 to entry: A distinction may be made between, for example, a designed building, new building after
construction, existing building in the use phase and existing building after major renovation.
[SOURCE: ISO 52000-1:2017, 3.1.1]
3.1.2
building
construction as a whole, including its envelope and all technical building systems, where energy may
be used to condition the indoor environment, to provide domestic hot water and illumination and other
services related to the use of the building
Note 1 to entry: The term refers to the physical building as a whole or to all parts thereof that at least include the
spaces and technical building systems that are relevant for the energy performance assessment.
Note 2 to entry: Parts of a building can be physically detached, but are on the same building site. For example, a
canteen or a guard house or one or more classrooms of a school in a detached part of a building or an essential
space in a dwelling (e.g. bedroom).
2 © ISO 2017 – All rights reserved

[SOURCE: ISO 52000-1:2017, 3.1.2]
3.1.3
building category
unit category
classification of buildings and/or building units related to their main use or their special status, for the
purpose of enabling differentiation of the energy performance assessment procedures and/or energy
performance requirements
EXAMPLE Buildings officially protected as part of a designated environment or because of their special
architectural or historical merit, buildings used as places of worship and for religious activities, residential
buildings, (a) single-family houses of different types;(b) apartment blocks;(c) offices;(d) educational buildings;(e)
hospitals;(f) hotels and restaurants;(g) sports facilities;(h) wholesale and retail trade services buildings;(i) data
centres; (j) other types of energy-consuming buildings.
Note 1 to entry: Building regulations often make a distinction between building categories.
Note 2 to entry: The building category, for instance, may determine if energy performance assessment is
mandatory (e.g., not for religious or historic buildings) and which are the minimum energy performance
requirements (e.g., for new buildings); in some countries measured energy performance of a building is
prescribed for specific categories of buildings (e.g., apartment buildings, large public buildings), etc. Another
type of categorization is the distinction between new and existing and renovated buildings.
Note 3 to entry: Many buildings or building units of a given (use) category contain spaces of different (use)
categories; for instance an office building may contain a restaurant; see 3.1.12 definition of space category.
Note 4 to entry: The allocation of a building category may also have a strong impact on other parts of the building
regulations, for instance on safety (e.g., emergency exits, strength of floor) or indoor environmental quality (e.g.,
minimum ventilation rates).
[SOURCE: ISO 52000-1:2017, 3.1.3]
3.1.4
building element
integral component of the technical building systems or of the fabric of a building
[SOURCE: ISO 52000-1:2017, 3.1.4]
3.1.5
building fabric
all physical elements of a building, excluding technical building systems
EXAMPLE Roofs, walls, floors, doors, gates and internal partitions.
Note 1 to entry: It includes elements both in the inside and outside of the thermal envelope, including the thermal
envelope itself.
Note 2 to entry: The fabric determines the thermal transmission, the thermal envelope airtightness and (nearly
all of) the thermal mass of the building (apart from the thermal mass of furniture and technical building
systems). The fabric also makes the building wind and water tight. The building fabric is sometimes described as
the building as such, i.e. the building without any technical building system.
[SOURCE: ISO 52000-1:2017, 3.1.5]
3.1.6
building portfolio
set of buildings and common technical building systems whose energy performance is determined
taking into account their mutual interactions
Note 1 to entry: An example of common equipment is an energy generation system (PV panels, wind turbine,
cogen unit, boiler etc.) serving the building portfolio.
[SOURCE: ISO 52000-1:2017, 3.1.6]
3.1.7
building thermal zone
thermal zone
internal environment with assumed sufficiently uniform thermal conditions to enable a thermal
balance calculation according to the procedures in the standard under EPB module M2-2
[4]
Note 1 to entry: The EPB standard under module M2–2 is ISO 52016-1 .
[SOURCE: ISO 52000-1:2017, 3.1.7]
3.1.8
building unit
section, floor or apartment within a building which is designed or altered to be used separately from
the rest of the building
EXAMPLE A shop in a shopping mall, an apartment in an apartment building or a rentable office space in an
office building.
Note 1 to entry: The building unit can be the assessed object.
[SOURCE: ISO 52000-1:2017, 3.1.8]
3.1.9
conditioned space
room or enclosure that is covered by one or more of the EPB services
3.1.10
reference floor area
floor area used as a reference size
Note 1 to entry: See definition of reference size.
[SOURCE: ISO 52000-1:2017, 3.1.12]
3.1.11
reference size
relevant metric to normalize the overall or partial energy performance and energy performance
requirements to the size of the building or part of a building and for the comparison against benchmarks
[SOURCE: ISO 52000-1:2017, 3.1.13]
3.1.12
space category
classification of building spaces related to a specific set of use conditions
EXAMPLE Office space, restaurant space, entrance hall, toilet, living space, assembly hall, shop, residential
bed room, indoor car park, heated indoor stair case, unheated indoor stair case, etc.
Note 1 to entry: The space category is relevant for the calculation of the energy performance assessment and for
defining the reference size.
[SOURCE: ISO 52000-1:2017, 3.1.14]
3.1.13
thermally conditioned space
heated and/or cooled space
[SOURCE: ISO 52000-1:2017, 3.1.16]
4 © ISO 2017 – All rights reserved

3.1.14
thermal envelope area
total area of all elements of a building that enclose thermally conditioned spaces through which thermal
energy is transferred, directly or indirectly, to or from the external environment
Note 1 to entry: The thermal envelope area depends on whether internal, overall internal or external dimensions
are being used.
Note 2 to entry: The thermal envelope area does not include the area to adjacent buildings; see ISO 13789.
Note 3 to entry: The thermal envelope area may play a role in the ways to express the overall and partial energy
performance and energy performance requirements and comparison against benchmarks.
[SOURCE: ISO 13789:2017, 3.9, modified — Notes 2 and 3 to entry have been added.]
3.1.15
thermally unconditioned space
room or enclosure that is not part of a thermally conditioned space
[SOURCE: ISO 52000-1:2017, 3.1.17]
3.1.16
useful floor area
area of the floor of a building needed as parameter to quantify specific conditions
of use that are expressed per unit of floor area and for the application of the simplifications and the
zoning and (re-)allocation rules
[SOURCE: ISO 52000-1:2017, 3.1.18]
3.2 Indoor and outdoor conditions
3.2.1
condition of use
requirement and/or restriction for the use of a building space category, related to the services for the
energy performance assessment and/or the boundary conditions
EXAMPLE Heating set point, cooling set point, minimum amount of ventilation related to air quality, net
domestic hot water needs (e.g. per m floor area or per person), lighting levels, internal heat gains, etc., including
the distribution over time (operation). Where relevant, the numbers are based on the number of occupants per
m per type of building space.
[SOURCE: ISO 52000-1:2017, 3.2.1]
3.2.9
solar irradiance
power density of radiation incident on a surface, i.e. the quotient of the radiant flux incident on the
surface and the area of that surface, or the rate at which radiant energy is incident on a surface, per unit
area of that surface
[SOURCE: ISO 52000-1: 2017, 3.2.6]
3.2.10
solar irradiation
incident solar heat per area over a given period
Note 1 to entry: Incident energy per unit area of a surface, found by integration of solar irradiance over a specified
time interval, often an hour or a day (see ISO 9488).
[SOURCE: ISO 52000-1:2017, 3.2.7]
3.3 Technical building systems
3.3.1
building service
service provided by the technical building systems and by appliances to provide the indoor environment
conditions, domestic hot water, illumination levels and other services related to the use of the building
[SOURCE: ISO 52000-1:2017, 3.3.3]
3.3.2
building service area
service area
part of a building consisting of one or more elementary spaces served by a specific technical building
system or sub-system
EXAMPLE Building service area for a specific heating system circuit, for a specific cooling system
circuit, for a specific domestic hot water distribution system, for a specific ventilation system, for a
specific air conditioning system, for a specific lighting (artificial light or daylight) configuration.
[SOURCE: ISO 52000-1:2017, 3.3.4]
3.3.3
other building service
service supplied by energy-consuming appliances
[SOURCE: ISO 52000-1:2017, 3.2.5]
3.3.4
recoverable system thermal loss
part of a system thermal loss which can be recovered to lower either the energy need for heating or
cooling or the energy use of the heating or cooling system
Note 1 to entry: This depends on the calculation approach chosen to calculate the recovered gains and losses
(detailed or simplified approach; see ISO 52000-1:2017, 11.3).
Note 2 to entry: In this document, if not directly taken into account as a reduction to the system losses, the
recoverable system thermal losses are calculated as part of the internal heat gains. It may be decided at national
level to report the recoverable system thermal losses separately from the other internal heat gains.
[SOURCE: ISO 52000-1:2017, 3.3.9, modified — Note 2 to entry has been added.]
3.3.5
recovered system thermal loss
part of a recoverable system thermal loss which has been recovered to lower either the energy need for
heating or cooling or the energy use of the heating or cooling system
Note 1 to entry: This depends on the calculation approach chosen to calculate the recovered gains and losses
(detailed or simplified approach; see ISO 52000-1:2017, 11.3).
[SOURCE: ISO 52000-1:2017, 3.3.10]
3.3.6
system thermal loss
thermal loss from a technical building system for heating, cooling, domestic hot water, humidification,
dehumidification or ventilation that does not contribute to the useful output of the system
Note 1 to entry: A system loss can become an internal heat gain for the building if it is recoverable.
Note 2 to entry: Thermal energy recovered directly in the sub-system is not considered as a system thermal loss
but as heat recovery and directly treated in the related system standard under EPB module M3 to M8.
Note 3 to entry: Heat dissipated by the lighting system or by other services (e.g. appliances of computer
equipment) is not part of the system thermal losses, but part of the internal heat gains.
6 © ISO 2017 – All rights reserved

[SOURCE: ISO 52000-1:2017, 3.3.11]
3.3.7
technical building system
technical equipment for heating, cooling, ventilation, humidification, dehumidification, domestic hot
water, lighting, building automation and control and electricity production
Note 1 to entry: A technical building system can refer to one or to several building services (e.g. heating, heating
and domestic hot water).
Note 2 to entry: A technical building system is composed of different sub-systems.
Note 3 to entry: Electricity production can include cogeneration, wind power and photovoltaic systems.
[SOURCE: ISO 52000-1:2017, 3.3.13]
3.4 Energy
3.4.1
energy need for heating or cooling
heat to be delivered to or extracted from a thermally conditioned space to maintain the
intended space temperature conditions during a given period of time
[SOURCE: ISO 52000-1:2017, 3.4.13, modified — the domain ‘sensible’ has been added.]
3.4.2
energy need for humidification or dehumidification
latent heat in the water vapour to be delivered to or extracted from a thermally conditioned space by
a technical building system to maintain a specified minimum or maximum humidity within the space
[SOURCE: ISO 52000-1:2017, 3.4.14]
3.5 Energy performance
3.5.1
energy performance
overall energy performance
calculated or measured amount of (weighted) energy needed to meet the
energy demand associated with a typical use of the assessed object, which includes energy used for
specific services (EPB services)
Note 1 to entry: See definition of EPB services and definition of assessed object.
Note 2 to entry: Also called overall energy performance, to distinct from partial energy performance.
[SOURCE: ISO 52000-1:2017, 3.5.7]
3.5.2
energy performance indicator
EPB indicator
calculated or measured numerical quantity that characterizes an energy feature of an assessed object
Note 1 to entry: EPB indicators are used for the energy performance rating, the energy performance requirements
and/or for the certificate. An EPB indicator can for example be expressed in energy performance per unit of floor
area or energy performance divided by the energy performance of a specific benchmark or another reference value.
Note 2 to entry: This covers both overall energy performance and partial energy performance.
[SOURCE: ISO 52000-1:2017, 3.5.10]
3.5.3
energy performance requirement
minimum level of the (partial or overall) energy performance that is to be achieved to obtain a right or
an advantage: e.g. right to build, lower interest rate, quality label
[SOURCE: ISO 52000-1:2017, 3.5.11]
3.5.4
EPB service
building service included in the assessment of the energy performance
Note 1 to entry: See definition of building service. Which services are included is a national or regional choice,
specified in Annex A/Annex B of ISO 52000-1.
Note 2 to entry: Energy used for heating, cooling, ventilation, humidification, dehumidification, domestic hot
water and lighting.
[SOURCE: ISO 52000-1:2017, 3.5.13]
3.5.5
EPB standard
[8]
standard that complies with the requirements given in ISO 52000-1, CEN/TS 16628 and
[9]
CEN/TS 16629
Note 1 to entry: These three basic EPB documents were developed under a mandate given to CEN by the European
Commission and the European Free Trade Association (Mandate M/480) and support essential requirements of
EU Directive 2010/31/EU on the energy performance of buildings (EPBD). Several EPB standards and related
documents are developed or revised under the same mandate.
[SOURCE: ISO 52000-1:2017, 3.5.14]
3.5.6
reference value
standard legal or calculated value against which an energy indicator is compared
Note 1 to entry: This can be a fixed value for specific types of buildings or for specific energy features, or a
variable value (formula or notional reference building) taking into account one or more data from the actual
building.
[SOURCE: ISO 52000-1:2017, 3.5.20]
3.6 Building heat transfer, heat gains and recoverable system thermal losses
3.6.1
heat gain
heat generated within, or entering into, the thermally conditioned space from heat sources other than
energy intentionally utilized for heating, cooling or domestic hot water preparation
Note 1 to entry: Internal heat gains and solar heat gains. Sinks that extract heat from the building, are examples
of heat gains, with a negative sign.
Note 2 to entry: For summer conditions, heat gains with a positive sign constitute extra heat load on the space.
[SOURCE: ISO 52000-1:2017, 3.6.5]
3.6.2
heat transfer coefficient
heat flow rate divided by the temperature difference between two environments, specifically used for
heat transfer coefficient by transmission or ventilation
Note 1 to entry: In contrast with a heat gain, the driving force for heat transfer is the difference between the
temperature in the considered space and the temperature of the environment at the other side (in the case of
transmission) or the supply air temperature (in the case of ventilation).
8 © ISO 2017 – All rights reserved

[SOURCE: ISO 52016-1:2017, 3.6.9]
3.6.3
internal heat gain
heat provided within the building by occupants (sensible metabolic heat) and by appliances such as
lighting, domestic appliances, office equipment, etc., other than energy intentionally provided for
heating, cooling or hot water preparation
Note 1 to entry: This includes recoverable system thermal losses, if the detailed approach for the calculation of
the recovered system losses is chosen, see 11.3 of ISO 52000-1.
Note 2 to entry: In this document, if not directly taken into account as a reduction to the system thermal losses,
the recoverable system thermal losses are included as part of the internal heat gains. It may be decided at national
level to report the recoverable system thermal losses separately.
Note 3 to entry: Included are heat from (warm) or to (cold) process sources that are not controlled for the purpose
of heating or cooling or domestic hot-water preparation. The heat extracted from the building, from the indoor
environment to cold sources (sinks), is included as gain with a negative sign.
[SOURCE: ISO 52000-1:2017, 3.6.7, modified — Notes 2 and 3 to entry have been added.]
3.6.4
solar heat gain
heat provided by solar radiation entering, directly or indirectly (after absorption in building elements),
into the building through windows, opaque walls and roofs, or passive solar devices such as sunspaces,
transparent insulation and solar walls
Note 1 to entry: Active solar devices such as solar collectors are considered as part of the technical building system.
[SOURCE: ISO 52000-1:2017, 3.6.10]
3.6.5
transmission heat transfer coefficient
heat flow rate due to thermal transmission through the fabric of a building, divided by the difference
between the environment temperatures on either side of the construction
Note 1 to entry: By convention, the sign is positive if the heat flow is going out of the space considered (heat loss).
[SOURCE: ISO 52016-1:2017, 3.6.13]
3.6.6
useful heat gains
part of internal and solar heat gains that contribute to reducing the energy need for heating
[SOURCE: ISO 52000-1:2017, 3.6.11]
3.6.7
ventilation heat transfer coefficient
heat flow rate due to air entering an enclosed space, either by infiltration or ventilation, divided by the
difference between the internal air temperature and the supply air temperature
Note 1 to entry: The sign of the coefficient is always positive. By convention, the sign of the heat flow is positive if
the supply air temperature is lower than the internal air temperature (heat loss).
[SOURCE: ISO 52016-1:2017, 3.6.16]
4 Symbols and subscripts
4.1 Symbols
For the purposes of this document, the symbols given in ISO 52000-1:2017, Clause 4 and Annex C and
the following apply.
Symbol Quantity Unit
A area m
E energy balance value W/(m ·K)
F, f factor, fraction —
f shape factor —
g total solar energy transmittance —
H heat transfer coefficient W/K
l length m
n air change rate —
P energy performance of windows kWh/m
Q quantity of heat kW∙h
3 2
q air flow per (thermal envelope or useful floor) area (m /h)/m
R thermal resistance m ⋅K/W
U thermal transmittance W/(m ·K)
Χ point thermal transmittance W/K
Ψ linear thermal transmittance W/(m·K)
4.2 Subscripts
For the purposes of this document, the subscripts given in I
...