EN ISO 10211:2017

SLOVENSKI STANDARD
01-september-2017
1DGRPHãþD
SIST EN ISO 10211:2008
7RSORWQLPRVWRYLYVWDYEDK7RSORWQLWRNRYLLQSRYUãLQVNHWHPSHUDWXUH3RGUREQL
L]UDþXQL,62
Thermal bridges in building construction - Heat flows and surface temperatures -
Detailed calculations (ISO 10211:2017)
Wärmebrücken im Hochbau - Wärmeströme und Oberflächentemperaturen - Detaillierte
Berechnungen (ISO 10211:2017)
Ponts thermiques dans les bâtiments - Flux thermiques et températures superficielles -
Calculs détaillés (ISO 10211:2017)
Ta slovenski standard je istoveten z: EN ISO 10211:2017
ICS:
91.120.10 Toplotna izolacija stavb Thermal insulation of
buildings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 10211
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2017
EUROPÄISCHE NORM
ICS 91.120.10 Supersedes EN ISO 10211:2007
English Version
Thermal bridges in building construction - Heat flows and
surface temperatures - Detailed calculations (ISO
10211:2017)
Ponts thermiques dans les bâtiments - Flux thermiques Wärmebrücken im Hochbau - Wärmeströme und
et températures superficielles - Calculs détaillés (ISO Oberflächentemperaturen - Detaillierte Berechnungen
10211:2017) (ISO 10211:2017)
This European Standard was approved by CEN on 27 February 2017.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10211:2017 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 10211:2017) has been prepared by Technical Committee ISO/TC 163 "Thermal
performance and energy use in the built environment" in collaboration with Technical Committee
CEN/TC 89 “Thermal performance of buildings and building components” the secretariat of which is
held by SIS.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2018 and conflicting national standards shall
be withdrawn at the latest by January 2018.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association.
This document is part of the set of standards and accompanying technical reports on the energy
performance of buildings and has been prepared under a mandate given to CEN by the European
Commission and the European Free Trade Association (Mandate M/480, see reference [EF3] below).
Directive 2010/31/EU recasting the Directive 2002/91/EC on energy performance of buildings (EPBD,
[EF4]) promotes the improvement of the energy performance of buildings within the European Union,
taking into account all types of energy uses (heating, lighting, cooling, air conditioning, ventilation) and
outdoor climatic and local conditions, as well as indoor climate requirements and cost effectiveness
(Article 1).
The directive requires Member States to adopt measures and tools to achieve the prudent and rational
use of energy resources. In order to achieve those goals, the EPBD requires increasing energy efficiency
and the enhanced use of renewable energies in both new and existing buildings. One tool for this is the
application by Member States of minimum requirements on the energy performance of new buildings
and for existing buildings that are subject to major renovation, as well as for minimum performance
requirements for the building envelope if energy-relevant parts are replaced or retrofitted. Other tools
are energy certification of buildings, inspection of boilers and air-conditioning systems.
The use of European standards increases the accessibility, transparency and objectivity of the energy
performance assessment in the Member States facilitating the comparison of best practices and
supporting the internal market for construction products. The use of EPB standards for calculating
energy performance, as well as for energy performance certification and the inspection of heating
systems and boilers, ventilation and air-conditioning systems will reduce costs compared to developing
different standards at national level.
The first mandate to CEN to develop a set of CEN EPBD standards (M/343, [EF1]), to support the first
edition of the EPBD ([EF2]) resulted in the successful publication of all EPBD related CEN standards in
2007-2008.
Mandate M/480 was issued to review the mandate M/343 as the recast of the EPBD raised the need to
revisit the standards and reformulate and add standards so that they become on the one hand
unambiguous and compatible, and on the other hand a clear and explicit overview of the choices,
boundary conditions and input data that need to be defined at national or regional level. Such national
or regional choices remain necessary, due to differences in climate, culture and building tradition,
policy and legal frameworks. Consequently, the set of CEN EPBD standards published in 2007-2008 had
to be improved and expanded on the basis of the recast of the EPBD.
The EPB standards are flexible enough to allow for necessary national and regional differentiation and
facilitate Member States implementation and the setting of requirements by the Member States.
Further target groups are users of the voluntary common European Union certification scheme for the
energy performance of non-residential buildings (EPBD article 11.9) and any other regional (e.g. pan
European) parties wanting to motivate their assumptions by classifying the building energy
performance for a dedicated building stock.
This document supersedes EN ISO 10211:2007.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands,
Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
the United Kingdom.
References:
[EF1] EPBD, Directive 2002/91/EC of the European Parliament and of the Council of 16 December
2002 on the energy performance of buildings
[EF2] EPBD Mandate M/343, Mandate to CEN, CENELEC and ETSI for the elaboration and adoption of
standards for a methodology calculating the integrated energy performance of buildings and
estimating the environmental impact, in accordance with the terms set forth in Directive
2002/91/EC , 30 January 2004
[EF3] Mandate M/480, Mandate to CEN, CENELEC and ETSI for the elaboration and adoption of
standards for a methodology calculating the integrated energy performance of buildings and
promoting the energy efficiency of buildings, in accordance with the terms set in the recast of
the Directive on the energy performance of buildings (2010/31/EU), 14 December 2010
[EF4] EPBD, Recast of the Directive on the energy performance of buildings (2010/31/EU). 14
December 2010
Endorsement notice
The text of ISO 10211:2017 has been approved by CEN as EN ISO 10211:2017 without any modification.
INTERNATIONAL ISO
STANDARD 10211
Second edition
2017-06
Thermal bridges in building
construction — Heat flows and surface
temperatures — Detailed calculations
Ponts thermiques dans les bâtiments — Flux thermiques et
températures superficielles — Calculs détaillés
Reference number
ISO 10211:2017(E)
©
ISO 2017
ISO 10211:2017(E)
© ISO 2017, Published in Switzerland
All rights reserved. Unless otherwise specified, 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
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. +41 22 749 01 11
Fax +41 22 749 09 47
copyright@iso.org
www.iso.org
ii © ISO 2017 – All rights reserved

ISO 10211:2017(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2  Normative references . 1
3  Terms and definitions . 2
4 Symbols and subscripts . 7
4.1 Symbols . 7
4.2 Subscripts . 7
5  Description of the method . 8
5.1 Output . 8
5.2 General description . 8
6 Output data and input data . 8
6.1 Output data . 8
6.2 Calculation time intervals . 9
6.3 Input data . 9
7  Modelling of the construction . 9
7.1 Dimension systems . 9
7.2 Rules for modelling . 9
7.2.1 General. 9
7.2.2 Cut-off planes for a 3-D geometrical model for calculation of total heat
flow and/or surface temperatures . 9
7.2.3 Cut-off planes for a 2-D geometrical model .11
7.2.4 Cut-off planes in the ground .12
7.2.5 Periodic heat flows via the ground .13
7.2.6 Adjustments to dimensions .13
7.2.7 Auxiliary planes .15
7.2.8 Quasi-homogeneous layers and materials .15
7.3 Conditions for simplifying the geometrical model .15
7.3.1 General.15
7.3.2 Conditions for adjusting dimensions to simplify the geometrical model .16
7.3.3 Conditions for using quasi-homogeneous material layers to simplify the
geometrical model .17
8  Input data specifications .20
8.1 General .20
8.2 Thermal conductivities of materials .21
8.3 Surface resistances .21
8.4 Boundary temperatures .21
8.5 Thermal conductivity of quasi-homogeneous layers .21
8.6 Equivalent thermal conductivity of air cavities .21
8.7 Determining the temperature in an adjacent unheated room .22
9 Calculation method .22
9.1 Solution technique .22
9.2 Calculation rules .22
9.2.1 Heat flows between material cells and adjacent environment .22
9.2.2 Heat flows at cut-off planes .22
9.2.3 Solution of the formulae .22
9.2.4 Calculation of the temperature distribution .23
10  Determination of thermal coupling coefficients and heat flow rate from 3-D calculations 23
10.1 Two boundary temperatures, unpartitioned model .23
10.2 Two boundary temperatures, partitioned model .23
ISO 10211:2017(E)
10.3 More than two boundary temperatures .24
11  Calculations using linear and point thermal transmittances from 3-D calculations .25
11.1 Calculation of thermal coupling coefficient .25
11.2 Calculation of linear and point thermal transmittances .25
12  Determination of thermal coupling coefficient, heat flow rate and linear thermal
transmittance from 2-D calculations .26
12.1 Two boundary temperatures .26
12.2 More than two boundary temperatures .26
12.3 Determination of the linear thermal transmittance .27
12.4 Determination of the linear thermal transmittance for wall/floor junctions .27
12.4.1 All cases .27
12.4.2 Option A .27
12.4.3 Option B .29
12.5 Determination of the external periodic heat transfer coefficient for ground floors .31
13  Determination of the temperature at the internal surface .32
13.1 Determination of the temperature at the internal surface from 3-D calculations .32
13.1.1 Two boundary temperatures .32
13.1.2 More than two boundary temperatures .32
13.2 Determination of the temperature at the internal surface from 2-D calculations .33
13.2.1 Two boundary temperatures .33
13.2.2 Three boundary temperatures .33
14 Report .33
14.1 Input data .33
14.2 Output data .34
14.2.1 General.34
14.2.2 Calculation of the heat transmission using the thermal coupling coefficient .34
14.2.3 Calculation of the surface temperatures using weighting factors .34
14.2.4 Additional output data .34
14.2.5 Estimate of error .35
Annex A (normative) Input and method selection data sheet — Template .36
Annex B (informative) Input and method selection data sheet — Default choices .38
Annex C (normative) Validation of calculation methods .40
Annex D (normative) Examples of the determination of the linear and point
thermal transmittances.47
Annex E (normative) Determination of values of thermal coupling coefficient and
temperature weighting factor for more than two boundary temperatures .50
Bibliography .55
iv © ISO 2017 – All rights reserved

ISO 10211:2017(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/d irectives).
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/p atents).
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/i so/f oreword. html.
ISO 10211 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).
This second edition cancels and replaces the first edition (ISO 10211:2007), which has been technically
revised.
The changes in the second edition are mostly editorial. The standard has been re-drafted according
to CEN/TS 16629:2014.
ISO 10211:2017(E)
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.
More information is provided in the Technical Report accompanying this document (ISO/TR 52019-2).
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 internal 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;
vi © ISO 2017 – All rights reserved

ISO 10211:2017(E)
— 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 appliances, technical
building systems, indoor environment, etc.
This document sets out the specifications for a geometrical model of a thermal bridge for the numerical
calculation of linear thermal transmittances, point thermal transmittances and internal surface
temperatures.
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 Tables A.1 and B.1.
Table 1 — Position of this document (in casu M2–5) within the modular structure of the set of
EPB standards
Building
Overarching Technical Building Systems
(as such)
Building
Ven- Dehu- PV,
Sub- Descrip- Heat- Cool- Humidi- Domestic automa-
Descriptions Descriptions tila- midifi- Lighting wind,
module tions ing ing fication 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 ex- Ways to ex-
express
4 press energy press energy
energy per-
performance performance
formance
Building
Heat trans-
categories ISO Emission and
5 fer by trans-
and building 10211 control
mission
boundaries
a
The shaded modules are not applicable.
ISO 10211:2017(E)
Table 1 (continued)
Building
Overarching Technical Building Systems
(as such)
Building
Ven- Dehu- PV,
Sub- Descrip- Heat- Cool- Humidi- Domestic automa-
Descriptions Descriptions tila- midifi- Lighting wind,
module tions ing ing fication hot water tion and
tion cation .
control
sub1 M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11
Building oc- Heat trans-
cupancy and fer by infil- Distribution
operating tration and and control
conditions ventilation
Aggregation
of energy
Internal Storage and
7 services
heat gains control
and energy
carriers
Building Solar heat Generation
zoning gains and control
Building Load dis-
Calculated
dynamics patching and
9 energy per-
(thermal operating
formance
mass) conditions
Measured Measured Measured
10 energy per- energy per- Energy Per-
formance formance formance
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.
viii © ISO 2017 – All rights reserved

INTERNATIONAL STANDARD ISO 10211:2017(E)
Thermal bridges in building construction — Heat flows
and surface temperatures — Detailed calculations
1 Scope
This document sets out the specifications for a three-dimensional and a two-dimensional geometrical
model of a thermal bridge for the numerical calculation of
— heat flows, in order to assess the overall heat loss from a building or part of it, and
— minimum surface temperatures, in order to assess the risk of surface condensation.
These specifications include the geometrical boundaries and subdivisions of the model, the thermal
boundary conditions, and the thermal values and relationships to be used.
This document is based upon the following assumptions:
— all physical properties are independent of temperature;
— there are no heat sources within the building element.
This document can also be used for the derivation of linear and point thermal transmittances and of
surface temperature factors.
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.
ISO 6946, Building components and building elements — Thermal resistance and thermal transmittance —
Calculation method
ISO 7345, Thermal insulation — Physical quantities and definitions
ISO 13370, Thermal performance of buildings — Heat transfer via the ground — Calculation methods
ISO 13788, Hygrothermal performance of building components and building elements — Internal surface
temperature to avoid critical surface humidity and interstitial condensation — Calculation methods
ISO 10456, Building materials and products — Hygrothermal properties — Tabulated design values and
procedures for determining declared and design thermal values
ISO 13789, Thermal performance of buildings — Transmission and ventilation heat transfer coefficients —
Calculation method
ISO 52000-1:2017, Energy performance of buildings — Overarching EPB assessment — Part 1: General
framework and procedures
NOTE 1 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 in Table A.1) and Annex B (informative default choice in
Table B.1).
ISO 10211:2017(E)
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).
NOTE 2 In this document, there are no choices in references to other EPB standards. The sentence and note
above is kept to maintain uniformity between all EPB standards.
3  Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7345, 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
thermal bridge
part of the building envelope where the otherwise uniform thermal resistance is significantly changed
by full or partial penetration of the building envelope by materials with a different thermal conductivity,
and/or a change in thickness of the fabric, and/or a difference between internal and external areas,
such as occur at wall/floor/ceiling junctions
3.2
linear thermal bridge
thermal bridge (3.1) with a uniform cross-section along one of the three orthogonal axes
3.3
point thermal bridge
localized thermal bridge (3.1) whose influence can be represented by a point thermal transmittance (3.20)
3.4
three-dimensional geometrical model
3-D geometrical model
geometrical model, deduced from building plans, such that for each of the orthogonal axes, the cross-
section perpendicular to that axis changes within the boundary of the model
Note 1 to entry: See Figure 1.
3.5
three-dimensional flanking element
3-D flanking element
part of a 3-D geometrical model (3.4) which, when considered in isolation, can be represented by a
2-D geometrical model (3.7)
Note 1 to entry: See Figure 1 and Figure 2.
3.6
three-dimensional central element
3-D central element
part of a 3-D geometrical model (3.4) which is not a 3-D flanking element (3.5)
Note 1 to entry: See Figure 1.
Note 2 to entry: A central element is represented by a 3-D geometrical model (3.4).
2 © ISO 2017 – All rights reserved

ISO 10211:2017(E)
3.7
two-dimensional geometrical model
2-D geometrical model
geometrical model, deduced from building plans, such that for one of the orthogonal axes, the cross-
section perpendicular to that axis does not change within the boundaries of the model
Note 1 to entry: See Figure 2.
Note 2 to entry: A 2-D geometrical model is used for two-dimensional calculations.
3.8
two-dimensional flanking element
2-D flanking element
part of a 2-D geometrical model (3.7) which, when considered in isolation, consists of plane, parallel
material layers
Note 1 to entry: The plane, parallel material layers can be homogeneous or non-homogeneous.
3.9
two-dimensional central element
2-D central element
part of a 2-D geometrical model (3.7) which is not a 2-D flanking element (3.8)
3.10
construction plane
plane in the 3-D geometrical model (3.4) or 2-D geometrical model (3.7) which separates different
materials, and/or the geometrical model from the remainder of the construction, and/or the flanking
elements from the central element
Note 1 to entry: See Figure 3.
3.11
cut-off plane
construction plane (3.10) that is a boundary to the 3-D geometrical model (3.4) or 2-D geometrical model
(3.7) by separating the model from the remainder of the construction
Note 1 to entry: See Figure 3.
3.12
auxiliary plane
plane which, in addition to the construction planes (3.10), divides the geometrical model into a number
of cells
3.13
quasi-homogeneous layer
layer which consists of two or more materials with different thermal conductivities, but which can be
considered as homogeneous with an equivalent thermal conductivity
Note 1 to entry: See Figure 4.
3.14
temperature factor at the internal surface
difference between internal surface temperature and external temperature, divided by the difference
between internal temperature and external temperature, calculated with a surface resistance R at the
si
internal surface
3.15
temperature weighting factor
weighting factor which states the respective influence of the temperatures of the different thermal
environments upon the surface temperature at the point under consideration
ISO 10211:2017(E)
3.16
external boundary temperature
external air temperature, assuming that the air temperature and the radiant temperature seen by the
surface are equal
3.17
internal boundary temperature
operative temperature, taken as the arithmetic mean value of internal air temperature and mean
radiant temperature of all surfaces surrounding the internal environment
3.18
thermal coupling coefficient
heat flow rate per temperature difference between two environments which are thermally connected
by the construction under consideration
3.19
linear thermal transmittance
heat flow rate in the steady-state compared to a reference heat flow rate calculated disregarding the
thermal bridge (3.1), divided by length and by the temperature difference between the environments on
either side of a linear thermal bridge (3.2)
Note 1 to entry: The linear thermal transmittance is a quantity describing the influence of a linear thermal bridge
on the total heat flow.
3.20
point thermal transmittance
heat flow rate in the steady-state compared to a reference heat flow rate calculated disregarding the
thermal bridge (3.1), divided by the temperature difference between the environments on either side of
a point thermal bridge (3.3)
Note 1 to entry: The point thermal transmittance is a quantity describing the influence of a point thermal bridge
on the total heat flow.
3.21
EPB standard
[5]
standard that complies with the requirements given in ISO 52000-1, CEN/TS 16628 and
[6]
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 and support essential requirements of EU
Directive 2010/31/EU on the energy performance of buildings. Several EPB standards and related documents
are developed or revised under the same mandate.
[SOURCE: ISO 52000-1:2017, 3.5.14]
4 © ISO 2017 – All rights reserved

ISO 10211:2017(E)
Key
F1, F2, F3, F4, F5 3-D flanking elements
C 3-D central element
NOTE 3-D Flanking elements have constant cross-sections perpendicular to at least one axis; the 3-D central
element is the remaining part.
Figure 1 — 3-D geometrical model with five 3-D flanking elements and one 3-D central element
Key
F1, F2, F3, F4, F5 3-D flanking elements
NOTE F2 to F5 refer to Figure 1.
Figure 2 — Cross-sections of the 3-D flanking elements in a 3-D geometrical model
treated as 2-D geometrical models
...