EN ISO 14505-2:2026

SLOVENSKI STANDARD
01-november-2026
Nadomešča:
SIST EN ISO 14505-2:2007/AC:2009
Ergonomija toplotnega okolja - Vrednotenje toplotnega okolja v vozilih - 2. del:
Ugotavljanje ekvivalentne temperature (ISO 14505-2:2026)
Ergonomics of the thermal environment - Evaluation of thermal environments in vehicles
- Part 2: Determination of equivalent temperature (ISO 14505-2:2026)
Ergonomie der thermischen Umgebung - Beurteilung der thermischen Umgebung in
Fahrzeugen - Teil 2: Bestimmung der Äquivalenttemperatur (ISO 14505-2:2026)
Ergonomie des ambiances thermiques - Évaluation des ambiances thermiques dans les
véhicules - Partie 2: Détermination de la température équivalente (ISO 14505-2:2026)
Ta slovenski standard je istoveten z: EN ISO 14505-2:2026
ICS:
13.180 Ergonomija Ergonomics
43.020 Cestna vozila na splošno Road vehicles in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 14505-2
EUROPEAN STANDARD
NORME EUROPÉENNE
August 2026
EUROPÄISCHE NORM
ICS 13.180; 43.020 Supersedes EN ISO 14505-2:2006
English Version
Ergonomics of the thermal environment - Evaluation of
thermal environments in vehicles - Part 2: Determination
of equivalent temperature (ISO 14505-2:2026)
Ergonomie des ambiances thermiques - Évaluation des Ergonomie der thermischen Umgebung - Beurteilung
ambiances thermiques dans les véhicules - Partie 2: der thermischen Umgebung in Fahrzeugen - Teil 2:
Détermination de la température équivalente (ISO Bestimmung der Äquivalenttemperatur (ISO 14505-
14505-2:2026) 2:2026)
This European Standard was approved by CEN on 20 July 2026.

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,
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Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14505-2:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 14505-2:2026) has been prepared by Technical Committee ISO/TC 159
"Ergonomics" in collaboration with Technical Committee CEN/TC 122 “Ergonomics” the secretariat of
which is held by DIN.
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 February 2027, and conflicting national standards
shall be withdrawn at the latest by February 2027.
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 supersedes EN ISO 14505-2:2006.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 14505-2:2026 has been approved by CEN as EN ISO 14505-2:2026 without any
modification.
International
Standard
ISO 14505-2
Second edition
Ergonomics of the thermal
2026-08
environment — Evaluation of
thermal environments in vehicles —
Part 2:
Determination of equivalent
temperature
Ergonomie des ambiances thermiques — Évaluation des
ambiances thermiques dans les véhicules —
Partie 2: Détermination de la température équivalente
Reference number
ISO 14505-2:2026(en) © ISO 2026

ISO 14505-2:2026(en)
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 14505-2:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Assessment principles . 2
4.1 General .2
4.2 General description of equivalent temperature .3
4.3 General determination principle of equivalent temperature .3
5 Specific equivalent temperatures . 4
5.1 General .4
5.2 Whole body equivalent temperature . .4
5.2.1 Determination principle .4
5.2.2 Calculation .4
5.3 Segmental equivalent temperature .5
5.3.1 Determination principle .5
5.3.2 Calculation .5
5.4 Directional equivalent temperature .5
5.4.1 Determination principle .5
5.4.2 Calculation .6
5.5 Omnidirectional equivalent temperature .6
5.5.1 Determination principle .6
5.5.2 Calculation .7
6 Measuring instruments . 7
7 Assessment . . 8
7.1 General .8
7.2 Determination of whole body equivalent temperature .8
7.2.1 General .8
7.2.2 Determination with omnidirectional sensors .8
7.2.3 Determination with a thermal manikin .8
7.3 Determination of local equivalent temperature .8
7.3.1 General .8
7.3.2 Determination with omnidirectional sensors or flat, heated sensors .8
7.3.3 Determination with a thermal manikin .9
8 Equivalent contact temperature . 9
8.1 General .9
8.2 Calculation methodology.9
Annex A (informative) Examples of measuring instruments . 14
Annex B (informative) Characteristics and specifications of measuring instruments . 17
Annex C (informative) Calibration and other determinations .22
Annex D (informative) Interpretation of equivalent temperature .24
Annex E (informative) Examples .28
Bibliography .32

iii
ISO 14505-2:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 5,
Ergonomics of the physical environment, in collaboration with the European Committee for Standardization
(CEN) Technical Committee CEN/TC 122, Ergonomics, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 14505-2:2006/Cor 1:2007), which has been
technically revised.
The main change is as follows:
— addition of an evaluation method for the contact areas (equivalent contact temperature).
A list of all parts in the ISO 14505 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
ISO 14505-2:2026(en)
Introduction
The interaction of convective, radiative and conductive heat exchange in a vehicle compartment is very
complex. External thermal loads in combination with the internal heating and ventilation system of the
vehicle create a local climate that can vary considerably in space and time. Asymmetric thermal conditions
arise, and these are often the main cause of complaints of thermal discomfort. In vehicles without or with
poor heating, ventilating and air-conditioning system (HVAC-system), thermal stress is determined largely
by the impact of the ambient climatic conditions on the vehicle compartment.
Subjective evaluation is integrative, as the individual combines into one reaction the combined effect
of several thermal stimuli. However, it is not sufficiently detailed or accurate for repeated use. Technical
measurements provide detailed and accurate information but must be integrated in order to predict the
thermal effects on humans. Since several climatic factors play a role for the final heat exchange of a person,
these factors must be integrated to a measure, representing their relative importance.
This document includes the equivalent temperature models t for the assessment of the thermal conditions.
eq
For special consideration of the seat, the equivalent contact temperature t can be applied for body
eq,cont
compartments in contact to surfaces. Methods for the calculation of t using thermal factors are described
eq
in ISO 14505-4. The methodology described in this document can also be used in specific performance
standards for testing of HVAC-systems for vehicles and similar confined spaces.

v
International Standard ISO 14505-2:2026(en)
Ergonomics of the thermal environment — Evaluation of
thermal environments in vehicles —
Part 2:
Determination of equivalent temperature
1 Scope
This document specifies requirements and recommendations for the assessment of the thermal conditions
inside a vehicle compartment. It can also be applied to other confined spaces with asymmetric climatic
conditions.
It applies to the assessment of thermal conditions, when deviations from thermal neutrality are relatively
small.
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 13731, Ergonomics of the thermal environment — Vocabulary and symbols
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13731 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
equivalent temperature
t
eq
temperature of a standard homogenous space, in which a person exchanges the same heat loss by convection
and radiation as in the actual conditions under assessment
Note 1 to entry: The standard homogenous space is defined as an environment in which the mean radiant temperature
is equal to the air temperature and there is zero air velocity.
3.2
whole body equivalent temperature
t
eq,whole
temperature of an imaginary enclosure with the same temperature in air and on surrounding surfaces and
with air velocity equal to zero in which a full-scale, human shaped, heated sensor will exchange the same
dry heat by radiation and convection as in the actual non-uniform environment

ISO 14505-2:2026(en)
3.3
segmental equivalent temperature
t
eq,segment
uniform temperature of an imaginary enclosure with the same temperature in air and on surrounding
surfaces and with air velocity equal to zero in which one or more selected zones of a thermal manikin will
exchange the same dry heat by radiation and convection as in the actual non-uniform environment
3.4
directional equivalent temperature
t
eq,direct
uniform temperature of an imaginary enclosure with the same temperature in air and on surrounding
surfaces and with air velocity equal to zero in which a small flat heated surface will exchange the same dry
heat by radiation and convection as in the actual non-uniform environment
3.5
omnidirectional equivalent temperature
t
eq,omni
uniform temperature of an imaginary enclosure with the same temperature in air and on surrounding
surfaces and with air velocity equal to zero in which a heated ellipsoid will exchange the same dry heat by
radiation and convection as in the actual non-uniform environment
3.6
equivalent contact temperature
t
eq,cont
uniform temperature of an imaginary contact surface in a standard homogeneous space, at which a person
will exchange the same amount of dry heat through thermal conduction for a virtual clothing insulation as
in the actual non-uniform environment
Note 1 to entry: The standard homogenous space is defined as an environment in which the mean radiant temperature
is equal to the air temperature and there is zero air velocity. In the actual non-uniform environment, the person
experiences sensible and latent heat transfer at the considered body parts.
3.7
segment
part of a human-shaped sensor, normally corresponding to a real body-part, consisting of one or several
whole zones, for which a segmental equivalent temperature, t , is presented
eq,segment
3.8
zone
physical partition of a manikin, which is independently regulated and within which the surface temperature
and heat exchange is measured
3.9
heating, ventilating and air-conditioning system
HVAC-system
devices that control the temperature, humidity, and purity of the air in an enclosed space
4 Assessment principles
4.1 General
The assessment principle is based on the measurement of the equivalent temperature. The equivalent
temperature provides a unified, physical measure of the climatic effects on the human dry heat exchange.
On the basis of the actual value for, and the variation in, equivalent temperature, it is possible to predict
the conditions for heat balance under conditions in or close to the thermoneutral zone. People’s thermal
sensation is primarily influenced by general and local levels and variations in skin surface heat flux. Values
for the equivalent temperature of a specified environment have been found to be closely related to how
[12]
people perceive thermal conditions when exposed to the same environment. This can be used for the
interpretation of the t value and assessment of the quality of the environment.
eq
ISO 14505-2:2026(en)
The climate is assessed in terms of a total equivalent temperature, which describes the level of thermal
neutrality.
The climate is also assessed for local effects on specified parts of the human body surface. The local
equivalent temperatures determine to what extent the actual body parts fall within the range of acceptable
levels of heat loss (local discomfort).
4.2 General description of equivalent temperature
The equivalent temperature is a pure physical quantity, that in a physically sound way integrates the
independent effects of convection and radiation on human body heat exchange. This relationship is best
described for the overall (whole body) heat exchange. There is limited experience with relations between
local dry heat exchange and local equivalent temperature. The standardized definition of t applies only
eq
for the whole body. Therefore, the definition is modified for the purposes of this document. t does not take
eq
into account human perception and sensation or other subjective aspects. However, empirical studies show
that t values are well related to the subjective perception of the thermal effect.
eq
4.3 General determination principle of equivalent temperature
Determination of t is based on Formula (1) and (2) for convective and radiative heat transfer for clothed
eq
persons. Heat exchange by conduction is assumed to be small and accounted for by radiation and convection.
Rh=× tt (1)

rskr
Ch=× tt (2)

cska
where
R is heat exchange by radiation, in watts per square metre (W/m );
C is heat exchange by convection, in watts per square metre (W/m );
h is the radiation heat transfer coefficient, in watts per square metre Kelvin [W/(m K)];
r
h is the convection heat transfer coefficient, in watts per square metre Kelvin [W/(m K)];
c
t is the skin temperature, in degrees Celsius (°C);
sk
t is the mean radiant temperature, in degrees Celsius (°C);
r
t is the ambient air temperature, in degrees Celsius (°C).
a
In practice, the equivalent temperature is determined according to Formula (3) based on the measured
convective and radiative heat losses (Formula (4)):
Q
tt= − (3)
eq s
h
cal
QR=+C (4)
where
t is the surface temperature, in degrees Celsius (°C);
s
t is the temperature of the standard environment, in degrees Celsius (°C);
eq
Q is the measured convective and radiative heat loss during the actual conditions, in watts per
square metre (W/m );
h is the combined heat transfer coefficient, determined during calibration in a standard
cal
environment, in watts per square metre Kelvin [W/(m K)].
The standard environment comprises homogenous, uniform thermal conditions with t = t and air velocity
a
r
v , < 0,1 m/s. A suitable calibration procedure is described in the informative Annex C.
a
ISO 14505-2:2026(en)
5 Specific equivalent temperatures
5.1 General
As there is no method available for measurement of the true total or local t , four specific equivalent
eq
temperatures are calculated according to different principles, according to 5.2 to 5.5. Depending on the
measuring principles, the following are specified, which are further described in Reference [13]:
a) whole body equivalent temperature;
b) segmental equivalent temperature;
c) directional equivalent temperature;
d) omnidirectional equivalent temperature.
5.2 Whole body equivalent temperature
5.2.1 Determination principle
The principle of determination is to measure the total heat flow from a human-sized test manikin consisting
of several zones, each with a specific measured surface temperature similar to that of a human being.
Theoretically, whole body equivalent temperature can be measured with thermal manikins or a large
number of flat heated sensors attached to an unheated manikin. The accuracy of the result is depending
on surface temperature, size of body, number and division of zones, posture etc. An appropriate method
to use is a thermal manikin divided into separate, individually heated zones covering the whole body, with
surface temperatures close to that of a real human being. A human-sized manikin with only one zone will
not determine a realistic whole body t because the thermal conditions vary too much over the surface. The
eq
more zones the manikin has, the more correct value it will measure.
5.2.2 Calculation
The calculation of the whole body equivalent temperature is based on the Formula (5) depending on the
whole body skin temperature, determined by Formula (6), and whole body heat loss, determined by
Formula (7).
Q
whole
tt= − (5)
eq,whole sk,whole
h
cal,whole
tA


sk,n n
t = (6)
sk,whole
A

n
QA


nn
Q = (7)
whole
A

n
where
A is a weighting factor based on the surface area;
h is determined by calibration in a standard environment (see informative Annex C);
cal,whole
n is the number of zones of the body (0 < n ≤ N).
In order to be able to compare results from other manikins, the measured t should be presented together
eq
with specifications of the manikin used, such as regulation principle, skin temperature, number of zones etc.
(see informative Annexes A and B).

ISO 14505-2:2026(en)
5.3 Segmental equivalent temperature
5.3.1 Determination principle
The principle of determination is to measure the total heat flow from a segment consisting of one or more
zones, each with a specific measured surface temperature similar to that of a human being.
The segmental t is based on the heat flow from a certain part of the body, i.e. a segment, such as hand,
eq
head or chest. The segmental t can only be measured with a full-sized, human-shaped heated sensor,
eq
e.g. a thermal manikin. The number of zones and the partition between them shall at least be such that it
corresponds to the actual segment that the segmental t should be measured for. Some segments, e.g. thigh,
eq
shall be divided into at least two zones within the segment, because the thermal conditions are different on
the front and the rear (seat contact) side in the case of the thigh.
5.3.2 Calculation
The calculation of the segmental equivalent temperature is based on the Formula (8) depending on
the segmental skin temperature, determined by Formula (9), and segmental heat loss, determined by
Formula (10).
Q
segment
tt= − (8)
eq,segment sk,segment
h
cal,segment
tA


sk,n n
t = (9)
sk,segment
A

n
QA


nn
Q = (10)
segment
A

n
where
h is determined by calibration in a standard environment (see informative Annex C);
cal,segment
N is the number of zones of the body (0 < n ≤ N).
The segment can be freely chosen, but it shall consist of one or more whole zones. Normally, body parts
like head, hands, arms, feet, legs, chest, back and seat are chosen. To be able to compare results from other
measurements, the measured t should be presented with specifications about the segment used, such
eq
as regulation principle, surface temperature, which body part, number, size and partition of zones of the
segment (see informative Annexes A and B).
5.4 Directional equivalent temperature
5.4.1 Determination principle
The principle of determination is to measure the total heat flow from a small flat surface with a measured
surface temperature. The directional t can be described as a normal vector to the measuring plane in every
eq
point, defined by magnitude and direction. It refers to the heat exchange within the half-sphere in front of
the infinitesimal plane. The directional t can only be measured with a flat sensor, which can be attached to
eq
an unheated manikin or other positioning device. Several sensors can be used simultaneously to determine
directional t at other locations or in other directions, provided that they are positioned so that they do not
eq
influence each other.
ISO 14505-2:2026(en)
5.4.2 Calculation
The calculation of the directional equivalent temperature is based on the Formula (11) depending on the
heat flow from the sensor.
Q
direct
tt= − (11)
eq,directsk,direct
h
cal,direct
where
t is the surface temperature of the sensor;
sk,direct
Q is the heat flow from the sensor;
direct
h is determined by calibration of the sensor in a standard environment (see informative Annex C).
cal,direct
A local equivalent temperature, t , can be calculated as an average value from several measurements
eq,local
at the same location but in different directions. It can be calculated as an arithmetic mean value without
weighting factors as shown in Formula (12) or with weighting as shown in Formula (13) to simulate a certain
body posture.
t
∑
eq,direct,n
t = (12)
eq,local
n
where n is the number of directions.
tt= A (13)


eq,local eq,direct,nn
where n is the number of measurements, with Σ(A ) = 1, and A represents body postures.
n
A total equivalent temperature can be calculated as a weighted mean value of local equivalent temperatures
as shown in Formula (14).
tt= A (14)


eq,total eq,local,nn
where n is the number of locations, with Σ(A ) = 1.
n
In order to be able to compare results from other measurements, the measured t should be presented
eq
with specifications about the sensor used, such as regulation principle, surface temperature, size and also
location and direction of the sensor (see informative Annexes A and B). Whole body t and total t is not
eq eq
the same. In an asymmetric climate and with seat contact, the difference between them will be considerable.
5.5 Omnidirectional equivalent temperature
5.5.1 Determination principle
The principle of determination is to measure the total heat flow from the surface of an ellipsoid with a
measured surface temperature. The omnidirectional t can be described as the weighted mean value of
eq
the directional t in all directions. The weighting factors for the different directions are dependent of the
eq
form of the ellipsoid. It refers to the heat exchange in all directions. The omnidirectional t can only be
eq
measured with an ellipsoid sensor with uniform heat flow over the surface. One or more sensors can be used
simultaneously. If more than one sensor is used, it shall be pointed out that the sensors will influence each
other as hot surfaces in the sphere that is measured.

ISO 14505-2:2026(en)
5.5.2 Calculation
The calculation of the omnidirectional equivalent temperature is based on the Formula (15) depending on
the heat flow from the sensor.
Q
omni
tt= − (15)
eq,omnisk,omni
h
cal,omni
where
t is the surface temperature of the sensor;
sk,omni
Q is the heat flow from the sensor;
omni
h is determined by calibration of the sensor in a standard environment (see informative Annex C).
cal,omni
Omnidirectional t determined with one ellipsoid sensor in an asymmetric climate is a local t . A total t
eq eq eq
can be calculated as an arithmetic mean value from sensors at different locations with weighting factors for
different body parts according to SAE-J-2234 as shown in Formula (16).
tt=A (16)

eq,total eq,loca,ln n
where n is the number of locations, with Σ(A ) = 1.
n
In order to be able to compare results from other measurements, the measured t should be presented
eq
with specifications about the sensor used, such as regulation principle, surface temperature, size and also
location and direction of the sensor (see informative Annexes A and B).
6 Measuring instruments
Several measurement methods and instruments, representing different measuring principles, are given in
informative Annexes A and B. Depending on needs, a method given in informative Annex A can be selected.
Measurement values obtained with principally different methods are not comparable with each other. They
represent different levels in terms of:
— reliability;
— relevance;
— validity;
— repeatability;
— accuracy;
— integration;
— complexity;
— cost;
— availability.
Performance and requirements of the specific methods are given in informative Annex B. Requirements for
calibration procedures are given in informative Annex C.

ISO 14505-2:2026(en)
7 Assessment
7.1 General
The equivalent temperature represents a quantitative assessment of the conditions for physical heat
exchange. The numeric value of t is a temperature level that can come close to “normal” expected room
eq
temperatures. Higher t values indicate lower heat losses (“warmer”), while lower t values indicate higher
eq eq
heat losses (“colder”).
The interpretation of equivalent temperature in terms of anticipated perceived thermal sensation is based
on series of experiments with participants in which the different types of equivalent temperature have
been measured. Examples of interpretation are given in informative Annex C. For some types of equivalent
temperature, data are not available for comparison with human responses. Nevertheless, these kinds of
measurement can be used for differential measurements of thermal conditions. Application examples for t
eq
are given in informative Annex E.
7.2 Determination of whole body equivalent temperature
7.2.1 General
Determination of whole body equivalent temperature should preferably be done with measurements using
a thermal manikin or by integration of discrete measurements using omnidirectional sensors placed at
specified positions in the vehicle cabin.
7.2.2 Determination with omnidirectional sensors
Omnidirectional sensors are described in informative Annexes A and B. Sensors are placed on a stand
simulating a person and placed in a seat of the vehicle. At least six sensors are placed in relevant positions and
measurements are made when steady state is achieved. Whole body equivalent temperature is determined
as the area-weighted average of the individual sensors. Interpretation of values should be made according to
informative Annex D.
7.2.3 Determination with a thermal manikin
Requirements for the manikin and procedures are described in informative Annexes A and B. The manikin
is placed in a seat in the vehicle and whole-body heat loss is measured when steady state conditions are
achieved. Whole body heat loss is the area-weighted average of the independent segments of the manikin.
Interpretation of values should be made according to informative Annex D.
7.3 Determination of local equivalent temperature
7.3.1 General
Determination of whole body equivalent temperature should preferably be done with measurements using a
thermal manikin or by the integration of discrete measurements using omnidirectional sensors.
7.3.2 Determination with omnidirectional sensors or flat, heated sensors
Omnidirectional sensors are described in informative Annex A. Sensors are placed on a stand simulating
a person and placed in a seat of the vehicle or at specified spots on the surface of the clothing of a person
or a manikin. Measurements are made when steady state is achieved. Local equivalent temperature is
determined as the value of the individual sensor. The more sensors located in the space, the better resolution
of the variation in the thermal field around the human body.

ISO 14505-2:2026(en)
7.3.3 Determination with a thermal manikin
Requirements for the manikin and procedures are described in informative Annexes A and B. The manikin
is placed in a seat in the vehicle and heat loss is measured from a local segment of the manikin when steady
state conditions are achieved. Local equivalent temperature is determined by the measured value of the
individual segment and represent that particular segment only. Interpretation of values should be made
according to informative Annex D.
8 Equivalent contact temperature
8.1 General
The heat exchange between a person and a contacting surface by heat conduction as well as moisture is not
negligible and has a significant influence on the thermal sensation. An example of the compensation effect
of seat heating is given in informative Annex E. The calculation of the equivalent contact temperature t
eq,cont
is based on the equations for heat conduction as well as latent and sensible heat exchange between a clothed
person and the contacting surfaces.
As shown in Figure 1, the principles for specification of the equivalent contact temperature t and
eq,cont
equivalent temperature t are similar to each other and both depend on the air velocity v in the real
eq air
environment. In the equivalent temperature model, the equivalent heat flux q depends on the convective
eq
q and radiant heat fluxes q in the real environment with the determined radiant temperature t , air
conv rad r
temperature t and skin temperature t . The equivalent contact temperature t includes the detailed
air skin eq,cont
description of the thermodynamic situation at the contact interface between a seat and the human body
surface. Here, the equivalent heat flux q depends on the combined effect of heat conduction through
eq,cont
the clothing q and the seat q as well as the change in enthalpy due to sensible and latent heat transfer
clo seat
in the real environment, such as by the moisture flow from skin to contact area q . These mechanisms can
evp
be influenced by the use of mechanically induced air flow rates (e.g. seat ventilation, q - q ) or heat
air,out air,in
sources (e.g. seat heating, q ).
heat
This clause describes an index for evaluating the thermal comfort of seats. A measure for the palm area
can be derived on the base of the contact temperature defined in ISO/TS 13732-2. This t evaluation
eq,cont
method is basically based on experiments with participants, but it can also be applied to evaluations using
thermal manikins, as described in Clause 7, by replacing the evaporation effects of perspiration on the seat
contact surface with a theoretical model. This means a suitable theoretical sweating model is available for
evaluating t with a thermal manikin instead of a participant.
eq,cont
8.2 Calculation methodology
As can be seen from Figure 1, the calculation of t is based on the balance of heat flux densities at an
eq,cont
infinitesimal volume element (green area). The equivalent heat flux q [see Figure 1 b), right-hand
eq,cont
side] depends on the heat fluxes in the real environment [see Figure 1 b), left-hand side] according to the
equations in the centre of Figure 1 b). The volume element is represented by node K at which the energy
balance is performed. Furthermore, K represents the contact interface between the human body and any
kind of contacting surface.
ISO 14505-2:2026(en)
a)
b)
NOTE The t is described using a nodal energy balance at node K (left-hand side: heat fluxes in real
eq,cont
environment, right-hand side: heat flux in equivalent environment with a calibrated insul
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