ISO/FDIS 14505-1

ISO/DISFDIS 14505-1:2025(en)
ISO /TC 159/SC 5
Secretariat: BSI
Date: 2025-06-252026-01-12
Ergonomics of the thermal environment — Evaluation of thermal
environments in vehicles —
Part 1:
Principles and methods for assessment of thermal stress
Ergonomie des ambiances thermiques — Évaluation des ambiances thermiques dans les véhicules —
Partie 1: Principes et méthodes d'évaluation de la contrainte thermique
FDIS stage
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Published in Switzerland
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ISO/DISFDIS 14505-1:20252026(en)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Assessment principles . 2
5 Methods for measurement of in-vehicle climate . 4
5.1 General . 4
5.2 Thermal comfort . 4
5.3 Heat stress . 5
5.4 Cold stress. 5
5.5 Metabolic rate and clothing. 6
6 Assessment by means of a numerical manikin . 6
7 Assessment by means of participants . 6
Annex A (informative) Measurement or estimation of metabolism and clothing characteristics . 7
Annex B (informative) Examples of thermal stress assessment . 8
Bibliography . 10

iii
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
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This document was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 5,
Ergonomics of the physical environment.
This first edition of ISO 14505-1 cancels and replaces ISO/TS 14505-1:2007.
The main change is as follows:
— inclusion of information from ISO 14505-4:2021.
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.
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ISO/DISFDIS 14505-1:20252026(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.
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DRAFT International Standard ISO/DIS 14505-1:2025(en)

Ergonomics of the thermal environment — Evaluation of thermal
environments in vehicles — —
Part 1:
Principles and methods for assessment of thermal stress
1 Scope
This document gives guidelines for the assessment of thermal stress inside vehicles used for land, sea and air
operation. It offers information about the assessment of hot, cold as well as moderate thermal environments
by referring to different methods and specifying the constraints and necessary adjustments for the special
case of vehicle climate assessment.
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 3.1
cold stress
climatic conditions under which body heat loss is just equal to, or too large for, heat balance at the expense of
significant and sometimes uncompensated physiological strain
3.2 3.2
equivalent temperature
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.
3.3 3.3
heat stress
climatic conditions under which the body heat loss is just equal to, or too small for, heat balance at the expense
of significant and sometimes uncompensated physiological strain (heat storage)
3.4 3.4
local equivalent temperature
temperature of a homogenous “room”, with mean radiant temperature equal to air temperature and zero air
velocity, in which a defined zone of the human body surface exchanges the same heat loss by convection and
radiation as in the actual conditions under assessment
3.5 3.5
numerical manikin
virtual thermal manikin recreating a thermal manikin, or a digital model of a thermal manikin used to calculate
performance
3.6 3.6
thermoneutral zone
temperature interval within which the body maintains heat balance exclusively by vasomotor reactions
3.7 3.7
vehicle
confined, normally fully enclosed, space of a mobile or stationary unit intended for transportation of or
operation by humans
3.8 3.8
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
The thermal environment in a vehicle changes as a function of the external climatic conditions and the quality
and capacity of the HVAC-system of the cabin. Most vehicles are able to supply heating or cooling of the cabin
under adverse external climatic conditions, thus reducing the extreme levels of climatic stress. However, in
simple vehicles and during break-down of the HVAC-system, the operator can possibly be subjected to high
levels of thermal stress.
The assessment of the thermal conditions in vehicles is based on three types of effect on the operator,
illustrated in Figure 1Figure 1::
a) a) heat stress (hot climate);
b) b) thermal discomfort (moderate climate);
c) c) cold stress (cold climate).
For all three types, an analysis of the actual conditions is made using methods described in existing
International standards or similar documents (see Figure 1Figure 1).). The evaluation focuses on the stress on
the exposed individual (stress test).
The methods do not provide information on the performance of the vehicle HVAC-system, as the external
conditions are not standardized, but are subject to evaluation in combination with the system. Performance
tests require standardized environmental conditions and focus on the evaluation of the performance of the
HVAC-system under standardized conditions (see example in Annex BAnnex B).). Recommendations for this
kind of test are given in ISO 14505-2.
If no test facilities are available, or if the prototype vehicles are incomplete, the performance evaluation can
be carried out by numerical simulation using a numerical manikin. Recommendations for this type of
simulation are given in ISO 14505-4. When the prototype vehicles are complete, the assessment can be carried
ISO/DISFDIS 14505-1:20252026(en)
out by measurement. Recommendations for the measurement and assessment are given in ISO 14505-2 and
other related standards (see Clause 5Clause 5).). Finally, the subjective assessment of the thermal conditions,
both as a result of thermal stress or as part of performance tests, can be carried out on the basis of ISO 14505-
3. For people with special requirements, assessment can be made by using ISO 28803.

Figure 1 — Schematic illustration of principles for climate evaluation
5 Methods for measurement of in-vehicle climate
5.1 General
This clause provides information on suggested methods for use in various types of thermal stress in vehicles
under driving conditions. Additional information for the actual assessment is given in Annex AAnnex A and
examples are given in Annex BAnnex B.
5.2 Thermal comfort
5.2.1 General
The achievement of thermally comfortable conditions in a vehicle cabin is the aim of the HVAC-system. Most
systems are able to create more or less comfortable climates after an in
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