ISO 14505-1:2026

Ergonomics of the thermal environment — Evaluation of thermal environments in vehicles — Part 1: Principles and methods for assessment of thermal stress

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.

Ergonomie des ambiances thermiques — Évaluation des ambiances thermiques dans les véhicules — Partie 1: Principes et méthodes d'évaluation de la contrainte thermique

L'ISO 14505-1:2007 fournit des directives relatives à l'évaluation de la contrainte thermique dans les véhicules utilisés pour le transport terrestre, maritime et aérien. Elle fournit des informations relatives à l'évaluation des ambiances thermiques chaudes, froides et modérées, en se référant aux différentes méthodes spécifiées dans les Normes internationales et en spécifiant les contraintes et ajustements requis pour le cas particulier de l'évaluation du climat dans les véhicules.

General Information

• Status: Published
• Publication Date: 07-May-2026
• ICS: 13.180 - Ergonomics
• ICS: 43.020 - Road vehicles in general
• Technical Committee: ISO/TC 159/SC 5 - Ergonomics of the physical environment
• Drafting Committee: ISO/TC 159/SC 5 - Ergonomics of the physical environment
• Current Stage: 6060 - International Standard published
• Start Date: 08-May-2026
• Due Date: 27-Apr-2026
• Completion Date: 08-May-2026

Relations

• Revises: ISO/TS 14505-1:2007 - Ergonomics of the thermal environment — Evaluation of thermal environments in vehicles — Part 1: Principles and methods for assessment of thermal stress
• Effective Date: 29-Apr-2023

Overview

ISO 14505-1:2026 outlines principles and methods for the assessment of thermal stress within vehicle environments. Developed by the International Organization for Standardization (ISO), this standard provides guidelines to evaluate how hot, cold, or moderate thermal conditions impact the occupants of vehicles used in land, sea, and air operations. The document addresses unique challenges present in vehicle climates, such as spatial and temporal variations influenced by external factors and HVAC systems. By referencing established measurement and evaluation methods, ISO 14505-1:2026 specifies adaptations critical for accurate vehicle climate assessments.

Key Topics

• Thermal Stress in Vehicles: Assessment of both heat stress (hot climates) and cold stress (cold climates), with consideration for moderate environments and thermal comfort.
• Assessment Principles:
  • Heat stress, thermal comfort, and cold stress are evaluated using objective measurements and, where suitable, subjective evaluations by participants.
  • Integration of environmental factors including air temperature, radiant temperature, air velocity, and humidity.
• Measurement Methods:
  • Use of whole-body indices such as Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD).
  • Evaluation of equivalent temperature for both whole body and local body zones to assess thermal neutrality and asymmetrical effects.
  • Application of numerical manikin simulations when physical prototypes are incomplete.
  • Performance testing of HVAC systems under standardized climatic conditions when possible.
• Participant-Based Assessment: Complementing technical measurements with human subjects to capture individual variation in thermal response.

Applications

• Vehicle Design and Evaluation: Manufacturers and designers can use ISO 14505-1 to assess and optimize cabin climate conditions for driver and passenger comfort and safety across a variety of vehicle types.
• Testing and Compliance: Laboratories and organizations conducting climate testing in vehicles can apply the standardized procedures for measuring heat and cold stress, supporting regulatory compliance and product certification processes.
• Performance Optimization: The standard assists in evaluating the effectiveness of HVAC systems under real or simulated environmental conditions, guiding improvements in energy efficiency and passenger comfort.
• Occupational Health: Fleet operators and health and safety managers benefit by understanding the limits of safe thermal exposures for vehicle operators, helping to prevent thermal injuries and promote well-being.
• HVAC Development: Engineers developing or benchmarking vehicle heating, ventilation, and air conditioning systems will find value in the structured assessment methods for both whole-cabin and localized climate analysis.
• Special Requirements: The standard considers the needs of individuals with specific thermal needs, referring to supportive standards for diverse occupant groups.

Related Standards

To ensure comprehensive and accurate assessment of vehicle thermal environments, ISO 14505-1:2026 references several related international standards:

• ISO 13731: Ergonomics of the thermal environment - Vocabulary and symbols.
• ISO 7730: Analytical determination and interpretation of thermal comfort using PMV and PPD indices.
• ISO 7243: Assessment of heat stress using the Wet Bulb Globe Temperature (WBGT) index.
• ISO 11079: Determination and interpretation of cold stress and required clothing insulation (IREQ).
• ISO 14505-2: Determination of equivalent temperature in vehicles.
• ISO 14505-3: Evaluation of thermal comfort using human subjects.
• ISO 14505-4: Determination of equivalent temperature by means of a numerical manikin.
• ISO 8996: Determination of metabolic rate.
• ISO 9920: Estimation of clothing insulation and water vapour resistance.
• ISO 13732 (all parts): Assessment of human responses to contact with surfaces.

Utilizing these standards in conjunction with ISO 14505-1:2026 allows stakeholders to achieve robust and internationally credible assessment of thermal environments in vehicles, advancing occupant safety, comfort, and performance.

Standards Content (Sample)

International
Standard
ISO 14505-1
First edition
Ergonomics of the thermal
2026-05
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
Reference number
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
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 . 3
5.1 General .3
5.2 Thermal comfort .3
5.2.1 General .3
5.2.2 Whole body evaluation .3
5.2.3 Detailed evaluation using equivalent temperature .4
5.3 Heat stress .4
5.3.1 General .4
5.3.2 Solar radiation .4
5.3.3 Air velocity . . .5
5.3.4 Evaporative heat exchange .5
5.4 Cold stress .5
5.5 Metabolic rate and clothing .5
6 Assessment by means of a numerical manikin . 5
7 Assessment by means of participants . 5
Annex A (informative) Measurement or estimation of metabolism and clothing characteristics. 6
Annex B (informative) Examples of thermal stress assessment. 7
Bibliography . 9

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
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
constitute an endorsement.
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.
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.

iv
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.

v
International Standard ISO 14505-1:2026(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
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
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
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
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
numerical manikin
virtual thermal manikin recreating a thermal manikin, or a digital model of a thermal manikin used to
calculate performance
3.6
thermoneutral zone
temperature interval within which the body maintains heat balance exclusively by vasomotor reactions
3.7
vehicle
confined, normally fully enclosed, space of a mobile or stationary unit intended for transportation of or
operation by humans
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 1:
a) heat stress (hot climate);
b) thermal discomfort (moderate climate);
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 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 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 protot
...