SIST EN ISO 14505-3:2006

Ergonomics of the thermal environment - Evaluation of the thermal environment in vehicles - Part 3: Evaluation of thermal comfort using human subjects (ISO 14505-3:2006)

ISO 14505-3:2006 gives guidelines and specifies a standard test method for the assessment, using human subjects, of thermal comfort in vehicles. It is not restricted to any particular vehicle but provides the general principles that allow assessment and evaluation. The method can be used to determine a measure of the performance of a vehicle for conditions of interest, in terms of whether it provides thermal comfort to people or not. This can be used in vehicle development and evaluation.
ISO 14505-3:2006 is applicable to all types of vehicles, including cars, buses, trucks, off-road vehicles, trains, aircraft, ships, submarines, and to the cabins of cranes and similar spaces. It applies where people are enclosed in a vehicle and when they are exposed to outside conditions. For those exposed to outside conditions, such as riders of bicycles or motorcycles, drivers of open sports cars and operators of fork lift trucks without cabins, vehicle speed and weather conditions can dominate responses. The principles of assessment, however, will still apply.
ISO 14505-3:2006 applies to both passengers and operators of vehicles where its application does not interfere with the safe operation of the vehicle.

Ergonomie der thermischen Umgebung - Bewertung der thermischen Umgebungen in Fahrzeugen - Teil 3: Bewertung der thermischen Behaglichkeit durch Versuchspersonen (ISO 14505-3:2006)

Dieser Teil von ISO 14505 enthält Leitlinien und legt ein genormtes Prüfverfahren für die Beurteilung der thermischen Behaglichkeit in Fahrzeugen durch Versuchspersonen fest. Er ist nicht auf bestimmte Fahrzeuge beschränkt, sondern liefert die allgemeinen Grundsätze für Beurteilung und Bewertung. Das Verfahren kann zur Bestimmung eines Maßes für die Leistung eines Fahrzeuges unter den interessierenden Bedingungen verwendet werden, um festzustellen, ob eine thermische Behaglichkeit für die Personen möglich ist. Dies kann sowohl bei der Entwicklung als auch bei der Bewertung von Fahrzeugen verwendet werden.
Dieser Teil von ISO 14505 ist für alle Arten von Fahrzeuge einschließlich Autos, Bussen, Lastkraftwagen, geländegängigen Fahrzeugen, Zügen, Flugzeugen, Schiffen, U Booten, Führerkabinen von Kranen und ähnlichen Räumen anwendbar. Er gilt für Situationen, in denen sich Personen in einem geschlossenen Fahrzeug befinden, aber auch für solche, in denen sie den Bedingungen im Freien ausgesetzt sind. Bei den Personen, die den Bedingungen im Freien ausgesetzt sind, beispielsweise bei Benutzern von Fahrrädern oder Motorrädern, Fahrern von Sportwagen und Gabelstaplern ohne Führerkabinen, werden möglicherweise die Reaktionen verstärkt durch die Fahrzeuggeschwindigkeit und die Wetterbedingungen beeinflusst sein. Die Grundsätze der Beurteilung gelten jedoch auch hier weiterhin.
Dieser Teil von ISO 14505 gilt sowohl für Fahrgäste als auch Fahrer/Bediener von Fahrzeugen, sofern durch die Anwendung der Norm die sichere Bedienung des Fahrzeuges nicht beeinträchtigt wird.
Er enthält die Grundsätze zur Beurteilung und Bewertung der thermischen Behaglichkeit, ein¬schließlich der Anwendung von Prüfverfahren und Versuchen. Er enthält auch subjektive Verfahren, die bei der Beurteilung angewendet werden können.

Ergonomie des ambiances thermiques - Évaluation des ambiances thermiques dans les véhicules - Partie 3: Évaluation du confort thermique en ayant recours a des sujets humains (ISO 14505-3:2006)

L'ISO 14505-3:2006 donne des lignes directrices et spécifie une méthode d'essai pour l'évaluation du confort thermique offert par les véhicules, en faisant appel à des sujets humains. Elle ne se limite pas à un véhicule particulier mais pose des principes généraux permettant l'évaluation et l'appréciation. Cette méthode peut servir à mesurer les performances d'un véhicule dans des conditions déterminées et peut permettre de vérifier si celui-ci offre ou non un confort thermique à ses utilisateurs. Elle peut être utilisée pour le développement et l'évaluation des véhicules.
L'ISO 14505-3:2006 est applicable à l'ensemble des véhicules, y compris les voitures particulières, les autobus, les camions, les véhicules tout terrain, les trains, les aéronefs, les navires, les sous-marins, les cabines de grue et les espaces assimilés. Elle est applicable aux personnes prenant place dans un véhicule ainsi qu'à celles exposées aux conditions extérieures. Pour celles exposées aux conditions extérieures, par exemple les cyclistes, les motocyclistes, les conducteurs et passagers de voitures de sport et les opérateurs de chariots élévateurs à fourche sans cabine, la vitesse du véhicule et les conditions météorologiques peuvent constituer des facteurs dominants qui conditionnent les réponses. Cependant, les principes d'évaluation demeurent applicables.
L'ISO 14505-3:2006 est applicable aux passagers ainsi qu'aux conducteurs ou opérateurs des véhicules, dans la mesure où son application n'entrave pas la bonne marche et la sécurité du véhicule.

Ergonomija toplotnega okolja – Vrednotenje toplotnega okolja v vozilih – 3. del: Vrednotenje toplotnega ugodja s pomočjo preskusnih oseb (ISO 14505-3:2006)

General Information

• Status: Published
• Publication Date: 30-Sep-2006
• ICS: 13.180 - Ergonomics
• ICS: 43.020 - Road vehicles in general
• Technical Committee: VSN - Safety of machinery
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Oct-2006
• Due Date: 01-Oct-2006
• Completion Date: 01-Oct-2006
• Ref Project: EN ISO 14505-3:2006 - Ergonomics of the thermal environment - Evaluation of the thermal environment in vehicles - Part 3: Evaluation of thermal comfort using human subjects (ISO 14505-3:2006)

Relations

• Revised: oSIST prEN ISO 14505-3:2025 - Ergonomics of the thermal environment - Evaluation of thermal environments in vehicles - Part 3: Evaluation of thermal comfort using human subjects (ISO/DIS 14505-3:2025)
• Effective Date: 03-May-2023

Overview

EN ISO 14505-3:2006 (ISO 14505-3:2006) - Ergonomics of the thermal environment - Part 3: Evaluation of thermal comfort using human subjects - provides guidelines and a standard test method for assessing thermal comfort in vehicles using human participants. The standard is vehicle‑type agnostic and applies to cars, buses, trucks, off‑road vehicles, trains, aircraft, ships, submarines and vehicle cabins (e.g., cranes). Its primary purpose is to determine whether a vehicle environment provides acceptable thermal comfort under conditions of interest and to support vehicle development and evaluation.

Key topics and technical requirements

• Scope and applicability: Assessment for passengers and operators where testing does not interfere with safe operation; applies where occupants are enclosed or exposed to outside conditions (principles still apply for open vehicles).
• Assessment methods: Defines three direct methods using human subjects:
  • Subjective methods (preferred for thermal comfort): standardized subjective scales for thermal sensation, preference, comfort and stickiness.
  • Objective methods: physiological and performance measurements (not the focus of this Part; related standards such as ISO 9886 cover physiological measures).
  • Behavioural methods: observation or quantification of occupant behaviours in response to thermal conditions.
• Design of human subject trials: guidance on trial aims, subject selection, measurement of responses, selection of operating conditions (including vehicle HVAC behaviour), and analysis/interpretation of results.
• Definitions and concepts: includes terms such as equivalent temperature, local equivalent temperature, thermal asymmetry, heat/cold stress, and thermoneutral zone.
• Test method and annexes: normative Annex A provides a test method; informative annexes include a sample subjective questionnaire, and practical examples (vehicle assessments, glazing, seats).
• Ethics and safety: testing must follow ethical guidance and medical supervision where required (see ISO 12894).

Applications and who uses it

• Vehicle manufacturers and OEMs: assess HVAC, glazing, seating and cabin thermal design during R&D and validation.
• Ergonomists and human factors engineers: design and conduct human subject trials to quantify occupant comfort.
• HVAC and thermal systems suppliers: evaluate system performance under realistic occupant responses.
• Test laboratories and standards bodies: develop and harmonize vehicle thermal comfort test procedures.
• Regulatory and certification teams: use as a reference for reproducible thermal comfort evaluation in vehicle certification and comparison tests.

Related standards

• ISO 14505-1 / ISO 14505-2 - other parts covering principles and equivalent temperature.
• ISO 12894 - medical supervision for exposure to extreme hot/cold environments.
• ISO 13731 - vocabulary and symbols for thermal environment ergonomics.
• ISO 9886 - physiological measurements (referenced but outside Part 3 scope).

Keywords: ISO 14505-3, EN ISO 14505-3:2006, thermal comfort, vehicles, ergonomics, human subject trials, equivalent temperature, HVAC, subjective assessment.

Standards Content (Sample)

SLOVENSKI STANDARD
01-oktober-2006
(UJRQRPLMDWRSORWQHJDRNROMD±9UHGQRWHQMHWRSORWQHJDRNROMDYYR]LOLK±GHO
9UHGQRWHQMHWRSORWQHJDXJRGMDVSRPRþMRSUHVNXVQLKRVHE,62
Ergonomics of the thermal environment - Evaluation of the thermal environment in
vehicles - Part 3: Evaluation of thermal comfort using human subjects (ISO 14505-
3:2006)
Ergonomie der thermischen Umgebung - Bewertung der thermischen Umgebungen in
Fahrzeugen - Teil 3: Bewertung der thermischen Behaglichkeit durch Versuchspersonen
(ISO 14505-3:2006)
Ergonomie des ambiances thermiques - Évaluation des ambiances thermiques dans les
véhicules - Partie 3: Évaluation du confort thermique en ayant recours a des sujets
humains (ISO 14505-3:2006)
Ta slovenski standard je istoveten z: EN ISO 14505-3:2006
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.

EUROPEAN STANDARD
EN ISO 14505-3
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2006
ICS 13.180; 43.020
English Version
Ergonomics of the thermal environment - Evaluation of the
thermal environment in vehicles - Part 3: Evaluation of thermal
comfort using human subjects (ISO 14505-3:2006)
Ergonomie des ambiances thermiques - Évaluation des Ergonomie der thermischen Umgebung - Bewertung der
ambiances thermiques dans les véhicules - Partie 3: thermischen Umgebungen in Fahrzeugen - Teil 3:
Évaluation du confort thermique en ayant recours à des Bewertung der thermischen Behaglichkeit durch
sujets humains (ISO 14505-3:2006) Versuchspersonen (ISO 14505-3:2006)
This European Standard was approved by CEN on 12 May 2006.
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 Central Secretariat 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 Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,
Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2006 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14505-3:2006: E
worldwide for CEN national Members.

Foreword
This document (EN ISO 14505-3:2006) 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 December 2006, and conflicting national
standards shall be withdrawn at the latest by December 2006.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

Endorsement notice
The text of ISO 14505-3:2006 has been approved by CEN as EN ISO 14505-3:2006 without any
modifications.
INTERNATIONAL ISO
STANDARD 14505-3
First edition
2006-06-01
Ergonomics of the thermal
environment — Evaluation of thermal
environments in vehicles —
Part 3:
Evaluation of thermal comfort using
human subjects
Ergonomie des ambiances thermiques — Évaluation des ambiances
thermiques dans les véhicules —
Partie 3: Évaluation du confort thermique en ayant recours à des sujets
humains
Reference number
ISO 14505-3:2006(E)
©
ISO 2006
ISO 14505-3:2006(E)
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ii © ISO 2006 – All rights reserved

ISO 14505-3:2006(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms, and definitions. 2
4 Assessment of vehicle environments using human subjects . 2
5 Principles of assessment. 3
5.1 Subjective methods. 3
5.2 Objective methods. 3
5.3 Behavioural methods . 3
5.4 Assessment of thermal comfort. 3
6 Design of human subject trials . 4
6.1 Aim of trial . 4
6.2 Selection of human subjects . 4
6.3 Measurement of subject responses. 4
6.4 Selection of operating conditions. 6
6.5 Analysis and interpretation of results . 7
7 Test method for assessing thermal comfort in vehicle . 7
Annex A (normative) Test method for assessment of vehicle thermal comfort. 8
Annex B (informative) Example of single-sheet subjective questionnaire . 10
Annex C (informative) Practical example of vehicle thermal comfort assessment using test
method . 11
Annex D (informative) Practical example of assessment of thermal comfort properties of vehicle
glazing. 13
Annex E (informative) Practical example of assessment of thermal comfort properties of vehicle
seats. 15
Bibliography . 17

ISO 14505-3:2006(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 14505-3 was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 5,
Ergonomics of the physical environment.
ISO 14505 consists of the following parts, under the general title Ergonomics of the thermal environment —
Evaluation of the thermal environment in vehicles:
⎯ Part 1: Principles and methods for assessment of thermal stress
⎯ Part 2: Determination of equivalent temperature
⎯ Part 3: Evaluation of thermal comfort using human subjects

iv © ISO 2006 – All rights reserved

ISO 14505-3:2006(E)
Introduction
Direct methods for the assessment of thermal environments (hot, moderate, cold) in vehicles involve
measurements of the responses of human subjects. There are three types: subjective methods, objective
methods, and behavioural methods. Subjective methods quantify the responses of people to an environment
using subjective scales. Objective methods are those which quantify the physical, physiological or mental
condition of a person by the use of instrumentation or measures of an output such as performance measures.
Behavioural methods quantify or represent human behaviour in response to an environment. Each of these
methods has been developed according to basic principles and the most appropriate form of the method and
combination of methods used in concert for the assessment of thermal environments in vehicles will depend
upon the context and vehicle environment of interest. This part of ISO 14505 provides both principles and
application of methods for the assessment of thermal comfort in vehicle environments using human subjects.
The most appropriate methods for evaluating thermal comfort in vehicles are subjective. The principles for the
construction of subjective assessment scales are given in ISO 10551 and are used in the development of the
test method specified in this part of ISO 14505. Physiological measurements on human subjects are
described in ISO 9886 and are beyond the scope of this part of ISO 14505.
This part of ISO 14505 complements standards concerned with the ergonomics of thermal environments and
in particular can be used together with thermal indices that are valid for use in vehicle environments.

INTERNATIONAL STANDARD ISO 14505-3:2006(E)

Ergonomics of the thermal environment — Evaluation of
thermal environments in vehicles —
Part 3:
Evaluation of thermal comfort using human subjects
1 Scope
This part of ISO 14505 gives guidelines and specifies a standard test method for the assessment, using
human subjects, of thermal comfort in vehicles. It is not restricted to any particular vehicle but provides the
general principles that allow assessment and evaluation. The method can be used to determine a measure of
the performance of a vehicle for conditions of interest, in terms of whether it provides thermal comfort to
people or not. This can be used in vehicle development and evaluation.
This part of ISO 14505 is applicable to all types of vehicles, including cars, buses, trucks, off-road vehicles,
trains, aircraft, ships, submarines, and to the cabins of cranes and similar spaces. It applies where people are
enclosed in a vehicle and when they are exposed to outside conditions. For those exposed to outside
conditions, such as riders of bicycles or motorcycles, drivers of open sports cars and operators of fork lift
trucks without cabins, vehicle speed and weather conditions can dominate responses. The principles of
assessment, however, will still apply.
This part of ISO 14505 applies to both passengers and operators of vehicles where its application does not
interfere with the safe operation of the vehicle.
It presents the principles of the assessment and evaluation of thermal comfort, including the use of test
methods and trials. It also presents subjective methods that can be used in assessment.
This part of ISO 14505 is a basic ergonomics standard which can contribute to the development of standards
concerned with specific vehicles and products.
2 Normative references
The following referenced documents are indispensable for the application 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 12894, Ergonomics of the thermal environment — Medical supervision of individuals exposed to extreme
hot or cold environments
ISO 13731, Ergonomics of the thermal environment — Vocabulary and symbols
ISO 14505-3:2006(E)
3 Terms, and definitions
For the purposes of this document, the terms and definitions given in ISO 13731 and the following apply.
3.1
cold stress
climatic conditions under which the body heat exchange is just equal to, or too large for, heat balance at the
expense of significant physiological strain that sometimes cannot be compensated
3.2
equivalent temperature
temperature of a homogenous “room”, with mean radiant temperature equal to air temperature and zero air
velocity, in which a person exchanges the same heat loss by convection and radiation as in the actual
conditions
3.3
heat stress
climatic conditions under which the body heat exchange is just equal to, or too small for, heat balance at the
expense of significant physiological strain that sometimes cannot be compensated
3.4
HVAC-system
heating, ventilation and air-conditioning system of the vehicle/cabin
3.5
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
3.6
thermal asymmetry
degree to which opposite parts of the human body are exposed to different climatic conditions
3.7
thermoneutral zone
temperature interval within which the body maintains heat balance exclusively by vasomotor reactions
4 Assessment of vehicle environments using human subjects
Although mathematical and physical models and thermal indices can provide repeatable, reliable methods of
assessment, vehicle environments are often complex, dynamic and influenced by many factors. Models and
indices are therefore often limited in validity. Human subjects are required to provide a direct means of
measuring thermal comfort and to validate other techniques. It is important, therefore, to develop assessment
methods involving human subjects. Such methods shall only be used where ethical considerations and
accepted practices involving human subjects, as provided in ISO 12894, have been carried out. They are
used for one of four main reasons:
⎯ to evaluate thermal comfort in vehicle environments;
⎯ to set up or carry out standardized test methods of thermal comfort in vehicles;
⎯ to compare measures of thermal comfort in vehicles with prediction methods (models, indices) based
upon measures of the thermal environment in vehicles;
⎯ to determine the relationship between objective measures, such as skin temperatures, and subjective
measures of thermal comfort.
2 © ISO 2006 – All rights reserved

ISO 14505-3:2006(E)
5 Principles of assessment
5.1 Subjective methods
Subjective methods quantify the response of people to an environment using subjective scales. Such scales
are based upon psychological continua (or constructs) that are relevant to the psychological phenomenon of
interest. It is important to know the properties of the scales in order to correctly interpret the results. Scales of
thermal sensation (hot or cold), preference, comfort, and stickiness are often used in thermal comfort
assessment. Advantages of subjective methods are that they are simple to administer and are directly related
to the psychological phenomenon. Disadvantages are that they can interfere with what they are measuring,
some groups may not be able to perform the subjective task (for example, babies, children, people with
disabilities) and there is no reason given as to why such a response is provided. ISO 10551 should be used
for guidance on the construction of subjective scales. Five types of scales are identified. These are:
Perceptual (How do you feel now? e.g. hot); Affective (How do you find it? e.g. comfortable); Preference (How
would you prefer to be? e.g. cooler); Acceptance (acceptable/unacceptable); Tolerance (Is the environment
tolerable?). From these basic subjective dimensions, questionnaires of subjective scales can be developed.
The subjective assessment methods presented in this part of ISO 14505 are concerned with thermal comfort
and therefore do not consider “tolerance”.
5.2 Objective methods
Objective methods are those which quantify the physical or mental condition of a person by the use of
instrumentation or measures of an output such as performance measures. The principle of the method is that
the measure can be interpreted in terms of the human condition of interest (e.g. thermal comfort). An example
would be the measurement of mean skin temperature of the body that would vary with the thermoregulatory
response to heat and cold (providing a rationale for the method) and that has been shown in research to
correlate with subjective responses of comfort. Another example would be skin wetness. Disadvantages of
objective methods can be that they might interfere with what they are attempting to measure, the correlation
between the measure and thermal comfort is not perfect and that thermal comfort is a psychological
phenomenon, a condition of mind. An advantage of objective measures is that they are often independent of,
and can be used to complement, the results of other methods such as subjective measures. ISO 9886 should
be used to provide methods for measurement and interpretation of physiological strain in terms of body core
temperature, mean skin temperature, heart rate and body mass loss. Other measures, such as heart rate
variability, may also be relevant.
5.3 Behavioural methods
Behavioural methods quantify or represent human behaviour in response to an environment. The particular
aspect of human behaviour observed is related to the human condition of interest (for example, thermal
comfort in vehicles) and a method of interpretation is required. Examples would include changes in posture,
movement patterns (for example, away from uncomfortable environments), and popularity of sitting
positions(for example, if some seats were in a cold draught they would be occupied “last”). Advantages of
behavioural methods include minimum interference with what is being measured and a direct “active” measure
of discomfort. Disadvantages include the difficulty in establishing validity and reliability of the method and
direct interpretation of the results in terms of thermal comfort. For example, a change in posture could be due
to chair discomfort or other “non-thermal” reasons.
5.4 Assessment of thermal comfort
Thermal comfort assessment is most effectively carried out using subjective methods. This is because comfort
is a psychological phenomenon and a subjective rating provides a direct and quantifiable method. The simple
test method provided in this part of ISO 14505 therefore uses subjective methods. Both objective and
behavioural methods can be used to complement the test method provided, however, they would require
expert advice beyond the scope of this part of ISO 14505.
ISO 14505-3:2006(E)
6 Design of human subject trials
6.1 Aim of trial
The design of any vehicle test or trial using human subjects will depend upon the specific aims of that test or
trial. However, there are general principles and these are outlined below.
A typical thermal comfort trial involves driving vehicles over a route and measuring operating conditions and
thermal responses of passengers. For specific investigations, simulators are often used.
An optimum trial design will achieve its aim with efficient use of resources. To achieve this it is important to be
clear about the specific aim or aims. For example, if the aim is to compare three types of vehicle seats for
thermal comfort then a repeated measures design, where all subjects sit on all seats (in a balanced order) in
identical conditions, could provide the best comparison of the seats. Contrast this with the evaluation of a
thermal comfort index where a wide range of environmental conditions, including seats, can be optimum. If
both aims need to be met then it is essential that both types of requirement are met in the design. It is
necessary, therefore, to be specific about the aims of the trial.
6.2 Selection of human subjects
A valid method of evaluating environments would be to use a panel of experts. This technique is used in wine
tasting, for example, where acknowledged experts give opinions concerning the quality of wines. This
technique depends upon identifying unbiased acknowledged experts. This is not possible in the area of
thermal comfort and the trial des
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