EN ISO 10551:2019

Ergonomics of the physical environment - Subjective judgement scales for assessing physical environments (ISO 10551:2019)

This document presents principles and examples of practical application for the construction of appropriate subjective scales for use in the assessment and evaluation of the physical environment. It does not standardize particular scales.
It considers scales of perception, comfort, preference, acceptability, expression form and tolerance, and environmental components such as thermal, visual, air quality, acoustic and vibration.
It does not consider other scales such as:
—         scales related to the effects of the environment on the ability to read displays or signs, on manual performance or on psychological conditions such as mood, etc.;
—         scales related to pain or scales related to stimuli that can lead to injury.
This document does not present principles of surveys (see Note) or questionnaire design. However, the scales that are developed using this document can be incorporated into surveys or questionnaires.
NOTE       Environmental surveys are described in ISO 28802. ISO 28802 includes scales that are complementary to, and based upon, the principles of scale construction that are described in this document.

Ergonomie des Umgebungsklimas - Subjektive Bewertungsskalen für die Beurteilung der physikalischen Umgebung (ISO 10551:2019)

Dieses Dokument stellt Grundsätze und Beispiele der praktischen Anwendung für die Erstellung geeigneter subjektiver Skalen für den Einsatz bei der Beurteilung und Bewertung der physikalischen Umgebung vor. Es standardisiert keine bestimmten Skalen.
Es berücksichtigt Skalen in Bezug auf Wahrnehmung, Komfort, Präferenzen, Annehmbarkeit, Ausdrucksform und Toleranz sowie Umgebungseigenschaften wie etwa Temperatur, Licht, Luftqualität, Akustik und Vibration.
Es berücksichtigt keine anderweitigen Skalen wie etwa:
- Skalen zu Auswirkungen der Umgebung auf die Fähigkeit, Anzeigen oder Schilder zu lesen, auf manuelle Leistungen oder auf psychologische Zustände wie Stimmung usw.;
- Skalen in Zusammenhang mit Schmerzen oder Reizen, die zu einer Verletzung führen können.
Dieses Dokument liefert keine Grundsätze für die Gestaltung von Umfragen (siehe Anmerkung) oder Fragebögen. Jedoch können die im Rahmen dieses Dokuments entwickelten Skalen in Umfragen oder Fragebögen integriert werden.
ANMERKUNG Umfragen zu Umgebungen sind in ISO 28802 beschrieben. ISO 28802 umfasst Skalen, die auf den Grundsätzen der Skalenerstellung basieren und diese ergänzen, die in diesem Dokument beschrieben sind.

Ergonomie de l'environnement physique - Échelles de jugements subjectifs pour l'évaluation des environnements physiques (ISO 10551:2019)

Le présent document donne les principes ainsi que des exemples d'application pratique pour la construction d'échelles subjectives appropriées servant à l'évaluation et à l'appréciation de l'environnement physique. Il ne normalise pas les échelles particulières.
Il couvre les échelles de perception, de confort, de préférence, d'acceptabilité, de forme d'expression et de tolérance, et les aspects environnementaux tels que l'aspect thermique, l'aspect visuel, la qualité de l'air, l'acoustique et les vibrations.
Il ne couvre pas les autres échelles telles que:
—         les échelles relatives aux effets de l'environnement sur la capacité de lecture des affichages ou des panneaux, sur les performances manuelles ou sur l'état psychologique comme le moral, etc.;
—         les échelles relatives à la douleur ou les échelles relatives aux stimuli susceptibles d'entraîner une blessure.
Le présent document ne présente pas les principes des enquêtes (voir Note) ni de conception des questionnaires. Cependant, les échelles qui sont élaborées en utilisant le présent document peuvent être intégrées dans les enquêtes ou les questionnaires.
NOTE       Les enquêtes environnementales sont décrites dans l'ISO 28802. L'ISO 28802 inclut des échelles qui viennent compléter ou s'appuyer sur les principes de construction des échelles qui sont décrits dans le présent document.

Ergonomija fizičnega okolja - Subjektivne lestvice za presojo fizičnih okolij (ISO 10551:2019)

Standard EN-ISO 10551 podaja pristope in primere praktične uporabe za izdelavo ustrezne subjektivne lestvice za presojo ter ocenjevanje fizičnih okolij. Ne standardizira določene lestvice. Upošteva lestvice zaznavanja, udobja, prednostne izbire, sprejemljivosti, oblike izražanja in tolerance ter okoljske elemente, kot so temperatura, vidljivost, kakovost zraka, akustika in vibracije. Ne upošteva pa drugih lestvic, kot so: – lestvice, povezane z učinki okolja na zmožnost branja prikazov ali znakov, na ročne zmogljivosti ali na psihološka stanja, kot je razpoloženje itd.; – lestvice, povezane z bolečino, ali lestvice, povezane z dražljaji, ki lahko privedejo do telesnih poškodb. Ta dokument ne podaja načel za načrtovanje anket (glej opombo) ali vprašalnikov. Vendar pa je v ankete ali vprašalnike mogoče vključiti lestvice, izdelane na podlagi tega dokumenta.

General Information

• Status: Published
• Publication Date: 30-Jul-2019
• Withdrawal Date: 30-Jan-2020
• ICS: 13.180 - Ergonomics
• Technical Committee: CEN/TC 122 - Ergonomics
• Drafting Committee: CEN/TC 122/WG 11 - Ergonomics of the Physical Environment
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 31-Jul-2019
• Completion Date: 31-Jul-2019
• Ref Project: SIST EN ISO 10551:2020 - Ergonomics of the physical environment - Subjective judgement scales for assessing physical environments (ISO 10551:2019)

Relations

• Replaces: EN ISO 10551:2001 - Ergonomics of the thermal environment - Assessment of the influence of the thermal environment using subjective judgement scales (ISO 10551:1995)
• Effective Date: 08-Jun-2022

Overview

EN ISO 10551:2019 - Ergonomics of the physical environment: Subjective judgement scales for assessing physical environments provides principles and examples for constructing valid, reliable subjective judgement scales used to assess indoor and outdoor physical environments. Published by ISO and adopted by CEN (EN ISO 10551:2019), the standard does not prescribe specific scales; instead it guides scale construction and use across environmental components such as thermal, visual, air quality, acoustic and vibration conditions.

Key Topics

• Principles of scale construction: guidance on wording, structure (including unipolar and bipolar forms), and presentation to reduce bias and improve validity and reliability.
• Types of subjective scales: perceptual, evaluative, preference, acceptability, tolerance and expressions of judgement.
• Instructions for administration: standard recommendations for instructions, repeat enquiries and format to ensure consistent data collection.
• Data handling and analysis: guidance on applying results from subjective ratings for evaluation and comparison.
• Annexed examples: commonly used scales and worked examples for thermal, acoustic, visual, vibration and air quality environments (informative annexes).
• Scope limits: explicitly excludes scales related to reading/display performance, manual performance, psychological mood, pain, injury-inducing stimuli and does not cover questionnaire design (see ISO 28802 for environmental survey procedures).

Applications

EN ISO 10551 is intended for professionals who need to assess human responses to physical environments, including:

• Ergonomists and human factors specialists conducting comfort and satisfaction studies.
• Building designers, architects and facility managers performing post-occupancy evaluations and indoor environmental quality (IEQ) assessments.
• HVAC and lighting engineers, acoustic and vibration consultants integrating occupant feedback with physical measurements.
• Occupational health & safety practitioners and researchers investigating environmental stressors and human perception. Practical uses include occupant surveys, field studies, laboratory experiments, diagnostic assessments of problematic environments, and supporting decisions to improve comfort, acceptability and performance.

Related standards

• ISO 28802 - Environmental surveys (complements EN ISO 10551 by covering survey procedures and includes scales based on the principles in this document).
• Part of the ISO series on assessment of comfort, stress and strain in physical environments (ISO/TC 159 ergonomics).

Using EN ISO 10551 helps create consistent, comparable subjective data on thermal comfort, noise annoyance, air quality perception, lighting satisfaction and vibration disturbance - improving evidence-based decisions for healthier, more comfortable environments.

Standards Content (Sample)

SLOVENSKI STANDARD
01-februar-2020
Nadomešča:
SIST EN ISO 10551:2002
Ergonomija fizičnega okolja - Subjektivne lestvice za presojo fizičnih okolij (ISO
10551:2019)
Ergonomics of the physical environment - Subjective judgement scales for assessing
physical environments (ISO 10551:2019)
Ergonomie des Umgebungsklimas - Subjektive Bewertungsskalen für die Beurteilung
des Umgebungsklimas (ISO 10551:2019)
Ergonomie de l'environnement physique - Échelles de jugements subjectifs pour
l'évaluation des environnements physiques (ISO 10551:2019)
Ta slovenski standard je istoveten z: EN ISO 10551:2019
ICS:
13.180 Ergonomija Ergonomics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 10551
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2019
EUROPÄISCHE NORM
ICS 13.180 Supersedes EN ISO 10551:2001
English Version
Ergonomics of the physical environment - Subjective
judgement scales for assessing physical environments (ISO
10551:2019)
Ergonomie de l'environnement physique - Échelles de Ergonomie des Umgebungsklimas - Subjektive
jugements subjectifs pour l'évaluation des Bewertungsskalen für die Beurteilung des
environnements physiques (ISO 10551:2019) Umgebungsklimas (ISO 10551:2019)
This European Standard was approved by CEN on 29 June 2019.

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, 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, Turkey 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
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 10551:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 10551:2019) 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 January 2020, and conflicting national standards shall
be withdrawn at the latest by January 2020.
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 10551:2001.
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, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 10551:2019 has been approved by CEN as EN ISO 10551:2019 without any modification.

INTERNATIONAL ISO
STANDARD 10551
Second edition
2019-06
Ergonomics of the physical
environment — Subjective judgement
scales for assessing physical
environments
Ergonomie de l'environnement physique — Échelles de jugements
subjectifs pour l'évaluation des environnements physiques
Reference number
ISO 10551:2019(E)
©
ISO 2019
ISO 10551:2019(E)
© ISO 2019
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]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 10551:2019(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Subjective judgement scales for physical environments: Principles of scale
construction and use . 1
5 Perceptual, evaluation and preferential judgement scales . 2
5.1 Instructions for using the judgement scales . 2
5.2 Scale of perception of the personal state . 4
5.2.1 Structure of the scale. 4
5.2.2 Wording of the degrees . 4
5.3 Evaluative scale . 4
5.3.1 Structure of the scale. 4
5.3.2 Wording of the points . 5
5.4 Preference scale . 5
5.4.1 Structure of the scale. 5
5.4.2 Wording of the degrees . 5
6 Personal acceptability statement and tolerance scale . 5
6.1 General . 5
6.2 Instructions for using the judgement expression forms . 5
6.3 Description of the forms of judgement expression . 6
6.3.1 Structure of the forms of judgement expression. 6
6.3.2 Wording of the degrees . 6
7 Instructions for repeat enquiries . 6
8 Summary of the scales . 7
9 Format and method of presentations of the scales . 7
10 Data analysis and application of the results . 7
Annex A (informative) Commonly used scales for assessing thermal environments .8
Annex B (informative) Commonly used scales for assessing acoustic environments .11
Annex C (informative) Commonly used scales for assessing visual environments .13
Annex D (informative) Commonly used scales for assessing vibration environments .15
Annex E (informative) Commonly used scales for assessing air quality environments .17
Annex F (informative) Application of assessment procedure and judgement scales:
Examples, including data analysis.18
Annex G (informative) Examples of scales that can be used in the environmental
ergonomics survey .26
Bibliography .28
ISO 10551:2019(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/directives).
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/patents).
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.
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.
This second edition cancels and replaces the first edition (ISO 10551:1995), which has been technically
revised. The main changes compared to the previous edition are as follows:
— the title has been changed;
— the Scope has been reworded;
— new references have been added to Clause 2;
— new entries have been added to Clause 3;
— in 5.2.1, a unipolar scale has been added;
— Annex B has been changed;
— Annexes C to G have been added.
iv © ISO 2019 – All rights reserved

ISO 10551:2019(E)
Introduction
By using this document, you can construct subjective scales that can be used to ask people how they feel
about their physical environment. That is whether they find it too hot, whether there is any noise and
if it is annoying, if the light is too bright, is it “smelly” and so on. By constructing the scales and using
them correctly, you can see, in a cost-effective way, how people find the environment. The information
can be applied to report on the environmental quality and to work out how to improve the environment.
People are exposed to a range of physical environments which can affect their health and safety,
comfort and performance. An important method for assessing physical environments, particularly
when considering psychological constructs such as comfort or satisfaction, is to use subjective scales.
The type of scale used and how it is administered is important in influencing the subjective responses of
people. There are principles for constructing scales and procedures for administering them that reduce
bias and ensure validity and reliability of response. There are also generic types of scale that can be
used across environmental stimuli, for example, scales on which people rate sensation or comfort or
acceptability or preference and so on.
This document provides a description of principles of scale construction and procedures for use. It also
provides examples of commonly used scales across environmental components. This document does
not standardize any particular scale but it provides the principles upon which appropriate scales can
be constructed. It is needed to provide consistency in the production of valid and reliable scales. It is
particularly useful to people who wish to conduct an environmental survey, for example to assess post
occupant satisfaction of new or existing buildings or other spaces, environments where dissatisfaction
occurs and a diagnosis of the problems is required and for people who are investigating the relationship
between conditions in the physical environment and human perception. A consistent approach to
subjective scale construction and use also allows a meaningful comparison of data obtained from
investigations internationally.
This document forms part of a group of international standards on the assessment of comfort, stress
and strain in physical environments.
This series is concerned, in particular, with:
1) establishing specifications on methods for measuring and estimating the characteristic physical
parameters of environments;
2) establishing methods for assessing stress in environments.
This document proposes a set of specifications on direct expert assessment of comfort/discomfort
expressed by persons subjected to various degrees of stress during periods spent in physical
environments. The data provided by this assessment can be used on its own or to supplement physical
and physiological methods of assessing loads. The methods belong to a psychological approach
consisting in gathering, as appropriate, the on-site opinions of persons exposed to the conditions under
consideration (diagnosis) and, thus, can complement data provided by predictive approaches described
elsewhere in this group. The information provided in this document can be used to construct valid
subjective scales for use in determining how people feel in their physical environment. This document
does not give guidance on questionnaire design and application although the scales may be used in the
construction of questionnaires.
If persons exposed to environments are to be asked about their corresponding experiences or
information requested on their cultural attitude in order to obtain the most appropriate subjective
judgement scales, favourable relationships may usefully be established between these persons and the
organization responsible, through the persons conducting the ergonomic investigation.
The environments which lend themselves to the application of subjective judgement scales relate to
conditions which differ to a moderate degree from comfortable conditions. Under extreme conditions,
physical and physiological assessment methods of the environmental load are preferred, provided
that their results can be used as criteria for a decision. In particular, tolerance limits for load cannot
be confidently based on subjective judgements and need to be decided in view of accepted health risk
ISO 10551:2019(E)
criteria. The decision of whether a person is exposed to an extreme environment is not left to the person
exposed as their judgement can be impaired by the conditions.
The opinions held by persons about their environment have a value in themselves. It is up to the ergonomist
whether or not to take them into account. The reputation of these data for lack of reliability does not
justify dismissing them out of hand. The aim of this document is precisely to improve their reliability by
specifying the appropriate tools to use in collecting them and the requirement for using them.
vi © ISO 2019 – All rights reserved

INTERNATIONAL STANDARD ISO 10551:2019(E)
Ergonomics of the physical environment — Subjective
judgement scales for assessing physical environments
1 Scope
This document presents principles and examples of practical application for the construction of
appropriate subjective scales for use in the assessment and evaluation of the physical environment. It
does not standardize particular scales.
It considers scales of perception, comfort, preference, acceptability, expression form and tolerance, and
environmental components such as thermal, visual, air quality, acoustic and vibration.
It does not consider other scales such as:
— scales related to the effects of the environment on the ability to read displays or signs, on manual
performance or on psychological conditions such as mood, etc.;
— scales related to pain or scales related to stimuli that can lead to injury.
This document does not present principles of surveys (see Note) or questionnaire design. However, the
scales that are developed using this document can be incorporated into surveys or questionnaires.
NOTE Environmental surveys are described in ISO 28802. ISO 28802 includes scales that are complementary
to, and based upon, the principles of scale construction that are described in this document.
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 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Subjective judgement scales for physical environments: Principles of scale
construction and use
There are a number of subjective judgement scales for physical environments. They differ in whether
emphasis is placed on some aspect of judgement:
— perceptual or affective (evaluative and preferential);
— global (encompassing the whole environment or organism) or localized;
— present or past;
ISO 10551:2019(E)
— instantaneous or extended over a period of time.
They also differ as to the object of judgement: environment or person, the whole or its component parts,
permanent or temporary situation.
This document retains judgements that people make about their own state as a whole. It distinguishes
between perception, present affective assessment (comfort/discomfort) and future preference.
NOTE 1 This document also suggests supplementing the perceptual, evaluative and preferential judgement
scales by a statement of acceptability and a scale of tolerance of environments
In most instances, the exposure to an environment lasts for several hours. Therefore, it is useful to
gather the person’s opinions throughout, by repeating the expression of the judgements at regular
intervals, using exactly the same scales.
By repeatedly applying the same scales, the evolution with time of the comfort or strain experienced
can be assessed and an integrated judgement obtained over the whole time of exposure by appropriate
computation of the data (e.g. overall mean, overall change, variation, etc.).
Basic difficulties are encountered in any area which involves the use of language. In this regard, bias
and variability in the data can result from inconsistencies and inappropriateness of accompanying
instructions. Therefore, it becomes crucial to standardized preparatory instructions which explain the
study, as well as the wording of the judgement scales. The terminology used to denote the degrees on
the judgement scales is of special importance. This document specifies the principles used to develop
subjective scales. The actual descriptors used can be influenced by the language structure and shall be
established with subject experts from National Standards Body.
NOTE 2 International usage and acceptance of the scales in this document will result in the fixing of suitable
wording of the degrees on the scales in various languages.
Other judgement scales are in use concerning the state of various parts of the body (e.g. head, torso,
hands, feet), the total environment or various components of it, other aspects of the experience of
the person or evaluations conducted over a certain period of time, including periods during which-
conditions have not been measured. Other scales, e.g. a bipolar affective evaluation scale, have been
structured differently on the model of perception; such a scale is useful for taking into account pleasure
and is more sensitive than the unipolar discomfort scale in the region near to comfort.
This document is limited to the five scales described in Clauses 4 and 5. The gathering of subjective
judgement should first be concerned with localized sensations (parts of the body) and in constant
conditions, given the current interest and application of these data. The second concern should be for
data gathered under transient conditions, which are extremely important but are not yet sufficiently
well known.
5 Perceptual, evaluation and preferential judgement scales
5.1 Instructions for using the judgement scales
It is important to distinguish between more objective ratings, such as sensations, and affective or
evaluative ratings, such as comfort and pleasure. In everyday language, however, these dimensions are
often confounded and distinctions are not made. In addition, the richness of the semantics for describing
environments and responses to them depends on individuals, their experiences, their language and
their culture, when investigating physical environments. Therefore, it is sometimes useful to first
investigate the psychological dimension (or constructs) which individuals and groups use to describe
[7]
their world .
Two commonly used approaches are semantic differential techniques and personal construct theory
methods. The methods invoke factor analysis or multidimensional scaling techniques to build a
psychological model of the way in which physical environments are perceived and “modelled” (represented
in psychological space) by the person. Similar stimuli on a particular dimension (or all combinations of
dimensions) are placed close together in the multidimensional model of psychological space.
2 © ISO 2019 – All rights reserved

ISO 10551:2019(E)
The form and method of administering the scales are important. For example, a continuous form of the
scale would be to draw a line through all points on the scale where subjective terms are placed. This
would allow a person exposed to the environment to choose values between ratings (e.g. between cool
and cold, a rating of −1,6 on a thermal sensation scale.). In an analysis of the results, this would enable
parametric statistics to be used. However, it is possible that the investigator does not consider that
data are “strong enough” for this and is prepared to use only ordinal data (ranks) and non-parametric
statistics. These, and other, points are of importance and, for further information, the reader is referred
to a text on the design and analysis of surveys and on the use of subjective assessment methods (see [6]).
The psychological interaction when the scale is administered can also influence the results. Usually, the
subjects are given the scale and asked to tick the place which represent “how they feel now”, for example.
It is important to avoid ambiguity, which can lead to a person providing his or her own interpretation,
for example, of what the environment is generally like or how other people perceive it. Other issues
include range effects. The range provided, (e.g. hot to cold) influences the subject’s judgement as do
leading questions: (e.g. “you are uncomfortable, aren’t you?”). The following important issues should be
considered when constructing questionnaires:
— question specificity;
— language;
— clarity;
— leading questions;
— prestige;
— bias;
— embarrassing questions;
— hypothetical questions; and
— impersonal questions.
Other issues include whether knowledge of the results is given. For example, if responses are requested
over time, is the subject informed of previous ratings that he or she made, and whether the ratings are
given in the presence of others? In some circumstances, people can avoid extremes such as end points
on scales or be influenced by the range presented.
Although subjective measurement techniques can be useful for measuring extreme environments, they
should not be used as a primary measure in health and safety. In these conditions, the ability of a person
to make a “rational” subjective judgement can be impaired. While a subject shall always be allowed
to withdraw from an investigation, he or she does not have the overriding right to remain in it. It is
the investigator’s judgement as to whether he or she should remain exposed (based on physiological
responses, etc.) even if the subject is willing (enthusiastic) to do so.
The three judgement scales should be applied in the following order: perceptual scale, evaluative scale,
scale of preference. The combination of possible replies provides all the required information.
The following introductory questions should be posed:
— before applying the perceptual scale: “How are you feeling (at this precise moment)?” (followed by
the replies from the scale);
— after the response given on the perceptual scale, and immediately before applying the evaluative
scale: "Do you find this. ?” (followed by the replies from the scale);
— after the response given on the evaluative scale, and immediately before the application of the
preference scale: “Please state how you would prefer to be now” (followed by the replies from
the scale).
ISO 10551:2019(E)
A 7-degree scale should be applied in the case of environments judged to be close to neutrality; a
9-degree scale should be applied in the case of environments judged to be more intense.
Full scales are presented, even in cases of surroundings located only in a limited range of conditions.
The wording of all the degrees of a scale provides a frame of reference useful to those asked to verbalize
their instantaneous experience.
There is utility to the investigator to consider a large number of environmental impacts and a variety of
scales. However, the desire for data shall be balanced with the willingness of the participants to provide
accurate perceptions, and the management’s tolerance for the use of the time required. The survey
is most acceptable if it is focused on legitimate environmental concerns specific to the environment
in question. The scales used and the ergonomic aspect assessed shall get to the point and provide
actionable data.
5.2 Scale of perception of the personal state
5.2.1 Structure of the scale
Scales can be unipolar or bipolar.
For a unipolar scale, a 4-degree one-pole scale, which can be extended to 5 degrees, with a point of
origin indicating the absence of the effect, and 3 (or 4) degrees of increasing intensity of the effect.
Point of origin Degrees of intensity
0 1 2 3 (4) Unique pole
For bipolar scales, a symmetrical 7-degree two-pole scale, which can be extended to 9 degrees,
comprising a central indifference point and two times 3 (or 4) degrees of increasing intensity.
Degrees of intensity Point of indifference Degrees of intensity
Pole A (–4) –3 –2 −1 0 +1 +2 +3 (+4) Pole B
5.2.2 Wording of the degrees
Poles A and B are at either end of the scale. The central point of indifference corresponds to absence
of sensation. The wording of the degrees depends on the vocabulary choices in each language. The
selection of the terms should be carried out carefully and tested beforehand on a representative number
of persons who are native speakers of the given language.
The following wordings should be taken as an example:
— for languages which have several (at least two) distinct terms to denote different degrees of intensity,
these terms are used along the lines of the English wording;
— for languages which do not have two terms for denoting different degrees of intensity for each of the
poles, a single term is used for each pole and its intensity modulated by the use of adverbs along the
lines of the French wording.
NOTE Tables A.1 and C.1 give examples for each case.
5.3 Evaluative scale
5.3.1 Structure of the scale
A 4-degree one-pole scale, which can be extended to 5 degrees, with a point of origin indicating the
absence of the effect, and 3 (or 4) degrees of increasing intensity of the effect.
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ISO 10551:2019(E)
Point of origin Degrees of intensity
0 1 2 3 (4) Unique pole
5.3.2 Wording of the points
The unique pole devoted to the evaluation of the load denotes a negative effect: DISPLEASURE,
DISSATISFACTION or DISCOMFORT. Its intensity can be modulated by adverbs. COMFORT, located at
the point of origin, and ABSENCE OF DISCOMFORT, are also classed as positive evaluations (pleasure,
satisfaction).
NOTE Tables A.2, C.2, D.1, and E.1 give examples for each case.
5.4 Preference scale
5.4.1 Structure of the scale
A symmetrical 7-degree bipolar scale comprises a central point of indecision and two times 3 degrees
of increasing intensity.
Degrees of intensity Point of indecision Degrees of intensity
Pole A –3 –2 −1 0 +1 +2 +3 Pole B
5.4.2 Wording of the degrees
Poles A and B are at either end of the scale. The central point of indecision corresponds to the ABSENCE
OF CHANGE.
The degrees should be worded using, for each pole, a comparative term which can be modulated in
intensity by means of adverbs. It is possible to reduce the three degrees of each of the poles to a single
degree worded by means of an unmodulated comparative term.
NOTE Tables A.3, B.2, and C.3 give examples for each case.
6 Personal acceptability statement and tolerance scale
6.1 General
In addition to the previous judgements, information should be obtained indicating how the workers
personally feel toward their situation.
This assessment would be in terms of rejection or acceptance on a personal level, complemented in any
case by a relative judgement of the degree of personal tolerance. Rejection or acceptance is expressed
on a personal level, i.e. out of context, the judgement being based purely on personal preference. The
expression of rejection on a personal level (unacceptability) is therefore not incompatible with actual
acceptance, which takes into account other contextual motivations (instructions, job requirement,
short duration of exposure, remuneration).
In contrast to the three preceding scales, the personal acceptability statement and the tolerance scale
consist of judgements made about the surroundings.
6.2 Instructions for using the judgement expression forms
The acceptability statement form and tolerance scale should be applied after the perception and
assessment scales described above, and should be in the following order: acceptability statement form,
then tolerance scale.
ISO 10551:2019(E)
The following introductory questions should be posed:
— before application of the acceptability statement form:
1) in explicit terms: “How do you judge this environment on a personal level?”;
2) with the initial statement: “Taking into account only your personal preference,” either:
a) “. would you rather accept this environment than reject it?”; or
b) “. would you rather reject this environment than accept it?”;
— before the application of the tolerance scale: “In your opinion, is the environment .?”.
6.3 Description of the forms of judgement expression
6.3.1 Structure of the forms of judgement expression
The form of the personal acceptability statement will be a binary structure of the type: PERSONAL
ACCEPTANCE (GENERALLY ACCEPTABLE) — PERSONAL REJECTION (GENERALLY UNACCEPTABLE).
The personal tolerance scale has a unipolar 5-degree structure, the single pole expressing DIFFICULTY
IN TOLERATING, with a point of origin indicating no difficulty in tolerating and with 4 degrees of
increasing difficulty in tolerating, the 4th degree expressing intolerable.
Point of origin Degrees of intensity
0 1 2 3 4 Unique pole
6.3.2 Wording of the degrees
The wording of the two categories on the personal acceptability statement form can consist of either:
a) a clarification of the judgement of the person questioned;
A.1.1.1.1  Categories A.1.1.1.2  Wording A.1.1.1.3  Response
ACCEPTABLE Environment acceptable rather than unacceptable
UNACCEPTABLE Environment unacceptable rather than acceptable
b) or the expression of agreement or disagreement of the person questioned with the initial statement.
Initial statement Category ACCEPTABLE Category UNACCEPT-
ABLE
Either “personal acceptance” Yes (agreement) No (disagreement)
Or “personal rejection.” No (disagreement) Yes (agreement)
NOTE The degrees on the personal tolerance scale can be worded in terms of difficulty in tolerating (or
bearing). An example is given in Table A.5.
7 Instructions for repeat enquiries
Persons submitted to repeated application of the same judgement scales should be informed
beforehand, in order to avoid undesired reactions and to present arguments justifying the application
of the procedure. The following instructions can be issued:
“As you usually stay several hours at this workplace, you will be asked several times, at regular
intervals, by means of the same scales, to judge the physical conditions; indicate your actual
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ISO 10551:2019(E)
experience at that moment. You will, thus, be in a position to express (more) accurately the possible
changes in the physical conditions you may experience over a longer period of exposure”.
8 Summary of the scales
Table 1 summarizes the various judgements which are recommended for an assessment of comfort or
stress based on subjective data.
Table 1 — Stress assessment
1 2 3 4 5
Subject under
Personal state Physical ambience
judgement
Type of Perception Evaluation Preference Personal Personal
judgement acceptability tolerance
Wording “How do you feel “Do you find it .?” “Please state “How do you “In your opinion
(at this precise how you would judge this en- is the environ-
4 or 5 degrees, from
moment)?” prefer to be vironment on a ment.?”
COMFORTABLE to
now.” personal level?”
7 or 9 degrees very (or extremely), 5 degrees, from
UNCOMFORTABLE 7 (or 3) degrees 2 degrees, perfectly
GENERALLY TOLERABLE to
ACCEPTABLE, INTOLERABLE
GENERALLY
UNACCEPTABLE
9 Format and method of presentations of the scales
Scales with more than two degrees can be presented in a discontinuous format: 3, 4, 7 or 9 separate
degrees at equal intervals; the response consists of ticking the degree corresponding to the judgement.
The same scales can also be presented using a continuous format, e.g. a segment of a straight line or
curve comprising 3, 4, 5, 7 or 9 equally spaced marks with the corresponding wording next to them.
This format not only makes it possible to indicate the mark corresponding to the judgement, but also to
locate the response anywhere within the intervals between marks.
Normally presented in written form to be completed manually, these scales can also be presented on a
video display unit and the responses given using a keyboard, or other equivalent, and an appropriate code.
10 Data analysis and application of the results
The numerical properties (i.e. in terms of mathematical structure) of the data collected by applying the
judgement scales above, and the statistical characteristics of the distributions of these data dictate the
type of quantitative analysis that can legitimately be applied to them.
The example given in Annex F illustrates a number of treatments and the results that can be obtained:
indices of central tendency, of scatter and of association in particular, or statistical tests for significance
of difference, of effects of factors or of association.
NOTE This document encourages practitioners and researchers with sufficient data, or those who are able
to collect data, to publish studies on the statistical characteristics of the sample distributions of such data.
ISO 10551:2019(E)
Annex A
(informative)
Commonly used scales for assessing thermal environments
Table A.1 — Scale of perceptual judgements on personal thermal state
(after the question “How are you feeling now?”)
Poles Degrees English
(+5) Extremely hot
(+4) Very hot
HOT +3 Hot
+2 Warm
+1 Slightly warm
INDIFFERENCE 0 Neutral
−1 Slightly cool
−2 Cool
COLD −3 Cold
(−4) Very cold
(−5) Extremely cold
Common introductory term(s) I am feeling/I am
NOTE  The central tendency of the perceptual judgements obtained by applying one of the above-mentioned scales
(in continuous form) yields an observed mean vote which can be compared with the Predicted Mean Vote (PMV index)
[2]
determined according to ISO 7730 .
Table A.2 — Scale of evaluative judgements on personal thermal state
(after the question “Do you find this….?”)
Pole Degree Wording of degrees
0 Comfortable
1 Slightly uncomfortable
DISCOMFORT 2 Uncomfortable
3 Very uncomfortable
4 Extremely uncomfortable
Common introductory terms I find the thermal environment….
NOTE  By summing up the judgements which express discomfort, one obtains an observed percentage of dissatisfied people,
which can be compared with the Predicted Percentage of Dissatisfied (PPD index) determined according to ISO 7730.
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ISO 10551:2019(E)
Table A.3 — Thermal preference scale
(after the instruction “Please state how you would prefer to be now.”)
Wording of degrees for Equivalent for 3-de-
Poles Degrees
7-degree scale gree scale
+3 Much warmer
WARMER +2 Warmer Warmer
+1 A little warmer
0 Neither warmer nor cooler (no change)
−1 Slightly cooler
COOLER −2 Cooler Cooler
−3 Much cooler
Common introductory terms I would prefer to be…
Preference scales are used in assessment as they provide a “value” judgement from subjects. If a subject
rates a sensation as “slightly warm” for example, it does not indicate whether or not he or she wishes to
be “slightly warm”. The preference rating compares how the subject is with how he or she would like to
be. “No change” indicates a form of acceptability, preference, and satisfaction. Other scales can be useful
depending upon the aims of the experiment. If a percentage of satisfaction is required then a “forced”
(the subject must choose) yes or no response to “Are you satisfied?” would give a direct measure.
Ratings of pleasure can be of interest. These can be confounded with visual stimuli (for example,
driving through the countryside on a sunny day) but solar radiation can elicit pleasant and unpleasant
responses and should be considered. Ratings of acceptability are useful to vehicle manufacturers. They
require a sophisticated judgement based on what a subject would feel is acceptable in that context. A
combination of scales integrated into a questionnaire provides a useful measurement too
...