ISO 11863:2011

INTERNATIONAL ISO
STANDARD 11863
First edition
2011-07-01
Buildings and building-related facilities —
Functional and user requirements and
performance — Tools for assessment and
comparison
Bâtiments et biens immobiliers associés — Exigences fonctionnelles,
exigences de l'utilisateur et performances — Outils pour l'évaluation et
la comparaison
Reference number
©
ISO 2011
©  ISO 2011
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ii © ISO 2011 – All rights reserved

Contents Page
Foreword .iv
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 How to determine levels of functional performance requirements and levels of
serviceability.5
4.1 Requirements for functional performance.5
4.2 Serviceability .6
4.3 Number of statements and of levels in a scale .6
4.4 Calibration and normalization of scales .7
4.5 Complex topics with multiple functions .7
4.6 Relative importance of requirements .7
4.7 Threshold or critical level.7
4.8 Main and variant requirement profiles .8
4.9 Generic profiles of demand.8
4.10 Calibration of scales .9
4.11 Gap analysis — Comparing demand and supply.9
4.12 Applicability in different cultures .9
4.13 Consistency and replicability of responses .9
4.14 Application during the whole life of a facility.10
4.15 Inclusion in the building information mode (BIM) .10
Annex A (informative) Concepts of functionality and serviceability .11
Annex B (informative) Principle of calibration for scales .13
Annex C (informative) Example of scales.14
Annex D (informative) Comparison and matching of profiles.17
Annex E (informative) Terms used for functionality and serviceability .21
Bibliography.23

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 11863 was prepared by Technical Committee ISO/TC 59, Buildings and civil engineering works,
Subcommittee SC 3, Functional/user requirements and performance in building construction.

iv © ISO 2011 – All rights reserved

INTERNATIONAL STANDARD ISO 11863:2011(E)

Buildings and building-related facilities — Functional and user
requirements and performance — Tools for assessment and
comparison
1 Scope
This International Standard specifies how to determine functional performance requirements (demand) for
buildings and building-related facilities, and how to check the capability of buildings and facilities to meet
identified requirements (supply). It specifies how to determine the relative importance of each requirement,
establish thresholds for capability, and evaluate the significance of differences between what is required and
actual capabilities.
This International Standard is applicable to any size or scope of assets of buildings and building-related
facilities, e.g. to a portfolio of assets at a single site or multiple sites, to assets of a single small building, and
to any constituent system, sub-system, component or element thereof. It is applicable to a range of roles, from
owners and managers to occupants, tenants, or other users or stakeholders. It is applicable to any asset type
within the field of buildings and civil engineering works, including certain public works, equipment and materiel.
It is particularly useful for entities having control or occupancy of a portfolio of such assets.
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 6707-1, Building and civil engineering — Vocabulary — Part 1: General terms
ISO 15686-10, Buildings and constructed assets — Service life planning — Part 10: When to assess
functional performance
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 6707-1 and the following apply.
3.1
aspect
〈functionality or serviceability〉 part or set of parts of the functionality (3.15) or serviceability (3.28) of an
asset (3.2), building or building-related facility (3.10)
NOTE An aspect usually encompasses multiple topics (3.33) of functionality or serviceability.
3.2
asset
〈building or building-related facility〉 whole building or structure or unit of construction works, or a system or
component or part thereof
3.3
behaviour in service
manner in which an asset (building or building related facility) (3.2) actually functions in its intended place and
use
3.4
calibrate
set the proper intervals between marks or levels (3.17) (3.18) (3.19) of a scale (3.26) (as a measuring
instrument)
3.5
calibration
act of marking the scale (3.26) of a measuring instrument used to determine the proper separation between
marks or levels (3.17) (3.18) (3.19)
3.6
capability
measure of ability to perform and support a function (3.12)
3.7
critical level
〈of functionality〉 level (3.17) (3.18) (3.19) at which resources necessary for work or other functions (3.12) are
essential or critical
3.8
demand
〈of a facility〉 requirement for functionality (3.15)
3.9
demand scale
scale (3.26) for use in determining the level of functionality (3.17) of a facility (3.10) on one topic (3.33) of
functional performance (3.13)
3.10
facility
physical setting used to serve a specific purpose
NOTE 1 A facility can be part of a building, or a whole building, or more than one building, and can include related
constructions (such as roads and walkways), which, taken as a whole, serve a specific function.
NOTE 2 The term encompasses both the physical object(s) and its (their) use.
3.11
feature
element or attribute of a facility (3.10) which indicates an aspect of its serviceability (3.28)
3.12
function
purpose or activity of users (3.34) and other stakeholders (3.29) for which an asset (3.2) or a facility (3.10)
is designed, used, or required to be used
3.13
functional performance
〈of a facility〉 performance (3.20) of a facility (3.10) to support required function(s) (3.12) under specified
use conditions
NOTE See also performance 〈of a facility〉 (3.20).
2 © ISO 2011 – All rights reserved

3.14
functional performance requirement
type and level of functional performance (3.13) which is required by stakeholders of a facility (3.10),
building or other constructed asset (3.2), or of an assembly, component or product thereof, or of a movable
asset, for a specific activity or function (3.12)
3.15
functionality
suitability or usefulness for a specific purpose or activity
3.16
gap
difference between the level of functionality (3.17) (or other attribute) which is required and the level of
serviceability (3.19) (capability) which is or will be provided
3.17
level of functionality
number indicating the relative functionality (3.15) for a group of users (3.34) or other stakeholders (3.29) for
one topic (3.33) on a predetermined demand scale (3.9) from the level of the least functionality (3.15) to the
level of the most functionality (3.15)
NOTE Level of functionality can be the consequence of several distinct functions (3.12) required to act in
combination.
EXAMPLE Scale of integers from 0 to 9.
3.18
level of performance
number indicating the relative performance (3.20) required or provided for one topic on a predetermined
scale (3.26) ranging from the level of the least performance (3.20) to the level of the most
performance (3.20)
NOTE Level of performance can be the consequence of several distinct performances [behaviours in service
(3.3)], of which one can be functional performance (3.13), which act in combination.
EXAMPLE Scale of integers from 0 to 9.
3.19
level of serviceability
number indicating the relative capability of a facility (3.10) for a group of users (3.34) or other stakeholders
(3.29) for one topic (3.33) on a predetermined supply scale (3.31) from the level of the least serviceability
(3.28) to the most serviceability (3.28)
NOTE Level of serviceability can be the consequence of several physical features (3.11) acting in combination.
EXAMPLE Scale of integers from 0 to 9.
3.20
performance
〈of a facility〉 behaviour in service (3.3) of a facility (3.10) for a specified use
NOTE The scope of this performance is of the facility (3.10) as a system, including its subsystems, components
and materials, and their interactions, such as those of an acoustical, hydro-thermal, or economic nature, and the relative
importance (3.25) of each performance requirement (3.21).
3.21
performance requirement
〈of a facility〉 performance (3.20) demanded or expected of a facility (3.10) for a specified use
NOTE Adapted from ISO 6707-1:2004, definition 9.1.16.
3.22
profile
〈of a facility〉 list of the levels of functionality (3.17) required by stakeholders (3.29) for a facility (3.10), or
of the levels of serviceability (3.19) provided by a facility, with respect to various topics (3.33)
3.23
rater
individual who conducts the rating (3.24) of a facility (3.10), or of the design of a facility, to determine its
profile (3.22) of serviceability (3.28)
3.24
rating
process of determining the serviceability (3.28) of a constructed asset (3.2), or of an asset which has been
designed but not yet built
3.25
relative importance
importance of any one topic (3.33) of functionality (3.15) for the operations or mission of the users (3.34)
3.26
scale
single set of statements, in which intervals between statements, from the most to the least, are calibrated
according to scalar rules
NOTE When people are asked to select one of the statements in a scale as most closely describing the level of
functionality (3.17) required, or as best describing the physical features present in a facility, the scale in effect functions
as a multiple choice questionnaire.
3.27
service life
period of time after installation during which a facility (3.10) or its component parts meet(s) or exceed(s) the
performance requirements (3.21)
NOTE Adapted from ISO 6707-1:2004, definition 9.3.84.
3.28
serviceability
capability (3.6) of a facility (3.10), building or other constructed asset (3.2), or of an assembly, component or
product thereof, or of a movable asset, to support the function(s) (3.12) for which it is designed, used, or
required to be used
NOTE Adapted from ISO 6707-1:2004, definitions 9.1.11 (capability) and 9.3.05 (serviceability).
3.29
stakeholder
person or entity with an interest in, or concern about, a facility (3.10)
NOTE The interest can include a financial interest, and can be continuing or temporary, as of a visitor.
3.30
suitability
〈of a facility〉 appropriateness for supporting the functions (3.12) or activities of users (3.34) or stakeholders
(3.29)
3.31
supply scale
scale (3.26) for use in determining the level of serviceability (3.19) of a facility on one topic (3.33) of
capability (3.6)
4 © ISO 2011 – All rights reserved

3.32
threshold level
number indicating the level of functionality (3.17) which, if not provided, would significantly or completely
impair the ability of users (3.34) to carry out their intended activities or operations
3.33
topic
single attribute of a facility (3.10) for which level of functionality (3.17), level of serviceability (3.19),
threshold level (3.32) and relative importance (3.25) can be determined
3.34
user
organization, person, animal or object which uses, or is intended to use, a building or other construction works
NOTE 1 Includes any person or entity who uses a facility (3.10), whether as occupant, visitor, member of the public, or
other stakeholder (3.29).
NOTE 2 Adapted from ISO 6707-1 2004, definition 8.1.
3.35
whole life
period of time commencing with the process of definition of need, before a project is explicitly launched,
continuing through the process of acquisition and including the end of life period, decommissioning,
deconstruction or disposal
NOTE 1 Whole life cycle includes all factors considered in whole life costing.
NOTE 2 Life cycle is less inclusive. It is the period of time from completion of construction or from a selected date to
the end of life of the asset (3.2), including the end of life period, decommissioning, deconstruction or disposal, or to
termination of a period of analysis.
4 How to determine levels of functional performance requirements and levels of
serviceability
4.1 Requirements for functional performance
The requirement for each topic (or aspect) of functionality of an asset building or building-related facility shall
incorporate either one specific function or several specific functions which act in combination for that topic.
Each such requirement shall be expressed as a level of demand. The level of demand for each function shall
be identified using a demand scale.
Typically, the level of demand is a minimum level. If the level of demand is a maximum value, that shall be so
indicated, as an exception.
Each demand scale shall contain a set of statements of functional performance requirements, one statement
for each level from the lowest requirement to the highest requirement and one statement for “no requirement”
or “shall not have” (which shall be level 0).
Demand scales for any functional type (category) of building or building-related facility shall be written in
language (terms and concepts) which are familiar to the users of that functional type. The scales shall enable
any occupant, owner, manager, user, visitor or other stakeholder — without guidance or technical
assistance — to select a block of text from a demand scale that best describes what they need to be able to
do, see, feel, hear or experience while in or near a facility.
Demand scales shall use statements of requirements for functionality that will apply to many users of a
functional category of facilities. A demand scale shall not be used to comply with this International Standard if
a requirement in it is unique to a single stakeholder. This is because comparing requirement levels of different
stakeholders is only possible when each set of levels of demand is determined using the same scales, which
are suitable for the same functional category.
If a suitable set of demand scales is not available, it shall be created.
Examples of the format for such scales are included in Annex B, and in References [1], [2], [3], [13], and [14]
in the Bibliography.
4.2 Serviceability
The serviceability for each topic of functionality shall be indicated by one feature or by a combination of
features which act in combination for that topic. The level of supply for each feature shall be indicated using
one supply scale. The level of supply for a topic shall be indicated by the level of supply for the feature or
combination of features
Each supply scale shall contain a set of statements of serviceability, one statement for each level from the
lowest serviceability to the highest serviceability and one statement for “not present” (which shall be level 0).
Supply scales shall use, as indicators of serviceability, descriptions of features for serviceability that will apply
to many facilities of a functional category. A supply scale shall not be used to comply with this International
Standard if the indicator in it is unique to a single unique asset. This is because comparing rating levels of
different buildings or building-related facilities is only possible when each set of levels has been determined
using the same scales, which are suitable for the same functional category.
If a suitable set of supply scales is not available, it shall be created.
Supply scales for any functional type of building or building-related facility shall be written in language (terms
and concepts) which can be understood by individuals who work in or are qualified in the field of providing or
managing facilities and related constructed assets, but who are not experts. The levels within each scale shall
offer indicators of what is likely to be physically present in that functional category of facility. The indicators
shall be observable, easily noted without instrumentation, and suitable as a consistent indicator of
serviceability, that is the capability of a facility to meet a given functional performance requirement at a
specific level of demand.
Examples of the format for such scales are included in Annex B, and in References [1], [2], [3], [13], and [14]
in the Bibliography.
4.3 Number of statements and of levels in a scale
The demand and supply scales are matched so that the statement in a supply scale at any level indicates that
the serviceability meets the performance requirement in the demand scale at that level.
There is not a mandatory count of levels or statements in a pair of scales (demand and supply scales on a
topic). Five statements is the recommended count of statements in a demand scale and in the matching
supply scale, plus a statement for level 0. If for a particular topic it is not possible to define five statements
which are significantly different from each other, then it is recommended that the count be reduced to four or
to three statements, or in exceptional and rare cases to two statements, one of which shall be at what would
be taken as the middle level if there were five statements.
It is recommended that each level be designated by a single-digit integer, from 9 to 1, plus 0. If another count
is used, for instance 5 to 1 plus 0, or 99 to 1 plus 0, or 9,99 to 1,00 plus 0, then provide guidance on how to
compare such levels to scales in which the levels do conform to the recommendation. When there are five
statements plus zero, and the levels are expressed as single-digit integers; the recommended numbering of
statements in a scale is 1, 3, 5, 7 and 9, with 1 being the statement for least of that topic, and 9 being the
statement for most of that topic. This enables the in-between even levels to be used when the individual
choosing a level considers that the correct level is in between two statements. For some topics, it can be
helpful to also provide a statement at level 2.
6 © ISO 2011 – All rights reserved

If five statements is the normal count, but less than five statements are used, then the statements shall be
numbered so as to represent what their positions would be if there were five statements. For instance, if there
are only three statements, then one shall be numbered 5 for typical, one shall be numbered 9 for most, and
one shall be numbered 1 for least.
4.4 Calibration and normalization of scales
In each of the supply scales, one of the statements, typically the middle supply statement, shall describe the
indicators of the feature which is actually most typically provided or installed in that region, country or locality,
for that topic. The demand statement at that typical level shall be the demand (requirement) statement which
would require that typical supply level of serviceability. Therefore, this demand statement is not automatically
what is typically required. Instead, it can actually be more or less demanding than what is most typically
provided or installed.
4.5 Complex topics with multiple functions
For a complex topic, for which the functional performance requirement involves several functions which act in
combination to define that requirement, a separate demand scale shall be created for each function, and the
scales shall then be grouped under one topic.
The demand level for a complex topic, involving several functions which act in combination, shall be taken as
the whole number (integer) closest to the arithmetic mean (average) of the demand levels for the various
functions. If the average is at the mid-point between two whole numbers (e.g. × 0,5), the level shall be
reported as the nearest odd whole number.
For a complex topic, for which the serviceability is indicated by a combination of features which act in
combination for that topic, a separate supply scale shall be created for each feature, and the scales shall then
be grouped under one topic.
The supply level for a complex topic, involving several features which act in combination, shall be taken as the
whole number (integer) closest to the arithmetic mean (average) of the supply levels for the various features.
If the average is at the mid-point between two whole numbers (e.g. × 0,5), the level shall be reported as the
nearest odd whole number.
4.6 Relative importance of requirements
When people are setting requirement levels for a topic, they shall be asked to indicate whether that
requirement is “exceptionally important”, “important”, or of “minor importance” compared to other topics being
considered.
For individual stakeholders or groups of stakeholders, at a specific time, requirements on some topics are
more important than requirements on other topics. Setting more fine-grained distinctions of relative importance
is discouraged, because experience shows that asking for more than three possible responses leads to
results which are not sufficiently replicable.
4.7 Threshold or critical level
When identifying a demand level on each demand scale, the respondent shall be given the opportunity to
indicate a critical level of functionality which, if not provided, would significantly or completely impair the ability
of users or other stakeholders to carry out their intended activities or operations or mission. This level can be
the same as, or can be quite different from, the level of demand. This level shall be designated as the
“threshold level”.
Typically, the threshold level is a minimum level of demand. If the threshold level is a maximum value, that
shall be so indicated, as an exception.
NOTE Threshold levels are often indicated for “exceptionally important” topics, and less frequently for “important”
topics or topics of “minor importance”.
4.8 Main and variant requirement profiles
A functionality requirement profile is a list of the levels of functionality with respect to various topics required
by stakeholders for a facility. Similarly, a serviceability rating profile is a list of the levels of serviceability with
respect to various topics provided by a facility.
The set of requirement levels corresponding to the majority of users or stakeholders shall be identified as the
main requirement profile. Within any building or building-related facility used by more than a few dozen
individuals, it is common for some users to have requirement levels on some of the topics which are more
demanding than in the main requirement profile. The more demanding profile shall be identified as a variant
requirement profile. A main requirement profile can be augmented in specific zones as required by the variant
profiles for those zones.
The functionality requirement profile of a group of stakeholders shall not be reported as the simple average of
the main and variant profiles, but appropriately weighted averages may be used. This is because the extent
and variance of the variant requirement profiles of an organization, or of the various serviceability profiles in a
building or building-related facility, would be unknown if the profiles were simply averaged, or if only a
consensus were recorded.
Typically, the base building is designed to accommodate the main demand profile, and the variant
requirement profiles are accommodated during fit-out. In that way, if the zone for a particular requirement
profile is required to be expanded because more people have those needs, the building can accommodate
them by modifying its fit-out. For instance, the organization using a headquarters office building housing
several hundred workplaces can have one variant requirement profile for the legal department, who work
mostly in enclosed offices with a high level of speech privacy, and another for the facility management
personnel who work mostly in open plan workstations for ease of communication. Accounting and human
relations personnel can often work in open plan but have a variant requirement profile because they require
added security for personnel files and checks. Yet another variant requirement profile might be for the
information technology personnel who require extra electrical supply, complete freedom from interruptions to
electricity for their servers and testing equipment, and extra heat removal for their server rooms. The
marketing department can need some enclosed offices for developing confidential plans and proposals, and
convenient on-floor holding rooms for sample point-of-sale displays being reviewed. In a courthouse, the main
profile would likely be for areas where user occupants work and have contact with the public; among the
variant profiles would be one for the courtrooms, with special acoustic, illumination and security requirements,
one for the judges' office suites and circulation, and another for the prisoner holding areas and related
facilities. Typically, the variant profiles would only differ from the main requirement profile, and from each other,
on a limited count of topics, perhaps ten topics and rarely as many as twenty.
4.9 Generic profiles of demand
If it is desired to consolidate demand profiles of organizations conducting similar functions into a generic
demand profile for that category of functions, the same set of scales shall be used to create those individual
demand profiles.
Organizations conducting similar functions tend to have similar demand profiles. One category of
organizations which has been found to have similar demand profiles is that of corporate headquarters of large
organizations in the private sector, which are far more similar to one other than they are to the administrative
offices of the same organizations, in the same geographic area. Some other categories of facilities with similar
demand profiles include the following:
a) call centres;
b) offices for software development which typically have a lot of high technology and undergo rapid change;
c) offices for control of high-technology systems such as pipelines or telecommunications, which have a lot
of high technology but have much slower rates of change;
d) offices with a special need for high security;
e) maintenance shops and service yards; and many others.
8 © ISO 2011 – All rights reserved

This permits the development of generic requirement profiles for a wide range of functional categories of users.
Organizations with access to such generic profiles are able to compare their own requirement profiles to the
generic profile(s), and perform a kind of benchmarking.
4.10 Calibration of scales
For each functional category of building or building-related facility, a calibration rule using terms and factors
adapted so as to be appropriate to its functions and features shall be used, and shall be identified in the set of
scales for that category. Such rules for calibration shall conform to the general guidance in Annex B. The
calibration rules for demand and supply for each functional category of building or building-related facilities
shall be matched.
4.11 Gap analysis — Comparing demand and supply
When conducting a gap analysis, the level of demand and the level of supply for each topic for which such
levels are known shall be compared. The significance of the result of this comparison on all topics for which
both levels are known shall be determined. The default rule for finding that the difference for a given topic is
“significant” shall be as follows.
⎯ The topic is exceptionally important and the gap is two levels.
⎯ The topic has ordinary importance, and the gap is four levels.
⎯ The topic has minor importance, and the gap is six levels.
⎯ Regardless of the above, the gap is significant if the level of serviceability is lower than a minimum
threshold level of demand, or is higher than a maximum threshold level of demand, or if there is any
positive level of serviceability when the threshold is level zero (shall not have or shall not provide).
If a different rule is used for determining significance of difference between demand and supply, it shall be
clearly documented.
When single-number reporting is required for comparing the usefulness of facilities, or for prioritizing projects,
a helpful metric is often the total count of significant gaps.
4.12 Applicability in different cultures
This approach can be used in any culture, and for buildings constructed in any way of building, but the scales
shall be appropriate for that culture and way of building. Existing scales that have been created elsewhere
shall be confirmed as appropriate, or shall be adjusted and/or translated as necessary.
Those differences can result in the need for differently worded scales. In some cases, it can be necessary to
create new scales, even though some exist already. For instance, partition walls between rooms in an office
are constructed differently in France than in North America, and office doors are more likely to be closed in
France than in North America, so practices and requirements for voice privacy are different in the two cultures.
In consequence, when the paired scales for demand and supply which are American National Standards were
translated for use in France, the texts reflected different ways of using offices, and different ways of building in
France – but the French scales produced equivalent levels for functional performance requirements and for
ratings of serviceability. (See Reference [5] in the Bibliography.)
4.13 Consistency and replicability of responses
In large organizations, demand levels of functional performance requirements shall be consistent within a
range of plus or minus one level, if the work processes of selected user groups are in fact closely similar and if
the individuals setting requirement levels are first-line supervisors, that is, people close to the work being done
but with a managerial perspective. If this consistency is not found, then the reasons for absence of
consistency shall be provided with the findings. If levels of demand are determined by groups or group
interviews, the individuals who lead such groups shall be professionals in the fields of real estate, facility
management, or human resource management, and shall have had at least two days of instruction and
practice in the role of informed facilitator and interviewer.
Similarly, the levels of capability assigned by different raters separately assessing the level of serviceability of
a facility shall be consistent, plus or minus one level, in more than 95 % of rated topics. If this level of
consistency is not achieved, then the reasons for the absence of such consistency shall be provided with the
findings. The individuals who assess levels of serviceability shall be professionals in the fields of real estate,
facility management, design or construction, and shall have had at least 2 days of instruction and practice in
the role of assessing capability, or know the properties well.
Because an average level of functional performance requirements is used for topics with several specific
functions (4.5), and an average level of serviceability is used for topics with a combination of several
features (4.5), it is possible that the difference between level of requirements and level of serviceability can
actually be only one tenth or a few tenths of a level, even though it will be reported as the difference between
whole-number integers. Therefore, since the target for consistency of rating levels is plus or minus one level in
more than 95 % of rated topics, an exact match between levels set independently by different individuals or
groups of individuals is not likely.
4.14 Application during the whole life of a facility
The rules and guidelines in this document shall apply throughout the whole life of a facility, as required in
ISO 15686-10.
4.15 Inclusion in the building information mode (BIM)
The building information model (BIM) contains the database about a building or other constructed asset, and
about each project to create or modify a constructed asset. The ISO specification giving the platform and rules
for data format and exchange in a BIM is ISO/PAS 16739.
Release IFC2x3 includes a property set giving guidance on how to store information about the functionality
and serviceability profiles, and gaps, in the BIM. The name and internet location of that property set is given in
Reference [4] in the Bibliography.
10 © ISO 2011 – All rights reserved

Annex A
(informative)
Concepts of functionality and serviceability
A.1 How functionality and serviceability work together
A.1.1 Matched terms
This annex discusses how the concepts of functionality (see 3.15) and serviceability (see 3.28) work together,
and how these terms relate to other terms used in this International Standard and in other related standards.
Users or other stakeholders usually document their requirements for functionality in a program or brief written
using vocabulary and technical terms that they understand. These documents summarize the purposes,
needs, functions and activities of the users and other stakeholders to be met by a facility.
The concept of serviceability complements that of functionality. The serviceability of a facility is its capability to
provide that functionality, that is, how serviceable is it for supporting those who have that requirement.
A.1.2 Using the terms
The description of what people require in order to be able to do what they want or need to do is called the
required level of functionality (see 3.17) on a given topic (see 3.33). Taken together, levels of functionality on
different topics form a profile (see 3.22) of the requirements of the users and stakeholders. The extent to
which the place is suitable or useful in relation to one of the topics describing the users' requirements is called
a level of serviceability (see 3.19) for that topic. Taken together they form a matching profile of serviceability.
The suitability (see 3.30) of a facility is assessed when the two profiles are compared.
For instance, consider the place where an individual does office work in an accounting firm, or the place
where a family eats dinner at home, or the place where a family doctor examines a patient. Each such place
can be more or less suitable or useful for what the respective individuals want to do. If the place is not as
suitable or useful as is required, then there is a gap between the level of functionality required and the level of
serviceability provided for that use by the place.
When considering what level (how much or how little) of a particular topic of functionality is required to support
the users (see 3.34) or other stakeholders (see 3.29), one thinks of the several topics which together describe
their needs. For instance, the functionality required by users of an office is affected by topics such as
illumination, speech privacy, load capacity of floors (e.g. strong enough to support desks and file cabinets,
etc.) and freedom from distracting sounds. How much of each such topic is needed by the users, or other
stakeholders, is their level of functional performance requirement (see 3.14), such as enough illumination for
people to read very small print, or sufficient freedom from reflected glare to easily read a computer screen.
As an example, to simplify stating how much and what kind of illumination is required, this International
Standard calls for users and other stakeholders to be able choose from a range of options, expressed in a
scale (see 3.26), from least to most. For instance, a level 9 might be the most of a topic that one might
reasonably require, and a level 1 might be the least.
A.2 Usability and satisfaction
A.2.1 General
Two other concepts, “usability” and “satisfaction”, need to be explained to show how they relate to the terms
functionality (see 3.15), serviceability (see 3.28) and capability (see 3.6).
A.2.2 Usability
Usability has been defined in ISO in terms of certain products. A product of manufacture, made in quantities of
identical products, such as a computer terminal, should meet the functional requirements of its users. For
instance, ISO 9241-11:1998 defines the term “usability” as follows:
“extent to which a product can be used by specified users to achieve specified goals with effectiveness,
efficiency and satisfaction in a specified context of use”.
As explained in Annex D of ISO 9241-11:1998, usability of a product could be measured
⎯ “by analysis of the features of the product, required for a particular context of use”,
⎯ “by analysis of the process of interaction” with the product, and
⎯ “by analysing the effectiveness and efficiency which results from use of the product in a particular context
and measuring the satisfaction of the users of the product”.
Usability as defined in Annex D of ISO 9241-11:1998 also depends on software qualities which “contribute to
quality of the work system in use. … This broad approach has the advantage that it concentrates on the real
purpose of design of a product – that it meets the needs of real users carrying out real tasks in a real technical,
physical and organizational environment.”
If buildings are also considered as tools or aids to users, then the concept of usability also applies, though
unlike manufactured products, each building or building-related facility is unique at least in its physical location
and typically in many other features (see 3.11) as well.
A.2.3 Satisfaction
Satisfaction of users has been an indicator of serviceability, and of when to give priority to resolving problems
in a building. Many large corporations and government providers of facilities in many countries use satisfaction
surveys as part of their facility management toolkit. For instance, for some years, the US General Services
Administration (GSA), the provider and facility manager of offices for the US government, conducted a
comprehensive user satisfaction survey of all the offices it provided. It adapted the survey developed for the
International Facility Management Association (see Reference [8] in the Bibliography) and set a target level for
occupant satisfaction. GSA found that occupant satisfaction was not actually telling it which buildings most
needed fixing, because of two intervening variables:
a) occupant satisfaction was dominated by the perceived responsiveness and helpfulness of the personnel
providing facility management, rather than by the serviceability of the physical building;
b) typically, respondents mistakenly thought that the facility administrators in their own units, to whom they
took their complaints, were the facility managers, rather than the GSA staff who actually managed their
buildings.
12 © ISO 2011 – All rights reserved

Annex B
(informative)
Principle of calibration for scales
B.1 General guidance on the meaning of B.2 General guidance on the meaning of
levels in a functionality requirements levels in a serviceability rating scale
sca
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