ISO 16000-41:2023

Indoor air — Part 41: Assessment and classification

This document specifies a procedure for the assessment of the indoor air quality that is valid for all interior rooms in residential and non-residential buildings with natural or mechanical ventilation, in which people do not only stay temporarily. This document is applicable to indoor environments as defined in ISO 16000-1. The assessment of working materials in workrooms or workplaces in buildings, that are subject to statutory occupational safety specifications, are excluded from this document. In these rooms, only air constituents that do not originate from working materials can be assessed according to this document. It is not possible to define classes with exact values for the individual pollutants, as the corresponding limit and guide values differ in individual countries. In addition, the values relate to different observation periods. Aspects concerning electromagnetic fields, noise and vibrations and their effect on the indoor air quality are not the object of this document. The classification of further consequences and measures, such as organisational steps, structural engineering measures, renovation proposals, further human medicine appraisals and the like, are not the object of this document. NOTE This document applies to of all types of indoor environments occupied by all kinds of persons, including regular users, clients and workers.

Air intérieur — Partie 41: Évaluation et classification

General Information

• Status: Published
• Publication Date: 03-Aug-2023
• ICS: 13.040.20 - Ambient atmospheres
• Technical Committee: ISO/TC 146/SC 6 - Indoor air
• Drafting Committee: ISO/TC 146/SC 6/WG 24 - Indoor Air Quality management system
• Current Stage: 6060 - International Standard published
• Start Date: 04-Aug-2023
• Due Date: 15-Oct-2022
• Completion Date: 04-Aug-2023

Overview

ISO 16000-41:2023 - "Indoor air - Part 41: Assessment and classification" specifies a standardized procedure to assess and classify indoor air quality (IAQ) in residential and non-residential interior rooms with natural or mechanical ventilation. The standard defines a stepwise assessment procedure for spaces where people occupy indoors for more than a short time, and it applies to indoor environments as defined in ISO 16000-1. It does not set universal numeric limits for pollutants (national guide values differ) and excludes assessment of working materials in workplaces subject to occupational-safety rules and non-air stressors such as electromagnetic fields, noise and vibrations.

Key Topics and Requirements

• Structured assessment procedure: preliminary survey → investigation plan → investigation → documentation → expert opinion.
• Parameters to consider:
  • Chemical: gases, volatile and semi-volatile organic compounds, inorganic compounds, particles, fibres, odours.
  • Biological: fungi, bacteria, viruses, pollen, allergens.
  • Physical: indoor air and surface temperatures, humidity and related environmental parameters.
• Main vs Secondary parameters:
  • Main parameters must always be considered in the overall assessment.
  • Secondary parameters are included when the preliminary survey identifies their relevance.
• Quality classes: classification into quality classes (A to C) based on criteria; class boundaries are to be defined by national institutions using national, European or international guide values and research.
• Assessment values and periods: definitions for assessment value (instant/mean/continuous) and assessment period tailored to measured parameters and usage.
• Documentation: investigation plans, sampling points, seasonal/ventilation conditions, and reporting requirements are required for reproducible IAQ classification.
• Informative annexes cover example quality classes for main parameters and standards useful for preliminary surveys and investigation plan design.

Applications and Users

ISO 16000-41 is practical for:

• Indoor air specialists, environmental consultants and hygienists
• Architects, building services engineers and HVAC designers
• Building owners, facility managers and developers
• Manufacturers and distributors of building products and furnishings
• Public authorities and clients assessing indoor environments (schools, offices, healthcare, residential)

Practical uses include IAQ surveys, planning investigation strategies, comparing measured data against national guide values, and generating expert assessments to inform building operation, renovation planning or product selection.

Related Standards

• ISO 16000 series (other parts covering measurement methods and parameters)
• ISO 16000-1 (definitions for indoor environments)
• ISO 16000-32 (investigation of buildings for pollutants)
• ISO 11665-8 (radon investigation methodologies)

Keywords: ISO 16000-41, indoor air quality, IAQ assessment, quality classes, investigation plan, preliminary survey, main parameters, building ventilation.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 16000-41
First edition
2023-08
Indoor air —
Part 41:
Assessment and classification
Air intérieur —
Partie 41: Évaluation et classification
Reference number
© ISO 2023
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
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General . 2
4.1 Procedure . 2
4.2 Parameters . 3
5 Indoor air quality . 3
6 Quality classes . 3
7 Criteria for the definition of the quality classes . 4
7.1 General . 4
7.2 Main parameters. 4
7.3 Secondary parameters . 5
8 A ss e ss ment pla n .6
8.1 Overview . 6
8.2 Documentation and reports . 7
8.3 Purpose of measurements . 8
8.3.1 Possible reasons . 8
8.3.2 Concretisation of assessment. 8
8.4 Preliminary survey . 8
8.4.1 General . 8
8.4.2 Basic investigation . 9
8.4.3 Local inspections . 9
8.4.4 Conditions for the omission of the measurement of parameters . 10
8.5 Investigation plan . 10
8.5.1 General . 10
8.5.2 Normative specifications . 10
8.5.3 Determination of sampling points . 11
8.5.4 Utilization of the interior room . 11
8.5.5 Seasonal fluctuations and ventilation . 11
8.5.6 Complementary outside air measurements .12
8.6 Investigation . 12
8.7 Report .12
8.8 Division in quality classes . 12
Annex A (informative) Quality classes for main parameters.14
Annex B (informative) Standards for the preliminary survey and the design of investigation
plans .21
Bibliography .24
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO document should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
patent rights in respect thereof. As of the date of publication of this document, ISO had not received
notice of (a) patent(s) which may be required to implement this document. However, implementers are
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database available at  www.iso.org/patents. ISO shall not be held responsible for identifying any or all
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Any trade name used in this document is information given for the convenience of users and does not
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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 146, Air quality, Subcommittee SC 6,
Indoor air.
A list of all parts in the ISO 16000 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
In our society, privately and professionally, people stay indoors most of the day. Therefore, the quality of
the indoor air is very decisive for the quality of life and health. This especially applies to small children,
sick people and other vulnerable groups of persons.
Numerous scientific studies verify the positive effects of good indoor air on the overall performance
during learning (e.g. in kindergartens and schools) and working. A consequence of improved indoor air
quality can be, for example, reduced sickness rates and absenteeism.
The entitlement to high-quality indoor air does not contradict economical aspects of energy- and cost-
efficiency. Improvements in the quality of indoor air are achievable with simple measures, for example,
change of behaviour patterns.
This document describes a procedure to classify the air quality of indoor spaces using quality classes.
These quality classes enable the allocation of the room air to a high, medium or low quality. The quality
classes are based on criteria for physical, chemical and biological parameters according to the state
of science and research. These criteria can be both concentration values in the room air (e.g. with
formaldehyde) as well as sensory and other findings in the room itself (e.g. with mould). The basis for
classifying a measured value of a parameter in a quality class is the definition of class boundaries for
quality classes A to C by national institutions, using guide values from national guidelines, European
and international publications and trade literature.
The most frequent pollutant sources indoors are human activities (e.g. domestic-, hobby- and cleaning
activities, tobacco smoke), combustion processes as well as building materials, furnishings and interior
design materials. The exception is the radioactive inert gas radon, which mostly originates from the
geological subsoil and enters the interior spaces via leaks in the building envelope.
A variety of substances can emit into the indoor air from the most diverse pollution sources. For
this reason, the single analysis of a source or pollutant cannot be used as a substitute for an overall
assessment of the indoor air. A meaningful assessment of the indoor air is only achievable by an overall
assessment of all pollutant sources and substances.
This document is intended for specialists who deal with the assessment of indoor air in the course
of planning, construction, operation and use of buildings (e.g. indoor-experts, architects, specialist
planners of trades, building owners, building developers and contracting authorities, maintenance
engineers, lessors). Also included are producers and distributors of products, that are installed and/or
operated indoors (e.g. building products), and possible users.
v
INTERNATIONAL STANDARD ISO 16000-41:2023(E)
Indoor air —
Part 41:
Assessment and classification
1 Scope
This document specifies a procedure for the assessment of the indoor air quality that is valid for all
interior rooms in residential and non-residential buildings with natural or mechanical ventilation, in
which people do not only stay temporarily.
This document is applicable to indoor environments as defined in ISO 16000-1.
The assessment of working materials in workrooms or workplaces in buildings, that are subject to
statutory occupational safety specifications, are excluded from this document. In these rooms, only air
constituents that do not originate from working materials can be assessed according to this document.
It is not possible to define classes with exact values for the individual pollutants, as the corresponding
limit and guide values differ in individual countries. In addition, the values relate to different
observation periods.
Aspects concerning electromagnetic fields, noise and vibrations and their effect on the indoor air
quality are not the object of this document. The classification of further consequences and measures,
such as organisational steps, structural engineering measures, renovation proposals, further human
medicine appraisals and the like, are not the object of this document.
NOTE This document applies to of all types of indoor environments occupied by all kinds of persons,
including regular users, clients and workers.
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 11665-8, Measurement of radioactivity in the environment — Air: radon-222 — Part 8: Methodologies
for initial and additional investigations in buildings
ISO 16000 (all parts), Indoor air
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
building product
product or building kit, that is manufactured or brought into circulation, to be installed permanently
in buildings or parts of buildings and whose performance affects the performance of the building with
regard to the basic requirements on buildings
[23]
[SOURCE: EU-BauPVO, Article 2 (1) ]
3.2
assessment value
value obtained from an assessment
Note 1 to entry: The assessment value can be an individual measured value, the arithmetic mean of individual
measured values or the result of a continuous measurement over a particular time period. In the case of carbon
dioxide (CO ), the assessment value is a statistical evaluation of the individual measured values.
3.3
assessment period
period during which the investigation of the indoor air takes place
Note 1 to entry: The assessment period is adapted to the parameter to be assessed and the measuring task and
linked to certain usage conditions.
3.4
emission
release of chemicals, vibration and radiation to the environment
Note 1 to entry: The emission of air constituents can be specified as mass flow. In relation to building products
(3.1), the mass flow can be related to area, length, mass, volume or component.
Note 2 to entry: The terms “emission” and “release” basically have the same meaning.
3.5
main parameter
parameter which, during an overall assessment, is taken into consideration without fail
3.6
secondary parameter
parameter that is also taken into consideration for the overall assessment, if references to its relevance
exist in the preliminary survey
3.7
guide value
default value that serves as a comparative value for the assessment
Note 1 to entry: Specific guide values for interior rooms are defined, for example, by the WHO and national/
professional institutions.
4 General
4.1 Procedure
The procedure for the assessment of the indoor air quality consists of the following steps:
a) preliminary survey;
b) investigation plan;
c) investigation;
d) documentation;
e) expert opinion.
When this document is applied, it should be taken into consideration that the concentrations of
substances in the room air can fluctuate greatly: spatially, time-related and usage-specific. This is
particularly dependent on ventilation, the building services and the individual user behaviour.
Individual results of certain parameters cannot sufficiently characterize the indoor air, therefore the
overall assessment described in this document is necessary in order to obtain a comprehensive and
differentiated picture of the room air situation.
An investigation of buildings for pollutants shall be carried out in accordance with ISO 16000-32.
4.2 Parameters
Chemical, biological and physical parameters play a role in the assessment of the indoor air.
— chemical parameters and particles: gases, volatile and hardly volatile organic and inorganic
compounds, fibres, dusts, dust constituents and odours;
— biological parameters: fungi, bacteria, viruses, pollen and other allergens (e.g. animal epithelia,
insects/insect compounds, mites, mite excrement, plant parts/fibres);
— physical parameters: room air and environment surface temperatures, operative temperature, air
humidity, air velocity, lighting, sounds and noise, electromagnetic fields and charged particles.
In the context of this document, only selected chemical and biological parameters are dealt with. The
room air temperature and the humidity should be regarded as supplementary physical parameters.
NOTE Physical parameters are dealt with in, for example, ISO 7730.
5 Indoor air quality
For the assessment of the indoor air according to this document, a classification of the room air
quality into three quality classes A (high), B (medium) and C (low) is performed based on prescribed
main parameters (see 7.2). In addition, further secondary parameters (see 7.3) should be taken into
consideration, if necessary.
The class limits of the quality classes are defined by:
— guide values in the sense of maximum permissible concentrations in the room air (e.g. with
formaldehyde) or distributions of measured values (e.g. with carbon dioxide CO ),
— sensory findings in the room itself (e.g. with mould, odours).
The use of a questionnaire can also contribute to the assessment of a room.
6 Quality classes
Table 1 provides an overview of the quality classes and describes the requirements on the room air
quality on which these classes are based. The designations and descriptions of the requirements
according to Table 1 are only partly applicable for the parameter “Mould – microbial infestation”.
Table 1 — Indoor air quality classes
Quality class Designation Description
A High room air quality Room air with low substance concentrations
B Medium room air quality Room air with average substance concentrations
C Low room air quality Room air with above-average substance concentrations
Lowest air quality class not fulfilled Substance concentrations above the class limits of quality class C
If any main criteria do not permanently fulfil even quality class C, the indoor air shall not be classified
but is considered to be “outside all quality classes”.
During the course of an assessment, the need for different quality classes can arise for a specific interior,
depending on which parameter is considered.
For the assessment, it shall be taken into consideration that many building products show a significant
decrease of their emissions, especially in the first days and weeks after their manufacturing. A
meaningful holistic assessment of the room air condition in the sense of this document is only possible
in an actual usage stage.
7 Criteria for the definition of the quality classes
7.1 General
The basis for classifying a measured value of a parameter in a quality class is the definition of class
boundaries for quality classes A to C. The limits of the quality classes can be defined on the basis of guide
values from national guidelines and European and international, publications and trade literature. For
the parameter "Mould – Microbial Infestation", in addition the condition of the room with regard to
mould infestation is adjudged.
7.2 Main parameters
Parameters most frequently giving rise for complaints due to the quality of indoor air are defined as
main parameters in this document.
In the framework of the overall assessment, the expert shall assess all these main parameters, however
a measurement of every parameter is not always necessary (see 8.4.4).
Table 2 lists the main parameters as well as the corresponding clauses in annexes of this document.
Table 2 — Main parameters
Parameter Clause
Formaldehyde A.2
Volatile organic compounds (VOC) A.3
Radon A.4
Carbon dioxide A.5
Mould - microbial infestation A.6
Odour A.7
Fine dust (PM1, PM2.5, PM10), ultrafine particles (UFP) —
The criteria for the parameter carbon dioxide were derived from considerations of comfort as well as the
users´ cognitive performance. Carbon dioxide levels are also used as an indicator for the concentration
of emissions of the user or animals by breathing and body effluence into indoor air.
The appearance of mould is usually associated with the presence of filamentous fungi and yeast. Often
bacteria are also present. In the case of air measurements, only the concentration of mould and bacteria
is usually recorded.
The physical parameters “room air temperature” and “relative humidity” shall be recorded separately in
the representation of the measurement results, because they influence the concentrations of pollutants
in the room air and are frequently associated by users with an inadequate indoor air quality.
7.3 Secondary parameters
Secondary parameters are used, when there are indications of an occurrence of substance concentrations
with a negative impact on the indoor air quality. In these cases, the investigation program shall be
complemented with these secondary parameters. The consideration of secondary parameters shall be
identified and justified accordingly in the overall assessment.
No quality classes are defined in this document for secondary parameters. That does not mean
that quality classes cannot be defined. For some of the compounds, no effectiveness threshold or
concentration can be specified, under which no health-related effects are to be expected.
The evaluation of secondary parameters is at the discretion of the expert.
In summary, secondary parameters include factors such as
— ammonia and heavy metals (e.g. mercury),
— asbestos,
— carbon monoxide,
— biocides (e.g. PCP, lindane),
— CMR substances in general,
— synthetic mineral fibres,
— nicotine,
— polychlorinated biphenyls (PCB),
— polychlorinated dioxins and furans (PCDD/PCDF),
— polycyclic aromatic hydrocarbons (PAH),
— sulfur dioxide,
— nitrogen oxides,
— other organic compounds besides VOC (VVOC, SVOC, MVOC), and
— parameters: fungi, bacteria, viruses, pollen and other allergens (e.g. animal epithelia, insects/insect
compounds, mites, mite excrement, plant parts/fibres).
ISO 16000-1:2004, Annex C contains a list of sources of air impurities in interior rooms and the
substances or substance groups emitted from them, that shall be used as a basis for the determination,
investigation and assessment of secondary parameters.
Before the implementation of measurements of identified hazardous substances in the room, the
investigation of possible sources in buildings is recommended.
8 Assessment plan
8.1 Overview
The overall assessment of the indoor air of an individual room or a building with multiple rooms shall
take the individual steps of the assessment procedure into account, as listed in Table 3.
Table 3 — Phases of an overall assessment
Phase 1: Finding
Compilation of the information and documents required for the planning of an investigation
Preliminary survey
(e.g. previous test results, medical findings, data sheets)
Decision, whether the sampling or investigation is to be carried out on-site; definition of the
Investigation plan
parameters to be considered in the planning of an investigation
Investigation Implementation of the planned investigation or sampling and evaluation of the samples
Documentation of the measurement procedure, measuring results and framework conditions
Documentation
of the investigation
Phase 2: Assessment
Classification in Assessment of the room air quality based on the quality classes according to this docu-
quality classes ment
Figure 1 shows the individual steps of Table 3 and the documents resulting therefrom.
Figure 1 — Procedure and steps of an assessment of the indoor air
8.2 Documentation and reports
The documentation shall include the findings and the assessment.
The introduction of the documentation shall include the aims and objectives of the indoor air
assessment and the reason why the assessment is performed. Subsequently every individual step shall
be documented separately in the report according to Figure 1 (preliminary survey, investigation plan,
sampling report and representation of the measurement results).
The conclusions from the results of the findings and the classification in quality classes shall be
documented in the form of a report.
8.3 Purpose of measurements
8.3.1 Possible reasons
An assessment of the room air of interior rooms can be triggered for numerous reasons. Possible
reasons are, for example:
a) Adherence to predetermined values: The adherence to predetermined values is verified. This can,
for example, be in connection with the certification of building performance or assessments of the
reasonableness of odours.
b) Acquisition of information through measurements: The background concentration, or a
concentration before, during and after a renovation measure is checked, based on e.g. control-,
work-accompanying- and release measurements. Likewise, such measurements can be performed
in the course of research studies, for which the parameters are usually predetermined.
c) Insufficient quality of the indoor air: There are general complaints by room users concerning a
room air quality perceived as poor. These complaints can be, for example, in connection with an
unpleasant smell.
d) Impairment of the health of room users: There are indications for an impairment of the health of
room users due to pollutants or physical parameters in the indoor air. These indications can be, for
example, specific symptoms in the respiratory tract of room users.
These various reasons can exist individually or also jointly and in each case result in different methods
of procedure of the respective competent specialist.
8.3.2 Concretisation of assessment
With cases 8.3.1 a) and b), a further concretization of the assessment plan is advisable, but not necessary.
In these two cases, a sampling strategy can be defined without further surveys.
In situations covered by 8.3.1 c) and d), a concretisation of the symptoms of the room users is required.
This concretisation should be carried out, for example, through systematic questioning of those affected
as well as other persons involved (e.g. locally knowledgeable, medical expert).
To record the subjective evaluation by those affected, for example, questionnaires can be used for the
perceived air quality.
8.4 Preliminary survey
8.4.1 General
A preliminary survey consists of a basic investigation and a local inspection, which together represent
the result of the preliminary survey.
In the course of the preliminary survey, initial technical or organisational measures can already
be recommended (e.g. elimination of obvious pollutant sources, change of the room utilization).
Furthermore, in this case, the need to consult other specialists can already arise (doctors, hygienists,
air-conditioning technicians, structural engineers and the like).
The preliminary survey forms the basis for the investigation plan. The results of the preliminary survey
shall be documented as part of the findings with regard to the type and scope of the surveys performed.
It should be taken into consideration that besides the chemical, biological and physical parameters,
psychological factors can also play a role. In the course of the preliminary survey, among other things
the following aspects are to be observed:
— symptoms of those affected by health problems or about the limitations of comfort;
— the type of use of the rooms;
— the building products used;
— the objects of equipment used and materials of the interior design;
— the ventilation (ventilation via windows/doors and/or mechanical ventilation) and the equipment
of the air purification (design and maintenance);
— sources in the vicinity of the room or the building (e.g. in adjacent rooms and the entry with the
outside air);
— events in the past, that can have an influence on the room air quality (e.g. fires).
The information gained in the course of the preliminary survey shall be considered holistically and
enables the definition of the next procedure.
Annex B provides a compilation of documents that may be used in the course of a preliminary survey.
8.4.2 Basic investigation
During a preliminary survey, the first step is an investigation with the aim of compiling already existing
documentation. For these details about the location, the building and the utilization shall be recorded.
The investigation records can include, for example:
— documentation of the radon potential of the subsurface,
— details from potentially registered contaminated sites,
— plans and sections of the room or building,
— official documents,
— already existing expert assessments,
— details about the building materials used,
— heating, sewage and ventilation systems,
— maintenance, renovation and conversion measures,
— former uses, and
— special events (e.g. accidents, water damage and fires).
8.4.3 Local inspections
An on-site visit is part of the assessment, during which the respective rooms are visually inspected.
The results of this inspection shall be documented in writing. If applicable, the writing shall be
complemented with additional mapped and pictorial representations. For a systematic representation,
technical building descriptions and building plans can be used. If mapped out documents are missing, it
is advisable to produce sketches true to scale. If areas cannot be inspected, these shall be listed and the
reason for not inspecting them shall be given.
Under certain circumstances, an initial identification of substances or substance classes is feasible by
means of sensory perception. In this case, the initial identification of said substances shall be used to
pre-determine main and secondary parameters for the assessment.
NOTE For a local inspection, it can be useful to bring tools such as lamp, mirror, tape measure, ladder, camera
and the like on site.
8.4.4 Conditions for the omission of the measurement of parameters
The measurement of main parameters can be omitted under the following conditions, whereby in any
case the assessment of these shall be carried out by an expert.
— A secured presence of quality class A with regard to a particular main parameter shall be determined
(e.g. if no sources for this substance are present). In this case, the assessment of this parameter
contains a comprehensive justification for the omission of the measurement.
— If there are investigation results present, which were performed according to the state of technology
and according to the methods and framework conditions (e.g. type of usage) defined in this document,
then these can also be included in the overall assessment.
— For the main parameter mould (microbial infestation, see Clause A.6), a classification into quality
classes, based solely on the inspection, is possible under certain circumstances. In this case, the
assessment of this parameter contains a comprehensible justification for the omission of the
measurement, based on the local inspection. It should be considered that hidden mould damage is
not covered in this case. To cover hidden mould damage, further investigation is needed.
If measurements are not carried out, the reasons shall be justified and documented comprehensively
by the expert. Otherwise, no overall assessment is possible in the sense of this document.
8.5 Investigation plan
8.5.1 General
Based on the results of the preliminary survey, the sampling strategy of the room air shall be defined,
which in turn determines the investigation plan. The investigation plan is based on the specific reason
for the investigation and documents its planned boundary conditions and the objective.
The investigation plan shall be documented as part of the findings with regard to the type and scope of
the measures to be performed.
The following aspects should be considered for the definition of the sampling strategy:
— main parameters to be investigated (see Table 2), consisting of the respective chemical, biological
and physical measurement parameters;
— secondary parameters to be investigated;
— parameters that cannot be acquired analytically;
— sampling methodology;
— times of the samplings;
— locations of the samplings;
— frequency of the samplings;
— duration of the measurements;
— use of the room (e.g. occupancy rate, activities).
8.5.2 Normative specifications
For the design of the investigation plan, the respective parts of the ISO 16000 series shall be considered,
in which the individual aspects of the sampling strategy are described.
ISO 16000-1 describes general aspects for planning indoor measurements that apply for all substances
or substance groups. Based on this, the other parts of the ISO 16000 series contain specifications that
shall be observed during the sampling planning for the respective substance or substance groups.
Annex B provides a list of the documents that can be used in the course of the investigation.
8.5.3 Determination of sampling points
The minimum number of sampling points per room shall be calculated in accordance with Formula (1):
PA=01,* (1)
where
P is the number of sampling points;
A is the area of the room or part of the building, in m .
The results shall be rounded up to the next whole number. For smaller rooms (P < 1), one sampling
point per room shall be set. For a building with multiple rooms, in which a similar room air quality can
be assumed, or for rooms that are connected, the sum of the areas of these rooms is used in the formula.
If a similar indoor air quality can be assumed in multiple rooms of the same building, the investigation
of all individual rooms may not be necessary. In these cases, the sampling can be performed in
representative and permanently occupied rooms. These rooms should comprise at least 10 % of the
occupied space. The selection of the respective rooms shall be justified by the expert.
In rooms with high occupancy and poor ventilation, additional measurements should be considered.
If the same room is equipped with multiple air conditioning systems, it is necessary to determine the
number of measurement points for each air conditioning system or zone of air conditioning units.
8.5.4 Utilization of the interior room
For the sampling planning, the actual use of the interior room should be considered. There are three
types of measurements that can be performed:
a) Measurements during normal usage: The normal usage can require the presence of persons and
under certain circumstances the implementation of particular activities. Such measurements can
enable identification of a background load.
b) Measurements during special used zones: Special uses can cause concentrations in the room air
deviating from the normal use. Simulations of the special usage are permitted.
c) Unoccupied zones: For some substances measurements under equilibrium conditions are required
(e.g. formaldehyde or VOCs).
EXAMPLE 1 Lower concentrations of some pollutants as CO during the absence of users.
EXAMPLE 2 Increased concentrations during the implementation of maintenance or renovation work.
8.5.5 Seasonal fluctuations and ventilation
In rooms, seasonally different conditions can exist. Such different conditions, for example caused by
the heating period (cold season/winter) can have an influence on the air quality. In this case, an overall
assessment for the whole year is not possible, and the assessment shall be subdivided seasonally, if
appropriate.
As a rule, measurements should be taken with the windows closed, unless the measurement task
requires a different approach. The specifications for ventilation (e.g. how long the windows have to
remain closed before the measurement) can be found in the ISO 16000 series or other methods, proven
to be equivalent to the respective part of the ISO 16000 series.
8.5.6 Complementary outside air measurements
Due to infiltration and ventilation, an exchange between indoor and outdoor air always takes place.
Therefore, in some cases, the need arises to complement indoor air measurements with outdoor air
measurements. These outdoor air measurements are required in cases in which it is expected that the
concentration of pollutants in the interior room is decisively influenced by the concentration of outside
air.
An outside air measurement or reference measurement in an uncontaminated area is always required
for measurements of mould.
8.6 Investigation
The implementation of the investigation plan shall take place through sampling.
The investigation shall be carried out by sampling with subsequent analysis and evaluation. Sampling
and analysis shall be carried out in accordance with the requirements of the ISO 16000 series or other
methods proven to be equivalent to the respective part of the ISO 16000 series.
8.7 Report
In all cases the sampling report shall contain the following details:
— indication of which rooms are representative of others and which have been classified only on the
basis of measurement of other rooms,
— chemical and biological measurement parameters (parameter scope),
— room air temperature and the relative humidity,
— sampling technique,
— times of the samplings,
— sampling points including room identification,
— sampling frequencies,
— duration of the measurements,
— type of use of the room, and
— reproducible justification for the omission of measurements of certain main parameters.
The measurement results shall be specified room by room, broken down according to parameter.
The representation of the measurement results shall be documented as part of the findings. For the
assessment, relevant boundary conditions and information, that are not regulated in the relevant
International Standards (e.g. the presence of persons for CO measurements), shall be specified.
8.8 Division in quality classes
The division of indoor air into quality classes with respect to a particular parameter is produced through
a comparison of the assessment values determined with the respective class limits of the quality classes
as well as through the results of the on-site findings of the expert. An example classification for CO and
other supporting information is provided in Clause A.5.
The quality classes shall be identified separately for each parameter. For the assessment of a room,
different quality classes can result for individual parameters. These quality classes need to be identified
for each room that was investigated.
The reduction of the classification of multiple parameters of rooms or buildings to one single quality
class is not permitted.
Annex A
(informative)
Quality classes for main parameters
A.1 General
This annex lists measurement methods for each main parameter. Indications for the determination of
the assessment value are also listed. The basis for classifying a measured value of a parameter in a
quality class is the definition of class boundaries for the quality classes by national institutions.
Based on existing specifications, three quality classes are defined for each main parameter (see Table 1).
The allocation of a room into the respective quality class results from the measurements. In cases of
mould, a perpetration, including a visual assessment by an expert shall be used for the classification.
The sampling of indoor air in general shall be carried out in accordance with the ISO 16000 series. If a
ventilation system exists, it should be operated at a realistic ventilation stage during the assessment.
A.2 Formaldehyde
A.2.1 General
Formaldehyde is a flammable, colourless, very reactive, pungent smelling gas with the chemical formula
®1)
HCHO. The aqueous solution is also called “Formaline” (CAS Registry Number 50-00-0).
Formaldehyde is one of the most well-known air pollutants in indoor spaces. It is used widespread as
constituent of products in everyday use. It is emitted from wood materials, building materials, smoking
and furnishing objects. In the past, formaldehyde frequently
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