CEN/TR 16797-2:2015

Construction products: Assessment of release of dangerous substances - Guidance on the statistical assessment of declared values - Part 2: Technical and statistical background

This Technical Report provides guidance on the statistical assessment of declared values with respect to the release, emission and/or content of dangerous substances. This report provides statistically-based criteria for type-testing (TT), further-testing (FT) and where a product has been shown to be consistent with measured values for the release, emission or content that are significantly below the declared values, the point where no-further-testing (NFT) is permitted.
A series of fundamental principles are defined in CEN/TR 16797-1 and two statistical approaches are defined. The first approach is to use assessment by variables and this approach requires the data to be normally or log-normally distributed. This approach is recommended as the default option. The alternative approach based on assessment by attributes is appropriate for data sets that are not normally or log-normally distributed. The downside to this form of assessment is that more test data are needed for the same level of reliability. CEN/TR 16797-1 introduces these assessment procedures and CEN/TR 16797-2 provides more detail and the statistical proof that they satisfy the principles defined in CEN/TR 16797-1. With both of these approaches the minimum frequency of testing is a function of the distance between the mean value and declared value and the variability of the data set, i.e. the sample standard deviation.
To reduce the costs of testing, production plants producing a similar product may share data, e.g. be grouping the product into clusters for statistical assessment of declared values. Rules for the use of clusters are given in this document.
This document also contains rules for identifying outliers within a data set and guidance on using tests other than the reference method for FT.
A list of tasks for product technical committees is given in this document as is a model clause for including in product standards and rules of applications that may be cited in the product standard or copied into product standards.

Produits de construction - Evaluation de l'émission de substances dangereuses - Guide pour l’évaluation de la performance et la vérification de sa constance - Partie 2 : Données techniques et statistiques

Gradbeni proizvodi – Ocenjevanje sproščanja nevarnih snovi - Navodilo za statistično ocenjevanje deklariranih vrednosti - 2. del: Tehnično in statistično ozadje

To tehnično poročilo CEN zagotavlja navodilo za statistično ocenjevanje deklariranih vrednosti v zvezi s sproščanjem, emisijami in/ali vsebnostjo nevarnih snovi. To poročilo zagotavlja merila na podlagi statističnih podatkov za tipsko preskušanje (TT), dodatno preskušanje (FT), kadar pa je dokazana skladnost proizvoda z izmerjenimi vrednostmi za sproščanje, emisije ali vsebnost, ki so bistveno nižje od deklariranih vrednosti, točko, ko ni dovoljeno dodatno preskušanje (NFT).
V dokumentu FprCEN/TR 16797-1 so opredeljeni sklop temeljnih načel in dva statistična pristopa. Prvi pristop zajema uporabo ocenjevanja s spremenljivkami, pri čemer je za ta pristop potrebna normalna ali logaritemsko normalna porazdelitev podatkov. Ta pristop se priporoča kot privzeta možnost. Alternativni pristop, ki temelji na ocenjevanju po atributih, je primeren za podatkovne sklope, ki niso normalno ali logaritemsko normalno porazdeljeni. Slaba plat te oblike ocenjevanja je, da je za enako raven zanesljivosti potrebnih več preskusnih podatkov. FprCEN/TR 16797-1 uvaja te postopke za ocenjevanje, FprCEN/TR 16797-2 pa zagotavlja več podrobnosti in statistični dokaz, da so izpolnjena načela iz dokumenta FprCEN/TR 16797-1. Pri obeh pristopih je najmanjša pogostost preskušanja funkcija razdalje med povprečno vrednostjo in deklarirano vrednostjo ter spremenljivosti podatkovnega sklopa, tj. standardni odklon vzorca.
Da bi se zmanjšali stroški preskušanja, si lahko proizvodni obrati, ki proizvajajo podoben proizvod, delijo podatke, npr. proizvod povežejo v skupine za statistično ocenjevanje deklariranih vrednosti. Pravila za uporabo skupin so določena v tem dokumentu.
Ta dokument vsebuje tudi pravila za opredelitev osamelcev v podatkovnem sklopu in navodilo za uporabo preskusov, ki niso referenčna metoda za dodatno preskušanje.
Seznam opravil za tehnične odbore za proizvode je naveden v tem dokumentu, pa tudi modelni člen, ki se vključi v standarde za proizvode, in pravila za uporabe, ki jih je mogoče citirati v standardu za proizvod ali kopirati v standarde za proizvode.

General Information

• Status: Published
• Publication Date: 25-Aug-2015
• ICS: 03.120.20 - Product and company certification. Conformity assessment
• ICS: 91.100.01 - Construction materials in general
• Technical Committee: CEN/TC 351 - Construction Products - Assessment of release of dangerous substances
• Drafting Committee: CEN/TC 351 - Construction Products - Assessment of release of dangerous substances
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 26-Aug-2015
• Due Date: 03-Sep-2015
• Completion Date: 26-Aug-2015
• Directive: 305/2011 - Regulation (eu) No 305/2011 of the European Parliament and of the Council of 9 march 2011 laying down harmonised conditions for the marketing of construction products and repealing council directive 89/106/eec
• Mandate: M/366 - Concerning the execution of standardisation work for the development of horizontal standardised assessment methods for harmonized approcaches relating to dangerous substances under the construction products directive (CPD)
• Ref Project: SIST-TP CEN/TR 16797-2:2015 - Construction products: Assessment of release of dangerous substances - Guidance on the statistical assessment of declared values - Part 2: Technical and statistical background

Overview

CEN/TR 16797-2:2015 is the Technical Report (Part 2) that provides the technical and statistical background for assessing declared values of the release, emission or content of dangerous substances from construction products. It complements CEN/TR 16797-1 by giving the statistical proofs and detailed procedures that underpin rules of application for type-testing (TT), further-testing (FT) and no-further-testing (NFT).

Keywords: CEN/TR 16797-2, declared values, statistical assessment, construction products, release of dangerous substances, AVCP

Key technical topics and requirements

• Two statistical approaches
  • Assessment by variables (recommended default): requires data to be normally or log‑normally distributed; uses mean and sample standard deviation to set test frequency and acceptance rules.
  • Assessment by attributes (alternative): used when data are not normally/log‑normally distributed; typically requires larger sample sizes for equivalent reliability.
• Decision rules for TT, FT and NFT
  • Testing frequency and acceptance depend on the distance between the measured mean and the declared value and on variability (sample standard deviation).
  • Gamma rule and other rules of application are defined and statistically justified in this report.
• Cluster assessment
  • Rules for pooling data from similar production plants or grouped product clusters to reduce testing costs while preserving statistical reliability.
• Outliers and detection limits
  • Procedures for identifying outliers and for handling values below the detection limit.
• Indirect and alternative tests
  • Guidance on using correlated indirect tests for FT and on cases where an indirect test shows no correlation with the reference method.
• Supporting material
  • Annexes include examples, distribution guidance, checklists for product technical committees, model clauses for product standards, critical values and the gamma factor.

Keywords: type-testing, further-testing, no-further-testing, cluster assessment, outliers, detection limit, indirect test

Practical applications and users

Who uses this standard:

• Product technical committees - to draft product standards and model clauses consistent with AVCP principles.
• Manufacturers and quality managers - to set declared values, determine sampling/testing strategies, and justify NFT.
• Testing laboratories and conformity bodies - to apply statistically based acceptance criteria for TT and FT.
• Regulators and enforcement authorities - to interpret and accept statistically valid verification procedures.

Typical uses:

• Defining sampling frequency and acceptance criteria for emissions/contents.
• Grouping similar product lines into clusters to reduce test costs.
• Selecting statistical approach (variables vs attributes) and handling non-detects and outliers.
• Incorporating model clauses into product standards or regulatory texts.

Related standards

• CEN/TR 16797-1: Principles and rules of application (companion document)
• Work prepared by CEN/TC 351 (Construction products: Assessment of release of dangerous substances)

Keywords: AVCP, CEN/TC 351, product standards, statistical proof

Standards Content (Sample)

SLOVENSKI STANDARD
01-oktober-2015
*UDGEHQLSURL]YRGL±2FHQMHYDQMHVSURãþDQMDQHYDUQLKVQRYL1DYRGLOR]D
VWDWLVWLþQRRFHQMHYDQMHGHNODULUDQLKYUHGQRVWLGHO7HKQLþQRLQVWDWLVWLþQR
R]DGMH
Construction products: Assessment of release of dangerous substances - Guidance on
the statistical assessment of declared values - Part 2: Technical and statistical
background
Produits de construction - Evaluation de l'émission de substances dangereuses - Guide
pour l’évaluation de la performance et la vérification de sa constance - Partie 2 :
Données techniques et statistiques
Ta slovenski standard je istoveten z: CEN/TR 16797-2:2015
ICS:
13.020.99 Drugi standardi v zvezi z Other standards related to
varstvom okolja environmental protection
91.100.01 Gradbeni materiali na Construction materials in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL REPORT
CEN/TR 16797-2
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
August 2015
ICS 03.120.20; 91.100.01
English Version
Construction products: Assessment of release of dangerous
substances - Guidance on the statistical assessment of declared
values - Part 2: Technical and statistical background
Produits de construction - Evaluation de l'émission de
substances dangereuses - Guide pour l'évaluation de la
performance et la vérification de sa constance - Partie 2 :
Données techniques et statistiques

This Technical Report was approved by CEN on 16 January 2015. It has been drawn up by the Technical Committee CEN/TC 351.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, 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: Avenue Marnix 17, B-1000 Brussels
© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16797-2:2015 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
0 Introduction . 5
0.1 General . 5
0.2 Background . 5
0.3 Assessment of construction products . 6
0.4 Reading guide to CEN/TR 16797-2 . 9
0.4.1 General introduction . 9
0.4.2 Rules of application . 9
0.4.3 Statistical background . 9
0.4.4 Annexes . 9
1 Scope . 10
2 Terms, definitions, abbreviations and symbols . 10
2.1 Terms and definitions . 10
2.2 Abbreviations and symbols . 14
3 Context . 16
4 Quality level of performance with respect to the release, emission or content of
RDS . 17
5 Methods for statistical assessment of declared values for RDS . 17
5.1 Goal of the assessment . 17
5.2 Assessment of the production . 17
5.3 Assessment of clusters . 19
5.4 Assessment of no-further-testing . 20
5.5 Methods of assessment . 23
5.5.1 Introduction . 23
5.5.2 Assessment by variables . 23
5.5.3 Assessment by attributes . 24
5.6 Description of the assessment procedure . 24
5.6.1 Type testing . 24
5.6.2 Further-testing . 25
5.6.3 Clusters . 26
5.6.4 No-further-testing . 29
5.7 Banned substances . 29
6 Assessment by variables . 30
6.1 Single production units . 30
6.1.1 Type testing . 30
6.1.2 Further-testing . 31
6.1.3 Rule of application for products where the test values are significantly below the
declared value (Gamma rule) . 33
6.1.4 Rule of application for products where a small number of test results may be
expected . 33
6.2 Cluster of production units . 34
6.2.1 Type testing . 34
6.2.2 Further-testing . 36
6.2.3 Rule of application for cluster products where the test values are significantly
below the declared value (Gamma rule). 37
6.3 No-further-testing . 37
6.4 Handling values lower than the detection limit . 38
6.5 Identifying outliers . 38
6.6 Choosing a declared value . 39
7 Assessment by attributes . 40
7.1 Single production units . 40
7.1.1 Type testing . 40
7.1.2 Further-testing . 41
7.2 Cluster of production units . 42
7.2.1 Type testing . 42
7.2.2 Further-testing . 43
7.3 No-further-testing . 44
7.4 Handling values lower than the detection limit . 44
7.5 Identifying outliers . 44
7.6 Choosing a declared value . 45
8 Statistical principles of the rules of application . 45
8.1 Introduction . 45
8.2 Assessment of a production part . 45
8.3 Test error . 50
8.4 Assessment by variables . 51
8.4.1 Type testing and further-testing . 51
8.4.2 Test frequency for further-testing . 52
8.4.3 Gamma rule . 56
8.4.4 No-further-testing . 56
8.5 Assessment by attributes . 57
8.5.1 Type testing and further-testing . 57
8.5.2 No-further-testing . 59
8.6 Consumer’s and producer’s risk . 60
8.6.1 Acceptance and non-acceptance of batches that exceed the declared value . 60
8.6.2 Estimation of the consumer’s risk . 63
8.6.3 Practical approach . 64
9 Additional sampling requirements . 65
9.1 General . 65
9.2 Probabilistic sampling . 66
9.3 Judgemental sampling. 68
10 Indirect tests . 68
10.1 General . 68
10.2 Correlation . 69
10.3 No correlation . 70
Annex A Examples of the rules of application . 71
Annex B Distribution of test values . 87
Annex C Checklist for Technical Committees . 90
Annex D Model clauses for product standards . 92
Annex E Critical values for assessment by variables . 113
Annex F Gamma factor . 117
Bibliography . 120

European foreword
This document (CEN/TR 16797-2:2015) has been prepared by Technical Committee CEN/TC 351
“Construction products: Assessment of release of dangerous substances”, the secretariat of which is
held by NEN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such
patent rights.
CEN/TR 16797, Construction products: Assessment of release of dangerous substances — Guidance
on the statistical assessment of declared values, comprises the following two parts:
— Part 1: Principles and rules of application;
— Part 2: Technical and statistical background [the present document].
0 Introduction
0.1 General
CEN/TR 16797-1 [1] provides a brief introduction to declaring performance for the potential release,
emission and/or content of dangerous substances from or in construction products and gives the
principles which underpin the assessment and verification of constancy of performance (AVCP) of the
product in respect of such declarations. The main rules of application are introduced, all of which
satisfy the given principles.
CEN/TR 16797-2 provides a more detailed background and technical explanation together with
examples and the statistical justification for the rules of application. The definitions and abbreviations
listed in Clause 2 also apply to CEN/TR 16797-1. Annex D contains a model clause and the rules of
application as normative text that may be copied into or cited by product standards. A recommended
solution is to copy the model clause into the product standard and specify the 'rule of application given
in CEN/TR 16797-2:2015, Annex D' to be used.
This Technical Report was developed on the basis of experience with the control of release into soil
and water. As it is an assessment of data against a declared value regardless of the source of the
data, it is the technical view of CEN/TC 351 that these procedures are also valid for the assessment of
emission from construction products into indoor air and assessment of gamma radiation from
construction products.
It is suggested that all product technical committees follow the principles set out in this CEN/TR and it
is hoped that all regulators will accept that these principles achieve their objectives with respect to an
acceptable AVCP procedure. The rules of application are examples of the ways in which these
principles may be applied. There is no obligation on a product technical committee to adopt these
rules of application and they are free to determine their own rules of application. The given rules of
application may also be used as a benchmark for assessing alternative rules of application.
If product technical committees and producers could streamline their approaches in a way that could
be accepted by all regulators, it might support a common understanding on the European market and
it might encourage regulators to harmonize their existing different approaches and requirements on
reliability and meaning of performance declarations in legislation and enforcement.
0.2 Background
CEN/TC 351 in its Resolution 162 (Milan 2011) has allocated to its TG 7 the task of drafting a
technical report with the following content:
‘This technical report provides guidance to Technical Committees on the evaluation of conformity of
test results with regard to dangerous substances from or in construction products. Where further-
testing is required, methods for assessing whether the product conforms to the information provided
on the potential release of dangerous substances is described and justified. This technical report also
describes the conditions and assumptions under which the proposals are given.’
In undertaking this task, TG 7 reviewed existing systems that are accepted by regulators. In practice
these were the Dutch Soil Quality Decree system, a statistically based system where the rate of
testing is a function of the closeness of the measured values to the regulatory limit value, and the
German technical approval system. Technical Approvals normally apply to products not covered by
CEN standards, but in Germany they are also being applied to the characteristic of release of
dangerous substances, as this characteristic is not yet covered by CEN procedures. The German
Technical Approval defines a rate of routine testing for release (not a constant between different
products) and the product needs to achieve a release not greater than the defined value. The
simplicity of this pass/fail criterion has merit, but there is no possibility of reducing the rate of testing
(or incentive to the producer to achieve the lowest possible values of potential release) and when used
in a CEN system, the declaration of non-conformity over a period of months would have
disproportionate consequences.
After reviewing the options, CEN/TC 351 is proposing a single statistically based system that includes
the concept of a producer being able to reach a point where no-further-testing is required and a
system that is applicable to a wide range of construction products, allowing a uniform assessment of
release or emission which is not dependent of the type of construction product.
The objective of this CEN/TR is to provide guidance to product technical committees and information
to regulators on the statistical assessment of declared values/classes for release, emission or content
of dangerous substances.
0.3 Assessment of construction products
CEN/TR 15858 [2] describes three procedures for classifying the potential release of RDS: without-
testing, without-further-testing and further-testing. Without-testing (WT) is a generic procedure where a
comprehensive dossier of information containing information and previous test data on release from a
product is prepared and submitted to the European Commission. The Commission appoints an expert
group that includes regulators and product experts to review the dossier of information. If approved by
the expert group and endorsed by the Commission, the product standard may include generic
procedures for declaring classes of release based on composition, without the need for type testing
and further-testing by the producer. Document DS 129 [4], however, describes this procedure as WFT
on the basis that a dossier will not be approved without test data.
In this technical report, only the term WFT will be used, following the way it is used in DS 129.
Where a WFT procedure is not provided in the product standard or not selected by the producer, the
producer undertakes type testing (TT) to determine the initial rate of further testing. Further-testing
usually follows type testing and this is where every batch (called ‘batch testing’) or more usually a
random batch selected from a defined period of production is tested (called ‘random testing’) and this
test result is used with previous test data to show the consistency of production and to determine the
frequency of testing. Further-testing by the producer (FT) and the assessment as to whether the
declared value is validated using these test data is fully described in this CEN/TR.
If the FT (and rarely the TT) shows the product is consistently safe and the distance between the
measured values and declared values is large, FT may end provided certain other requirements are
met (essentially to ensure the composition of the product or the process is not changed significantly)
and with the involvement of an independent third party. The criteria for no-further-testing (NFT) are
defined in this technical report. This technical report recommends that any NFT decision is approved
and audited by an independent third party.
NOTE CEN/TR 15858 [2] described this end to FT as ‘without-further-testing’, but this term is used in
DS 129 [4] and in this technical report to mean something else; see text above.
All methods of verifying the declared value/class have equal status and validity. Figure 1 shows the
outline procedure for these options.
The conditions under which the statistical assessment of declared values/classes described in this
CEN/TR applies are:
— the product is covered by a harmonized European product standard requiring information on the
potential release, emission or content of RDS or the contract of supply requires the provision of
information on the potential release of RDS;
— there is one or more RDS that require FT to confirm the technical class or value declared by the
producer;
— the FPC system has specifically addressed the control of RDS.
This CEN/TR provides guidance on the statistical assessment of declared values where type testing
followed by further testing is required with respect to RDS for:
— potential release into soil, groundwater and surface water;
— potential emission into indoor air;
— content;
— potential gamma radiation or emission (exhalation) of radon gas into indoor air
to support:
— declarations of performance made under CE-marking;
— for showing conformity of RDS restricted at the Community level;
— for showing conformity of RDS restricted by provisions valid in the place of use;
— for showing conformity to limits for RDS specified in the contract of supply.
In all four cases the procedure for the statistical assessment of the declared value is the same.
Figure 1 — Possibilities of WFT, FT and NFT for construction products
0.4 Reading guide to CEN/TR 16797-2
0.4.1 General introduction
A general introduction to the statistical assessment of declared values for the release, emission or
content of RDS from or in construction products is given in Clauses 0, 1, 2 and 3. Terms and
definitions are given in Clause 2 and Clause 3 puts CEN/TR 16797-2 into its context and identifies the
tasks that need to be undertaken by CEN Technical Committees.
0.4.2 Rules of application
The rules of application are explained in Clauses 4 to 7. In Clause 4 the quality level of performance of
the rules of application are defined. The methods and basic rules for the statistical assessment of
declared values are described in Clause 5 followed by a technical description of the rules of
application for assessment by variables (Clause 6) and assessment by attributes (Clause 7), all of
which satisfy the given principles.
0.4.3 Statistical background
The statistical background of the rules of application is described in Clause 8. Clause 9 contains
additional sampling requirements not addressed in CEN/TR 16220 [3], while Clause 10 gives
guidance on the use of alternative, indirect test methods.
0.4.4 Annexes
Annex A contains examples of the rules of application described in this CEN/TR. Background
information on the statistical distribution of RDS are given in Annex B. Annex C contains a checklist for
technical aspects related to RDS that need to be addressed in product standards. In Annex D
examples of model text are given on how to include normative requirements for statistical assessment
of declared values. Annex E gives an extensive table with values for some of the statistical parameters
used in this CEN/TR. Annex F gives values for the factor of a specific tool called the gamma rule.
1 Scope
This Technical Report provides guidance on the statistical assessment of declared values with respect
to the release, emission and/or content of dangerous substances. This report provides statistically-
based criteria for type-testing (TT), further-testing (FT) and where a product has been shown to be
consistent with measured values for the release, emission or content that are significantly below the
declared values, the point where no-further-testing (NFT) is permitted.
A series of fundamental principles are defined in CEN/TR 16797-1 and two statistical approaches are
defined. The first approach is to use assessment by variables and this approach requires the data to
be normally or log-normally distributed. This approach is recommended as the default option. The
alternative approach based on assessment by attributes is appropriate for data sets that are not
normally or log-normally distributed. The downside to this form of assessment is that more test data
are needed for the same level of reliability. CEN/TR 16797-1 introduces these assessment procedures
and CEN/TR 16797-2 provides more detail and the statistical proof that they satisfy the principles
defined in CEN/TR 16797-1. With both of these approaches the minimum frequency of testing is a
function of the distance between the mean value and declared value and the variability of the data set,
i.e. the sample standard deviation.
To reduce the costs of testing, production plants producing a similar product may share data, e.g. be
grouping the product into clusters for statistical assessment of declared values. Rules for the use of
clusters are given in this document.
This document also contains rules for identifying outliers within a data set and guidance on using tests
other than the reference method for FT.
A list of tasks for product technical committees is given in this document as is a model clause for
including in product standards and rules of applications that may be cited in the product standard or
copied into product standards.
2 Terms, definitions, abbreviations and symbols
2.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE The following definitions are used in this document for the purposes of using and explaining the
system of assessment. These definitions align with those given in EN 16687 [6], ISO 3534-1 [10] and ISO 3534-2
[11].
2.1.1
assessment by attributes
assessment by noting the presence (or absence) of one or more particular characteristic(s) in each of
the items in the group under consideration, and counting how many items do, or do not, possess the
characteristic(s)
[SOURCE: [11] (adapted)]
Note 1 to entry: With respect to the assessment of the release, emission and/or content of RDS ‘presence’ or
‘possessing the characteristic’ means that the test result is greater than the declared value and ‘absence’ or ‘not
possessing the characteristic’ means that the test results is equal to or lower than the declared value.
2.1.2
assessment by variables
assessment by measuring the magnitude(s) of the characteristic(s) of an item
[SOURCE: [11] (adapted)]
Note 1 to entry: With respect to the assessment of the release, emission or content of RDS ‘magnitude of the
characteristic’ means the test result.
2.1.3
batch
amount of construction product at which conformity is established
Note 1 to entry: Within this document the size of a batch is undefined. The batch size should be defined in the
product standard.
2.1.4
batch testing
procedure where every batch is tested prior to it being placed on the market
2.1.5
cluster
group of production units that are considered as one with respect to type testing and routine control of
RDS
2.1.6
coefficient of variation
standard deviation divided by the mean
[SOURCE: [10]]
2.1.7
conformity
fulfilment of a requirement
2.1.8
construction product
product which is produced for incorporation in a permanent manner in construction works and placed
as such on the market
[SOURCE [6]]
2.1.9
consumer’s risk
probability of accepting a batch that has a release greater than the declared value
[SOURCE [11] (adapted)]
2.1.10
continuous random variable
random variable having a continuous distribution
[SOURCE [10]]
2.1.11
declared value
level, expressed as a numerical value, declared by the producer, having a very low probability of being
exceeded in the production
Note 1 to entry: Where the term ‘declared value’ is used in this document, it may be interchanged with the
terms ‘regulatory class limit’ or ‘technical class limit’.
2.1.12
discrete random variable
random variable having a discrete distribution
[SOURCE [10]]
Note 1 to entry: The value of a discrete random variable is not expressed as a number but as a non-
arithmetical expression, e.g. yes/no, pass/fail.
2.1.13
further-testing (FT)
assessment procedure where the AVCP requires routine testing by the manufacturer to verify that the
declared value is being achieved
[SOURCE: [2] (adapted)]
Note 1 to entry: Further-testing is applied when the type assessment shows there is a risk that the declared
value may be exceeded.
2.1.14
mean
sum of the test values divided by the number of test values
[SOURCE: [10] (adapted)]
Note 1 to entry: For a series of n random test results, i.e. {x , x , …., x }, the sample mean is:
1 2 n x
n
(1)
x= x
∑ i
n
i=1
2.1.15
no-further-testing (NFT)
deemed-to-conform assessment procedure for determining the declared value based on type
assessment, type testing and routine testing where at some point it is shown that there is a very low
risk that the declared value may be exceeded
2.1.16
non-conformity
non-fulfilment of a requirement
[SOURCE: [11]]
2.1.17
operation characteristic curve (OC-curve)
curve showing the relationship between the probability of acceptance of a batch and the percentage of
the production that has a release greater than the declared value and the incoming quality level for a
given assessment scheme
[SOURCE: [11] (adapted)]
2.1.18
outlier
member of a set of values which is inconsistent with the other members of that set
[SOURCE: [10] ]
2.1.19
process
set of interrelated or interacting activities which transform inputs into outputs
[SOURCE: [11]]
2.1.20
producer’s risk
probability of rejecting a batch that has a release equal to or lower than the declared value
[SOURCE: [11] (adapted)]
2.1.21
product
result of a process
[SOURCE: [11]]
2.1.22
production
entire (statistically assumed to be infinite) amount of construction product that has been and will be
produced, that is divided into batches of equal size for testing purposes and that may be defined as
the amount represented by:
— one type of construction product as defined in the product standard from one production unit; or
— a group of construction products with similar properties from one production unit; or
— one type of construction product as defined in the product standard that is grouped into a cluster
for AVCP; or
— a group of construction products with similar properties from a cluster
Note 1 to entry: In the case of RDS, the declaration of performance (covered by CE-marking) is based on the
properties of the production and not on the properties of single batches except when testing every batch.
2.1.23
production unit
location where a construction product is manufactured
2.1.24
random testing
procedure where a limited number of randomly selected batches is tested
2.1.25
sample
representative portion of material selected from a batch and which reflects the average properties of
that batch as much as possible
[SOURCE: [6] (adapted)]
2.1.26
standard deviation
non-negative square root of the variance
[SOURCE: [10] (adapted)]
Note 1 to entry: This is a measure of the spread of results around their mean.
2.1.27
variance
sum of squared deviations of the test values from their mean divided by the number of test values
minus one
[SOURCE: [10] (adapted)]
Note 1 to entry: For a series of n random test results, i.e. {x , x , …., x }, with sample mean the sample
1 2 n x
variance s is:
n
1 2
(2)
s ( xx− )
∑ i
n−1
i=1
2.1.28
without-further-testing (WFT)
deemed-to-conform assessment procedure for determining the declared value based on assessment
of the generic product alone and specified in the relevant product standard
[SOURCE: [2] (adapted)]
Note 1 to entry: Assessment by the WFT procedure means that the release, emission or content of the
relevant RDS in the construction product is determined on a generic level; an individual producer does not need
to determine the release, emission or content of the relevant RDS in the construction product by type testing
followed by further-testing. Type assessment is required to show that the product conforms to the requirements
for using a declaration of performance based on WFT.
2.2 Abbreviations and symbols
For the purposes of this document, the following abbreviations and symbols apply:
AVCP Assessment and verification of constancy of performance
CB certification body
CEN Comité Européen de Normalisation (European Committee for Standardization)
EEA European Economic Area
FPC factory production control
FT further-testing
NB notified body
NFT no-further-testing
NPD no performance determined
P{event} probability of the event
RDS regulated dangerous substance(s)
TC technical committee
TG task group
TR technical report (CEN deliverable)
TT type testing (determination of the prototype)
WFT without-further-testing
=
For the purposes of this document, the following symbols apply:
a slope
b intercept
c
coefficient of variation of due to the sampling error
s
c coefficient of variation due to the testing error
t
c coefficient of variation of the test value
v
c coefficient of variation due to the spatial and/or temporal variation
w
G critical value according to Grubbs’ test
p
H null hypothesis
i index number
critical value for k multiplication factor of the non-central t-distribution
k n
declared value
L
D
m number of increments per sample
n number of test values
acceptable number of test values that exceed the declared value
n
a
number of test values that exceed the declared value
n
e
p percentage of the production exceeding the declared value
PF precision factor
s
sample standard deviation
x
test value
equivalent value for the reference test
x’
x sample mean
the last (most recent) test value
x
test value
x
i
largest test value
x
max
smallest test value
x
min
upper 100i percentage point of the standard normal distribution
z
i
α
uncertainty
β fraction of production that exceeds the declared value
Γ gamma factor
μ true value of the mean of a property
μ true production mean
σ true value of the standard deviation
σ standard deviation due the sampling error
s
σ standard deviation due to the testing error (see test standard)
t
σ
standard deviation of the test value
v
σ standard deviation of the spatial and/or temporal variation
w
3 Context
In order to put this CEN/TR into its context, the following is a brief review of the overall procedure for
declaring performance from the viewpoint of a producer. Much more detail is provided in
CEN/TR 15858 [2] and CEN/TR 16496 [5]. For the producer, the starting point is the product standard
and/or the contract to supply. The actions before this point are for the product technical committee
preparing the product standard and those preparing a generic dossier of information (see Figure 1).
The European product standard that has a revised or amended mandate for the product being
produced should give a list of dangerous substances. Except where the dangerous substance is
limited at the European level, these lists will not contain limit values as these values, if any, are set at
the national level. Producers identify their market (national members of the EEA) to determine if it
includes one or more regulated markets, i.e. ones with defined limits on the release, emission or
content of dangerous substances, and identify from the list in the product standard those dangerous
substances that are applicable in their regulated markets. In addition to the dangerous substances
listed in the product standards, there may be the need to conform to other regulations valid in the
place of use that set limits or ban certain additional dangerous substances. The applicable RDS may
be some, all or more than those listed in the product standard. Producers are expected to know what
regulations (legal requirements) are placed on the products they are putting on the market.
Producers may use the database CP-DS (http://ec.europa.eu/growth/tools-databases/cp-ds/) for
information on national and European legislation on dangerous substances and construction products,
and they may make use of the contact points for the CPR in each Member State.
NOTE The rules of application described in this CEN/TR are applicable to all RDS, including those not listed
in product standards.
For those substances listed in the product standard, the producer is required to provide information to
the market in the form of a technical class or declared value (where permitted in the product standard)
under CE-marking. Essential characteristics (in particular for the release, emission or content of
dangerous substances) shall be declared according to the cited harmonized standard or as NPD to
legally place products in the market (EFTA). The regulations of some Member States may require the
declaration of some essential characteristics for specific intended uses.
Some essential characteristics may be declared through the WFT procedure. In this case the declared
value/class is fixed and does not require testing. For essential characteristics not covered by the WFT
procedure, manufacturers shall follow the defined AVCP and declare the value/class or NPD.
Where a WFT procedure is applicable and used, the producer needs to document in the FPC system
that the product conforms to the requirements for using the WFT procedure. After TT and periods of
routine testing, the producer may have the opportunity to see if the test data satisfy the requirements
for declaring performance with no-further-testing (the NFT-procedure). The criteria for such
assessments are given in this CEN/TR, but they only have validity if these criteria are transposed into
the relevant product standard or cited in a normative way as being applicable. The procedures that are
relevant to the NFT-procedure are given in 5.4.
4 Quality level of performance with respect to the release, emission or
content of RDS
With respect to the release, emission or content of RDS it is highly recommended to apply the same
quality level of performance to all construction products. In this way users of construction products and
regulators are able to compare performances of different (competitive) construction products without
doubt about the risk of getting a non-conforming product, e.g. a product that has a higher release,
emission or content of one or more RDS than declared by the producer.
For the release, emission and content of RDS the following two quality levels of performance are
proposed:
The rules of application verify with a confidence of 90 % that the 50th percentile of the
production is less than or equal to the declared value/class.
Assessment of NFT verifies with a confidence of 99 % that the 90th percentile of the production
is less than or equal to the declared value/class.
The assessment system described in this CEN Technical Report and the according consumer’s ri
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