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

This CEN 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 FprCEN/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. FprCEN/TR 16797-1 introduces these assessment procedures and FprCEN/TR 16797-2 provides more detail and the statistical proof that they satisfy the principles defined in FprCEN/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
Public Enquiry End Date
04-Dec-2014
Publication Date
09-Sep-2015
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
02-Sep-2015
Due Date
07-Nov-2015
Completion Date
10-Sep-2015

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SLOVENSKI STANDARD
SIST-TP CEN/TR 16797-2:2015
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
SIST-TP CEN/TR 16797-2:2015 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CEN/TR 16797-2:2015
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SIST-TP CEN/TR 16797-2:2015
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.
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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

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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

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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].
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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

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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;
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— 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.

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Figure 1 — Possibilities of WFT, FT and NFT for construction products
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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.

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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 int
...

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