CEN/TR 16797-1:2015

SLOVENSKI STANDARD
01-oktober-2015
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Construction products: Assessment of release of dangerous substances - Guidance on
the statistical assessment of declared values - Part 1: Principles and rules of application
Produits de construction - Evaluation de l'émission de substances dangereuses  Guide
pour l’évaluation de la performance et la vérification de sa constance - Partie 1 :
Principes et règles d’application
Ta slovenski standard je istoveten z: CEN/TR 16797-1:2015
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 16797-1
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 1: Principles and rules of application
Produits de construction - Evaluation de l'émission de
substances dangereuses  Guide pour l'évaluation de la
performance et la vérification de sa constance - Partie 1 :
Principes et règles d'application

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 16797-1:2015 E
worldwide for CEN national Members.

Contents Page
European foreword .3
Introduction .4
1 Scope .5
2 Declared values.5
3 Other principles .6
4 Uncertainty .8
5 Rules of application .8
5.1 Introduction to the rules of application .8
5.2 Rule of application based on assessment by variables . 11
5.2.1 Principles of assessment by variables . 11
5.2.2 Type-testing . 14
5.2.3 Further-testing . 14
5.2.4 Use of existing data and sharing data . 16
5.2.5 Outliers . 17
5.2.6 No-further-testing (NFT) . 17
5.3 Rule of application for products where the test values are significantly below the
declared value (gamma rule) . 18
5.4 Rule of application based on assessment by attributes . 20
5.4.1 Where assessment by attributes should be selected . 20
5.4.2 Type-testing . 21
5.4.3 Further-testing . 21
5.4.4 Use of existing data and sharing data . 22
5.4.5 Outliers . 22
5.4.6 No-further-testing . 22
Bibliography . 24

European foreword
This document (CEN/TR 16797-1:2015) 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 [the present document];
— Part 2: Technical and statistical background.

Introduction
The present document provides a brief introduction as to how to declare performance for the potential release,
emission and/or content of dangerous substances from or in construction products and gives the principles
which underpin the acceptance criteria of test results in relation to a declared value. The main rules of
application are introduced, all of which satisfy the given principles.
CEN/TR 16797-2 [1] provides more detailed background and technical explanation together with examples
and the statistical justification for the rules of application. The definitions and abbreviations listed in
CEN/TR 16797-2:2015, Clause 2 also apply to CEN/TR 16797-1:2015. CEN/TR 16797-2:2015, Annex D
contains a model clause and the rules of application introduced in this Part are drafted 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 Technical Report
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.
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 Technical 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 the present document 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. The present document introduces these assessment procedures and CEN/TR 16797-2 provides
more detail and the statistical proof that they satisfy the principles defined in this document. 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 CEN/TR 16797-2.
CEN/TR 16797-2 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 CEN/TR 16797-2 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 Declared values
Any declared value with respect to the potential release, emission and/or content of dangerous substances
needs to be justified. This justification is based on either:
— the product conforming to the conditions given in the relevant product standard for a declared value/class
based on the without-further-testing concept; or,
— type-testing followed by further-testing at the determined frequency.
Where there is no requirement to carry out a determination, the producer may declare performance for this
characteristic as 'NPD' using the ‘no-performance determined’ option.
The Construction Products Regulation [2] defines the ways in which a declaration of performance may be
made by the producer. The declared value, or declared class, provides a level of release, emission and/or
content that has a low probability of being exceeded in the production. A producer is free to select the value to
be declared. The validity of the declared value is assessed using statistical techniques described in this
CEN Technical Report using a sufficient number of tests according to a standardized test procedure (the
reference test or a combination of tests with the reference test and adequate indirect tests). The declared
value applies on the scale of a batch as defined in the product standard. As it is a numerical value it can,
where required, be compared directly with a limit value in a regulation or specification. If, in those cases, the
declared value is equal to or less than the limit value, the product satisfies the requirement. A product
technical committee is also free to introduce classes (as technical classes), but the upper numerical value
defining these classes has the same technical meaning as a declared value. The lower numerical limit of the
class will be zero.
Where a product is to be placed on a regulated market, and where the mean value based on the reference
test method is low in relation to the regulatory limit, a producer may benefit from setting the declared value at
the regulatory limit. Doing so will tend to minimize the test frequency and may lead to satisfying the conditions
for no-further-testing (NFT) given in 5.2.6 and 5.4.6. Whereas, a declared value that is significantly lower than
the regulatory limit, and hence much nearer to the mean value, will probably result in a higher test frequency
or even batch testing under these rules of application. On the other hand, setting a high declared value in
order to minimize the test frequency might affect a product's competitiveness in relation to products with a
lower declared value. So the freedom for the producer to select the declared value introduces more flexibility.
It is, however, for the product technical committee to decide whether performance should be declared usin
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