SIST EN 17871:2024

Glass in building - Spectrophotometric characteristics of glass products - Validation procedure for calculation tool

This standard provides a procedure to validate a calculation tool of spectrophotometric and thermal characteristics of the glass products following EN 410 or EN 673. It provides also the methodology to correctly use measured data in the calculation tool.  
The following characteristics are included in the scope of this standard:
- light transmittance (tv)
- light reflectance - both sides (rv, r'v)
- solar direct transmittance (te)
- solar direct reflectance – both sides (re, r'e)
- total solar energy transmittance (solar factor or g value) (g)
- thermal transmittance (U value) in the vertical position
The following characteristics are excluded from the scope of this standard:
- UV transmittance (tuv)
- shading coefficient (SC)
- general colour rendering index (Ra)
- thermal transmittance (U value) at angles other than vertical

Glas im Bauwesen - Spektralphotometrische Eigenschaften von Glasprodukten - Validierungsverfahren für das Berechnungstool

Dieses Dokument liefert ein Verfahren zur Validierung eines Berechnungstools für spektralphotometrische und thermische Eigenschaften von Glaserzeugnissen nach EN410 oder EN673. Es liefert zudem die Methodik für eine korrekte Verwendung von Messdaten im Berechnungstool.
Die folgenden Eigenschaften liegen im Anwendungsbereich dieses Dokuments:
- Lichttransmissionsgrad (tv);
- Lichtreflexionsgrad–beidseitig (rv, r’v);
- direkter Strahlungstransmissionsgrad (te);
- direkter Strahlungsreflexionsgrad–beidseitig (re, r’e);
- Gesamtenergiedurchlassgrad (Sonnenfaktor oder g-Wert) (g);
- Wärmedurchgangskoeffizient (U-Wert) in der aufrechten Position.
Die folgenden Eigenschaften liegen außerhalb des Anwendungsbereiches dieses Dokuments:
- UV-Transmissionsgrad (tuv);
- mittlerer Durchlassfaktor (SC, en: shading coefficient);
- allgemeiner Farbwiedergabeindex (Ra);
- Wärmedurchgangskoeffizient (U-Wert) in anderen Winkeln als der aufrechten Position.

Verre dans la construction - Caractéristiques spectrophotométriques des produits verriers - Mode opératoire de validation pour l’outil de calcul

Le présent document fournit un mode opératoire pour valider un outil de calcul des caractéristiques spectrophotométriques et thermiques des produits verriers, conformément à l'EN 410 ou à l'EN 673. Il fournit également la méthodologie pour utiliser correctement les données mesurées dans l’outil de calcul.
Les caractéristiques suivantes sont incluses dans le domaine d’application du présent document :
⎯ facteur de transmission lumineuse (tv)
⎯ facteur de réflexion lumineuse, des deux côtés (rv, r’v)
⎯ facteur de transmission directe de l’énergie solaire (te)
⎯ facteur de réflexion directe de l’énergie solaire, des deux côtés (re, r’e)
⎯ facteur de transmission totale de l’énergie solaire (facteur solaire ou valeur g) (g)
⎯ coefficient de transmission thermique (valeur U) en position verticale
Les caractéristiques suivantes ne sont pas incluses dans le domaine d’application du présent document :
⎯ facteur de transmission de l’ultraviolet (tuv)
⎯ coefficient d’ombrage (SC)
⎯ indice général de rendu des couleurs (Ra)
⎯ coefficient de transmission thermique (valeur U) à des angles autres que la verticale

Steklo v gradbeništvu - Spektrofotometrične značilnosti steklenih izdelkov - Validacijski postopek za računsko orodje

Ta standard podaja validacijski postopek za računsko orodje v zvezi s spektrofotometričnimi in toplotnimi značilnosti steklenih izdelkov v skladu s standardom EN 410 ali EN 673. Podaja tudi metodologijo za pravilno uporabo izmerjenih podatkov v računskem orodju.  
Področje uporabe tega standarda zajema naslednje značilnosti:
– prehodnost svetlobe (tv)
– odbojnost svetlobe – obe strani (rv, r'v)
– direktna sončna prehodnost (te)
– direktna sončna odbojnost – obe strani (re, r'e)
– celotna prehodnost sončne energije (sončni faktor ali vrednost g) (g)
– toplotna prehodnost (vrednost U) v navpičnem položaju
Naslednje značilnosti ne spadajo na področje uporabe tega standarda:
– prehodnost UV-žarkov (tuv)
– koeficient senčenja (SC)
– splošni indeks barvnega videza (Ra)
– toplotna prehodnost (vrednost U) pod koti, ki niso navpični

General Information

• Status: Published
• Public Enquiry End Date: 30-Jan-2023
• Publication Date: 15-May-2024
• ICS: 81.040.20 - Glass in building
• Technical Committee: STV - Steklo, svetloba in razsvetljava v gradbeništvu
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 17-Apr-2024
• Due Date: 22-Jun-2024
• Completion Date: 16-May-2024
• 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/135 - Mandate to CEN/CENELEC concerning the execution of standardization work for harmonized standards on flat glass, profiled glass and glass block products
• Ref Project: EN 17871:2024 - Glass in building - Spectrophotometric characteristics of glass products - Validation procedure for calculation tool.

Overview

SIST EN 17871:2024 is a European standard developed by CEN that specifies the validation procedure for calculation tools used to determine the spectrophotometric and thermal characteristics of glass products in buildings. This standard ensures that software tools calculating key glass properties conform to reliable, consistent methodologies in line with EN 410 and EN 673 standards. It covers the verification of tools used for energy-related glass parameters, offering a trusted process for manufacturers and notified bodies to validate computational methods.

The standard focuses on important spectrophotometric qualities such as light transmittance and reflectance on both sides, solar transmittance and reflectance, solar heat gain coefficient (g value), and thermal transmittance (U value) in vertical orientation, excluding UV transmittance, shading coefficient, and color rendering index.

Key Topics

• Scope of Validation
  SIST EN 17871:2024 addresses the validation of calculation tools computing glass properties related to energy conservation and heat retention, including:

  • Light transmittance (tv)
  • Light reflectance front and back (rv, r'v)
  • Solar direct transmittance (te)
  • Solar direct reflectance both sides (re, r'e)
  • Total solar energy transmittance (solar factor or g value)
  • Thermal transmittance (U value) at vertical orientation

  Excluded parameters include UV transmittance, shading coefficient (SC), and general colour rendering index (Ra).

• Validation Procedure
  The procedure involves comparison of results from the calculation tool under validation with a reference calculation tool managed by the validator (usually a notified body). Key steps include:

  • Selection of representative glass products (float, tinted, low-e coated, solar control, laminated) for testing
  • Validation across various thicknesses and configurations (single, double, triple glazing)
  • Agreement on reference data between applicant and validator, with reference spectra available on the Glass for Europe website
  • Execution of calculation tasks outlined in Table 1 of the standard to assess the tool’s performance
  • Application of strict difference criteria for acceptance of results as per defined tolerances

• Defined Test Cases
  The standard specifies at least 15 test tasks covering diverse product types and configurations such as:

  • Uncoated float glass at different thicknesses
  • Coated glass variants with different coatings and substrates
  • Laminated glass with various interlayer thicknesses and coatings
  • Double and triple glazing with different gas fills and cavity widths
    This comprehensive set ensures robust validation across typical building glass products.

• Normative References
  Key related standards referenced include:

  • EN 410: Determination of luminous and solar characteristics of glazing
  • EN 673: Calculation method for thermal transmittance (U value)
  • EN 12898: Determination of emissivity relevant to thermal calculations

Applications

SIST EN 17871:2024 plays a critical role in the building glass industry by guaranteeing trusted and uniform results from calculation tools used to declare glass performance. Its practical applications include:

• Manufacturer Compliance
  Glass manufacturers using calculation software to generate Declaration of Performance (DoP) reports for glazing products ensure their tools meet EN 17871 validation requirements, supporting regulatory compliance under EU Construction Products Regulation (CPR 305/2011).

• Notified Body Assessment
  Notified bodies utilize this standard to verify computation tools submitted by manufacturers, confirming accuracy before certification and DoP issuance.

• Energy Performance Optimization
  Accurate calculation of solar factors and U values facilitates energy-efficient building design by enabling selection of appropriate glazing configurations.

• Quality Assurance
  Building designers, architects, and façade engineers benefit from validated tools to confidently specify glass products with predictable energy and light performance characteristics.

• Research and Development
  Developers of glazing products and software can employ this standard to benchmark and improve their calculation methodologies in alignment with European harmonized standards.

Related Standards

• EN 410: Glass in building - Determination of luminous and solar characteristics of glazing
  Provides measurement and calculation methods for key optical and solar parameters of glass products.

• EN 673: Glass in building - Determination of thermal transmittance (U value) - Calculation method
  Governs calculation methods for thermal insulation properties of glazing.

• EN 12898: Glass in building - Determination of emissivity
  Specifies measurement of glass emissivity, essential for thermal transmittance computations.

• EU Regulation 305/2011 (CPR)
  Regulates the Declaration of Performance requirements for construction products including building glass.

• prEN 17940:2023
  Addresses thermal conductivity of interlayers in laminated glass, referenced in validation details.

SIST EN 17871:2024 integrates with these standards to provide a complete framework for reliable energy and spectrophotometric characterization of glazing products through validated calculation tools.

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Keywords:
SIST EN 17871:2024, glass in building, calculation tool validation, spectrophotometric characteristics, thermal transmittance, light transmittance, solar factor, U value validation, glazing product standards, energy performance glass, CEN standard, glass calculation software validation

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2024
Steklo v gradbeništvu - Spektrofotometrične značilnosti steklenih izdelkov -
Validacijski postopek za računsko orodje
Glass in building - Spectrophotometric characteristics of glass products - Validation
procedure for calculation tool
Glas im Bauwesen - Spektralphotometrische Eigenschaften von Glasprodukten -
Validierungsverfahren für das Berechnungstool
Verre dans la construction - Caractéristiques spectrophotométriques des produits
verriers - Mode opératoire de validation pour l’outil de calcul
Ta slovenski standard je istoveten z: EN 17871:2024
ICS:
81.040.20 Steklo v gradbeništvu Glass in building
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 17871
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2024
EUROPÄISCHE NORM
ICS 81.040.20
English Version
Glass in building - Spectrophotometric characteristics of
glass products - Validation procedure for calculation tool.
Verre dans la construction - Caractéristiques Glas im Bauwesen - Spektralphotometrische
spectrophotométriques des produits verriers - Eigenschaften von Glasprodukten -
Procédure de validation des outils de calcul Validierungsverfahren für das Berechnungstool
This European Standard was approved by CEN on 29 January 2024.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 17871:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Validation procedure. 6
4.1 General outline . 6
4.2 Choice of the reference products and data . 6
4.3 Reference calculation tool . 10
4.4 Calculation program to be validated . 10
4.5 Comparison procedure . 10
4.6 Difference criteria . 10
4.7 Calculation tool update validation . 10
4.8 Report content . 11
Bibliography . 12

European foreword
This document (EN 17871:2024) has been prepared by Technical Committee CEN/TC 129 “Glass in
building”, the secretariat of which is held by NBN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by October 2024, and conflicting national standards shall
be withdrawn at the latest by October 2024.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United
Kingdom.
Introduction
EN 410 is in part a measurement standard and in part a calculation standard. EN 673 is a calculation
method based on input of the emissivity according to EN 12898. The Annex ZAs of the harmonized
standards for glass assign the initial determination of both radiation and thermal properties as tasks for
a notified laboratory (AVCP system 3).
Under AVCP system 3, when some characteristics have to be calculated (e.g. U value, g value, …) the
manufacturer undertakes the calculation according to the relevant standards. In this case, the calculation
tool is validated by a notified body who provides a report according to this document.
The purpose of this document is to cover only those energy conservation and heat retention
characteristics that are stated on the Declaration of Performance under the EU Regulation 305/2011,
namely:
— thermal properties
— radiation properties: light transmittance and reflectance
— radiation properties: solar energy characteristics
Characteristics other than the above are not covered as they are not required for the Declaration of
Performance.
1 Scope
This document provides a procedure to validate a calculation tool of spectrophotometric and thermal
characteristics of the glass products following EN 410 or EN 673. It provides also the methodology to
correctly use measured data in the calculation tools.
The following characteristics are included in the scope of this document:
)
— light transmittance (tv
— light reflectance - both sides (r r' )
v, v
— solar direct transmittance (t )
e
— solar direct reflectance – both sides (r r' )
e, e
— total solar energy transmittance (solar factor or g value) (g)
— thermal transmittance (U value) in the vertical position
The following characteristics are excluded from the scope of this document:
— UV transmittance (t )
uv
— shading coefficient (SC)
— general colour rendering index (Ra)
— thermal transmittance (U value) at angles other than vertical
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.
EN 410, Glass in building - Determination of luminous and solar characteristics of glazing
EN 673, Glass in building - Determination of thermal transmittance (U value) - Calculation method
EN 12898, Glass in building - Determination of the emissivity
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 410, EN 673 and EN 12898 and
the following 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
applicant
party that provides the calculation tool for validation
3.2
validator
party that verifies the results of the calculation tool following the procedure described in this document
Note 1 to entry: Within the framework of the EU Regulation 305/2011, the validator is a notified body
4 Validation procedure
4.1 General outline
The applicant shall provide the validator with access to the calculation tool. Results obtained with the
calculation tool to be validated shall be compared by the validator to results obtained with the reference
calculation tool of the validator for defined reference products in accordance with 4.2. The difference
shall not exceed the value specified in Clause 4.6.
The reference data for tasks 1 to 15 in Table 1 shall be agreed between the validator and the applicant.
The reference data can be provided by the validator, applicant or Glass for Europe website.
NOTE Reference spectral data that can be used for the purpose of validation can be found on the Glass for
Europe website at: https://glassforeurope.com/spectral-data/.
In the case of reference data obtained from the Glass for Europe website, the applicant and validator
should use the same version (e.g. same date, version number, etc.).
4.2 Choice of the reference produ
...