FprEN 1873-1

SLOVENSKI STANDARD
01-oktober-2020
Predizdelani dodatki za ostrešja - Plastični svetlobniki - Specifikacija proizvoda in
preskusne metode
Prefabricated accessories for roofing - Individual plastic rooflights - Product specification
and test methods
Vorgefertigte Zubehörteile für Dacheindeckungen - Teil 1: Lichtkuppeln aus Kunststoff -
Produktfestlegungen und Prüfverfahren
Accessoires préfabriqués pour couverture - Partie 1 : Lanterneaux ponctuels en matière
plastique - Spécifications des produits et méthodes d'essais
Ta slovenski standard je istoveten z: prEN 1873-1
ICS:
91.060.20 Strehe Roofs
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
prEN 1873-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
August 2020
ICS 91.060.20 Will supersede EN 1873:2014+A1:2016
English Version
Prefabricated accessories for roofing - Individual plastic
rooflights - Product specification and test methods
Accessoires préfabriqués pour couverture - Partie 1 : Vorgefertigte Zubehörteile für Dacheindeckungen - Teil
Lanterneaux ponctuels en matière plastique - 1: Lichtkuppeln aus Kunststoff - Produktfestlegungen
Spécifications des produits et méthodes d'essais und Prüfverfahren
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 128.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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, Turkey and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1873-1:2020 E
worldwide for CEN national Members.

prEN 1873-1:2019 (E)
Contents Page
European foreword . 6
Introduction . 7
1 Scope . 8
2 Normative references . 9
3 Terms, definitions, symbols, units and abbreviated terms . 11
3.1 Terms and definitions . 11
3.2 Symbols and abbreviations . 14
4 Product characteristics . 16
4.1 General. 16
4.2 Radiation properties . 16
4.2.1 General. 16
4.2.2 Light transmittance τ . 17
D65
4.2.3 Solar direct transmittance τ . 17
e
4.2.4 Total solar energy transmittance g . 17
4.3 Durability of radiation properties . 17
4.4 Watertightness . 18
4.5 Mechanical resistance . 18
4.5.1 General. 18
4.6 Resistance to upward loads . 18
4.6.1 General. 18
4.6.2 Resistance to downward loads . 18
4.7 Durability of mechanical resistance . 18
4.8 Impact resistance . 19
4.8.1 Small, hard body impact . 19
4.8.2 Large soft body impact . 19
4.9 Reaction to fire. 19
4.9.1 General. 19
4.9.2 Classification without further testing (CWFT) . 19
4.9.3 Classification without testing (WT). 20
4.10 Resistance to fire . 20
4.11 External fire performance . 20
4.12 Air permeability . 20
4.13 Thermal resistance . 20
4.14 Direct airborne sound insulation . 21
5 Testing, assessment and sampling methods . 21
5.1 General. 21
5.2 Radiation properties . 22
5.2.1 Determination of light transmittance τ . 22
D65
5.2.2 Determination of solar direct transmittance τ . 22
e
5.2.3 Determination of total solar energy transmittance g . 22
5.3 Durability of radiation properties . 23
5.3.1 Categories for variation of light transmittance τ and yellowness index YI (ΔYI) . 23
D65
5.3.2 Conditions for accelerated ageing . 23
5.3.3 Assessment of variation of light transmittance . 24
5.3.4 Assessment of variation in yellowness index . 24
5.4 Watertightness . 25
prEN 1873-1:2019 (E)
5.4.1 General . 25
5.4.2 Procedure . 25
5.4.3 Apparatus . 25
5.4.4 Test specimen . 25
5.5 Mechanical resistance . 27
5.5.1 Resistance to upward and downward loads . 27
5.6 Durability of mechanical resistance . 28
5.6.1 Categories for variation of Young’s-Modulus and variation of tensile strength with
ageing . 28
5.6.2 Assessment of variation of Young’s-Modulus and tensile strength with ageing . 29
5.7 Impact resistance . 29
5.7.1 Small hard body impact . 29
5.7.2 Large soft body impact. 30
5.8 Reaction to fire . 31
5.9 Resistance to fire . 32
5.10 External fire performance . 32
5.11 Air permeability . 32
5.12 Thermal transmittance . 34
5.13 Direct airborne sound insulation . 34
6 Assessment and verification of constancy of performance - AVCP . 35
6.1 General . 35
6.2 Assessment of performance . 35
6.2.1 General . 35
6.2.2 Test samples, testing and assessment criteria. 36
6.3 Verification of constancy of performance. 36
6.3.1 Factory production control (FPC) . 36
6.3.2 Initial inspection of factory and of FPC . 38
6.3.3 Continuous surveillance of FPC . 38
Annex A (informative) Indicative list of provisions for a proper application, use and
maintenance . 39
A.1 General . 39
A.2 Remarks for risk assessement . 39
A.3 Provisions for application and use . 39
A.4 Provisions for maintenance . 40
Annex B (normative) Alternative test method for determination of light transmittance
τ . 41
D65
B.1 General . 41
B.2 Apparatus . 41
B.3 Test pieces . 41
B.4 Procedure . 42
B.5 Expression of results . 42
Annex C (normative) Test method for air permeability . 43
C.1 General . 43
C.2 Test apparatus . 43
C.3 Test specimen . 43
prEN 1873-1:2019 (E)
C.4 Test procedure . 44
C.5 Evaluation of the results . 44
C.6 Rounding off to be used for the air permeability . 45
C.7 Test report . 45
Annex D (normative) Determination of thermal transmittance of individual plastic
rooflight . 46
D.1 General. 46
D.2 Determination of thermal transmittance of rooflight components . 46
D.2.1 Determination by measurement . 46
D.2.2 Determination by calculation . 46
D.3 Determination of areas of an individual plastic rooflight . 48
D.3.1 Components . 48
D.3.2 Area of the upstand . 49
D.3.3 Area of the edge profile . 50
D.3.4 Area of the junction part . 53
D.3.5 Area of the translucent part A . 53
t
D.3.6 Surface area of the individual plastic rooflight . 54
D.4 Total thermal transmittance of individual plastic rooflights . 54
D.4.1 General. 54
D.4.2 Total thermal transmittance U of individual plastic rooflights without upstand
r
including the edge profile . 56
D.4.3 Total thermal transmittance U of individual plastic rooflights including with
rc
upstand the edge profile . 57
D.4.4 Total thermal transmittance U of individual plastic rooflights with upstand
rc
including the edge profile (alternative calculation U combined for A +A ) . 58
up,e e up
D.4.5 Total thermal transmittance U of individual plastic rooflights with upstand,
rc
without edge profile . 60
D.4.6 Total thermal transmittance U of individual plastic rooflights with upstand
rc
including the edge profile with more than one translucent part . 61
D.4.7 Rounding off to be used for thermal transmittance in calculation . 62
D.5 Test specimen for evaluation of thermal transmittance: U U . 62
r,ref, rc,ref300
D.5.1 Introduction . 62
D.5.2 General. 62
D.5.3 Reference models . 63
D.6 Characteristics for supplied rooflight . 64
Annex E (normative) Conditions for reaction to fire testing . 65
E.1 General conditions for assessment of reaction to fire for individual plastic rooflights . 65
prEN 1873-1:2019 (E)
E.1.1 Testing and classification in accordance with EN 13501-1:2018 . 65
E.1.2 Limitation of substantial components . 66
E.2 Conditions for the single burning item test according to EN 13823:2020 . 66
E.3 Conditions for the ignitability test according to EN ISO 11925-2:2010 . 66
Annex F (normative) Relationship between characteristics, families and test specimens . 68
F.1 General . 68
F.2 Guidance for product families and test specimen . 68
Annex ZA (informative) Relationship of this European Standard with Regulation (EU)
No.305/2011 . 70
ZA.1 Scope and relevant characteristics . 70
ZA.2 System of Assessment and Verification of Constancy of Performance (AVCP) . 72
ZA.3 Assignment of AVCP tasks . 72
Bibliography . 76

prEN 1873-1:2019 (E)
European foreword
This document (prEN 1873-1:2020) has been prepared by Technical Committee CEN/TC 128 “Roof
covering products for discontinuous laying and products for wall cladding”, the secretariat of which is
held by NBN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 1873:2014+A1:2016.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive(s).
For relationship with the Regulation (EU) 305/2011, see informative Annex ZA, which is an integral
part of this document.
Significant technical changes between this document and the previous edition include:
— Editorial revision;
— Number, title and scope revised;
— Normative references updated;
— Radiation properties updated;
— Watertightness of the translucent sheet (translucent parts) deleted;
— Air permeability updated;
— Thermal resistance updated;
— Clause AVCP updated;
— Annex ZA updated.
EN 1873 consists of 3 parts:
— Part 1: Product specification and test methods
— Part 2: Product specification and test methods for rooflights of glass
prEN 1873-1:2019 (E)
Introduction
This document describes characteristics and assessment procedures for individual rooflights consisting
of light transmitting sheets made of plastic materials.
This document belongs to a series of standards for rooflights which is consisting of prEN 1873-1 and
prEN 1873-2 for individual rooflights, and prEN 14963-1 and prEN 1873-2 for continuous rooflights.
prEN 1873-1:2019 (E)
1 Scope
This document specifies characteristics for individual plastic rooflights. These rooflights have
translucent parts made of plastic materials (e.g. GF-UP, PC, PMMA, PVC) which serve the primary
purpose of introducing daylight.
This document applies to individual plastic rooflights with upstands made of e.g. GF-UP, PVC, steel,
aluminium or wood and to individual plastic rooflights without upstand, intended for use on upstands.
These individual plastic rooflights are intended for installation in flat and slightly inclined roofs.
This document applies to individual plastic rooflights with a rectangular or circular ground plan (see
Figures 1 and 2), with an opening span (width) or diameter not larger than 2,5 m and an opening length
not larger than 3,0 m. This document does not cover rooflights which contribute to the load-bearing or
stiffness of the roof itself.
This document applies to individual plastic rooflights without upstand, where a single manufacturer
provides all components of the rooflight and individual plastic rooflights with upstand, where a single
manufacturer provides all components of the rooflight with upstand, which are bought in a single
purchase.
This document applies to rooflights with one or several translucent parts.
Individual plastic rooflights can be opened by means of opening devices in one or more parts for
ventilation.
The possible additional functions of day to day ventilation, smoke and heat ventilation e.g. in case of fire
in accordance with EN 12101-2 and roof access, are outside the scope of this document.
This document does not apply to:
— “Individual glass rooflights” acc. to prEN 1873-2
— “Continuous plastic rooflights” according to prEN 14963-1 and “Continuous glass rooflights”
according to prEN 14963-2
— “Roof windows” according to EN 14351-1
NOTE An indicative list of provisions for a proper application, use and maintenance of individual plastic
rooflights is presented in Annex A.
prEN 1873-1:2019 (E)
Section X –X with and without additional horizontal skin

Key
a daylight diameter f roof opening length
b roof opening diameter g daylight size
c daylight width h roof opening size
d roof opening width i upstand height
e daylight length j rooflight height
Figure 1 — Typical individual plastic rooflights
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 410:2011, Glass in building - Determination of luminous and solar characteristics of glazing
EN 596:1995, Timber structures - Test methods - Soft body impact test of timber framed walls
EN 673:2011, Glass in building - Determination of thermal transmittance (U value) - Calculation method
EN 674:2011, Glass in building - Determination of thermal transmittance (U value) - Guarded hot plate
method
prEN 1873-1:2019 (E)
EN 1013:2012+A1:2014, Light transmitting single skin profiled plastics sheets for internal and external
roofs, walls and ceilings - Requirements and test methods
CEN/TS 1187:2012, Test methods for external fire exposure to roofs
EN 12412-2:2003, Thermal performance of windows, doors and shutters - Determination of thermal
transmittance by hot box method - Part 2: Frames
EN 13501-1:2018, Fire classification of construction products and building elements - Part 1:
Classification using data from reaction to fire tests
EN 13501-2:2016, Fire classification of construction products and building elements - Part 2:
Classification using data from fire resistance tests, excluding ventilation services
EN 13501-5:2016, Fire classification of construction products and building elements - Part 5:
Classification using data from external fire exposure to roofs tests
EN 13823:2020, Reaction to fire tests for building products - Building products excluding floorings
exposed to the thermal attack by a single burning item
EN 16153:2013+A1:2015, Light transmitting flat multiwall polycarbonate (PC) sheets for internal and
external use in roofs, walls and ceilings - Requirements and test methods
EN 16240:2013, Light transmitting flat solid polycarbonate (PC) sheets for internal and external use in
roofs, walls and ceilings - Requirements and test methods
EN ISO 178:2019, Plastics - Determination of flexural properties (ISO 178:2019)
EN ISO 527-1:2012, Plastics - Determination of tensile properties - Part 1: General principles
(ISO 527-1:2012)
EN ISO 527-2:2012, Plastics - Determination of tensile properties - Part 2: Test conditions for moulding
and extrusion plastics (ISO 527-2:2012)
EN ISO 1716:2018, Reaction to fire tests for products - Determination of the gross heat of combustion
(calorific value) (ISO 1716:2018)
EN ISO 1182:2010, Reaction to fire tests for products - Non-combustibility test (ISO 1182:2010)
EN ISO 4892-1:2016, Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance
(ISO 4892-1:2016)
EN ISO 4892-2:2013, Plastics - Methods of exposure to laboratory light sources - Part 2: Xenon-arc lamps
(ISO 4892-2:2013)
EN ISO 6946:2017, Building components and building elements - Thermal resistance and thermal
transmittance - Calculation methods (ISO 6946:2017)
EN ISO 10077-2:2017, Thermal performance of windows, doors and shutters - Calculation of thermal
transmittance - Part 2: Numerical method for frames (ISO 10077-2:2017)
EN ISO 10140-1:2016, Acoustics - Laboratory measurement of sound insulation of building elements -
Part 1: Application rules for specific products (ISO 10140-1:2016)
prEN 1873-1:2019 (E)
EN ISO 10140-2:2010, Acoustics - Laboratory measurement of sound insulation of building elements -
Part 2: Measurement of airborne sound insulation (ISO 10140-2:2010)
EN ISO 10140-4:2010, Acoustics - Laboratory measurement of sound insulation of building elements -
Part 4: Measurement procedures and requirements (ISO 10140-4:2010)
EN ISO 10140-5:2010, Acoustics - Laboratory measurement of sound insulation of building elements -
Part 5: Requirements for test facilities and equipment (ISO 10140-5:2010)
EN ISO 10211:2017, Thermal bridges in building construction - Heat flows and surface temperatures -
Detailed calculations (ISO 10211:2017)
EN ISO 11664-1:2011, Colorimetry - Part 1: CIE standard colorimetric observers (ISO 11664-1:2007)
EN ISO 11664-2:2011, Colorimetry - Part 2: CIE standard illuminants (ISO 11664-2:2007)
EN ISO 11925-2:2010, Reaction to fire tests - Ignitability of products subjected to direct impingement of
flame - Part 2: Single-flame source test (ISO 11925-2:2010)
EN ISO 12017:1996, Plastics - Poly(methyl methacrylate) double- and triple-skin sheets - Test methods
(ISO 12017:1995)
EN ISO 12567-2:2005, Thermal performance of windows and doors - Determination of thermal
transmittance by hot box method - Part 2: Roof windows and other projecting windows (ISO 12567-
2:2005)
EN ISO 14125:1998, Fibre-reinforced plastic composites - Determination of flexural properties
(ISO 14125:1998)
3 Terms, definitions, symbols, units and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
3.1.1
individual plastic rooflight without upstand
building component used to introduce daylight and intended for the installation on an upstand which
consists of one or several translucent part(s) and associated edge profiles, if applicable
Note 1 to entry: See Figure 2.

As impacted by EN ISO 10140-5:2010/A1:2014.
As impacted by EN ISO 14125:1998/AC:2002 and EN ISO 14125:1998/A1:2011.
prEN 1873-1:2019 (E)
2a) Individual plastic rooflight without upstand

2b) Individual plastic rooflight with upstand

2c) Individual plastic rooflight with upstand and edge profile

with edge profile without edge profile
2d) Vertical upstands
Key
1 multi skin 4 insulated upstand 7 roof finish
2 single skin 5 non insulated upstand
3 edge profile 6 splayed upstand
Figure 2 — Cross sections of typical individual plastic rooflights and upstands
prEN 1873-1:2019 (E)
3.1.2
translucent part
consists of at least an outside plastic skin which ensures water run off by form or orientation and can
include several additional translucent skins below
Note 1 to entry: See Figure 3.
Note 2 to entry: The additional skins can follow or be integrated with the outer skin or be an additional flat
skin.
Note 3 to entry: Additional flat skin may not be in plastic.

Key
a single skin, solid sheet
b double skin, solid sheet
c triple skin, solid sheet
d multiwalled sheet
NOTE In case of more than one skin, thicknesses of the sheets can be different.
Figure 3 — Cross sections of typical plastic translucent parts
3.1.3
upstand
element which is single or multi-walled or composite with vertical and/or pitched walls; with or
without thermal insulation and having the two-fold purpose of providing an area for the fixture of
individual plastic rooflights and for connection to the substructure, the roof covering or the roof sealing
Note 1 to entry: The upstand transmits the loads acting upon the individual plastic rooflight into the
substructure.
Note 2 to entry: Upstands may include ventilation devices.
prEN 1873-1:2019 (E)
3.1.4
accessories
connections, opening and locking devices and seals for the assembly of the elements (rooflight,
translucent part, upstand and edge profile)
3.1.5
individual plastic rooflight with upstand
building element which consists of at least the separate elements in accordance with individual plastic
rooflight without upstand, and upstand and accessories
3.1.6
edge profile
any frame and/or profile necessary to fix and/or open the translucent part of the individual plastic
rooflight
3.1.7
junction part
any additional element (e.g. frame and/or profile) used with the edge profile to assemble two
translucent parts, when the rooflight is made with more than one translucent part
3.1.8
filling material
any material, or combinations thereof, in any physical state, which is filled into all or some of the hollow
spaces of the translucent part as defined in 3.1.2 to modify certain performances
3.2 Symbols and abbreviations
ΔYI Change in the yellowness index
H Energy applied during ageing procedure
c
L Light transmission of a test piece
s
L Light transmission of the nth test piece
sn
τ Total luminous transmittance for the CIE-standard illuminant D in %
D65 65
M Average (see B.5.1) of R and R
s 1 3
M Light transmission of the sample
v
R 2
Thermal resistance in m ·K/W
R and R Reading of galvanometer without any test piece
1 3
R Reading of galvanometer with the test piece
R Airborne sound index in dB
w
U 2
Heat transmittance in W/(m ·K)
YI Value of the yellowness index of aged test piece
YI Value of the yellowness index of unaged test piece
ΔE Variation of Young’s-modulus (E) in %
Δσ Variation of tensile strength (σ) in %
prEN 1873-1:2019 (E)
X Y Colourimetric coordinates
CIE, CIE,
Z
CIE
A 2
e Area of the outer exposed surface of the edge profile, in m
A 2
j Area of the outer exposed surface of the junction part, in m
A 2
r Area of the surface of the rooflight without upstand, in m
A 2
rc Area of the surface of the rooflight with upstand, in m
A 2
rc,ref Area of the surface of the rooflight without upstand of the reference model, in m
A 2
rc,ref300 Area of the surface of the rooflight with upstand of the reference model, in m
A Area of the outer exposed surface of the translucent part bordered with the perimeter
t
of the translucent part, in m
A Area of the horizontal projection of the clear opening of the translucent part of
t,flat
individual plastic rooflight, in m
A 2
up Area of the outer exposed surface of the upstand, in m
e Width of the edge profile, in m
e
e Horizontal distance between the upper outside border of the insulation and the clear
e,h
opening of the translucent part, in m
e Vertical distance between the upper level of the translucent part and the upper level
e,v
of the upstand, in m
e Width of the junction part, in m
j.h
e Height of the upstand, in m
up
Glass-fibre reinforced unsaturated polyester resin – type of plastic material
GF-UP
h Horizontal envelope boundary
k Factor to take into account the shape of the translucent part
l Length of the sealing of the edge profile, in m
e
l Length of the transition zone between translucent part and upstand, in m
et
l Length of the transition zone between translucent part and junction part, in m
j
l Length of the transition zone between translucent part and edge profile, in m
t
Polycarbonate – type of plastic material
PC
P Virtual outer perimeter of the edge profile, in m
e
Poly(methyl methacrylate) – type of plastic material
PMMA
P Perimeter of the translucent part, equal to the perimeter of the clear opening of the
t
translucent part, in m
P Reference perimeter of the upstand
up
P Upper outer perimeter of the upstand, in m
up,u
prEN 1873-1:2019 (E)
P Lower outer perimeter of the upstand, in m
up,l
Polyvinylchloride – type of plastic material
PVC
U 2
e Thermal transmittance of the edge profile, in W/(m ⋅K)
U 2
j Thermal transmittance of the junction part, in W/(m ⋅K)
U 2
r Total thermal transmittance of a rooflight without upstand, in W/(m ⋅K)
U Total thermal transmittance of a rooflight without upstand (reference model), in
r,ref
W/(m ⋅K)
U 2
rc Total thermal transmittance of a rooflight with upstand, in W/(m ⋅K)
U Total thermal transmittance of a rooflight with upstand (300 mm height, reference
rc,ref300
model), in W/(m ⋅K)
U 2
t Thermal transmittance of the translucent part, in W/(m ⋅K)
U 2
up Thermal transmittance of the upstand, in W/(m ⋅K)
U 2
up,e Thermal transmittance of the upstand and the edge profile, in W/(m ⋅K)
v Vertical envelope boundary
Ψ Linear thermal transmittance in the transition zone of edge profile and upstand, in
e
W/(m⋅K)
Ψ Linear thermal transmittance in the transition zone of translucent part and upstand,
et
in W/(m⋅K)
Ψ Linear thermal transmittance in the transition zone of translucent part and junction
j
part, in W/(m⋅K)
Ψ Linear thermal transmittance in the transition zone of translucent part and edge
t
profile, in W/(m ⋅ K)
4 Product characteristics
4.1 General
For individual plastic rooflights without upstand, the quality of the as built upstand should reach the
quality of the tested upstand to guarantee the test results in use.
4.2 Radiation properties
4.2.1 General
The radiation properties of an individual plastic rooflight with and without upstand indicate the ability
to transmit light and energy through the translucent part.
The radiation properties are essentially characterized by the light transmittance τ , the solar direct
D65
transmittance τ and the total solar energy transmittance g. These spectral characteristics of the
e
translucent part of an individual plastic rooflight include the luminous and solar characteristics, and the
reflection and transmission characteristics.
The characteristics are as follows:
prEN 1873-1:2019 (E)
— the spectral transmittance τ(λ) and the spectral reflectance ρ(λ) in the wavelength range from
300 nm to 2450 nm;
— the light transmittance τ and the light reflectance ρ for standard illuminant D65;
D65 D65
— the solar direct transmittance τ and the solar direct reflectance ρ ;
e e
— the total solar energy transmittance (solar factor) g.
The characteristics are determined for quasi-parallel, near normal radiation incidence using the
radiation distribution of standard illuminant D65 (see EN 410:2011, Table 1), solar radiation in
accordance with EN 410:2011, Table 2 and ultraviolet (UV) radiation in accordance with EN 410:2011,
Table 3.
The solar factor depends, as all other optical material characteristics, on the angle of incidence. The
angle of incidence should be taken into account for different sun positions.
4.2.2 Light transmittance τ
D65
The light transmittance, τ , of the translucent part is determined as light transmittance of each skin
D65
and possible combinations of skins including any filling material and all variants of each skin in new
individual plastic rooflights and shall be stated according to 5.2.1 and the result shall be stated in %.
4.2.3 Solar direct transmittance τ
e
The solar direct transmittance, τ , of the translucent part is determined as the solar transmittance of
e
each skin and possible combinations of skins including any filling material and all variants of each skin
in new individual plastic rooflights according to 5.2.2 and the result shall be stated in %.
4.2.4 Total solar energy transmittance g
The total solar energy transmittance, g, as defined in EN 410:2011 shall be determined by calculation
according to 5.2.3 or by measurement according to 5.2.3 and the result shall be stated in %.
The calculation method is applicable only to transparent parts with symmetrical on-plan cross-section.
Where the calculation method is not applicable, then the total solar energy transmittance shall be
measured
...