EN 14500:2021

SLOVENSKI STANDARD
01-julij-2021
Nadomešča:
SIST EN 14500:2008
Rolete in polkna - Toplotno in vizualno ugodje - Preskus in računske metode
Blinds and shutters - Thermal and visual comfort - Test and calculation methods
Abschlüsse - Thermischer und visueller Komfort - Prüf- und Berechungsverfahren
Fermetures et stores - Confort thermique et lumineux - Méthodes d'essai et de calcul
Ta slovenski standard je istoveten z: EN 14500:2021
ICS:
91.060.50 Vrata in okna Doors and windows
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 14500
EUROPEAN STANDARD
NORME EUROPÉENNE
March 2021
EUROPÄISCHE NORM
ICS 91.060.50 Supersedes EN 14500:2008
English Version
Blinds and shutters - Thermal and visual comfort - Test
and calculation methods
Fermetures et stores - Confort thermique et lumineux - Abschlüsse - Thermischer und visueller Komfort - Prüf-
Méthodes d'essai et de calcul und Berechungsverfahren
This European Standard was approved by CEN on 21 October 2019.

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, Turkey 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
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14500:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 5
Introduction . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
3.1 Processes . 8
3.2 Characteristics . 9
3.3 Angle definitions . 10
4 Notations used . 12
4.1 General . 12
4.2 Visual or solar properties . 13
4.3 Geometry of the radiation . 13
4.4 Optical factors . 15
5 Test and calculation methods to be used according to product - Guidelines . 15
5.1 General . 15
5.2 Venetian blinds and louvres. 16
5.3 Roller blinds . 16
5.4 Pleated blinds . 16
5.5 Projecting awnings . 16
5.6 Shutters . 16
6 Determination of transmittance and reflectance with an integrating sphere . 17
6.1 Measurement principles . 17
6.1.1 Spectral and integral methods . 17
6.1.2 Absolute and relative measurements (according to CIE 130) . 17
6.2 Measuring equipment . 18
6.2.1 General . 18
6.2.2 Equipment for irradiation . 18
6.2.3 Equipment for detection . 22
6.3 Reference samples . 25
6.4 Test samples . 26
6.4.1 General . 26
6.4.2 Samples with directional features . 26
6.4.3 Samples with scattering properties . 26
6.4.4 Thick translucent samples . 26
6.5 Measurement procedures . 27
6.5.1 General . 27
6.5.2 Warm-up. 27
6.5.3 Preliminary checks of the samples . 28
6.5.4 Test method A – Single beam integrating sphere (substitution method) . 31
6.5.5 Test method B – “Quasi-simultaneous” double beam integrating sphere . 37
6.5.6 Test method C - “Sequential” double-beam integrating sphere . 45
7 Determination of τ and τ from direct measurement . 50
n-n dir-dir
7.1 Measurement principle . 50
7.2 Measuring equipment . 50
7.2.1 General . 50
7.2.2 Equipment for irradiation . 50
7.2.3 Equipment for detection . 50
7.2.4 Equipment for accurate positioning of the optical components and sample . 50
7.3 Test samples . 51
7.4 Measurement procedure . 51
7.4.1 Determination of τ . 51
n-n
7.4.2 Determination of τ . 54
dir-dir
8 Determination of the cut-off angle . 55
8.1 General . 55
8.2 Measurement of a directional cut-off angles χ (φ), for a specific rotation angle φ . 56
dir
8.3 Determination of all directional cut-off angles χ . 57
dir
8.4 Determination of the cut-off angle χ . 58
9 Determination of darkening performance of solar protection devices and opacity
performance of curtain materials . 58
9.1 General . 58
9.2 Qualification of the observer and testing conditions . 58
9.3 Samples . 59
9.4 Test equipment. 59
9.4.1 General . 59
9.4.2 Area 1 – Illumination of the sample . 60
9.4.3 Area 2 – Observation of the sample . 61
9.5 Test procedure . 62
9.5.1 Curtain material testing . 62
9.5.2 Product testing . 63
10 Calculation of the diffuse hemispherical transmittance τ . 64
dif-h
10.1 Fabrics and other products with rotationally symmetric transmittance . 64
10.2 Venetian blinds and other products with transmittance with profile angle symmetry . 64
11 Test report . 65
Annex A (informative) Examples of test equipment for darkening and opacity characteristics
determination . 66
A.1 General . 66
A.2 Example 1 . 66
A.3 Example 2 . 68
Annex B (informative) Determination of openness coefficient . 70
B.1 Method for fabrics made from opaque material . 70
B.2 Method for venetian blinds . 70
Annex C (informative) Determination of infrared properties . 71
C.1 General . 71
C.2 Determination . 71
Annex D (informative) Approach in case of projecting solar protection devices. 74
D.1 General . 74
D.2 Detailed model. 74
D.3 Simplified approach for summer . 76
D.4 Examples of calculation . 76
Annex E (informative) Decision tree for critical samples . 80
Annex F (informative) Additional information for venetian blinds and louvres . 81
F.1 Venetian blinds . 81
F.2 Louvres . 83
Annex G (informative) Additional information for shutters . 84
Bibliography . 85

European foreword
This document (EN 14500:2021) has been prepared by Technical Committee CEN/TC 33 “Doors,
windows, shutters, building hardware and curtain walling”, the secretariat of which is held by AFNOR.
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 September 2021, and conflicting national standards shall
be withdrawn at the latest by September 2021.
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.
This document supersedes EN 14500:2008.
The main modifications of this project of revision are relating to:
— the improvement of the method for the determination of the optical properties with an integrating
sphere. The major improvement concerns the consideration of samples with scattering properties
(critical samples). This implied the definition of specific requirements relating to the geometry of the
test equipment and a methodology to identify if a sample is critical or not;
— the addition of a new method for the determination of the optical properties from direct
measurement (without integrating sphere);
— the addition of a method for the determination of the cut-off angle;
— the improvement of the method for the determination of the darkening performance of curtain
materials and complete products, including a method to qualify both the test equipment and the
observer.
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, Turkey and the United
Kingdom.
Introduction
This document is part of a series of standards dealing with blinds and shutters for buildings as defined in
EN 12216.
1 Scope
This document defines test and calculation methods for the determination of the reflection and
transmission characteristics to be used to determine the thermal and visual comfort performance classes
of external blinds, internal blinds and shutters, as specified in EN 14501:2021.
This document also specifies the method to determine the darkening performance of external blinds,
internal blinds and shutters, as specified in EN 14501:2021.
This document applies to the whole range of shutters, awnings and blinds defined in EN 12216, described
as solar protection devices in this document. Some of the characteristics (e.g. g ) are not applicable when
tot
products are not parallel to the glazing (e.g. folding-arm awnings).
NOTE 1 Informative Annex D presents an approach for the determination of characteristics in case of projectable
products.
Retro-reflecting products are outside the scope of this document for reflectance measurements.
NOTE 2 Retro-reflecting products refer to products for which the reflected radiation comes back to the light
source in the same direction.
Products using a significant amount of fluorescent are outside the scope of this document.
NOTE 3 “Significant amount” refers to materials which are designed to be fluorescent or retroreflective and
marketed as such. It does not refer to trace amounts of materials exhibiting fluorescence, e.g. for colour or
identification purposes. Small amounts of materials such as titanium dioxide, which are not primarily included to
achieve fluorescence, can be present.
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 12216, Shutters, external blinds, internal blinds — Terminology, glossary and definitions
EN 14501:2021, Blinds and shutters — Thermal and visual comfort — Performance characteristics and
classification
EN ISO 52022-1, Energy performance of buildings — Thermal, solar and daylight properties of building
components and elements — Part 1: Simplified calculation method of the solar and daylight characteristics
for solar protection devices combined with glazing (ISO 52022-1)
EN ISO 52022-3:2017, Energy performance of buildings — Thermal, solar and daylight properties of
building components and elements — Part 3: Detailed calculation method of the solar and daylight
characteristics for solar protection devices combined with glazing (ISO 52022-3:2017)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 12216, EN 14501:2021 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1 Processes
3.1.1
reflection
process by which radiation is returned by a surface or medium, without change of frequency of its
monochromatic components
The following sub-processes are defined herewith:
— specular (or directional or regular) reflection: reflection in accordance with the laws of geometrical
optics, without diffusion;
— diffuse reflection: reflection due to light scattering, in which, on the macroscopic scale, there is no
specular reflection;
— isotropic diffuse reflection: diffuse reflection in which the spatial distribution of the reflected
radiation is such that the radiance or luminance is the same in all directions in the hemisphere into
which the radiation is reflected
3.1.2
transmission
passage of radiation through a medium without change of frequency of its monochromatic components
The following sub-processes are defined herewith:
— directional (or direct-direct) transmission: transmission in accordance with the laws of geometrical
optics, without diffusion or redirection;
— diffuse transmission: transmission due to light scattering, in which, on the macroscopic scale, there
is no direct transmission;
— isotropic diffuse transmission: diffuse transmission in which the spatial distribution of the
transmitted radiation is such that the radiance or luminance is the same in all directions in the
hemisphere into which the radiation is transmitted
3.1.3
absorption
process by which radiant energy is converted to a different form of energy (e.g. heat) by interaction with
matter
3.2 Characteristics
3.2.1
reflectance
ρ
ratio of the reflected flux to the incident flux
The following sub-characteristics are defined:
— directional-directional (or direct-direct) reflectance: ratio of the specularly reflected flux to the
directional incident flux;
— directional-diffuse reflectance: ratio of the diffusely reflected flux to the directional incident flux;
— directional-hemispherical (or total) reflectance: ratio of the total reflected flux to the directional
incident flux;
— diffuse-hemispherical reflectance: ratio of the total reflected flux to the ideally diffuse incident flux.
Ideally diffuse irradiation means that the radiance or the luminance is equal for the whole
hemisphere of the incident irradiation
3.2.2
transmittance
τ
ratio of the transmitted flux to the incident flux
The following sub-characteristics are defined:
— directional-directional transmittance: ratio of the directly transmitted flux to the directional incident
flux;
— directional-diffuse transmittance: ratio of the diffusely transmitted flux to the directional incident
flux;
— directional-hemispherical transmittance: ratio of the total transmitted flux to the directional incident
flux;
— diffuse-hemispherical transmittance: ratio of the total transmitted flux to the ideally diffuse incident
flux. Ideally diffuse irradiation means that the radiance or the luminance is equal for the whole
hemisphere of the incident irradiation
3.2.3
absorptance
α
ratio of the absorbed flux to the incident flux
3.3 Angle definitions
All the following angles are defined in a coordinate system which is fixed relative to the orientation of the
solar protection device.
3.3.1
angle of incidence
θ
angle between the normal to the plane of the solar protection device and the direction of the incident
radiation
Note 1 to entry: See Figure 1.
3.3.2
altitude angle
αs
projection of the angle of incidence on the vertical plane which contains the direction of the incident
radiation
Note 1 to entry: See Figure 1.
3.3.3
azimuth angle
γ
projection of the angle of incidence on a plane which is normal to the plane of the solar protection device
Note 1 to entry: The intersection of this projection plane and the plane of the solar protection device is horizontal.
Note 2 to entry: See Figure 1.
3.3.4
profile angle
α
p
projection of the altitude angle on a vertical plane which is perpendicular to the façade under
consideration
Note 1 to entry: The profile angle is given by the following formula: tg α = tg α / cos γ
p s
Note 2 to entry: See Figure 1.
Key
1 direction of the incident radiation
2 vertical plane normal to the solar protection device
3 projected direction of the incident radiation
4 direction normal to the solar protection device
5 altitude angle α (angle in the vertical plane)
s
6 azimuth angle γ (angle in the horizontal plane)
7 profile angle αp
8 angle of incidence θ
9 solar protection device
Figure 1 — Angle definitions
3.3.5
directional cut-off angle χ
dir
minimum angle of incidence, within a given plane normal to the solar protection device, at which the
is below a defined level
direct-direct transmittance τdir-dir
3.3.6
cut-off angle χ
maximum directional cut-off angle χ , taking into account any plane normal to the solar protection
dir
device
Note 1 to entry: The maximum directional cut-off angle is described as “first angle” in EN 14501:2021.
3.3.7
rotation angle φ
within the plane of the sample, angle of rotation of the sample from the reference arrow defined
conventionally by the supplier of the sample
Note 1 to entry: See Figure 2 and 7.4.2.

Key
1 test sample
2 reference arrow
3 upright position of the sample at the test equipment
Figure 2 — Rotation angle
4 Notations used
4.1 General
For the purpose of this document, the optical factors τ (transmittance), ρ (reflectance) and α
(absorptance) are labelled with subscripts which indicate:
— the visual or solar properties;
— the geometry of the incident and the transmitted or reflected radiation.
4.2 Visual or solar properties
According to the respective spectrum, the following subscripts are used:
— “e” solar (energetic) characteristics, given for the total solar spectrum (wavelengths λ from 300 nm
to 2 500 nm), according to EN 410;
— “v” visual characteristics, given for the standard illuminant D weighted with the sensitivity of the
human eye (wavelengths λ from 380 nm to 780 nm), according to EN 410.
4.3 Geometry of the radiation
The following subscripts are used to indicate the geometry of the incident radiation (see Figure 3):
— « dir » for directional (parallel beam radiation with arbitrary direction θ);
— « n » for normal (parallel beam radiation with normal incidence θ = 0° or near normal in case of
reflected radiation θ ≤ 8°);
— « dif » for diffuse (radiation evenly distributed from all incident directions θ).
The following subscripts are used to indicate the geometry of the transmitted or reflected radiation:
— « dir » for directional (radiation reflected or transmitted in the specular or regular direction
respectively);
— « n » for normal (radiation transmitted in the normal direction or near normal in case of reflected
radiation θ ≤ 8°);
— « h » for hemispherical (radiation collected in the half space behind the sample plane);
— « dif » for diffuse (radiation collected in all outgoing directions except the direct.
Complementary a particular subscript is used to distinguish values for the two different sides:
— « ’ »  for properties of the reverse side of the main labelled side.
NOTE For example, when ρ relates to one side of a sample, ρ’ relates to the reverse side.
Key
1 solar protection device
2 incident directional light or solar radiation
3 transmitted direct component of light or solar radiation
4 transmitted diffuse component of light or solar radiation
Figure 3 — Direct and diffuse components of transmitted radiation
4.4 Optical factors
The optical factors are designated as follows:
— τ normal-normal solar transmittance
e, n-n
— τ normal-normal light transmittance
v, n-n
— τ normal-diffuse light transmittance
v, n-dif
— τ normal-hemispherical light transmittance
v, n-h
— τ direct-hemispherical light transmittance
v, dir-h
— τ direct-direct light transmittance
v, dir-dir
— τ diffuse-hemispherical light transmittance
v, dif-h
— τ normal-hemispherical solar transmittance
e, n-h
— τ direct-hemispherical solar transmittance
e, dir-h
— τ direct-direct solar transmittance
e, dir-dir
— ρv, n-h normal-hemispherical light reflectance
— ρ direct-hemispherical light reflectance
v, dir-h
— ρ normal-hemispherical solar reflectance
e, n-h
— ρ direct-hemispherical solar reflectance
e, dir-h
5 Test and calculation methods to be used according to product - Guidelines
5.1 General
The test methods described in this document are intended to be used for testing the characteristics of the
curtain elements of solar protection devices. Curtain elements are for example flat sheets of coated
aluminium for slats for venetian blinds, fabric materials for roller blinds or glass slats with or without
patterns for external glass venetian blinds. When combined to a glazing, the properties of the whole
product, which consists of one or more elements, shall be then calculated according to EN ISO 52022-1
or EN ISO 52022-3.
A whole product may also be tested. However, except when it is specified (e.g. for the darkening
performances in Clause 9), methods described in this standard are not intended to be used directly on
complete products.
Spectral properties shall be displayed with at least 3 digits (e.g. 0,123 or 12,3 %) and integrated
properties shall be displayed with 2 digits (e.g. 0,12 or 12 %). Conventional rounding rules shall be
applied.
NOTE 1 ISO 19467 provides a method to determine the solar factor of complete products (windows and doors
with or without sola shading).
NOTE 2 This document characterizes the product performance through the properties of the curtain (centre of
product values). However, peripheral gaps and/or holes and the installation conditions can have an effect on the
performance under real conditions.
For all solar protection devices, it is assumed that the products are fully extended (not partially retracted)
when solar protection or glare protection is required.
NOTE 3 For building planning it can be useful to take into consideration partially retracted solar protection
devices. The properties of the whole window can then be approximated by considering the weighted mean of areas
covered and not covered by the solar protection device.
5.2 Venetian blinds and louvres
The solar and light characteristics of venetian blinds and louvres shall be calculated using the properties
of individual slats.
The slats characteristics shall be measured according to Clause 6 or Clause7. The characteristics of a
complete venetian blind or a louvre combined to a glazing shall be calculated according to
EN ISO 52022-3:2017, Annex D.
Additional information given in Annex F should be considered.
NOTE 1 If products cannot be appropriately characterized using EN ISO 52022-3 (for example mirror finished
and/or special shaped slats), a more detailed calculation method (e.g. raytracing) can be necessary.
NOTE 2 CEN ISO/TR 52022-2:2017, Annex G presents a more detailed calculation method for the calculation of
solar and light characteristics of complete venetian blinds combined with a glazing. This method is based on
EN ISO 52022-3:2017, Annex D but considers a direct transmission of the incident radiation through the venetian
blind.
5.3 Roller blinds
The solar and light characteristics of roller blinds shall be calculated using the properties of the fabric.
The fabric characteristics shall be measured according to Clause 6 or Clause 7. It is assumed that the
properties of the complete product are the same as those of the curtain material.
The characteristics of a complete roller blind combined to a glazing shall be calculated according to either
EN ISO 52022-1 or EN ISO 52022-3.
Darkening performance shall be determined either on the curtain material or on a complete product, as
specified in Clause 9.
5.4 Pleated blinds
As an approximation the properties of the curtain material may be used as properties of the curtain in
the same way as for roller blinds (see 5.3).
5.5 Projecting awnings
Fabric properties of projecting awnings may be determined according to Clause 6 or Clause 7.
5.6 Shutters
The solar and light characteristics of shutters shall be calculated using the properties of the curtain
material (e.g. laths).
The curtain material characteristics shall be measured according to Clause 6 or Clause 7. It is assumed
that the properties of the complete product are the same as those of the curtain material.
The characteristics of a complete shutter combined to a glazing shall be calculated according to either
EN ISO 52022-1 or EN ISO 52022-3.
Darkening performance shall be determined either on the curtain material or on a complete product, as
specified in Clause 9.
Additional information given in Annex G should be considered.
6 Determination of transmittance and reflectance with an integrating sphere
6.1 Measurement principles
6.1.1 Spectral and integral methods
Any characteristic referring to optical properties of materials shall be determined under broad-band
conditions with a spectrally for defined wavelengths λ (spectral method) or a specified illuminant
(integral method).
Spectral method
The relevant spectral characteristic (e.g. the normal-hemispherical spectral transmittance τ (λ)) is
n-h
measured as a function of the wavelength. Spectral measurements can be made either with
monochromatic light or with a source having a broad spectrum and a spectrometer as detector. When a
spectral characteristic of a sample is known, the corresponding integral characteristic can be calculated
according to EN 410.
Integral method
The relevant weighted characteristic is measured directly, using a source with a standard spectral power
distribution S(λ) and a broad-band detector with the required relative spectral weighting function:
— for broad-band measurements of solar properties characteristic (e.g. the normal-hemispherical solar
transmittance τ ), the detector system shall have a flat spectral response over the whole solar
e,n-h
range and the spectral power distribution of the incident irradiation S(λ) shall correspond to the EN
410 solar spectrum;
— for broad-band measurements of the light characteristics (e.g. the normal-hemispherical light
transmittance τ ), the sensitivity of the detector shall correspond to the photopic spectral
v,n-h
sensitivity of the human eye V(λ) and the spectral power distribution SD65(λ) of the light source
shall correspond with the standard illuminant D65 (according to EN 410);
— for broad band measurements of light characteristics, it is also possible to use a light source with a
spectral power distribution S(λ) that corresponds with the standard solar spectrum and to use a
detector with a spectral sensitivity w(λ), so that S(λ)w(λ) = SD65(λ)V(λ).
Accuracy
A broad-band light-source/detector system shall be considered to be sufficiently accurate, when the solar
or light characteristics for a solar control glazing with a selectivity of τ / τ > 1,5 and the results of a clear
v e
glass sample do not differ more than 4 % relatively from the results determined with a calibrated
spectrometer with a relative accuracy of 2 % or better.
6.1.2 Absolute and relative measurements (according to CIE 130)
Since they are defined as the ratio of two fluxes, reflectance and transmittance are, in themselves, relative
characteristics, but, whenever their values are measured directly without the use of another material
standard as a reference, the corresponding measurement is termed absolute.
Reflectance measurements are carried out with the help of a standard and are accordingly classified as
relative measurements.
NOTE 1 Absolute measurements for reflectance determination do exist, but they are outside the scope of this
standard.
In the case of transmittance, similar considerations apply. Since the flux is transmitted through an
unknown sample it is to be referred to the flux incident on it. This comparison with the incident flux does
not, theoretically, require any standard. It is only necessary to leave a free passage for the flux. According
to this principle, measurements of transmittance are classified as absolute measurements.
NOTE 2 Relative transmittance measurements can be more appropriate in the case of diffusing test samples.
Then a diffusing reference sample can be more accurate.
6.2 Measuring equipment
6.2.1 General
An instrument for measuring the characteristics of materials consists of:
— equipment for irradiation (see 6.2.2);
— equipment for detection (see 6.2.3);
— reference samples (see 6.3).
6.2.2 Equipment for irradiation
6.2.2.1 Single or double-beam instrument
Two types of instruments are possible:
— a single beam recording instrument uses only one light beam;
— a double beam instrument. In double-beam instruments, the beam is switched between a path which
has an incidence on the sample and one which does not.
Key
1 reference beam ϕ
r
2 port N°2
3 port N°3
4 support N°4
5 port N°5
6 sample beam ϕs
7 reference port
8 detector (e.g. at the highest or the lowest point of the sphere)
Figure 4 — Schematic representation of a double beam spectrometer
with an integrating sphere
6.2.2.2 Geometric conditions
The equipment for irradiation shall fulfil the following geometric requirements:
— the minimum beam cross-section at the sample port (Port N°3), ab3, shall fulfil one of the following
requirement:
— rectangular: 6 mm ∙ 10 mm (ab3 = wb3 ∙ hb3);
— circular:  9 mm diameter (ab3 = π ∙ db3 / 4);
— the beam cross-section at the sample port (Port N°3), ab3, shall be a minimum of 60 mm .
Additionally the perimeter of the beam-cross section, perib3, shall not exceed the following
specific ratio of the beam surface: perib3 < 0,55 ∙ ab3.
The actual beam shall at least cover one of the minimum cross-sections defined above;
— the irradiance shall be nearly homogeneous on the relevant area;
— the required minimum area between the aperture area (a3) and the cross-sectional beam area (ab3)
and of Port N°3 in Figure 4 and Figure 5 shall ensure that there are no lateral losses;
— the area between the beam cross-section ab3 and the area a3 of Port N°3 in Figure 4 and Figure 5
2 2
shall be at least 50 mm (a3 – ab3 ≥ 50 mm );
NOTE 1 This limit is not specified as a dimensionless quantity relative to a sphere parameter, because here
the sample thickness is relevant as a scaling factor with reference to lateral shift.
NOTE 2 If a sample is optically “thick” or thicker than 1 mm, special care should be taken for the
measurement in order to ensure there are no lateral losses. Specific requirements for thick translucent samples
are given in 6.4.4.
— the beam cross-sectional area at Port N°5, ab5, in Figure 4 and Figure 5 shall be smaller than the area
(a5) of Port N°5 in Figure 4 and centred within it.
For measurement of samples less than 1 mm thick, a minimum “gap” between the edges of the beam
cross-section and Port N°5 corresponding to (a5 – ab5)/A > 0,001 shall be ensured when no sample
is mounted. The clearance between the edges of port N°5 and the beam cross section when there is
no sample shall be at least 1/20 of the radius of the port N°5;
NOTE 3 Special care should be taken for the measurement of sample of more than 1 mm thick.
— stray radiation outside the irradiated area of the sample shall be avoided;
— in the case of diffuse irradiation, an integrating sphere shall be used as a light source.
Key
1 port N°3
2 sample
3 incident beam
4 port N°5
Figure 5 — Definition of geometrical parameters for integrating spheres
Rectangular ports and beams are characterized by the height h and the width w. The beam cross-sectional
areas ab3 and ab5, the port areas a3 and a5 and the sphere area A are calculated directly from the linear
dimensions. It is important to note that the beam cross sections at port N°3 and port N°5 are different in
general due to non-parallel light beams.
6.2.2.3 Polarization
The characteristics of solar protection devices or materials for non-normal incidence depend on the state
of polarization of the irradiating beam. Directional measurements can only be performed with
unpolarised incident irradiation if no polarization arises from the source or the deflecting or focusing
optics (if present) and if the detector is insensitive to polarization. Therefore, in general, for non-normal
measurements, two separate measurements shall be made with the incident radiation fully linearly
polarized in the plane perpendicular to the plane of incidence and in the plane parallel to the plane of
incidence, respec
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