ISO 9050:2003
(Main)Glass in building — Determination of light transmittance, solar direct transmittance, total solar energy transmittance, ultraviolet transmittance and related glazing factors
Glass in building — Determination of light transmittance, solar direct transmittance, total solar energy transmittance, ultraviolet transmittance and related glazing factors
ISO 9050:2003 specifies methods of determining light and energy transmittance of solar radiation for glazing in buildings. These characteristic data can serve as a basis for light, heating and ventilation calculations of rooms and can permit comparison between different types of glazing. ISO 9050:2003 is applicable both to conventional glazing units and to absorbing or reflecting solar-control glazing, used as glazed apertures. The appropriate formulae for single, double and triple glazing are given. Furthermore, the general calculation procedures for units consisting of more than components are established. ISO 9050:2003 is applicable to all transparent materials. One exception is the treatment of the secondary heat transfer factor and the total solar energy factor for those materials that show significant transmittance in the wavelength region of ambient temperature radiation (5 microns to 50 microns), such as certain plastic sheets.
Verre dans la construction — Détermination de la transmission lumineuse, de la transmission solaire directe, de la transmission énergétique solaire totale, de la transmission de l'ultraviolet et des facteurs dérivés des vitrages
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INTERNATIONAL ISO
STANDARD 9050
Second edition
2003-08-15
Glass in building — Determination of
light transmittance, solar direct
transmittance, total solar energy
transmittance, ultraviolet transmittance
and related glazing factors
Verre dans la construction — Détermination de la transmission
lumineuse, de la transmission solaire directe, de la transmission
énergétique solaire totale, de la transmission de l'ultraviolet et des
facteurs dérivés des vitrages
Reference number
©
ISO 2003
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ii © ISO 2003 — All rights reserved
Contents Page
Foreword. iv
1 Scope. 1
2 Normative references . 1
3 Determination of characteristic parameters. 2
3.1 General. 2
3.2 Performance of optical measurements. 2
3.3 Light transmittance. 3
3.4 Light reflectance . 5
3.5 Total solar energy transmittance (solar factor) .6
3.6 UV-transmittance . 14
3.7 CIE damage factor. 14
3.8 Skin damage factor . 15
3.9 Colour rendering . 15
4 Reference values. 16
5 Test report. 16
Annex A (normative) Calculation procedures . 22
Bibliography . 27
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 9050 was prepared by Technical Committee ISO/TC 160, Glass in building, Subcommittee SC 2, Use
considerations.
This second edition cancels and replaces the first edition (ISO 9050:1990), which has been technically revised.
iv © ISO 2003 — All rights reserved
INTERNATIONAL STANDARD ISO 9050:2003(E)
Glass in building — Determination of light transmittance, solar
direct transmittance, total solar energy transmittance,
ultraviolet transmittance and related glazing factors
1 Scope
This International Standard specifies methods of determining light and energy transmittance of solar radiation
for glazing in buildings. These characteristic data can serve as a basis for light, heating and ventilation
calculations of rooms and can permit comparison between different types of glazing.
This International Standard is applicable both to conventional glazing units and to absorbing or reflecting
solar-control glazing, used as glazed apertures. The appropriate formulae for single, double and triple glazing
are given. Furthermore, the general calculation procedures for units consisting of more than components are
established.
This International Standard is applicable to all transparent materials. One exception is the treatment of the
secondary heat transfer factor and the total solar energy factor for those materials that show significant
transmittance in the wavelength region of ambient temperature radiation (5 µm to 50 µm), such as certain
plastic sheets.
NOTE For multiple glazing including elements with light-scattering properties, the more detailed procedures of
ISO 15099 can be used. For daylighting calculations, procedures can be found in reference [1].
2 Normative references
The following referenced documents are indispensable for the application 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.
ISO 9845-1:1992, Solar energy — Reference solar spectral irradiance at the ground at different receiving
conditions — Part 1: Direct normal and hemispherical solar irradiance for air mass 1,5
ISO 10291:1994, Glass in building — Determination of steady-state U values (thermal transmittance) of
multiple glazing — Guarded hot plate method
ISO 10292:1994, Glass in building — Calculation of steady-state U values (thermal transmittance) of multiple
glazing
ISO 10293:1997, Glass in building — Determination of steady-state U values (thermal transmittance) of
multiple glazing — Heat flow meter method
ISO 10526:1999/CIE S005:1998, CIE standard illuminants for colorimetry
ISO/CIE 10527:1991, CIE standard colorimetric observers
CIE 13.3:1995, Technical report — Method of measuring and specifying colour rendering properties of light
source
3 Determination of characteristic parameters
3.1 General
The characteristic parameters are determined for quasi-parallel, almost normal radiation incidence. For the
measurements, the samples shall be irradiated by a beam whose axis is at an angle not exceeding 10° from
the normal to the surface. The angle between the axis and any ray of the illuminating beam shall not exceed
5° (see reference [2]).
The characteristic parameters are as follows:
the spectral transmittance τ (λ), the spectral external reflectance ρ (λ) and the spectral internal
o
reflectance ρ (λ) in the wavelength range of 300 nm to 2 500 nm;
i
the light transmittance τ , the external light reflectance ρ and the internal light reflectance ρ for
v v,o v,i
illuminant D65;
the solar direct transmittance τ and the solar direct reflectance ρ ;
e e
the total solar energy transmittance (solar factor) g;
the UV-transmittance τ ;
UV
the general colour rendering index R .
a
If the value of a given characteristic is required for different glass thicknesses (in the case of uncoated glass)
or for the same coating applied to different glass substrates, it may be obtained by calculation (see Annex A).
If nothing else is stated, the published characteristic parameters shall be determined using the standard
conditions given in 3.3 to 3.7. Other optional conditions given in Clause 4 shall be stated.
When calculating the characteristic parameters of multiple glazing, the spectral data of each glass component
instead of integrated data shall be used.
3.2 Performance of optical measurements
Optical measurements in transmission and reflection require special care and much experimental experience
to achieve an accuracy in transmittance and reflectance of about ± 0,01.
Commercial spectrophotometers (with or without integrating spheres) are affected by various sources of
inaccuracy when used for reflectance and transmittance measurements on flat glass for building.
The wavelength calibration and the photometric linearity of commercial spectrophotometers shall be checked
periodically using reference materials obtained from metrological laboratories.
The wavelength calibration shall be performed by measuring glass plates or solutions which feature relatively
sharp absorption bands at specified wavelengths; the photometric linearity shall be checked using grey filters
with a certified transmittance.
For reflectance measurements, reference materials having a reflection behaviour (i.e. reflectance level and
ratio of diffuse and direct reflectance) similar to the unknown sample shall be selected.
Thick samples (e.g. laminated glass or insulating units) can modify the optical path of the instrument’s beam
as compared to the path in air and therefore the sample beam hits an area of the detector having a different
responsivity.
2 © ISO 2003 — All rights reserved
A similar source of inaccuracy occurs in case of samples with significant wedge angles which deflect the
transmitted (and reflected) beams. It is recommended to check the reproducibility by repeating the
measurement after rotating the sample.
Additionally, in the case of reflectance measurements, glass sheets cause a lateral shear of the beam
reflected by the second surface, causing reflectance losses (whose extent is particulary evident in the case of
thick and/or wedged samples). This source of inaccuracy shall be taken into account particularly in the case of
reflectance measurements through the uncoated side. In order to quantify and correct systematic errors, it is
recommended to use calibrated reflectance standards with a thickness similar to the unknown sample.
In the case of diffusing samples (or samples with a non-negligible diffusing component or wedged samples),
transmittance and reflectance measurements shall be performed using integrating spheres whose openings
are sufficiently large to collect all the diffusely transmitted or reflected beam. The sphere diameter shall be
adequate and the internal surface adequately coated with a highly diffusing reflectance material, so that the
internal area can provide the necessary multiple reflections. Reference materials with characteristics similar to
the unknown sample as specified above shall be used.
If the transmittance or reflectance curve recorded by the spectrometer exhibits a high level of noise for some
wavelengths, the values to be considered for those wavelengths should be obtained after a smoothing of the
noise.
In this International Standard, these requirements are not all treated in detail. For more information, see
reference [3] which gives comprehensive and detailed information on how to perform optical measurements.
3.3 Light transmittance
The light transmittance τ of glazing shall be calculated using the following formula:
v
780 nm
τλλDV ∆λ
() ()
∑ λ
λ = 380 nm
τ = (1)
v
780 nm
DVλλ∆
()
λ
∑
λ = 380 nm
where
D is the relative spectral distribution of illuminant D65 (see ISO/CIE 10526),
λ
τ (λ) is the spectral transmittance of glazing;
V(λ) is the spectral luminous efficiency for photopic vision defining the standard observer for photometry
(see ISO/CIE 10527);
∆λ is the wavelength interval.
Table 1 indicates the values for D V(λ)∆λ for wavelength intervals of 10 nm. The table has been drawn up in
λ
such a way that ΣD V(λ)∆λ = 1.
λ
In the case of multiple glazing, the spectral transmittance τ (λ) shall be obtained by calculation from the
spectral characteristics of the individual components. Alternatively measurements on non-diffusing multiple
units may be performed using an integrating sphere. This may be achieved after reducing the interspaces
under conditions that allow the collection of the whole transmitted beam (see 3.2).
The calculation of
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