ASTM E972-96(2013)

Standard Test Method for Solar Photometric Transmittance of Sheet Materials Using Sunlight

SIGNIFICANCE AND USE
5.1 Glazed apertures in buildings are generally utilized for the controlled admission of both light and solar radiant heat energy into the structure. Other devices may also be used to reflect light and solar radiant heat into a building.  
5.2 The bulk of the solar radiant energy entering a building in this manner possesses wavelengths that lie from 300 to 2500 nm (3000 to 25 000 Å). Only the portion from 380 to 760 nm (3800 to 7600 Å) is visible radiation, however. In daylighting applications, it is therefore important to distinguish the radiant (solar radiant energy) transmittance or reflectance of these materials from their luminous (light) transmittance or reflectance.  
5.3 For comparisons of the energy and illumination performances of building fenestration systems it is important that the calculation or measurement, or both, of solar radiant and luminous transmittance and reflectance of materials used in fenestration systems use the same incident solar spectral distribution.  
5.4 Solar luminous transmittance and reflectance are important properties in describing the performance of components of solar illumination systems including windows, clerestories, skylights, shading and reflecting devices, and other passive fenestrations that permit the passage of daylight as well as solar radiant heat energy into buildings.  
5.5 This test method is useful for determining the solar luminous transmittance and reflectance of optically inhomogeneous sheet materials and diffusely reflecting materials used in natural lighting systems that are used alone or in conjunction with passive or active solar heating systems, or both. This test method provides a means of measuring solar luminous transmittance under fixed conditions of incidence and viewing. This test method has been found practical for both transparent and translucent materials as well as for those with transmittances reduced by reflective coatings. This test method is particularly applicable to the measurement o...
SCOPE
1.1 This test method covers the measurement of solar photometric transmittance of materials in sheet form. Solar photometric transmittance is measured using a photometer (illuminance meter) in an enclosure with the sun and sky as the source of radiation. The enclosure and method of test is specified in Test Method E1175 (or Test Method E1084).  
1.2 The purpose of this test method is to specify a photometric sensor to be used with the procedure for measuring the solar photometric transmittance of sheet materials containing inhomogeneities in their optical properties.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Oct-2013
• ICS: 17.180.20 - Colours and measurement of light
• Technical Committee: E44 - Solar, Geothermal and Other Alternative Energy Sources

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E972 − 96 (Reapproved 2013)
Standard Test Method for
Solar Photometric Transmittance of Sheet Materials Using
1
Sunlight
This standard is issued under the fixed designation E972; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
3.1 Definitions—For definitions of other terms used in this
1.1 This test method covers the measurement of solar
test method, refer to Terminology E772.
photometric transmittance of materials in sheet form. Solar
3.1.1 illuminance, n—luminous irradiance.
photometric transmittance is measured using a photometer
(illuminance meter) in an enclosure with the sun and sky as the
3.1.2 luminous (photometric), adj—referring to a radiant
source of radiation. The enclosure and method of test is
(or radiometric) quantity,indicatestheweightedaverageofthe
specified in Test Method E1175 (or Test Method E1084).
spectral radiometric quantity, with the photopic spectral lumi-
nous efficiency function (see Annex A1) being the weighting
1.2 The purpose of this test method is to specify a photo-
function.
metric sensor to be used with the procedure for measuring the
3.1.3 radiant flux, Φ = d Q/dt[Watt (W)], n— power
solar photometric transmittance of sheet materials containing
emitted, transferred, or received in the form of electromagnetic
inhomogeneities in their optical properties.
waves or photons. See radiometric properties and quantities.
1.3 This standard does not purport to address all of the
3.1.4 reflectance, ρ, Φ /Φ,n—the ratio of the reflected flux
r i
safety concerns, if any, associated with its use. It is the
to the incident flux.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- 3.1.5 solar irradiance at a point of a surface, E =dΦ/dA,
s
n—the quotient of the solar flux incident on an element of a
bility of regulatory limitations prior to use.
surface containing the point, by the area of that element,
measured in watts per square metre.
2. Referenced Documents
3.1.5.1 Discussion—Measured values of transmittance and
2
2.1 ASTM Standards:
reflectance depend upon angle of incidence, solid angles of
E772 Terminology of Solar Energy Conversion
incidence and of transmission and reflection, the method of
E1084 Test Method for Solar Transmittance (Terrestrial) of
measurement of the reflected or transmitted flux, and the
Sheet Materials Using Sunlight
spectral composition of the incident flux. Because of this
E1175 Test Method for Determining Solar or Photopic
dependence, complete information on the technique and con-
Reflectance, Transmittance, andAbsorptance of Materials
ditions of measurement should be specified.
Using a Large Diameter Integrating Sphere
3.1.6 solar, adj—(1) referring to a radiometric term, indi-
2.2 CIE Standard:
cates that the quantity has the sun as a source or is character-
3
Standard Illuminant D65
istic of the sun. (2) referring to an optical property, indicates
the weighted average of the spectral optical property, with the
solar spectral irradiance E used as the weighting function.
sλ
1
These test methods are under the jurisdiction of ASTM Committee E44 on
3.1.7 spectral, adj—(1) for dimensionless optical
Solar, Geothermal and Other Alternative Energy Sources and is the direct respon-
properties, indicates that the property was evaluated at a
sibility of Subcommittee E44.05 on Solar Heating and Cooling Systems and
specific wavelength, λ, within a small wavelength interval, ∆λ
Materials.
Current edition approved Nov. 1, 2013. Published December 2013. Originally
aboutλ,symbolwavelengthinparentheses,as L(350nm,3500
approved in 1983. Last previous edition approved in 2007 as E972 – 96 (2007).
Å), or as a function of wavelength, symbol L(λ). (2) for a
DOI: 10.1520/E0972-96R13.
radiometric quantity, indicates the concentration of the quan-
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
tity per unit wavelength or frequency, indicated by the sub-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
dL
Standards volume information, refer to the standard’s Document Summary page on
script lambda, as L = ⁄dλ, at a specific wavelength. The
λ
the ASTM website.
wavelength at which the spectral concentration is evaluated
3
Available from Commission Internationale de l’Eclairage (International Com-
may be indicated by the wavelength in parentheses following
mission on Illumination), Barean Central de la CIE, 4 Av. du Recteur Poincaré,
75-Paris, France. the symbol, L (350 nm).
λ
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