ASTM E1477-98a(2003)
(Test Method)Standard Test Method for Luminous Reflectance Factor of Acoustical Materials by Use of Integrating-Sphere Reflectometers
Standard Test Method for Luminous Reflectance Factor of Acoustical Materials by Use of Integrating-Sphere Reflectometers
SIGNIFICANCE AND USE
Acoustical materials are often used as the entire ceiling of rooms and are therefore an important component of the lighting system. The luminous reflectance of all important components must be known in order to predict the level of illumination that will be obtained.
The reflecting properties of a surface are measured relative to those of a standard reflector, the perfect reflecting diffuser, to provide a reflectance factor. The luminous reflectance factor is calculated for a standard illuminant, and a standard observer, for the standard hemispherical (integrating-sphere) geometry of illumination and viewing, in which all reflected radiation from an area of the surface is collected. In this way the reflecting properties of an acoustical material can be represented by a single number measured and calculated under standard conditions.
Acoustical materials generally have a non-glossy white or near-white finish. The types of surface cover a wide range from smooth to deeply fissured. Measurement with integrating-sphere reflectometers has been satisfactory although multiple measurements may be required to sample the surface adequately. Instruments with other types of optical measuring systems may be used if it can be demonstrated that they provide equivalent results.
The use of this test method for determining the luminous reflectance factor is required by Classification E 1264.
SCOPE
1.1 This test method covers the measurement of the luminous reflectance factor of acoustical materials for use in predicting the levels of room illumination.
1.2 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.
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Designation: E 1477 – 98a (Reapproved 2003)
Standard Test Method for
Luminous Reflectance Factor of Acoustical Materials by Use
of Integrating-Sphere Reflectometers
This standard is issued under the fixed designation E 1477; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope including or excluding the specularly reflected components.
(E 284)
1.1 This test method covers the measurement of the lumi-
3.1.2 luminous, adj—weighted according to the spectral
nous reflectance factor of acoustical materials for use in
luminous efficiency function V (l) of the CIE. (E 284)
predicting the levels of room illumination.
3.1.3 reflectance factor, R, n—ratio of the flux reflected
1.2 This standard does not purport to address all of the
from the specimen to the flux reflected from the perfect
safety concerns, if any, associated with its use. It is the
reflecting diffuser under the same geometric and spectral
responsibility of the user of this standard to establish appro-
conditions of measurement. (E 284)
priate safety and health practices and determine the applica-
3.1.4 perfect reflecting diffuser—idealreflectingsurfacethat
bility of regulatory limitations prior to use.
neither absorbs nor transmits light, but reflects light in a
2. Referenced Documents
diffused manner with the radiance of the reflecting surface
being the same for all reflecting angles, regardless of the
2.1 ASTM Standards:
angular distribution of the incident light. (E 284)
E 284 Terminology of Appearance
E 308 Practice for Computing the Colors of Objects by
4. Summary of Test Method
Using the CIE System
4.1 Test specimens are measured for (total) luminous reflec-
E 1164 Practice for Obtaining Spectrophotometric Data for
tance factor by standard color-measurement techniques using a
Object-Color Evaluation
spectrophotometer, tristimulus (filter) colorimeter, or other
E 1264 Classification for Acoustical Ceiling Products
reflectometer having a hemispherical optical measuring sys-
E 1331 Test Method for Reflectance Factor and Color by
tem, such as an integrating sphere. The specular component is
Spectrophotometry Using Hemispherical Geometry
included to provide the total reflectance factor condition. The
E 1345 Practice for Reducing the Effect of Variability of
2 instrument standard is referenced to the perfect reflecting
Color Measurement by Use of Multiple Measurements
diffuser. Luminous reflectance factor is calculated as CIE
E 1347 Test Method for Color and Color-Difference Mea-
2 tristimulus value Y for the CIE 1964 (10°) standard observer
surement by Tristimulus (Filter) Colorimetry
and CIE standard illuminant D 65 (daylight) or F 2 (cool white
3. Terminology fluorescent).
3.1 Definitions—Definitions of appearance terms in Termi-
5. Significance and Use
nology E 284 are applicable to this test method.
5.1 Acoustical materials are often used as the entire ceiling
3.1.1 integrating sphere, n—an optical device used either to
of rooms and are therefore an important component of the
collect flux reflected or transmitted from a specimen into a
lighting system. The luminous reflectance of all important
hemisphere or to provide isotropic irradiation of a specimen
components must be known in order to predict the level of
from a complete hemisphere, consisting of an approximately
illumination that will be obtained.
spherical cavity with apertures (ports) for admitting and
5.2 The reflecting properties of a surface are measured
detecting flux, and usually having additional apertures over
relative to those of a standard reflector, the perfect reflecting
which sample and reference specimens are placed and for
diffuser, to provide a reflectance factor. The luminous reflec-
tance factor is calculated for a standard illuminant, and a
This test method is under the jurisdiction of ASTM Committee E12 on Color
standard observer, for the standard hemispherical (integrating-
and Appearance and is the direct responsibility of Subcommittee E12.02 on
sphere) geometry of illumination and viewing, in which all
Spectrophotometry and Colorimetry.
reflected radiation from an area of the surface is collected. In
Current edition approved July 10, 2003. Published July 2003. Originally
this way the reflecting properties of an acoustical material can
approved in 1992. Last previous edition approved in 1998 as E 1477 - 98a.
Annual Book of ASTM Standards, Vol 06.01.
Annual Book of ASTM Standards, Vol 04.06.
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E 1477 – 98a (2003)
be represented by a single number measured and calculated 7.4
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