ASTM C1549-09

Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer

SIGNIFICANCE AND USE
The temperatures of opaque surfaces exposed to solar radiation are generally higher than the adjacent air temperatures. In the case of roofs or walls enclosing conditioned spaces, increased inward heat flows result. In the case of equipment or storage containers exposed to the sun, increased operating temperatures usually result. The extent to which solar radiation affects surface temperatures depends on the solar reflectance of the exposed surface. A solar reflectance of 1.0 (100 % reflected) would mean no effect on surface temperature while a solar reflectance of 0 (none reflected, all absorbed) would result in the maximum effect. Coatings of specific solar reflectance are used to change the temperature of surfaces exposed to sunlight. Coatings and surface finishes are commonly specified in terms of solar reflectance. The initial (clean) solar reflectance must be maintained during the life of the coating or finish to have the expected thermal performance.
The test method provides a means for periodic testing of surfaces in the field or in the laboratory. Monitor changes in solar reflectance due to aging and exposure, or both, with this test method.
This test method is used to measure the solar reflectance of a flat opaque surface. The precision of the average of several measurements is usually governed by the variability of reflectances on the surface being tested.
Use the solar reflectance that is determined by this method to calculate the solar energy absorbed by an opaque surface as shown in Eq 1.
SCOPE
1.1 This test method covers a technique for determining the solar reflectance of flat opaque materials in a laboratory or in the field using a commercial portable solar reflectometer. The purpose of the test method is to provide solar reflectance data required to evaluate temperatures and heat flows across surfaces exposed to solar radiation.
1.2 This test method does not supplant Test Method E903 which measures solar reflectance over the wavelength range 250 to 2500 nm using integrating spheres. The portable solar reflectometer is calibrated using specimens of known solar reflectance to determine solar reflectance from measurements at four wavelengths in the solar spectrum: 380 nm, 500 nm, 650 nm, and 1220 nm. This technique is supported by comparison of reflectometer measurements with measurements obtained using Test Method E903. This test method is applicable to specimens of materials having both specular and diffuse optical properties. It is particularly suited to the measurement of the solar reflectance of opaque materials.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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-2009
• ICS: 27.160 - Solar energy engineering
• Technical Committee: C16 - Thermal Insulation
• Drafting Committee: C16.30 - Thermal Measurement

Relations

• Replaces: ASTM C1549-04 - Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer
• Effective Date: 01-Nov-2009
• Replaced By: ASTM C1549-09(2014) - Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer
• Effective Date: 01-Sep-2014
• Referred By: ASTM C1864-17(2022) - Standard Test Method for Determination of Solar Reflectance of Directionally Reflective Material Using Portable Solar Reflectometer
• Effective Date: 01-Nov-2009
• Referred By: ASTM E2813-18 - Standard Practice for Building Enclosure Commissioning
• Effective Date: 01-Nov-2009
• Referred By: ASTM D2824/D2824M-18 - Standard Specification for Aluminum-Pigmented Asphalt Roof Coatings, Nonfibered, and Fibered without Asbestos
• Effective Date: 01-Nov-2009
• Referred By: ASTM D7897-18(2023) - Standard Practice for Laboratory Soiling and Weathering of Roofing Materials to Simulate Effects of Natural Exposure on Solar Reflectance and Thermal Emittance
• Effective Date: 01-Nov-2009
• Referred By: ASTM D3794-22 - Standard Guide for Testing Coil Coatings
• Effective Date: 01-Nov-2009

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:C1549 −09
StandardTest Method for
Determination of Solar Reflectance Near Ambient
1
Temperature Using a Portable Solar Reflectometer
This standard is issued under the fixed designation C1549; 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 E691 Practice for Conducting an Interlaboratory Study to
Determine the Precision of a Test Method
1.1 This test method covers a technique for determining the
E903 Test Method for Solar Absorptance, Reflectance, and
solar reflectance of flat opaque materials in a laboratory or in
Transmittance of Materials Using Integrating Spheres
the field using a commercial portable solar reflectometer. The
3
(Withdrawn 2005)
purpose of the test method is to provide solar reflectance data
E1980 Practice for Calculating Solar Reflectance Index of
required to evaluate temperatures and heat flows across sur-
Horizontal and Low-Sloped Opaque Surfaces
faces exposed to solar radiation.
2.2 Additional Reference:
1.2 This test method does not supplant Test Method E903
“Instructions for the Solar Spectrum Reflectometer Model
which measures solar reflectance over the wavelength range
4
SSR-ER,” Devices and Services Company
250 to 2500 nm using integrating spheres. The portable solar
reflectometer is calibrated using specimens of known solar
3. Terminology
reflectance to determine solar reflectance from measurements
3.1 Definitions—For definitions of some terms used in the
at four wavelengths in the solar spectrum: 380 nm, 500 nm,
test method, refer to Terminology C168.
650 nm, and 1220 nm. This technique is supported by
3.2 Definitions of Terms Specific to This Standard:
comparison of reflectometer measurements with measurements
obtained using Test Method E903. This test method is appli- 3.2.1 air mass—airmassisrelatedtothepathlengthofsolar
radiation through the Earth’s atmosphere to the site of interest.
cable to specimens of materials having both specular and
diffuse optical properties. It is particularly suited to the Air mass 1 is for a path of normal solar radiation at the Earth’s
equator while air mass 2 indicates two times this path length.
measurement of the solar reflectance of opaque materials.
3.2.2 solar reflectance—the fraction of incident solar radia-
1.3 The values stated in SI units are to be regarded as
tion upon a surface that is reflected from the surface.
standard. No other units of measurement are included in this
standard.
3.3 Symbols:
2
1.4 This standard does not purport to address all of the A = area normal to incident radiation, m
2
safety concerns, if any, associated with its use. It is the Q = rate at which radiant heat is absorbed per m of
abs
responsibility of the user of this standard to establish appro- area, W
2
priate safety and health practices and determine the applica- q = solar flux, W/m
solar
bility of regulatory limitations prior to use. r = solar reflectance, dimensionless
4. Summary of Test Method
2. Referenced Documents
2
4.1 This test method employs a diffuse tungsten halogen
2.1 ASTM Standards:
lamp to illuminate a flat specimen for two seconds out of a
C168 Terminology Relating to Thermal Insulation
ten-second measurement cycle. Reflected light is measured at
an angle of 20° from the incident angle with four detectors.
Each detector is equipped with color filters to tailor its
1
ThistestmethodisunderthejurisdictionofASTMCommitteeC16onThermal
Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
Measurement.
3
Current edition approved Nov. 1, 2009. Published January 2010. Originally The last approved version of this historical standard is referenced on
approved in 2002. Last previous edition approved in 2002 as C1549 – 02. DOI: www.astm.org.
4
10.1520/C1549-09. The sole source of supply of the apparatus known to the committee at this time
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or isDevices&ServicesCompany,10024MonroeDrive,Dallas,TX75229.Ifyouare
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM aware of alternative suppliers, please provide this information to ASTM Interna-
Standards volume information, refer to the standard’s Document Summary page on tional Headquarters.Your comments will receive careful consideration at a meeting
1
the ASTM website. of the responsible technical committee , which you may attend.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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C1549−09
electrical response to a range of wavelengths in the solar 6. Apparatus
spectr
...

This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:C1549–04 Designation: C1549 – 09
Standard Test Method for
Determination of Solar Reflectance Near Ambient
1
Temperature Using a Portable Solar Reflectometer
This standard is issued under the fixed designation C1549; 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
1.1 This test method covers a technique for determining the solar reflectance of flat opaque materials in a laboratory or in the
field using a commercial portable solar reflectometer. The purpose of the test method is to provide solar reflectance data required
to evaluate temperatures and heat flows across surfaces exposed to solar radiation.
1.2 This test method does not supplant Test Method E903 which measures solar reflectance over the wavelength range 250 to
2500 nm using integrating spheres. The portable solar reflectometer is calibrated using specimens of known solar reflectance to
determine solar reflectance from measurements at four wavelengths in the solar spectrum: 380 nm, 500 nm, 650 nm, and 1220 nm.
This technique is supported by comparison of reflectometer measurements with measurements obtained using Test Method E903.
This test method is applicable to specimens of materials having both specular and diffuse optical properties. It is particularly suited
to the measurement of the solar reflectance of opaque materials.
1.3The values stated in SI units are to be regarded as the standard. The values in parenthesis are for information only.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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.
2
2. Referenced Documents
2.1 ASTM Standards:
C168 Terminology Relating to Thermal Insulation
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E903 Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres
E1980 Practice for Calculating Solar Reflectance Index of Horizontal and Low-Sloped Opaque Surfaces
2.2 Additional Reference:
3
“Instructions for the Solar Spectrum Reflectometer Model SSR-ER,” Devices and Services Company
3. Terminology
3.1 Definitions—For definitions of some terms used in the test method, refer to Terminology C168.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 air mass—air mass is related to the path length of solar radiation through the Earth’s atmosphere to the site of interest.
Air mass 1 is for a path of normal solar radiation at the Earth’s equator while air mass 2 indicates two times this path length.
3.2.2 solar reflectance—the fraction of incident solar radiation upon a surface that is reflected from the surface.
3.3 Symbols:
2
A = area normal to incident radiation, m
2
Q = rate at which radiant heat is absorbed per m of area, W
abs
2
q = solar flux, W/m
solar
r = solar reflectance, dimensionless
1
This test method is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
Measurements.
Current edition approved Sept.Nov. 1, 2004.2009. Published October 2004.January 2010. Originally approved in 2002. Last previous edition approved in 2002 as
C1549 – 02. DOI: 10.1520/C1549-049.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The sole source of supply of the apparatus known to the committee at this time is Devices & Services Company, 10024 Monroe Drive, Dallas, TX 75229. If you are
aware of alternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the
responsible technical committee , which you may attend.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
C1549 – 09
4. Summary of Test Method
4.1 This t
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