1、Designation: C1549 09 (Reapproved 2014)Standard Test Method forDetermination of Solar Reflectance Near AmbientTemperature Using a Portable Solar Reflectometer1This standard is issued under the fixed designation C1549; the number immediately following the designation indicates the year oforiginal ado
2、ption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a technique for determining thesolar reflectanc
3、e of flat opaque materials in a laboratory or inthe field using a commercial portable solar reflectometer. Thepurpose of the test method is to provide solar reflectance datarequired to evaluate temperatures and heat flows across sur-faces exposed to solar radiation.1.2 This test method does not supp
4、lant Test Method E903which measures solar reflectance over the wavelength range250 to 2500 nm using integrating spheres. The portable solarreflectometer is calibrated using specimens of known solarreflectance to determine solar reflectance from measurementsat four wavelengths in the solar spectrum:
5、380 nm, 500 nm,650 nm, and 1220 nm. This technique is supported bycomparison of reflectometer measurements with measurementsobtained using Test Method E903. This test method is appli-cable to specimens of materials having both specular anddiffuse optical properties. It is particularly suited to them
6、easurement of the solar reflectance of opaque materials.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is therespo
7、nsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationE691 Practice for Conducting an Interlaborato
8、ry Study toDetermine the Precision of a Test MethodE903 Test Method for Solar Absorptance, Reflectance, andTransmittance of Materials Using Integrating SpheresE1980 Practice for Calculating Solar Reflectance Index ofHorizontal and Low-Sloped Opaque Surfaces2.2 Additional Reference:“Instructions for
9、the Solar Spectrum Reflectometer ModelSSR-ER,” Devices and Services Company33. Terminology3.1 DefinitionsFor definitions of some terms used in thetest method, refer to Terminology C168.3.2 Definitions of Terms Specific to This Standard:3.2.1 air massair mass is related to the path length of solarrad
10、iation through the Earths atmosphere to the site of interest.Air mass 1 is for a path of normal solar radiation at the Earthsequator while air mass 2 indicates two times this path length.3.2.2 solar reflectancethe fraction of incident solar radia-tion upon a surface that is reflected from the surfac
11、e.3.3 Symbols:A = area normal to incident radiation, m2Qabs= rate at which radiant heat is absorbed per m2ofarea, Wqsolar= solar flux, W/m2r = solar reflectance, dimensionless4. Summary of Test Method4.1 This test method employs a diffuse tungsten halogenlamp to illuminate a flat specimen for two se
12、conds out of aten-second measurement cycle. Reflected light is measured atan angle of 20 from the incident angle with four detectors.Each detector is equipped with color filters to tailor itselectrical response to a range of wavelengths in the solarspectrum. Software in the instrument combines the o
13、utputs ofthe four detectors in appropriate proportions to approximate the1This test method is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Sept. 1, 2014. Published November 2014
14、. Originallyapproved in 2002. Last previous edition approved in 2009 as C1549 09. DOI:10.1520/C1549-09R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standa
15、rds Document Summary page onthe ASTM website.3The sole source of supply of the apparatus known to the committee at this timeis Devices reflectometer; solar reflectance;solar reflectometerAPPENDIX(Nonmandatory Information)X1. TECHNIQUE FOR MEASURING SOLAR REFLECTANCE OF A FLAT, OPAQUE, AND HETEROGENE
16、OUS SURFACEUSING A PORTABLE SOLAR REFLECTORX1.1 ScopeThis is a technique for measuring the meansolar reflectance of a flat, opaque, and heterogeneous surfacesuch as a variegated, granule-covered asphalt roofing shingle atstandard conditions. The mean solar reflectance of the surfaceis determined by
17、averaging the solar reflectances of spots(small regions) measured with a commercial portable solarreflectometer built and operated in accordance with ASTMC1549. This technique does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user
18、to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use. The results obtained using this appen-dix apply only to the material tested.X1.2 TerminologyX1.2.1 estimate of sample mean standard errorthesample standard deviation divided by
19、the square root of thenumber of elements in the sample.X1.2.2 heterogeneousconsisting of dissimilar or diverseingredients or constituents.X1.2.3 populationthe set of values about which conclu-sions are to be drawn, such as a set of solar reflectance valuesdetermined from non-overlapping spots that c
20、over an entire testsurface.X1.2.4 population meanthe arithmetic mean of the prop-erty values (that is, solar reflectances) measured for all mem-bers of a population.X1.2.5 population standard deviationthe square root ofthe arithmetic mean of the squares of the deviation from thepopulation mean.X1.2.
21、6 reflectometera device that measures reflectance.X1.2.7 sample meanthe arithmetic mean of the propertyvalues (that is, solar reflectances) measured for all members ofa sample set.X1.2.8 sample mean standard errorthe population stan-dard deviation divided by the square root of the number ofsamples.X
22、1.2.9 sample seta subset of the population, such as a setof non-overlapping spots on a test surface.X1.2.10 sample standard deviationthe square root of theratio of the sum of the squares of the deviation from the samplemean to a number one less than the number of samples.X1.2.11 spota small region o
23、f a test surface, such as a 25by 25 mm square or a 25 mm diameter circle.X1.2.12 test surfacea flat, opaque, and heterogeneoussurface, for example, a variegated, granule-covered asphaltshingle.X1.2.13 test surface mean solar reflectancethe ratio ofsolar energy reflected from a test surface to the so
24、lar energyincident on a test surface (equal to the ratio of area-integratedsolar reflectance to area).X1.2.14 variegatedhaving discrete markings of differentcolors.X1.3 Summary of TechniqueX1.3.1 For a flat, opaque, and heterogeneous test surface,solar reflectances shall be measured in accordance wi
25、th TestMethod C1549 at a series of randomly located, non-overlapping spots until the sample mean standard error is smallenough to use the sample mean as an estimate of the mean solarreflectance of the test surface. An algorithm for selectingmeasurement locations, computing the sample mean, andcomput
26、ing the sample mean standard error is available fromthe Cool Roof Rating Council (CRRC).5X1.4 Significance and UseX1.4.1 This technique provides a method for determiningthe mean solar reflectance of a flat, opaque, and heterogeneoussurface, from multiple, random and non-duplicative spot mea-surement
27、s of solar reflectance.X1.5 ProcedureX1.5.1 Set-up:X1.5.1.1 Obtain a representative test specimen, as definedby CRRC 1.5X1.5.1.2 Let w and h represent the width and height of thetest surface in mm.X1.5.1.3 Place a pair of rulers at a right angle on two sidesof the test Surface to establish a grid of
28、 square cells, each 25 by25 mm and centered on integer coordinates. (A ruler marked ininches is convenient for this step.) If the area of the test surface5Available from Cool Roof Rating Council (CRRC)1610 Harrison StreetOakland, CA 94612. http:/www.coolroofs.orgC1549 09 (2014)4does not exceed 0.019
29、 m2, then apply Procedure A. If the areais 0.019 m2or greater, then apply Procedure B.X1.5.1.4 Procedure A:(1) Measure the solar reflectance at the center of each cellwith a solar spectrum reflectometer in accordance with TestMethod C1549, centered over each cell.(2) Report the mean value of cell so
30、lar reflectance as themean solar reflectance of the test surface.X1.5.1.5 Procedure B:(1) Measure the solar reflectances at the centers of aminimum of 30 different and randomly selected cells inaccordance with Test Method C1549.(2) Compute the mean, standard deviation, and estimate ofstandard error
31、of the solar reflectance of the sample set. Thesequantities are defined in Equations in X1.5.2.(3) If the estimate of sample mean standard error exceeds0.005, increase the number of samples by measuring solarreflectances of additional, different, and randomly selectedcells(4) Repeat (2) and (3) unti
32、l the estimate of sample meanstandard error of the sample set does not exceed 0.005.(5) Report the sample mean plus or minus twice theestimate of sample mean standard error as the mean solarreflectance to within 95% confidence.X1.5.2 Calculations:X1.5.2.1 All reflectances in the following discussion
33、 aresolar reflectances.The mean reflectance:rA21*ArdA (X1.1)of a test surface of area is equal to the mean reflectance ofthe entire population of surface “spots,”1n(i51nri(X1.2)Each spot is a region of reflectance and area that is smallenough to be measured with the reflectometer, and does notoverla
34、p any of its neighbors. If is large, it is convenient toestimate the population mean spot reflectance , and hencethe test surface mean reflectance , of a large surface by ran-domly sampling a population subset. Consider a sample setof different, non-overlapping, and randomly located spotsthat have m
35、ean reflectance:r (X1.3)1n(i51nriwith standard deviation:s1n(i51n ri2 rn!2(X1.4)By the Central Limit theorem, the sample mean has a stan-dard error:r5 /=n (X1.5)where is the standard deviation of the spot reflectances ofthe entire population (Crow et al., 1960). The populationmean spot reflectance (
36、which is also the mean solar reflec-tance of the test surface,) is equal to (95% confidence). Ifthe sample size n is sufficiently large (say, n 30), then thepopulation standard deviation is well approximated by thesample standard deviation s , and the estimate of the samplemean standard error isrs=n
37、 (X1.6)The instrument used to measure spot reflectance in accor-dance with Test Method C1549 has a circular aperture.Hence, the test surface formed by a matrix of contiguous,non-overlapping circular measurement spots will cover afraction /4 0.79 of the rectangular region bounding thematrix of circle
38、s. The remaining 21% of the rectangular re-gion will not be sampled. This should be acceptable if theoptical properties of the area between each measurementcircle and its bounding square are expected to be the sameas those of the surface within each measurement circle.X1.6 ReportX1.6.1 Include the f
39、ollowing in the report in addition to therequirements stated in Test Method C1549.(1) The width, length, and area of the test surface,(2) The solar reflectance measurement procedure followed(A or B),(3) The central coordinates and solar reflectance of eachcell measured,(4) For Procedure A, the mean
40、solar reflectance of the testsurface, equal to the mean value of cell solar reflectance,(5) For Procedure B (applied to test surfaces exceeding0.019 m2, the mean solar reflectance of the test surface towithin 95% confidence, expressed as the sample mean plus orminus two times the estimate of sample
41、mean standard error,(6) Manufacturer of the product,(7) Manufacturer-designated product name and color, and(8) Date specimen was tested.X1.7 Precision and BiasX1.7.1 BiasNo statement concerning bias is made sincethere is no standard reference material for solar reflectance.X1.7.2 Procedure B was eva
42、luated in a round robin involv-ing five laboratories and six products. A precision statementbased on E691 is shown in Table X1.1. Precision characterizedby the reproducibility standard deviations, SR, and the 95%reproducibility limits R have been determined. R values werecalculated using 2.8 times S
43、R. Data needed for repeatabilitywere not obtained.X1.7.3 PrecisionThis precision statement is provisionalsince the data obtained do not meet the minimum requirementsof E691.C1549 09 (2014)5ASTM International takes no position respecting the validity of any patent rights asserted in connection with a
44、ny item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technica
45、l committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration
46、at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor
47、 Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.as
48、tm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ X1.1 Solar Reflectance (%) for Six MaterialsMaterialAverage SolarReflectanceSRR1 6.06 0.57 1.592 3.76 0.26 0.733 19.10 1.09 3.044 6.90 0.33 0.935 6.14 0.34 0.966 5.66 0.47 1.30C1549 09 (2014)6
