1、Designation:E108486(Reapproved 2015)Standard Test Method forSolar Transmittance(Terrestrial)of Sheet Materials UsingSunlight1This standard is issued under the fixed designation E1084;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,th
2、e 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 the measurement of solartransmittance(terrestrial)of materials in sheet form by using apy
3、ranometer,an enclosure,and the sun as the energy source.1.2 This test method also allows measurement of solartransmittance at angles other than normal incidence.1.3 This test method is applicable to sheet materials that aretransparent,translucent,textured,or patterned.1.4 This standard does not purp
4、ort to address all of thesafety concerns,if any,associated with its use.It is theresponsibility 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.Terminology2.1 Definitions:2.1.1 pyranometer,na
5、 radiometer used to measure thetotal solar radiant energy incident upon a surface per unit timeper unit area.This energy includes the direct radiant energy,diffuse radiant energy,and reflected radiant energy from thebackground.2.1.2 solar reflectance,nthe ratio of reflected to incidentsolar flux.2.1
6、.3 solar transmittance,nthe ratio of transmitted toincident solar flux.2.2 Definitions of Terms Specific to This Standard:2.2.1 solar flux,nthe total radiation from the sun,bothdirect and diffuse.3.Summary of Test Method3.1 Using a pyranometer to measure the solar irradiance,thetest specimen is inse
7、rted in the path of the rays from the sun tothe pyranometer.An enclosure with a nonreflecting bottom isused to avoid measuring flux from around the edges of thespecimen or from multiple reflections between the box and thespecimen.The transmittance is the ratio of the flux measuredwith the specimen i
8、n the light path to the flux measured withoutthe specimen in the path.4.Significance and Use4.1 Solar transmittance is an important factor in the admis-sion of energy through fenestration,collector glazing,andprotective envelopes.This test method provides a means ofmeasuring this factor under fixed
9、conditions.While the datamay be of assistance to designers in the selection and specifi-cation of glazing materials,the solar transmittance is notsufficient to define the rate of net heat transfer withoutinformation on other important factors.4.2 This test method has been found practical for bothtra
10、nsparent and translucent materials,as well as for those withtransmittance reduced by highly reflective coatings.This testmethod is particularly applicable to the measurement oftransmittance of inhomogeneous,fiber reinforced,patterned,orcorrugated materials since the transmittance is averaged over al
11、arge area.4.3 This test method may be used to measure transmittanceof glazing materials at angles up to 60 off normal incidence.NOTE1A technique similar to the one described but using apyrheliometer has been used for the measurement of specular solarreflectance;however,there is insufficient experien
12、ce with this techniquefor standardization at present.5.Apparatus5.1 EnclosureThe required apparatus is a box capable ofsupporting a 0.60 m(24 in.)square specimen.The box shallhave a square,clear aperture of no less than 0.50 m by 0.50 m(20 in.by 20 in.).The enclosure shall have provisions to holdspe
13、cimens planar across the aperture with the additionalcapability to remove and replace the specimen easily during themeasurement process.It shall also have the capability to movethe specimen across the aperture in a systematic way.Lightbaffled air vents at the top and bottom of the enclosure arerecom
14、mended to aid cooling of all components when aspecimen is in place.The inside of the box shall have side wallscovered with mirrors having specular,solar reflectance greaterthan 0.85 that extend from the opening down to the plane of the1This test method is under the jurisdiction of ASTM Committee E44
15、 on Solar,Geothermal and OtherAlternative Energy Sources and is the direct responsibility ofSubcommittee E44.05 on Solar Heating and Cooling Systems and Materials.Current edition approved March 1,2015.Published April 2015.Originallyapproved in 1986.Last previous edition approved in 2009 as E108486(2
16、009).DOI:10.1520/E1084-86R15.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 sensor element.The rest of the inside of the box shall beblackened so that its solar reflectance is less than 0.10.Atypical unit is shown in Fig.1.NOTE2Mirrors having the necessary specular reflectance are brightanodized aluminum lighting sheet,aluminized polymer films,and con-ventionally mirrored glass.For highly diffusing materials,a box with thespecified a