ASTM D7990-21

Standard Test Method for Using Reflectance Spectra to Produce an Index of Temperature Rise in Polymeric Siding

SIGNIFICANCE AND USE
5.1 Heat buildup of polymeric building products due to absorption of energy from the sun may lead to distortion problems. Test Method Test Method D4803 was developed to predict a building product’s heat buildup (temperature rise). It compares the relative temperature changes of a pigmented PVC product and a PVC panel containing carbon black when exposed to an infrared heat lamp. Based on experimental results that determined the maximum temperature for this black panel under both solar exposure and in the laboratory test, a method for determining the exterior temperature rise and heat buildup for a test panel was developed. This test has shown to be useful and reliable but is time consuming and requires controlled conditions to minimize sources of variation.  
5.2 This test method uses a spectrophotometer to measure a specimen’s reflectance in the ultraviolet, visible, and near infrared region and uses the spectral power distribution of the heat lamp specified in Test Method D4803 to determine an intensity factor, which is an index of the relative spectral energy absorption by the specimen.  
5.2.1 The temperature rise that would occur under an Test Method D4803 test is proportional to this intensity factor. An equation has been derived from the correlation of the intensity factor and temperature rise data obtained from Test Method D4803 testing of samples with a wide range of color and lightness. A total of 99 samples were studied and represent samples with the lowest to highest temperature rise. Linear regression analysis yields a R2 correlation coefficient of 0.98.  
5.2.2 The procedure in Appendix X1 allows prediction of temperature rise that would result from testing of the same sample under Test Method D4803.  
5.2.3 As this procedure is a correlation to results obtained by Test Method D4803, it is a method that yields a relative temperature rise compared to black under certain defined severe conditions, but does not predict actual field application tempera...
SCOPE
1.1 This test method uses reflectance spectra from the ultraviolet, visible, and near infrared region to produce an index of the temperature rise of polymeric siding above ambient temperature that occurs due to absorption of the sun’s energy.  
1.2 The test method determines the intensity factor of a sample color. The intensity factor is a function of the sample’s reflectance spectra and the energy output of the heat lamp used in the test method Test Method D4803.  
1.3 Appendix X1 provides a method for using the intensity factor to determine the maximum temperature rise of a sample under severe solar exposure.  
1.3.1 A correlation between intensity factor and heat buildup (temperature rise) as predicted by Test Method D4803 exists.  
1.3.2 The heat buildup (temperature rise) for a polymeric building product specimen is determined from its reflectance spectra and the correlation’s regression equation.  
1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2021
• ICS: 83.140.99 - Other rubber and plastics products
• ICS: 91.060.10 - Walls. Partitions. Facades
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.24 - Plastic Building Products

Relations

• Refers: ASTM D4803-24 - Standard Test Method for Predicting Heat Buildup in PVC Building Products
• Effective Date: 01-Feb-2024
• Refers: ASTM E1331-15(2023) - Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry
• Effective Date: 01-Nov-2023
• Refers: ASTM E1331-15(2019) - Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry
• Effective Date: 01-Nov-2019
• Refers: ASTM D4803-18 - Standard Test Method for Predicting Heat Buildup in PVC Building Products
• Effective Date: 01-Oct-2018
• Refers: ASTM D4803-10(2018)e1 - Standard Test Method for Predicting Heat Buildup in PVC Building Products
• Effective Date: 01-Apr-2018
• Refers: ASTM D2244-15a - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Aug-2015
• Refers: ASTM E1331-15 - Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry
• Effective Date: 01-Jul-2015
• Refers: ASTM D2244-15e1 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Jan-2015
• Refers: ASTM D2244-15 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Jan-2015
• Refers: ASTM D2244-14 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-May-2014
• Refers: ASTM D2244-11 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Jun-2011
• Refers: ASTM D4803-10 - Standard Test Method for Predicting Heat Buildup in PVC Building Products
• Effective Date: 01-Nov-2010
• Refers: ASTM E1331-09 - Standard Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry
• Effective Date: 01-Dec-2009
• Refers: ASTM D2244-09a - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Aug-2009
• Refers: ASTM D2244-09 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Jul-2009

Overview

ASTM D7990-21 is the Standard Test Method for Using Reflectance Spectra to Produce an Index of Temperature Rise in Polymeric Siding. Developed by ASTM International, this standard provides a laboratory method to estimate the potential temperature increase, or "heat buildup," in polymeric siding materials resulting from solar energy absorption. The test quantifies how much a siding material heats up above ambient temperature by using its spectral reflectance in the ultraviolet (UV), visible (VIS), and near-infrared (NIR) regions.

Through a combination of spectrophotometric measurement and calculation, this standard offers a faster and less variable alternative to extended physical heat lamp tests, providing manufacturers, specifiers, and testing laboratories with a robust tool for evaluating thermal performance and risk of distortion in polymer-based cladding products.

Key Topics

• Reflectance Spectra Measurement: Utilizes spectrophotometric analysis in the UV, VIS, and NIR wavelengths to determine how much solar energy is reflected or absorbed by siding materials.
• Intensity Factor Calculation: The reflectance data are used, along with the specified spectral power distribution of an infrared heat lamp (per ASTM D4803), to compute an "intensity factor" representing the material's total energy absorption.
• Temperature Rise Correlation: The standard correlates the computed intensity factor against known temperature rise data, enabling users to estimate the maximum temperature rise of the product using a regression equation.
• Analysis Efficiency: Offers a more streamlined and reproducible assessment relative to traditional physical heat build-up tests (ASTM D4803), reducing time and minimizing environmental variation.
• Comparative Evaluation: The intensity factor enables comparison between different formulations and colors of polymeric siding regarding their propensity for heat buildup.

Applications

ASTM D7990-21 is widely applicable in the polymeric building products sector, particularly for:

• Product Development: Assists R&D teams in comparing the thermal performance of new formulations, colors, and pigment systems early in design.
• Quality Control: Ensures that siding products meet requirements for resistance to heat-induced distortion by providing objective, comparable data.
• Specification and Purchasing: Helps builders, architects, and specifiers to select products with reduced risk of excessive heat buildup in specific climates or installations.
• Regulatory Compliance: Supports compliance with building codes and industry standards related to thermal performance of exterior cladding systems.
• Thermal Distortion Testing: Serves as a screening method for categorizing products by risk of thermal deformation, informing subsequent physical or field testing strategies.

Related Standards

• ASTM D4803 – Test Method for Predicting Heat Buildup in PVC Building Products: The basis for the intensity factor correlation and physical heat lamp testing.
• ASTM D2244 – Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates: Relevant for the color measurement component of reflective properties.
• ASTM E903 – Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres: Provides protocols for reflectance measurements.
• ASTM E1331 – Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry: Guides instrumental color and reflectance assessment.

Practical Value

Adopting ASTM D7990-21 strengthens the evaluation of polymeric siding thermal properties, enabling manufacturers to develop and market higher-performing, energy-efficient, and more durable exterior cladding systems. The standard ensures reproducibility, comparability, and alignment with internationally recognized testing principles, delivering significant value for thermal risk management throughout the siding product lifecycle.

Keywords: ASTM D7990-21, polymeric siding, reflectance spectra, heat buildup, temperature rise, intensity factor, thermal performance, siding distortion, building products, ASTM standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:D7990 −21 An American National Standard
Standard Test Method for
Using Reflectance Spectra to Produce an Index of
Temperature Rise in Polymeric Siding
This standard is issued under the fixed designation D7990; 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* 2. Referenced Documents
1.1 This test method uses reflectance spectra from the 2.1 ASTM Standards:
ultraviolet, visible, and near infrared region to produce an
D2244 Practice for Calculation of Color Tolerances and
index of the temperature rise of polymeric siding above Color Differences from Instrumentally Measured Color
ambient temperature that occurs due to absorption of the sun’s
Coordinates
energy. D4803 Test Method for Predicting Heat Buildup in PVC
Building Products
1.2 The test method determines the intensity factor of a
E903 Test Method for Solar Absorptance, Reflectance, and
sample color. The intensity factor is a function of the sample’s
Transmittance of Materials Using Integrating Spheres
reflectance spectra and the energy output of the heat lamp used
E1331 Test Method for Reflectance Factor and Color by
in the test method Test Method D4803.
Spectrophotometry Using Hemispherical Geometry
1.3 Appendix X1 provides a method for using the intensity
factor to determine the maximum temperature rise of a sample
3. Terminology
under severe solar exposure.
3.1 Definitions of Terms Specific to This Standard:
1.3.1 A correlation between intensity factor and heat
3.1.1 fractional absorptance—one minus Fractional
buildup (temperature rise) as predicted by Test Method D4803
Reflectance,1–R.
exists.
3.1.2 fractional reflectance—the percentage of energy re-
1.3.2 The heat buildup (temperature rise) for a polymeric
flected by a sample at a given wavelength, divided by 100.
building product specimen is determined from its reflectance
spectra and the correlation’s regression equation.
3.1.3 intensity factor—an indicator of a specimen’s heat
buildupbasedonitsreflectancespectrumandtheenergyoutput
1.4 Units—The values stated in SI units are to be regarded
of the IR lamp used in Test Method D4803.
as standard. No other units of measurement are included in this
3.1.3.1 Discussion—The intensity factor is a summation
standard.
product of the heat lamp’s relative intensity and the specimen’s
1.5 This standard does not purport to address all of the
fractional absorptance at 20 nm intervals between 200 and
safety concerns, if any, associated with its use. It is the
2,500 nm.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 3.1.4 heat buildup—the temperature rise above that of
ambient air due to the amount of energy absorbed from the sun
mine the applicability of regulatory limitations prior to use.
by a specimen.
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3.1.5 relative intensity (of heat lamp)—the lamp’s spectral
ization established in the Decision on Principles for the
output across the range of 200 nm to 2500 nm, normalized to
Development of International Standards, Guides and Recom-
a value of 100 at the lamp’s maximum output.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4. Summary of Test Method
4.1 The specimen’s size must cover the spectrophotometer’s
measurement port, typically 25.4 mm in diameter. Typical
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
sample dimensions are 102 by 102 by 1.3 mm.
and is the direct responsibility of Subcommittee D20.24 on Plastic Building
Products.
4.2 Ablackbackercardorplaqueisuseddirectlybehindthe
Current edition approved April 1, 2021. Published April 2021. Originally
specimen to absorb any radiant energy transmitted through the
approved in 2015. Last previous edition approved in 2015 as D7990 – 15. DOI:
10.1520/D7990–21. specimen.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7990−21
4.3 The spectral reflectance curve of the test specimen is influenced by incident angle of the sun, clouds, wind speed,
measured to determine the amount of energy the specimen insulation, installation behind glass, etc.
absorbs at each wavelength.
5.3 The intensity factor itself is a dimensionless index of the
4.4 The intensity factor of the test specimen is the result of relative energy absorption of the specimen, without conversion
to a temperature rise. It can be used to compare the heat
a series summation for the specimen’s spectral absorptance and
the relative intensity of the IR lamp used in Test Method buildup characteristics of different colors, or different candi-
date formulations for the same color. It can also be used to
D4803.Theproductofthespecimen’sspectralabsorptanceand
relative intensity is determined for the spectral region of 200 – categorize color into ranges of intensity factor, to be used as a
basis for testing of full siding products for resistance to thermal
2,500 nm at an interval of 20 nm
distortion.
4.5 Appendix X1 provides a method for using the intensity
factor to determine the maximum temperature rise of a sample
6. Apparatus
under severe solar exposure.
6.1 UV/VIS/NIR Spectrophotometer—The spectral reflec-
4.5.1 A correlation of intensity factors and heat buildup
tance data are obtained using a spectrophotometer equipped
(temperature rise) results from Test Method D4803 for a
with a PTFE-coated integrating sphere detector, capable of
number of specimens was determined to derive an equation
reading spectral reflectance across the range of 200 nm to 2500
expressing a specimen’s temperature rise as a function of its
nm.
reflectance.
4.5.2 Aspecimen’sheatbuildupisdeterminedbymeasuring
7. Sampling and Test Specimens
its reflectance in the UV, VIS, and NIR spectral region and the
7.1 Samples shall be representative of the color or pigment
correlation’s regression equation.
system under study.
7.2 Test specimens shall consist of the actual product or
5. Significance and Use
material in which the color is used, in a thickness typical of the
5.1 Heat buildup of polymeric building products due to
actual product.
absorption of energy from the sun may lead to distortion
7.3 An opaque black backing material is placed behind the
problems. Test Method Test Method D4803 was developed to
specimen. The backer shall be a card, plaque or other rigid or
predict a building product’s heat buildup (temperature rise). It
semi-rigid material. The black color shall cover the entire
compares the relative temperature changes of a pigmented
surface.
PVC product and a PVC panel containing carbon black when
7.3.1 Measure the color of the backer in acco
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM 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: D7990 − 15 D7990 − 21 An American National Standard
Standard Test Method for
Using Reflectance Spectra to Produce an Index of
Temperature Rise in Polymeric Siding
This standard is issued under the fixed designation D7990; 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 Scope*
1.1 This test method uses reflectance spectra from the ultraviolet, visible, and near infrared region to produce an index of the
temperature rise of polymeric siding above ambient temperature that occurs due to absorption of the sun’s energy.
1.2 The test method determines the intensity factor of a sample color. The intensity factor is a function of the sample’s reflectance
spectra and the energy output of the heat lamp used in the test method Test Method D4803.
1.3 Appendix X1 provides a method for using the intensity factor to determine the maximum temperature rise of a sample under
severe solar exposure.
1.3.1 A correlation between intensity factor and heat buildup (temperature rise) as predicted by Test Method D4803 exists.
1.3.2 The heat buildup (temperature rise) for a polymeric building product specimen is determined from its reflectance spectra and
the correlation’s regression equation.
1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.5 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D2244 Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
D4803 Test Method for Predicting Heat Buildup in PVC Building Products
E903 Test Method for Solar Absorptance, Reflectance, and Transmittance of Materials Using Integrating Spheres
E1331 Test Method for Reflectance Factor and Color by Spectrophotometry Using Hemispherical Geometry
This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.24 on Plastic Building Products.
Current edition approved Dec. 1, 2015April 1, 2021. Published December 2015April 2021. Originally approved in 2015. Last previous edition approved in 2015 as
D7990 – 15. DOI: 10.1520/D7990–1510.1520/D7990–21.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7990 − 21
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 fractional absorptance—one minus Fractional Reflectance, 1 – R.
3.1.2 fractional reflectance—the percentage of energy reflected by a sample at a given wavelength, divided by 100.
3.1.3 intensity factor—an indicator of a specimen’s heat buildup based on its reflectance spectrum and the energy output of the
IR lamp used in Test Method D4803.
3.1.3.1 Discussion—
The intensity factor is a summation product of the heat lamp’s relative intensity and the specimen’s fractional absorptance at 20
nm intervals between 200 and 2,500 nm.
3.1.4 heat buildup—the temperature rise above that of ambient air due to the amount of energy absorbed from the sun by a
specimen.
3.1.5 relative intensity (of heat lamp)—the lamp’s spectral output across the range of 200 nm to 2500 nm, normalized to a value
of 100 at the lamp’s maximum output.
4. Summary of Test Method
4.1 The specimen’s size must cover the spectrophotometer’s measurement port, typically 25.4 mm in diameter. Typical sample
dimensions are 102 by 102 by 1.3 mm.
4.2 A black backer card or plaque is used directly behind the specimen to absorb any radiant energy transmitted through the
specimen.
4.3 The spectral reflectance curve of the test specimen is measured to determine the amount of energy the specimen absorbs at
each wavelength.
4.4 The intensity factor of the test specimen is the result of a series summation for the specimen’s spectral absorptance and the
relative intensity of the IR lamp used in Test Method D4803. The product of the specimen’s spectral absorptance and relative
intensity is determined for the spectral region of 200 – 2,500 nm at an interval of 20 nm
4.5 Appendix X1 provides a method for using the intensity factor to determine the maximum temperature rise of a sample under
severe solar exposure.
4.5.1 A correlation of intensity factors and heat buildup (temperature rise) results from Test Method D4803 for a number of
specimens was determined to derive an equation expressing a specimen’s temperature rise as a function of its reflectance.
4.5.2 A specimen’s heat buildup is determined by measuring its reflectance in the UV, VIS, and NIR spectral region and the
correlation’s regression equation.
5. Significance and Use
5.1 Heat buildup of polymeric building products due to absorption of energy from the sun may lead to distortion problems. Test
Method Test Method D4803 was developed to predict a building product’s heat buildup (temperature rise). It compares the relative
temperature changes of a pigmented PVC product and a PVC panel containing carbon black when exposed to an infrared heat
lamp. Based on experimental results that determined the maximum temperature for this black panel under both solar exposure and
in the laboratory test, a method for determining the exterior temperature rise and heat buildup for a test panel was developed. This
test has shown to be useful and reliable but is time consuming and requires controlled conditions to minimize sources of variation.
5.2 This test method uses a spectrophotometer to measure a specimen’s reflectance in the ultraviolet, visible, and near infrared
region and uses the spectral power distribution of the heat lamp specified in Test Method D4803 to determine an intensity factor,
which is an index of the relative spectral energy absorption by the specimen.
D7990 − 21
5.2.1 The temperature rise that would occur under an Test Method D4803 test is proportional to this intensity factor. An equation
has been derived from the correlation of the intensity factor and temperature rise data obtained from Test Method D4803 testing
of samples with a wide range of color and lightness. A total of 99 samples were studied and represent samples with the lowest to
highest temperature rise. Linear regression analysis yields a R2 correlation coefficient of 0.98.
5.2.2 The procedure in Appendix X1
...