GB/T 31389-2015 English PDF (GBT31389-2015)

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GB/T 31389-2015: Technical requirements and evaluation methods of solar reflective materials for exterior walls and roofs
GB/T 31389-2015
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 91.100.01
Q 10
Technical Requirements and Evaluation Methods of
Solar Reflective Materials for Exterior Walls and Roofs
ISSUED ON: FEBRUARY 04, 2015
IMPLEMENTED ON: NOVEMBER 01, 2015
Issued by: General Administration of Quality Supervision, Inspection
and Quarantine;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 5
4 Classification ... 6
5 Requirements ... 6
6 Test and Comprehensive Reflective Performance Rating Methods ... 7
Appendix A (Normative) Determination of Total Solar Reflectance and Near
Infrared Reflectance – Relative Spectrometry ... 12
Appendix B (Normative) Determination of Total Solar Reflectance and Near
Infrared Reflectance – Radiation Integration Method ... 16
Appendix C (Normative) Determination of Hemispherical Emittance –
Radiometer Method ... 18
Appendix D (Normative) Instructions of Weight Coefficient of Solar Reflective
Performance Index ... 20
Technical Requirements and Evaluation Methods of
Solar Reflective Materials for Exterior Walls and Roofs
1 Scope
This Standard specifies the terms and definitions, classification, requirements, tests,
and evaluation methods of comprehensive solar reflective performance of solar
reflective materials for exterior walls and roofs.
This Standard is applicable to the evaluation of the solar reflective performance of solar
reflective materials for exterior walls and roofs.
2 Normative References
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) are applicable to this document.
GB/T 1865 Paints and Varnishes - Artificial Weathering and Exposure to Artificial
Radiation - Exposure to Filtered Xenon-Arc Radiation
GB/T 3181-2008 Color Standard for Paint Film
GB/T 9780-2013 Test Method for Dirt Pickup Resistance and Stain Removal of
Film of Architectural Coatings and Paint
GB/T 11186.2 Method for Measuring the Color of Paint Films - Part 2: Color
Measurement
GB/T 11186.3 Method for Measuring the Color of Paint Films – Part 3: Calculation
of Color Differences
GB/T 16422.3-2014 Plastics - Methods of Exposure to Laboratory Light Sources -
Part 3: Fluorescent UV Lamps
JG/T 235 Architectural Reflective Thermal Insulation Coatings
JG/T 402-2013 Roofing Products from Metal Sheet with Reflect Thermal Coating
3 Terms and Definitions
For the purpose of this document, the following terms and definitions apply.
3.1 Solar reflective materials for exterior walls and roofs
Materials that are applied to the exterior wall and roof, and have a high total solar
reflectance, near infrared reflectance and hemispheric emittance.
3.2 Solar reflective coating for buildings
Paint that is applied to the surface of building with higher total solar reflectance, near
infrared reflectance and hemispherical emittance.
3.3 Solar reflective metal sheet for roofs
The metal sheets with surface coated with a solar-reflective coating for building roofs.
3.4 Lightness
The visual perception characteristic value that indicates the brightness of the surface
color of the object; gives division on the basis of absolute white and absolute black;
and is expressed by L*. (one of the three attributes of color).
[GB/T 3181-2008, definition 3.14]
3.5 Total solar reflectance
The ratio of solar radiation flux BEWTEEN the visible light and near-infrared band
reflection in 300nm ~ 2500nm AND the incident in the same band.
3.6 Near infrared reflectance
The ratio of solar radiation flux BEWTEEN near-infrared band reflection in
780nm~2500nm AND the incident in the same band.
3.7 Hemispherical emittance
The ratio of the radiant exitance BETWEEN the thermal radiator in the direction of the
hemisphere AND the full radiator (black body) at the same temperature.
3.8 Thermal insulation temperature difference
Under the specified test conditions, the difference of the surface temperature facing
away from the heat source between the heat insulation test plate and the standard
blackboard.
3.9 Comprehensive reflective performance rating
The L* value is measured according to the provisions of GB/T 11186.2; the total solar
reflectance and near infrared reflectance are measured according to the provisions of
Appendix A or Appendix B. Refer to Appendix A for arbitration inspection.
6.1.2.3 Hemispherical emittance
It shall be carried out according to the provisions of Appendix C.
6.1.2.4 Change rate of total solar reflectance after contamination
Test the initial solar reflectance according to the provisions of 6.1.2.2; then carry out
the contamination treatment according to the method A specified in GB/T 9780-2013;
and then test the total solar reflectance after contamination according to the provisions
of 6.1.2.2. For coatings that require ultraviolet light irradiation, the test panels that have
expired shall be irradiated for 4h by ultraviolet light before contamination treatment (UV
light irradiation is carried out according to the provisions of the GB/T 16422.3-2014
standard, exposure method A, cycle number 1, The light source adopts UV-A340 lamp).
The result is calculated according to Formula (1):
Where:
c1 – change rate of total solar reflectance after contamination, in %;
ρ0 – initial solar reflectance;
ρ1 – total solar reflectance after contamination.
6.1.2.5 Artificial weathering aging
Test the initial solar reflectance according to the provisions of 6.1.2.2; and then conduct
the artificial weathering aging test according to the provisions of GB/T1865. According
to the type of coating and the corresponding product standards, the artificial weathering
aging time shall meet the requirements of Table 4.
Appendix A
(Normative)
Determination of Total Solar Reflectance and Near Infrared
Reflectance – Relative Spectrometry
A.1 Principle
Use an ultraviolet spectrophotometer with an integrating sphere, a visible light
spectrophotometer, a near-infrared spectrophotometer, or a spectrometer to accurately
measure the reflectance of materials at different wavelengths. According to the relative
energy distribution of sunlight in the wavelength range of heat rays, calculate the total
solar reflectance and near infrared reflectance of materials within a certain wavelength
range through the weighted average method.
A.2 Testing device
A.2.1 Spectrophotometer or spectrometer
The wavelength range is 300nm~2500nm or above; the minimum wavelength interval
is 5nm; the wavelength accuracy is no less than 1.6nm; and the photometric
measurement accuracy is ±1%.
A.2.2 Integrating sphere
The inner diameter is no less than 60mm, and the inner wall shall be highly-reflective
material.
A.2.3 Standard whiteboard
Pressed barium sulfate or Teflon plate is used for baseline calibration.
A.3 Preparation of test plate
Solar reflective coating for buildings shall be conducted in accordance with the
provisions of 6.1.2.1; and solar reflective metal sheet for roofs shall be conducted in
accordance with the provisions of 6.1.3.1.
A.4 Test process
A.4.1 Preheat to a stable state after booting.
A.4.2 Set the instrument parameters and use the instrument configured standard
wh...