GB/T 36261-2018On-site test technical condition and calculation for optical and thermal parameters of energy saving glass for building (English PDF)

3.1 Terms and definitions

The following terms and definitions apply to this document.

3.1.1 Photothermal parameters

Abbreviation for glass optical parameters and thermal parameters. Optical parameters generally refer to visible light transmittance, visible light reflectance, direct sunlight transmission Ratio, direct reflection ratio of sunlight, direct absorption ratio of sunlight, direct transmittance of infrared thermal energy of sunlight; thermal parameters generally refer to total solar transmission Ratio, solar infrared thermal total transmittance, shading coefficient, heat transfer coefficient, photothermal ratio, etc.

3.1.2 Basic parameter for optical and thermal calculation

Measured parameters for glass optics and thermal calculations, including. glass and gas spacer thickness, film position, corrected radiance, spectrum Transmittance, spectral reflectance, volumetric inert gas volume concentration, and the like.

3.2 Symbol

The following symbols apply to this document.

g --- total solar transmittance;

gIR --- solar infrared thermal energy total transmittance;

K --- heat transfer coefficient [W/(m2 · K)];

LSG --- light to heat ratio;

SC --- shading coefficient;

rhoe --- direct reflection ratio of sunlight;

rhov --- visible light reflectance;

rho(lambda) --- spectral reflectance;

taue --- direct transmittance of sunlight;

tauIR --- direct infrared transmittance of solar thermal energy;

tauv --- visible light transmittance;

tau(lambda) --- spectral transmittance.

4.1 First class test

The first category is the architectural glass test that can directly test all photothermal parameters using non-destructive testing.

4.2 Second type of test

The second type is that the optical parameters can only be directly tested by non-destructive testing at the site, and the architectural glass test of thermal parameters cannot be directly tested.

The common building glass types applicable to specific field tests are shown in Table 1.

Note 2. The optical parameter test is not applicable to glass whose surface is scattering, such as embossed glass, frosted glass, glazed glass, etc.

4.3 Requirements

In the first type of test, the photothermal parameters were tested directly on site using a non-destructive test method. The second type of test, optical parameters using non-destructive testing Conduct on-site direct test, thermal engineering parameters according to Appendix A for sample consistency verification, the basis for photothermal calculation of small replacement samples Parameters (hereinafter referred to as the basic parameters) fragmentation test, calculate the total solar transmittance and heat transfer coefficient according to JGJ/T 151, calculated according to GB/T 2680 Solar infrared thermal energy total transmittance.

6.1 General requirements

6.1.1 Measurements should be made under conditions where the instrument is allowed to use ambient temperature and humidity.

6.1.2 Avoid direct sunlight measurement area during measurement.

6.1.3 The surface of the measurement area to be measured should be clean and free of visible scratches. The sample should be flat glass.

6.2 Glass and spacer thickness measurement

6.2.1 The instrument used to measure the composition of the glass shall be capable of directly measuring the thickness of each piece of glass and spacer layer on the spot, and the maximum allowable instrument The error should be no more than 0.2mm.

6.2.2 For rectangular glass specimens, in the middle of each side and at a distance of no more than 100 mm from the side, as a measuring point, as shown in Figure 2.

The thickness of each piece of glass and the thickness of the spacer layer at four points were measured, and the average value of the thickness of each piece of glass and the thickness of the spacer layer was calculated as a glass structure. parameter.

6.3 Spectral transflective ratio measurement

6.3.1 Measurement method

Spectrophotometric measurement.

6.3.2 Spectral conditions

Wavelength range. 300nm~2500nm, at least 380nm~2500nm;

Wavelength interval. The wavelength interval requirement of each parameter in this standard should be met.

6.3.3 Measuring geometry

The 8°.8° geometry was used. The angle between the optical axis of the illumination beam and the normal to the surface of the sample does not exceed 10°, and any light in the illumination beam The angle of the optical axis does not exceed 5°. When measuring the transmittance, the measuring instrument should be able to receive the transmission of each side of the insulating glass through multiple reflections. Light. When measuring the reflectance, the measuring instrument should be able to receive the reflected light from multiple reflections on each side of the insulating glass.

6.3.4 Maximum allowable error of the instrument

The maximum allowable error for measuring visible light transmittance and direct sunlight transmittance should not be greater than 0.01; measuring visible light reflectance and the sun The maximum allowable error of the direct light reflectance should not be greater than 0.02.

6.4 Emissivity measurement

The radiance of the hollow glass film surface is measured by non-destructive measurement, and the radiance is the film surface corrected radiance. The maximum allowable error of the instrument measurement is not Should be greater than 0.02. The measurement position should be greater than 100 mm from the edge of the glass sample.

6.5 Cavity inert gas volume concentration measurement

6.5.1 The volumetric inert gas volume concentration in the hollow cavity is measured by non-destructive measurement. The maximum allowable error of the instrument should not exceed 3.5%.

6.5.2 On both sides of the sample, about 100mm from the edge, select 5 points from top to bottom as the measurement point, as shown in Figure 3. Measured The inert gas volume concentration values at 10 measurement points are calculated and the arithmetic mean is calculated as the volumetric inert gas volume concentration.

7.1 Optical parameters

7.1.1 Overall visible light transmittance and reflectance of glass

The calculation of the overall visible light transmittance tauv of the glass is shown in equation (1).

In the formula:

tauv --- the visible light transmittance of the sample as a whole;

tau(lambda) --- the spectral transmittance of the sample as a whole;

Dlambda --- relative spectral power distribution of the standard illuminant D65;

V(lambda) --- CIE standard view function;

deltalambda --- wavelength interval, is 10 nm;

The product of DlambdaV(lambda)deltalambda---Dlambda, V(lambda) and the wavelength interval deltalambda, and the value of DlambdaV(lambda) deltalambda are shown in Appendix B.

The calculation of the overall visible light reflectance rhov of the glass is given by equation (2).

In the formula:

rhov --- the visible light reflectance of the sample as a whole;

rho(lambda) --- the spectral reflectance of the sample as a whole;

Dlambda --- relative spectral power distribution of the standard illuminant D65;

V(lambda) --- CIE standard view function;

deltalambda --- wavelength interval, is 10 nm;

The product of DlambdaV(lambda)deltalambda---Dlambda, V(lambda) and the wavelength interval deltalambda, and the value of DlambdaV(lambda) deltalambda are shown in Appendix B.

7.1.2 Glass direct sunlight transmittance, reflectance

The calculation of the direct transmittance taue of the glass as a whole is shown in equation (3).

In the formula:

taue --- the direct direct transmittance of sunlight of the sample;

tau(lambda) --- the spectral transmittance of the sample as a whole;

Slambda --- relative spectral distribution of solar radiation;

deltalambda --- wavelength interval;

Slambdadeltalambda---Slambda is the product of the wavelength interval deltalambda, and the value of Slambdadeltalambda is shown in Appendix C.

The direct solar reflectance ratio rhoe of the glass is calculated as shown in equation (4).

In the formula:

rhoe --- the direct direct reflectance of the sample;

rho(lambda) --- the spectral reflectance of the sample as a whole;

Slambda --- relative spectral distribution of solar radiation;

deltalambda --- wavelength interval;

Slambdadeltalambda---Slambda is the product of the wavelength interval deltalambda, and the value of Slambdadeltalambda is shown in Appendix C.

7.1.3 Glass overall sunlight infrared thermal energy direct transmittance

The glass direct sunlight infrared thermal energy direct transmittance tauIR calculation is shown in equation (5).

In the formula:

tauIR --- the direct transmittance of the solar infrared thermal energy of the sample as a whole;

tau(lambda) --- the spectral transmittance of the sample as a whole;

Slambda --- relative spectral distribution of solar radiation;

deltalambda --- wavelength interval;

Slambdadeltalambda ---Slambda is the product of the wavelength interval deltalambda, and the value of Slambdadeltalambda is shown in Appendix C.

7.2 Thermal parameters

7.2.1 Total solar transmittance

The calculation of the total solar total transmittance g value of the glass is shown in equation (6).

g=taue qi (6)

In the formula:

g --- the total solar energy transmittance of the sample as a whole;

Direct sunlight transmittance in taue ---7.1.2;

qi --- The secondary heat transfer coefficient of the sample to the indoor side.

Among them, qi is calculated according to the calculation method specified in JGJ/T 151, and the basic parameters used are obtained by the test specified in Chapter 6 of this standard.

The spectral transmittance and spectral reflectance of each piece of glass used in the calculation process are shown in Appendix D.

7.2.2 Heat transfer coefficient

The heat transfer coefficient K value is calculated according to JGJ/T 151, and the basic parameters used in the calculation process are obtained by the test specified in Chapter 6 of this standard.

7.2.3 Solar infrared thermal energy total transmittance

The total solar infrared thermal energy total transmittance gIR calculation of the glass is shown in equation (7).

gIR=tauIR qIR,i (7)

In the formula:

gIR --- the total solar infrared thermal energy total transmittance of the sample;

tauIR ---7.1.3 direct infrared transmittance of solar thermal energy;

qIR,i --- Sun infrared secondary heat transfer coefficient of the sample to the indoor side.

qIR,i is calculated according to the calculation method specified in GB/T 2680, and the basic parameters used are obtained by the test specified in Chapter 6 of this standard.

For the calculation of the spectral transmittance and spectral reflectance of each piece of glass used in the calculation, see Appendix D.

7.2.4 Photothermal ratio

The overall photothermal ratio of the glass is calculated by the formula (8).

In the formula:

LSG --- the photothermal ratio of the sample;

Visible light transmittance in tauv ---7.1.1;

g --- The total solar energy transmittance of the sample.

A.1 Purpose

For glass products that cannot be directly tested in the field without lossless direct testing of thermal parameters, which cannot be cut into small pieces for laboratory testing, generally Laboratory tests were performed using small pieces instead of samples, but there is no guarantee that the small replacement samples will be consistent with the characteristics of the glass product. Optical parameters The lossless alignment test verifies the consistency of the small replacement sample with the finished glass product and ensures the reliability of the replacement test.

A.2 Verification method

A.2.1 Testing

A.2.1.1 Directly test the overall spectral transmittance, spectral reflectance (indoor side or outdoor side) of glass products, and calculate the direct sunlight The transmittance taue and the direct sunlight reflectance rhoe.

A.2.1.2 A small piece of the same material and the same process shall be used to form a small replacement sample of the same configuration as the glass product, which is the same as A.2.1.1.

The test method directly tests the overall spectral transmittance, spectral reflectance (indoor side or outdoor side) of the small block substitute sample, and calculates the sunlight separately. Direct transmittance tau'e, direct sunlight reflectance rho'e.

A.2.2 Calculation

A.2.2.1 Absolute value of direct transmittance difference of sunlight

The absolute value of the direct transmittance difference of sunlight is calculated according to the formula (A.1).

deltataue= taue-tau'e (A.1)

In the formula:

deltataue---the absolute value of the direct transmittance difference of sunlight;

taue --- glass direct product direct sunlight transmittance;

tau'e --- small block replaces the overall direct sunlight transmittance of the sample.

A.2.2.2 Absolute value of direct reflectance difference of sunlight

The absolute value of the direct reflectance difference of sunlight is calculated according to equation (A.2).

deltarhoe= rhoe-rho'e (A.2)

In the formula:

deltarhoe---the absolute value of the direct reflectance difference of sunlight;

rhoe --- glass direct product direct reflectance of the finished product;

rho'e --- small block replaces the overall direct sunlight reflectance of the sample.

A.2.2.3 Average value of the absolute value of the 10-point spectral transmittance difference

Calculate the average value of the absolute value of the 10-point spectral transmittance difference according to formula (A.3). The 10 wavelength points are selected according to Table A.1.

In the formula:

The average value of the absolute value of the deltatau -10 point spectral transmittance difference;

lambdai ---10 wavelength points, see Table A.1;

tau(lambdai)--the value of the overall spectral transmittance of the glass product at the wavelength lambdai;

tau'(lambdai)---The value of the overall spectral transmittance of the small block replacement sample at the wavelength lambdai.

A.2.2.4 Average value of the absolute value of the 10-point spectral reflectance difference

Calculate the average value of the absolute value of the 10-point spectral reflectance difference according to formula (A.4). The 10 wavelength points are selected according to Table A.1.

In the formula:

The average value of the absolute value of the deltarho ---10 point spectral reflectance difference;

lambdai ---10 wavelength points, see Table A.1;

rho(lambdai)---the value of the overall spectral reflectance of the glass product at the wavelength lambdai;

rho'(lambdai)---The value of the overall spectral reflectance of the small block substitute sample at the wavelength lambdai.

A.2.3 Determination

It is determined that the thermal parameters of the tested glass products and the small substitute samples are consistent, and the following four conditions should be met.

a) deltataue is not more than 0.03;

b) deltarhoe is not more than 0.03;

c) deltatau is not more than 0.03;

d) deltarho is not more than 0.03.