The amount of heat transferred is determined by both the heat transfer from the air and the radiation from the glass from Phyllis Lucius's blog

Because of its high vacuity, VIG has provided the world with excellent heat insulation, condensation resistance, and sound insulation.

1 Insulation against the heat

Regarding VIG structure, the edge is soldered, and the center is separated by supports to form a vacuum chamber. As a result of the above structure, the heat transfer coefficient in the central area of the VIG is far less than that in its edge, and when considering practice in the real world, the heat transfer in the edge is associated with the window frames. Consequently, the U value in the central area of the glass is only measured for the purpose of parameter comparability and not for any other reason.


Heat transfer through insulated glass is determined by both air heat transfer and quisure insulated glass radiation, with air heat transfer taking precedence over display cabinet door radiation in the majority of cases. The heat transfer coefficient of insulated glass is significantly higher than the coefficient of VIG from the original glass with the same emissivity on which it is based.

Table 2 shows that when the outside temperature is 25 degrees Celsius, the temperature inside the vacuum observation box stays at 60 degrees Celsius for an hour; the surface temperature of the VIG (2 # observation window) is 25.3 degrees Celsius, which is nearly consistent with the outdoor temperature. The vacuum observation box has shown better insulating ability when compared to the observation box made of other materials.

Note: R1 represents the thermal resistance of the inside display cabinet door; R2 represents the thermal resistance of the outside glass; Rradiation represents the thermal resistance of the radiation; Rsupport represents the thermal resistance of the support; Rair represents the thermal resistance of the gas residual; Rvacuum represents the thermal resistance of the VIG; Cvacuum represents the conductivity of the VIG.


Table 3 shows a comparison of the condensation performance of insulated glass and VIG, with the result being that VIG has a better anticondensation performance than insulated glass. To start condensing the VIG under the conditions of 25 degrees Celsius inside and 75% relative humidity, the temperature outside must be at least -69.5 degrees Celsius; however, with insulated glass, the critical temperature is only required to be reached at -4 degrees Celsius.

As shown in Figure 4, the acoustic insulation performance is relatively poor in the frequency range of 160-6300 Hz for frequencies less than 500 Hz. The reason for this is that the low frequency is more likely to cause the display cabinet insulated glass door to vibrate, and the sound energy is transferred from one side to the other side through the pillars.

When operating in the frequency range of 500Hz to 3150Hz, the sound insulation properties of glass are relatively good. In this case, the maximum is 42. 5dB at 1250Hz, and the minimum is 35dB. This means that the sound insulation performance of VIG is significantly better than that of laminated glass and insulated display cabinet door. For example, the sound transmission loss of 5+ 0.3V +5 VIG is only 26dB, while that of 5+9A+5 insulated display cabinet insulated glass door is only 32dB; and that of 5+0.76p +5 laminated quisure insulated glass is only 32dB.