Due to the different structures, the heat transfer mechanism of vacuum glass and insulating glass is also different. Figure 2 is a simplified schematic of heat transfer, where the heat transfer in the center of the vacuum glass consists of radiative heat transfer and support heat transfer, in which residual gas heat transfer is neglected. Insulating glass, on the other hand, consists of gas heat transfer (including conduction and convection) and radiative heat transfer.
It can be seen that in order to reduce the heat transfer caused by the temperature difference, both vacuum glass and insulating glass should reduce radiation heat transfer, and the effective method is to use glass coated with a low-emissivity film (LOW-E glass), and the lower the emissivity (also known as emissivity) under the condition of taking into account other optical performance requirements, the better. The difference between the two is that the vacuum glass also needs to reduce the heat transfer of the lattice support as much as possible.
The thermal insulation performance of vacuum glass is based on the principle of vacuum thermos. The thermal insulation effect of tempered vacuum glass V glass products is more than 1 meter thick brick wall, which is 4~6 times that of ordinary insulating glass, and the U value (also called heat transfer coefficient or K value) is as low as 0.4 W/m2· K (European IFT Laboratory Report).
The acoustic and noise reduction properties of vacuum glass are based on the fact that sound does not propagate under vacuum conditions. The weighted sound insulation of tempered vacuum glass V glass reaches 39 decibels (CTC national inspection group report), and the weighted sound insulation of general insulating glass is about 28 decibels.
With tempered vacuum glass V-Glass, even at airports, viaducts or along main roads, the interior is as quiet as a library.
Note: The higher the weighted sound insulation, the better the sound insulation effect. For example, the outdoor noise is 75 decibels, and the indoor sound is 36 decibels (75-39=36) after using tempered vacuum glass V glass, and the indoor sound is generally less than 40 decibels.
The life expectancy of tempered vacuum glass V glass can reach more than 25 years, with a high vacuum inner cavity, so that the gas heat transfer can be ignored, and at the same time, high-performance Low-E glass is used to greatly inhibit radiation heat transfer, and ensure that the heat transfer coefficient (U value) of V glass is as low as 0.4W/(m2· K). At the same time, the thermal insulation performance of V glass is 2-4 times that of insulating glass and 6-10 times that of single glass, and it can meet the requirements of the international passive house for the heat transfer coefficient of doors and windows when used independently.
