Vacuum Glazing for Transparent Thermal Insulating Material

Osamu Asano, Toru Futagami, Tsuguhisa Takamoto, Tetsuo Minaai

In vacuum glazing, which consists of a pair of glass sheets with an evacuated spacing gap containing a lot of small support pillars, the insulating property depends on heat flow through the pillars, radiation from the inside glass surface and convection of quite small amount of air in the spacing gap. For higher thermal insulation, low temperature manufacturing process was developed to enable the use of tempered glass necessary for wider pillar separation. This process was realized with the use of specific lead free metallic solder. Furthermore, radiation of the glass surface could be reduced by using specifically modifi ed sputter Low-E coating.

The sample thus obtained showed extremely low U-value 0.45 W/m2K. This value is equivalent to the
performance of 100mm thick glasswool insulation. Vacuum glazing prepared with tempered glass based on the low temperature process is expected to drastically change architectural design concept.

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