Impact of support pillars on the thermal insulation performance of vacuum glazing

People spend most of their daily lives indoors and indoor environments should be warm in winter and cool in summer to be considered comfortable. With the increasing human population, more energy needs arise due to the required comfort conditions, therefore, energy efficiency gains great importance. Thermal insulation of windows in closed environments is extremely important to reduce energy use. This study presents a new approach on supporting pillars in vacuum glass technology, which has gained importance in recent years. The effect of using divergent and convergent cylindrical pillars instead of traditional cylindrical pillars on window thermal insulation performance was evaluated. With the 2D CFD model, firstly, after the verification from the company data and literature, the simulations were repeated by changing the thermal properties of the glass and pillars material. The effect of this change on the window heat transfer coefficient (Uw) was examined. In all analyses, the outdoor temperature was assumed to be 5 degrees centigrade and the indoor temperature to be 25 degrees centigrade. It was seen that the Uw value in the reference state was 1.21 W/m2K. With divergent cylindrical pillars, the Uw value decreased by 37.5% to 0.76 W/m2K; with convergent cylindrical pillars it decreased by 24.4% to 0.919 W/m2K. It was understood that for vacuum glass, the thermal properties of glass were more decisive than the properties of pillars. It was also understood that better insulation would be obtained in vacuum glass by using divergent cylindrical pillars. In the study, the results of Uw were given for values ranging between 0.1-0.4 W/mK for glass and 0.04-0.20 W/mK for pillars.