Evacuated Glazing with Silica Aerogel Spacers
Abstract
Glazing has come a long way and are subject to continuous development, especially under the premise of climate change. Highly porous monolithic silica aerogels feature optical transparency at ultra-low thermal conductivity – well below the conductivity of free gas. Thus they are excellent candidates even at ambient gas pressure for filling the interpane gap in glass windows. Aerogel glazing is known to exhibit amazing thermal properties (Ug-values down to 0.5 W/(m²K)) with the drawback of a high price due to difficulties in large-scale production. An alternative approach is using silica aerogel spacers with an areal coverage of just 10 % in combination with partial evacuation of the interpane volume to suppress convection in between the aerogel spacers and panes. With this, the costs for such a glazing may be greatly reduced; however, the mechanical load on the aerogel is significantly increased. In this paper, we present silica aerogel for application as spacer in the shape of pillars, investigate their ability to withstand mechanical stress, measure thermal characteristics and perform simulations on how they are expected to perform in a double glazing. With a krypton atmosphere of 1 10^4 Pa in the interpane gap, Ug-values down to 0.5 W/(m²K) are predicted.