A team of materials scientists from Empa (Swiss Federal Laboratory for Science and Technology) and the Slovak University of Technology has developed a translucent and thermally insulating building component based on silica aerogel granules — an aerogel glass brick.
Visualization of the glazed wall made with translucent aerogel bricks. Image credit: Ganobjak et al., doi: 10.1016/j.jobe.2022.105600.
Building envelopes of existing buildings represent a great opportunity to improve energy efficiency and thermal comfort of our cities and countryside.
Aside from improvements on building technology, HVAC (heating, ventilation and air conditioning) energy demands are typically reduced by increasing the thickness of the insulation layer.
However, this solution does not work for the transparent façade elements, and in fact, thick insulation layers increase shadowing around the windows.
Thus, a new envelope construction system that can reduce lighting and HVAC energy demands simultaneously would be a highly attractive solution.
“Silica aerogels are high-performance thermal insulation materials that are becoming increasingly popular in the construction sector. The most common are opaque insulating mats and plasters,” said Empa researcher Jannis Wernery and his colleagues.
“Back in 2017, we had the idea of integrating the insulating material directly into a building brick and presented a new type of brick filled with aerogel, the so-called aerobrick.”
“Thanks to its excellent thermal insulation, this brick saves heating costs — without the need for an additional insulation layer applied to the masonry.”
“However, aerogel can also be virtually transparent, which makes for a translucent, insulating building system.”
The researchers developed an aerogel glass brick that has a high thermal insulation performance for its limited thickness, and simultaneously increases solar gains, reduces the use of the artificial light, and improves visual comfort.
“We achieved this combination of strength, insulation and light transmission by using offset spacers between the glass panes within the glass brick, which ensure static stability with minimal heat transmission,” they said.
“The glass brick has a measured thermal conductivity of 53 mW/m*K and a compressive strength of nearly 45 MPa.”
“This is the highest insulating performance of any brick found in the technical literature, let alone on the market. Additionally, it comes with the property of light transmission.”
“The aerogel glass brick is suitable for applications in which there are simultaneous requirements for high daylight penetration, glare protection and privacy protection, such as in offices, libraries and museums,” they added.
“An important aspect is that a building envelope made of such glass bricks couples the inside of the building with the outside in terms of daylight.”
“This can have a positive effect on the circadian rhythm of the building users.”
The team’s work was published in the Journal of Building Engineering.
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Michal Ganobjak et al. 2023. Get the light & keep the warmth – A highly insulating, translucent aerogel glass brick for building envelopes. Journal of Building Engineering 64: 105600; doi: 10.1016/j.jobe.2022.105600
