Application of silicon | aerogel for thermal insulation of door and window glass

On March 16, the website of Nature published the technical progress of "research on highly transparent cellulose aerogel and its thermal insulation application for door and window glass" from the School of Physics, University of Colorado, USA.

In order to maintain a comfortable indoor environment, buildings consume 40% of the world's energy. In terms of passively isolating the interior of a building from cold or hot outdoor environments, windows and skylights are the least efficient parts of the building envelope, as achieving high transparency and glass insulation at the same time remains a challenge. Here, the research team of the University of Colorado in the United States demonstrated the highly transparent aerogel made of the abundant biopolymer cellulose on the earth, which uses colloid self-assembly and roll to roll processing compatibility and other methods. The visible light transmittance of the aerogel is 97-99% (better than glass), the haze is~1%, and the thermal conductivity is lower than that of still air. These lightweight materials can be used as multi-layer insulating glass interlayers or to retrofit existing windows. In this research paper, how does aerogel improve energy efficiency and may provide advanced technical solutions for insulating glass units, skylights, daylighting and facade glass.

In order to provide ideal indoor conditions, it is necessary to minimize indoor external energy exchange through heat conduction, convection, and emissions with little or no additional energy supply. Achieving this with glass is particularly challenging. Although the current solution to this problem is to use insulated glass units (IGUs) with air or filled gas, the high thermal barrier performance of this type of IGU requires a large gap thickness between glass panes, which in turn is limited by gas convection, number of panes, and structure. On the other hand, the use of thinner vacuum insulated glass units is limited by sealing integrity and high cost. Low emissivity silver and other coatings can limit the energy loss caused by similar black body electromagnetic emission from the interior of a room temperature building. Although these methods can adjust the indoor and outdoor temperature difference to a certain extent, they must sacrifice the transparency of the visible range.

Aerogel is a kind of high thermal insulation material, which can be applied to pipeline insulation and Mars rover. As a solid substitute for gas filler in igu, it has always been popular because it is a kind of high efficiency heat barrier material that can be superior to static air and other gas fillers. However, aerogel are usually mechanically fragile and strongly scatter light. It is still a challenge to manufacture aerogel with low haze, high transparency and mechanical robustness at the scale and cost related to buildings. The development of transparent aerogel (including cellulose aerogel) is still limited to a small scale. At the same time, the haze and transparency are still insufficient for most types of glass.

Here, the research team of the University of Colorado in the United States demonstrated the scalable manufacturing of highly transparent cellulose silane aerogel (SiCellAs), whose material properties are suitable for glass applications. These highly insulated SiCellA materials are sandwiched between glass panes, providing excellent temperature regulation. The research team of the University of Colorado in the United States showed how SiCellA film can be used as IGU filler, and how to replace the internal glass panel in the multi pane IGU design, and it is fully compatible with the existing thermal range emissivity and solar gain control solutions.