Buildings are energy hogs, consuming approximately 40% of the world's generated energy to maintain comfortable indoor conditions. A considerable chunk of this energy is lost through windows and skylights, the least energy-efficient parts of a building. Existing solutions such as insulating glass units (IGUs) filled with air or other gases and vacuum-insulated glass units have limitations, including gas convection, structural constraints, seal integrity, and exorbitant costs. But what if there was a better way?
Scientists have recently turned their attention to a unique class of materials called aerogels. Known for their extremely lightweight and porous nature, aerogels are exceptional thermal insulators. However, traditional aerogels fall short due to their mechanical fragility and significant light scattering, making them unsuitable for application in IGUs. Until now.
The Birth of a New Solution: Silanized Cellulose Aerogels
The recent study presents a novel, scalable manufacturing process for a groundbreaking type of aerogel: highly transparent, silanized cellulose aerogels (SiCellAs). Possessing high thermal insulation, high visible-range light transmission (97-99%, better than glass), low haze (~1%), and lower thermal conductivity than still air, SiCellAs are primed to revolutionize energy efficiency in buildings.
The authors argue that SiCellAs sandwiched between glass panes in IGUs could overcome many limitations of current insulating solutions and significantly increase the energy efficiency of windows and skylights, potentially even exceeding the standards for building walls.
Creating SiCellAs involved a combination of the intelligent design of cellulose nanofibres, a process called TEMPO-mediated oxidation, and the supercritical drying of hydrogel. The result is an aerogel consisting of well-defined, rod-like particles with thin fibres and pores typically smaller than 100 nm. The unique porosity of SiCellA is directly proportional to the mass density of the material, a relationship that can be controlled by varying the initial concentration of cellulose nanofibres.
SiCellA Shines Bright
SiCellA has shown impressive optical, thermal, and mechanical properties through meticulous development and testing. With high visible-range transmissivity surpassing that of clear glass, excellent thermal barrier properties outperforming still air, and robust mechanical stability allowing it to withstand substantial mechanical loads, SiCellA is a promising solution for enhancing the energy efficiency of windows and skylights.
SiCellA in the Real World
SiCellA adheres well to glass and plastic films and could be used to retrofit single-pane windows, improving their thermal resistance. It also performs admirably within IGUs, maintaining high optical properties. This blend of characteristics coupled with an economically viable manufacturing process could revolutionize building technologies, enhancing the role of glazing in building envelopes, and contributing to more sustainable energy management in buildings.
Final Thoughts: The Future of Building Insulation
Although more research and development are required, using SiCellA in building glazing is a promising step forward. The use of aerogels has traditionally been hindered by their mechanical fragility and substantial light scattering. But with the advent of SiCellA, these problems are things of the past. Silanized cellulose aerogels offer a viable solution to the energy inefficiencies of windows and skylights and an exciting potential to redefine the future of building insulation and energy management.
With a simple and low-cost production process, promising optical, thermal, and mechanical properties, and the potential for significant energy savings, SiCellA is poised to transform the energy efficiency landscape of buildings worldwide. The glass windows of the future could indeed be greener and more energy-efficient than ever.
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