  Improving building energy performance requires the development of new highly
insulative materials. An affordable retrofitting solution comprising a thin
film could improve the resistance to heat flow in both residential and
commercial buildings and reduce overall energy consumption. Here we propose
cellulose aerogel films formed from pellicles produced by the bacteria
Gluconacetobacter hansenii as insulation materials. We studied the impact of
density and nanostructure on the aerogels' thermal properties. Thermal
conductivity as low as 13 mW/(K*m) was measured for native pellicle-based
aerogels dried as-is with minimal post-treatment. The use of waste from the
beer brewing industry as a solution to grow the pellicle maintained the
cellulose yield obtained with standard Hestrin-Schramm medium, making our
product more affordable and sustainable. In the future, our work can be
extended through further diversification of the sources of substrate among food
wastes, facilitating larger potential production and applications.
