“A viable candidate for radiative cooling”
A group of Chinese scientists from Nanjing Forestry University has developed a biofilm with a clear message about solar radiation: right at you.
This is because the material – an airgel based on nanocellulose – can reflect sunlight and infrared light. Moreover, it is self-cleaning and sustainable, all in accordance with AZo materials.
If this film can be made suitable for coating roofs and other surfaces, it could revolutionize how we cool our homes and buildings. It’s important, as AZo reports that up to 20% of a building’s electricity use runs air conditioners and fans.
The National Renewable Energy Laboratory indicates that air conditioning, including dehumidification, creates about 3.94% of the world’s planet-warming air pollution.
This way of cooling the temperature inside our walls is made possible by cell walls. Cellulose is “the most abundant organic compound on Earth,” because it’s an essential part of cell walls in plant life, ScienceDirect reports.
“Cellulose has been identified as a viable candidate for radiative cooling,” first author of the study and assistant professor at Nanjing Qinyang Cai said in the AZo report.
Nanjing’s material is also planet-friendly, in part because it is biodegradable. When part of an airgel, the National Library of Medicine notes that it is “well suited” for thermal insulation. Airgels can be made using cellulose from rice straw, cotton, and even hemp, among other plants.
As an added bonus, Nanjing’s airgel is dust-resistant, overcoming a hurdle of other cellulose-based innovations. Dust can negate some of the cooling and reflectivity benefits, all according to AZo.
The material can lower temperatures by 6.9 degrees Celsius (about 12.4 degrees Fahrenheit) “under direct sunlight in hot conditions while also exhibiting dust-repellent properties,” Tsai said in the story.
His team isn’t alone in looking for more sustainable and cleaner cooling alternatives. More efficient air conditioning is the subject of research and design projects around the world. Some architects use geometry to improve airflow. An Israeli company has developed a way for ice to store the energy needed for cooling during peak demand hours.
The Nanjing team’s goal is to commercialize its airgel through “freeze-drying” and “hot-pressing” technology, which cleanly reflects solar and infrared energy.
“We hope that our study will open new horizons for scientists to further explore cellulose-based materials for thermoregulation, addressing the issue of high energy consumption,” Kay said in the AZo story.
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