A team of scientists led by Singapore’s Nanyang Technical University (NTU Singapore) has developed “fungal tiles” that may one day help reduce the heat of the building without consuming energy.
These wall tiles are composed of a new combination of biological materials that combine the fungus’ root network (called mycelium) and organic waste. Earlier research[1] It has been shown that mycelium-bound composites are more energy-efficient than traditional building insulation such as enlarged vermilite and lightweight expanded clay aggregates.
Based on this proven insulating property, the NTU Singapore team has partnered with local ecological and biomimetic design company Biosea to add a bumpy, wrinkle texture to the tiles, mimicking the ability of large images to regulate heat from their skin. The large image has no sweat glands and relies on these wrinkles and gaps in the skin to regulate the heat.
In laboratory experiments, scientists found that the cool rate of its skin-inspired mycelium tiles was 25% better than that of completely flat mycelium tiles and 2% lower in heating. They also found that the cooling effect of skin-inspired tiles was further improved by 70% during the simulated rainy season, making them suitable for tropical climates.
The construction industry accounts for nearly 40% of all energy-related emissions worldwide, so finding environmentally friendly insulation is crucial. Hortense Le Ferrand, an associate professor at NTU who led the study, said mycelium-bound composites could be a promising option.
“Insulation materials are increasingly integrated into building walls to improve energy efficiency, but they are Synthetic, but they are Synthetic and bring the entire life cycle throughout their life. In fact, its thermal conductivity is comparable to or better than some synthetic insulation materials used in buildings today.”
“We worked closely with Biosea to integrate natural design principles that can optimize its performance as a building insulator. The result is a promising proof of concept that brings us closer to efficient, sustainable and cheaper passive cooling solutions in hot and humid conditions.”
Dr. Anuj Jain, founding director of Bio-Oceans, explained the inspiration behind the innovations associated with elephants: “Elephants are large animals that live in hot, sometimes even humid tropical climates. To withstand heat, elephants evolve to develop a severe skin that can be recovered efficiently by evaporation, making the animals easy to recover. To understand how we replicate the same cooling mechanisms of shadows, capture cold air and increase surface area to evaporate.”
The study, published in Energy and Buildings in February, is based on the work of Professor Le Ferrand, involving mycelium-bound composite materials, such as green building materials.
Turn fungi into functional material
The mycelium-bound composite material is created by planting fungi such as wood chips or organic matter such as agricultural waste. As the fungus grows, it binds organic matter into solid porous composites.
In this study, NTU scientists used oyster mushroom mycelium (Pleurotus Outeatus), a common fungus, as well as bamboo shavings collected from furniture stores.
Mix the two components with oats and water and fill with a skin-inspired texture, using computational modeling and algorithms to select the best design.
The mycelium tiles were grown in the dark for two weeks, then removed from the hexagonal mold and then grown for another two weeks under the same conditions.
Finally, dry the tiles in an oven at 48°C for three days. The final step eliminates any remaining moisture and prohibits further mycelial growth.
Great skin-inspired texture improves thermal regulation
Previous studies have shown that mycelium-bound composites have a thermal conductivity comparable to traditional building insulation materials such as glass wool and extruded polystyrene.
To evaluate how the texture of large skin-inspired effects the thermal regulation of mycelial tiles, the scientists heated mycelial tiles on a 100°C hot plate for 15 minutes and used an infrared camera to track temperature changes.
They found that skin-inspired tiles absorbed less heat. When its textured surface faces a heat source, its temperature increases by 5.01°C per minute, while when the flat surface is exposed to heat, the temperature increases by 5.85°C per minute. As a control, the scientists also heated a flat mycelium tiles and found that it gained 5.11°C per minute.
To measure the cooling efficiency of the tiles, the scientists heated the tiles on one side at 100°C for 15 minutes, then exposed it to ambient conditions (22°C, 80% humidity) and measured the temperature changes on the opposite side of the tiles.
When heated from the flat side, skin-inspired tiles cooled the fastest, losing 4.26°C per minute. When heated from the texture side, its flat side loses 3.12°C per minute. The completely flat control tiles lose 3.56°C per minute.
Based on these findings, scientists suggest tile mounting on fixed sides that are affixed to flat sides of the building facade, as well as textured surfaces exposed to external heat for optimal thermal performance (see Notes in Notes of Notes to Editor How to Use Tiles).
Ceramic tiles perform better in wet weather
To simulate the effect of rainwater on the tiles, the scientists heated the tiles as mentioned earlier. While allowing them to cool, scientists sprayed water onto the tiles at one-minute intervals over 15 minutes.
When the fog is on the bumpy side, the skin-inspired tiles lose 7.27°C per minute, which is 70% better than their performance in dry conditions.
Scientists attribute this effect to the hydrophobicity of the mycelium-bound composite. “Fungal skin developing on the surface of the tiles drains water, keeping the droplets on the surface instead of rolling down immediately. This promotes evaporative cooling and increases the cooling rate,” explained NTU researchers and first author Eugene Soh, explains.
Based on this proof of concept, scientists are now exploring ways to enhance the tiles that are realistically used in ceramic tiles, such as improving their mechanical stability and durability or using different mycelial strains.
The scientists also worked with local startup Mykílio to expand the size of mycelium tiles and conduct outdoor testing on the construction facade.
They foresee the challenge of expanding tiles production is the time it takes to grow mycelium tiles. While it requires minimal energy resources, the process takes three to four weeks.
Scientists also hope that mycelium tiles are used as alternative building materials because good infrastructure is established in the production, storage and transportation of public insulation materials.
“We have developed a promising environmentally friendly alternative that can convert waste into valuable resources while rethinking traditional thermal management materials. This opens up avenues for more skin-like designs and the use of different Mycelium strains to overcome the challenges posed by using Mycelium Tiles as an alternative building material,” Assoc Le Ferrand said.
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