Mechanical and Aerospace Engineering
Materials Science and Engineering
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NANYANG TECHNOLOGICAL UNIVERSITY
SINGAPORE
Mycelium Tiles
Currently, only 15% of households in Southeast Asia have an air conditioner, but this number is expected to rise, leading to an increase in demand in energy consumption, electricity, and CO2 emissions which could further worsen global pollution and climate change [1]. There is therefore an urgent need to find alternative solutions to cool buildings and regulate their temperatures.
Learn more about our mycelium tiles by watching the videos and scrolling down:
Nature’s Blueprint: Mycelium…and Elephant Skin?
Elephants can cool themselves thanks to the wrinkles on their skin that can limit heat gain, dissipate energy by evaporative cooling and store water. To emulate elephants’ cooling, tiles with elephant skin-inspired surface texture are designed. This natural cooling mechanism has now inspired a groundbreaking innovation in sustainable architecture.
Figure 1: Comparison of Tile Texture to Elephant Skin. Reproduced from Biomimicry for young children.
Mycelium as a Building Block
Harnessing the binding properties of mycelium, we have developed biodegradable tiles using the Pleurotus ostreatus and Ganoderma lucidum species. To fabricate the mycelium-bound composite (MBC) tile, a solid substrate of bamboo fibers, oats, and deionised water is prepared in a 2:1:3 ratio. Figure 2 shows the process after making the substrate, where the mycelium spawn is sprinkled in the solid substrate and packed into the silicon mould after sterilisation.
Figure 2: Flow of making MBC. Reproduced from Soh et al.
At 22 ℃ room temperature and relative humidity of 80%, the samples are left to grow for 2 weeks (3 weeks causes mycelium to adhere to the mould which causes defects during unmoulding). After 2 weeks, the samples were unmoulded and left to grow in the same conditions. During this time, uniform white mycelium skin developed. After 3 days in an oven set at 40℃ for drying, the product is final. As illustrated in Figure 3, this process takes 31 days.
Figure 3: 31 day process of tile formation.
By cultivating this fungus on bamboo fibers, a sturdy, lightweight composite material is created to be placed in outdoor conditions for thermal management, as seen in Figure 4.
Figure 4: Demonstration of elephant skin-inspired tiles’ placement in outdoor conditions. Reproduced from Soh et al.
Revolutionising Performance
Laboratory testing revealed promising results. Compared to flat mycelium tiles, the elephant-skin-inspired tiles displayed a 25% improvement in cooling performance and a 10% lower surface temperature of buildings when placed on their flat side, providing an energy-efficient method to mitigate urban heat. Rough grooves on the surface allow for concentration of heat in these areas (Figure 5).
Figure 5: Infrared images showing the concentration of heat in rough grooves (yellow: hot, blue: cold). Reproduced from Soh et al.
Under simulated rain conditions, the cooling efficiency of the textured tiles increased by an impressive 42%, due to adhesion of water droplets on the tiles’ surface despite mycelium’s hydrophobic properties. These tiles have immense potential for working in tropical regions where humidity and heavy rainfall are part of routine weather, like our concrete jungle — Singapore.
Tile Installation
This installation in NTU is an experiment to better assess these tiles' performances in Singapore’s tropical context. Three different textures: smooth, rough, rougher, and three different materials: concrete known for its durability but high thermal mass, clay which is traditional and breathable with moderate insulation capacity, and mycelium. Each combination of material and texture is monitored using temperature sensors and visible degradation as a test of durability. This installation will help answer the question if biomimicry can be used to outperform traditional building tiles in passive cooling performance.
To make the tiles for the installation, we collaborated with BioSEA Ltd Pte and Mykilio. BioSEA generated CAD models of the tiles (Figure 6) that were then 3D printed using fused deposition modeling (Figure 7). Silicone molds were produced (Figure 8). The final tiles were molded in the molds (Figure 9) and installed on the wall using brackets and mortar (Figure 10).
Figure 6: 3D rendering of the tiles (credit: Anuj Jain, BioSEA)
Figure 7: 3D printed tiles (credit: Eugene Soh)
Figure 8: Silicone molds (credit: Eugene Soh)
Figure 9: Smooth, rough, and rougher tiles before installation.
Figure 10: The tiles ready to be installed.
You can come and see the installation at NTU North spine level 2, at the entrance of the School of Mechanical and Aerospace Engineering. Once there, please access the QR code on the poster to provide your feedback and inputs!
Figure 11: The installation! (credit: Eugene Soh)
Text prepared by Praseeda Chowdary, high-school student Anglo-Chinese school, Singapore.