The promise of mycelium bricks

The mycelia of an oyster mushroom (Pleurotus ostreatus) growing in a petri dish of ground coffee seeds.
| Photo Credit: Tobi Kellner

In the light of climate change, the construction industry like many others is considering how it can reduce its carbon footprint and become more sustainable.

One opportunity is concerned with bricks. Fired clay bricks have been the mainstay of the construction industry but their production also emits nearly 300 million tonnes of carbon dioxide every year, which could increase with more urbanisation.

A new advance on this front is mycelium bricks. Mycelia are the branching filaments of fungi that make up its vegetative part. Researchers have them harnessed to create biodegradable, fire-resistant, and insulative bricks. They are made by combining husk, sawdust, and fungal spores to create a fibrous network that solidifies into a lightweight material. Within a few days, these materials become a hardier structure.

Mycelium bricks have the potential to reduce the building sector’s carbon footprint, its proponents have said. They are relatively more lightweight and good insulators of heat. Aside from potential use as panelling material in interior designs, researchers believe mycelium-based components can be used in liquid filters, sports equipment, and printed circuit boards.

But before they can find wider use, mycelium materials need to improve in many ways. At present they can’t bear heavier loads for longer periods. One 2020 review found that while mycelium composites have a high strength to weight ratio, it is two orders of magnitude lower than concrete. They are also susceptible to moisture, biodegrade in a few years, and can’t be produced en masse.

“The cost of growing and treating fungi for construction purposes is currently higher due to lack of infrastructure,” Rakesh Jha, a civil engineer and the founder of Patna-based Veritech Infrastructure, said.

India’s tropical weather exacerbates these problems. “Mycelium-based materials are not as strong as conventional materials like concrete or brick or steel. Due to mycelium being highly absorbent, it … vulnerable to moisture and fungal decay in India’s climate,” Jha added.

While mycelium is naturally fire-resistant, prolonged exposure to heat could cause structural failure. Mycelium composites also absorb more moisture than synthetic foams and plywood, which is inimical for damp environments with leaking walls or roofs. They also don’t resist termites.

But these are problems to be solved rather than reasons to discard mycelium bricks. For example: “Mycelium can be treated with non-toxic flame retardants that can enhance fire resistance, followed by a UV-protective coating that can prevent photo-degradation in outdoor applications,” Jha said.

The biggest challenge is consumers’ attitude, which experts have said will require more investment in research and development, to make mycelium bricks more competitive with clay bricks, and awareness campaigns to shift.

But thanks to climate change and the advent of concepts like high-performance buildings, interest is already growing in alternative and sustainable materials. “This shift along with policy pushes can drive demand for sustainable alternatives and help in growing the market for mycelium,” Aditya Srinivas Kandaala, founder of Roha Biotech, a startup incubated at IIT Madras, said.

Aditya Ansh is an independent media journalist based in New Delhi.