Why fungi could be the future of environmentally sustainable building materials

Originally published Feb. 28, 2020.

As the construction industry struggles to deal with its impact on the climate, a new crop of people with big ideas are looking for alternative materials to build with.

Phil Ayres, an architect and associate professor of architecture in Copenhagen, says the future of building materials might not be high tech polymers or specialty metals — but mushrooms.  

Ayres joined Spark host Nora Young to discuss how he and his team are looking at how mycelium — the fibrous network that exists underneath a fungus — might be used as an environmentally sustainable building material.

What's wrong with building out of regular old bricks and concrete? What problem are you trying to address? 

We're really interested in the fact that we have some real societal issues in terms of requirements for building. We have growing populations. We've got rapid urbanization. And we're starting to understand that the amounts that we need to build really aren't sustainable. 

We understand that current practices and methods of building, particularly with materials such as concrete, are actually having a negative environmental impact. Concrete in itself isn't particularly a high impact material, but the sheer quantities in which we're using it is turning it into a major contributor to CO2 and a major sink for resources. That's leading actually to shortages of raw materials such as sand. So we have a real pressure to try and find viable alternatives.

And so looking toward biological materials, this is where this project is starting to contribute. 

What about mycelium makes it a good building material?

Mycelium is freely available and it binds to waste sources that are cellulose-rich.

It grows incredibly quickly and actually binds to the substrate that you combine with it. You can grow it to shape — in a way you could understand it a little bit like the way in which we might cast concrete to shape. We can do the very same with mycelium, but doing so by growing it in the space of between five days and two weeks.

It also has very little impact on the environment. In fact, it could be understood as being environmentally positive because you're making use of these waste streams.

The way it's currently been explored, within more experimental practices, is to actually kill the mycelium. So you are casting it essentially in blocks and bricks and then assembling it from there. One of the things that we're doing in our research is actually considering the idea of growing things monolithically, which requires us to keep the mycelium alive.

Another reason we are needing to keep the mycelium alive is because our partners in the U.K.-based Unconventional Computing Group are looking to functionalize it and to turn it into a rudimentary sensing and computing device. 

What do you mean by growing things monolithically? 

Rather than thinking about our construction as being an assembly of discrete elements, we are thinking about actually growing entire buildings in one go. 

The mycelium is a fibrous network that starts to grow through substrate — like sawdust, straw, hemp and coffee grounds — and as it decomposes it and actually binds to that substrate. 

This kind of role also requires us to think about methods for being able to hold that substrate and allow the mycelium to propagate in it. And this is where we're looking at the use of woven scaffolds as a way of essentially creating a stay-in-place framework and reinforcement for it, but also acting as a kind of mould for the mycelium.

What would this mycelium framework look like?

We have a very specific approach to this, which is to use an old weaving technique called Kagome weaving, this weaving is essentially a tri-axial weaving system. 

One of the really nice things about this method is that there are very clear principles for being able to control shape. And so using these principles, we can create very complex morphologies by using very simple methods.

We essentially build a holder out of the Kagome weave. It's like a double skinned basket, which we would then fill with the substrate, which is inoculated with the mycelium and this grows over a certain period. 

What are some of the actual challenges to making this work? 

The key challenge for us is with this target of growing monolithically. Most of the growing that we see in the industry happens in very controlled and sterile conditions. The methodology at the moment, in terms of producing mycelium, is very much predicated on working in sterile environments.

As we start to think about growing on an architectural scale, this may need to be questioned. And some of our initial work is really looking at trying to see how we can try and promote the growth of mycelium in non-sterile conditions.

The other interesting challenge, from an architectural perspective, is how architectural scale, features and spatial organizations might impact the computational capacity of the mycelium.

Written by Adam Jacobson. Produced by Nora Young. Q&A has been edited for length and clarity. To hear the full interview, listen in the player at the top of this page.