Experts in Germany are looking to nature to find alternative construction materials to concrete. How about building with fungus, for example? In many African countries, mudbrick homes are returning as they offer advantages over concrete ones.
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00:00Concrete everywhere. Grey has replaced green.
00:05We're constantly building more, higher, faster.
00:09Concrete production is responsible for around 8% of CO2 emissions worldwide.
00:15As we're using a dwindling resource, namely sand and various other fossil resources that we can't use forever,
00:23we have to think about how we can build more sustainably.
00:28We absolutely need more greenery in our cities because they are overheating.
00:34If you think about it, architecture and nature are diametrically opposed.
00:39We build primarily to protect ourselves from wildlife or the weather, for example,
00:43and that means we're always destroying nature in some way when we build.
00:51But what if we were to work with nature in our building rather than against it?
00:56An exhibition in Berlin is showcasing projects that seek to do just that.
01:01How do trees grow together to form a structure?
01:04This question has fascinated architect Ferdinand Ludwig for 20 years.
01:09He wants to connect buildings with trees and is constructing a kind of treehouse in the city.
01:17You have to work a lot with others as it's interdisciplinary.
01:21We work with botanists, forestry scientists, civil engineers, ecologists.
01:26We all work together to pool our knowledge from different disciplines so it can be used in the design process.
01:34The pilot project in southern Germany shows what a building made of trees could look like.
01:39After 12 years, the plain tree cube is over 10 meters high and taller than the neighboring kindergarten.
01:46The children use the shady space inside to play.
01:50Otherwise, it's home to insects and birds.
01:55The trunks of the young plain trees have branched out and grown together.
01:59The architects check their growth regularly.
02:02Plain trees were planted on all six levels at the same time, each in its own planter box.
02:12The idea is that the plain trees outgrow their planters and interconnect with the plain trees further up.
02:18They're then screwed together too and gradually grow into one unit.
02:22Then they can remove the boxes.
02:24They planted more than 1,000 plain trees because, like with many urban trees, some of the seedlings died from disease or frost.
02:33In the years to come, the treetops will grow together to form a roof.
02:40A quicker option might be fungus.
02:42This igloo hut is made of wood and fungus panels.
02:46The surface is soft to the touch, but the panels are robust.
02:50So how do you get a hard material from soft fungus?
02:53Here, too, nature is the inspiration.
02:57The tinder fungus likes to grow on deciduous trees, attaching itself to the wood.
03:03Biologist Lisa Stelzer helped work on the fungi house, cultivating tinder fungus in the laboratory.
03:10She needs a saw to cut through it on the tree as it's so hard.
03:16This fungus is great for building.
03:19Because through the mycelium, the root structure of the fungus that grows underground,
03:23residues are brought together and that interlinking creates a more stable material.
03:32That makes it ideal for the developers of the fungi house.
03:36The collective of scientists, architects and artists grows fungi cultures and mixes them with various other materials,
03:43always including organic waste like wood shavings or millet.
03:49Then they press the mixture into shape.
03:51After a few weeks, they kill off the fungus by heating it.
03:55The material then remains solid.
03:57It's already used for insulation, but building with it is new.
04:02Scientists in Namibia are further ahead.
04:05Oyster mushrooms thrive here.
04:07Using a similar process, they've used the remains of the mushroom as a composite material,
04:12moulding blocks from the mixture.
04:14Together with architects, they've used them to build the first house.
04:18The hot climate here makes it possible.
04:20The team wants to facilitate affordable and environmentally friendly housing.
04:26African countries are also ahead on clay construction.
04:29Traditional mud homes were largely replaced in cities during the colonial era.
04:34Now they're making a comeback, especially in West Africa.
04:38In Ghana, large houses are being built with compacted mud walls.
04:42They provide a good indoor climate and stay cool.
04:46In Mali, the traditional Nubian vault has also been rediscovered.
04:50It's built with mud bricks, fitted together with mortar.
04:55In Europe, only a few pioneers are working with mud.
04:58Like Austria's Martin Rauch, who even produces larger projects with rammed earth walls.
05:04But mud brick buildings are otherwise rare here.
05:09It's a dubious privilege of the Western world that we no longer build with mud.
05:13During the industrialisation of construction in the 19th century, mud was replaced mainly by concrete.
05:19In other parts of the world, it's still used.
05:22Around 40 percent of the global population live in mud houses today.
05:26We've just forgotten how to build this way.
05:30How would the visitors here like to live in future?
05:33In a fungi house, a mud house, or a house made of trees?
05:43I'd actually like a combination of all three.
05:45Mud bricks for the load-bearing walls, fungus insulation, and trees on the outside, like the tree house.
05:56Instead of big machinery, you can just use plants or build with trees, something very simple and cheaper in the long term.
06:03I think we need to be more daring.
06:09I think this is the future. We need to work much more with nature and not against it.
06:16And nature offers a number of other materials, like seaweed, which could also be suitable for construction.
06:22Even if research is still in its infancy, the projects on display show how architecture and housing could protect both the environment and us humans.