It’s Not Rocket Science #2: Ventilation
Many architects look to Nature for inspiration for how to make their buildings look more natural even though buildings are very unnatural objects. Instead of actually growing out of the ground or landscape like plants, buildings are constructed from putting lots of building materials together and it takes a lot of people, resources and money to do that. We can conclude two things from this.A building that looks as it it’s built out of lots of building materials will:
- have more integrity than a building that, say, is trying to look like a rock or a tree or a cloud or a river and
- will therefore cost less than an equivalent building encrusted with ornament or trying to look like something it’s not.
As you would expect, misfits is totally against biomimicry in the sense of making buildings look like the result of natural processes like, say, this building does
or the architecture of Greg Lynn
(and its brand extensions).
However, misfits is all for the use or adaption of natural world processes if better performing buildings in the artificial world are going to be the result. Biomimicry is passive design, basically. Biomimicry is to building performance what ‘organic’ was/wasn’t to building aesthetics.
The air conditioning system design for the Eastgate Building in Harare, Zimbabwe is famously mentioned as an exemplar of biomimicry for having been modelled on the configuration that Macrotermes michaelseni (termites, to us) use to maintain the temperature inside their nests. Dave Parr, over at biomimicron.wordpress.com, coins the word biomythology for the claim that these termites maintain a temperature of 87 ± 1°F inside their nests, and offers us the following graph from this interesting paper.
Parr,D., 2012, Biomimicry Lessons for Building Ventilation, Submitted for qualification of Environmental Design of Buildings MSc, at Cardiff University – Welsh School of Architecture. (Thanks Dave – good luck!)
The graph shows that the temperature is anything but constant and sometimes even greater than ambient temperature. From this I conclude that this entire system, ingenious as it is, is to encourage ventilation in order to prevent excessive heat buildup rather than regulate to temperature per-se. But let’s give the architect, Mick Pearce and those nice folks at Arup some credit for trying to learn something from termites.
Let’s also give the termites some credit because – unlike the Eastgate Centre – they don’t use any electricity to open and close the air intake vents and nor do they use fans to regulate the flow of air and the internal temperature. If ants can develop such a system perhaps we should at least try to do something similar for our own structures and maybe even improve upon it if we can. With these termite nests, all the action is really happening underground where there’s less diurnal variation in temperature.
For the ants, the towery bit adds to the convection effect. For the architects, juxtaposing photos of their own towers adds to the eco-cred effect.
Leafcutter ants and their nests are perhaps even more impressive but don’t get as much publicity since they don’t build towers but high-density lo-rise. Here’s what a leafcutter nest looks like above ground. The average population of a nest is about 5 million. The average size of a nest is about 3-4 metres across like this one.
Here’s a link to a larger one being excavated.
Again, most of the action is underground. Now these leafcutter ants are pretty amazing creatures.
- There are 3 types of leafcutter ant: the queen, soldier and worker and there are five types of worker ant: foragers, gardeners, those that chop up leaves, tiny ants that distribute leaf bits to the fungi and those called minimae that tend the fungus and dispose of waste produced by the fungus. Different types have different sizes.
- The forager ants leave a chemical trail so they can always find their way back to the the nest. They collect leaves from all layers of the forest, from the floor to the upper canopy. They are capable of carrying over 50 times their own body weight. They will travel several hundred metres in search of the right kind of leaves.
- Leaves brought back to the nest are used as a fertiliser for a fungus ‘garden’ in the nest. This fungus is the big grey mass at the centre of the nest. This fungus is the only food source for the ants. Not only that, if the ants bring the wrong kind of leaves, the fungus will create a chemical to tell the ants. Wild ants collect leaves from all layers of the forest, from the floor to the upper canopy.
There are other amazing things about these ants but here’s a schematic of a nest.
- When the nutrients have been removed from the leaf material, the waste is transported to the peripheral dump chambers where dead ants and dead fungus are also placed.
Kleineidam C, Ernst R, Roces F have researched how these nests are ventilated. This is the abstract of their paper,
Wind-induced ventilation of the giant nests of the
leaf-cutting ant Atta vollenweideri
“Surface wind, drawing air from the central tunnels of the nest mound, was observed to be the main driving force for nest ventilation during summer. This mechanism of wind-induced ventilation has so far not been described for social insect colonies. Thermal convection, another possible force driving ventilation, contributed very little. According to their predominant airflow direction, two functionally distinct tunnel groups were identified: outflow tunnels in the upper, central region, and inflow tunnels in the lower, peripheral region of the nest mound. The function of the tunnels was independent of wind direction. Outflow of air through the central tunnels was followed by a delayed inflow through the peripheral tunnels. Leaf-cutting ants design the tunnel openings on the top of the nest with turrets which may reinforce wind-induced nest ventilation.” (Kleineidam et al. 2001:301, from asknature)
Biologist Bert Hoelldobler at Arizona State University says that ant colonies provide scientists with an invaluable way to gain empirical data around how living in societies developed. Compare the biological blueprint of an ant society with that of humans, he says, and you quickly see that much of human society is built on culture rather than genetics. The basic blueprints for society in our genes are much simpler than those coded within the ant’s.
Biologists Wilson and Hoelldobler have proposed a new class of life: the superorganism. “A superorganism is a closely knit group that divides labour among its members altruistically,” says Wilson. “There are individuals who reproduce in the group and are promoted to be reproducers, and those that do not reproduce and are workers. This allows the group to function as a giant organism.”
In their recent book, Superorganism, Wilson and Hoelldobler describe their idea by comparing each ant in a colony with a cell in, say, the human body, each one specialised for a task and working for the good of the organism as a whole.
Hoelldobler says a superorganism has a sort of intelligence where an ant colony acts as a problem-solving unit (or even a simple brain). “When you look at the incredible nest structures of these leaf-cutter ants – 8 metres down, an area of 50 sq metres – no single ant could do that, or even has the concept of it, but the interaction, the behaviour of millions of individuals that react to particular stimuli that are created by other workers, leads to these fantastic structures. An ant colony is a problem-solving instrument, in a way.” [guardianonline]
The most impressive thing of all is that leafcutter ants have been around for about THREE MILLION YEARS doing exactly the same thing. If we’re talking about future generations and stuff, I think that’s as sustainable as sustainable needs to get. For most of those three million years, leafcutter ants have been the most complex and ecologically successful social systems on the planet. And probably still are.
About 60,000 years ago Homo sapiens began to spread out from Africa, were established in Europe 42,000 years ago and in Indonesia about the same time. About 20,000 years ago, they crossed the Bering Strait to Alaska and had colonised most of the Americas by 15,000 years ago and most of the remaining parts of the Pacific by 3,000 years ago. Check out this book for the relative achievements of ants and humanity.
Man learned how to use fire to catch animals and birds about 45,000 years ago and, by about 10,000 years ago, had worked out how to make tools, weapons, containers, and how to clear and cultivate land. The first known city in the world was probably Eridu from about 5,400BC and the first permanent settlements not that much earlier. The oldest pyramid is from about 4,900BC.
Humans have really only been in a position to control their environment for the past 60,000 years. But now we know how to use fire and make tools and telescopes, play the piano, understand the rules of perspective and some other stuff as well, it might be time to think about how to work together in groups to solve problems like how to grow enough food to feed ourselves, how to design our structures so their climate can be effortlessly regulated and how not to screw up the environment while we’re at it.
It’s still early days.