termite mound

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:

  1. 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
  2. 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

forest refugeor the architecture of Greg Lynn

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(and its brand extensions).

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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.

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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.

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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.

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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.

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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.

006b2700800e0c512fcd78c70306638e Here’s a link to a larger one being excavated.

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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.

    Leaf-cutter ants can take over when predator p...

    A forager ant (Photo credit: Wikipedia)

  • 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.

Chemical002

  • 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,

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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.”

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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.

conquestjpg-477ff884e699d551

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.

7 thoughts on “It’s Not Rocket Science #2: Ventilation

  1. davergp

    Apologies, can’t seem to leave another comment in the string. One of the most interesting parts of this article to me was the need for specific leaves. That was a track which my intial research really didn’t lead me down, and very interesting to note. Sorry if I came across as a little militant ‘Ant’s aren’t humans’ in my previous text, reading it back it comes off a little holier than thou maybe, but that very much wasn’t my intent. Best of luck with your continued forays into manipulating interior climates. I’ve been having zero luck with the ‘advetised jobs’ on that front, so I’m going to be striking out on my own a bit and making my own work. Check back to the blog, hopefully some case studies/success stories should be turning up there in due course!

  2. davergp

    Thanks so much for the mention, and dropping a reference in there too! I must admit though, the term ‘biomythology’ is not my own. It’s taken from Michael Pawlyns book on biomimicry, which also mentions the Turner and Soar paper. Interestingly, the dissertation goes on to look at ant nest ventilation in a very similar way to you. Termites and Ants are definately linked, but I am pretty sure that: a) there are obviously subtle differences and b) that even current research is only half the story. I’m looking at developing a new concept for both biomimicry interior homeostasis templates, based, inversely on current human building design, but that’s very much in development…

    More on topic a chap called Tschinkle has done some amazing work casting ant’s nests and quantifying the results, plus the shots of him next to them really put it in scale: http://en.wikipedia.org/wiki/Walter_R._Tschinkel

    1. Graham McKay Post author

      You’re welcome Dave. Tschinkel’s nests are indeed impressive but I worry that people (including me!) will be impressed with them for the wrong reasons – like how “architectural” they are. I guess this is why termite towers get more press than ant low-rise high-density. Architectural publicity has always had the problem of justifications being chosen to suit the product rather than objects of study being chosen to suit the problem that needs to be solved. When Speedo developed those swimsuits with surfaces biomimicking the skin of sharks, you could immediately see the sense in “Speedo” studying the surface of creatures that move through the water quickly and efficiently. (Apparently, there is something that makes them work, but it’s not what they thought.) Ships and tankers also need to move through water quickly and efficiently but it wasn’t the designers of ships who first thought to study the skin of sharks, although I suspect there are ship and yacht designers who tried to make their vessels look more sharky. This sums up the problem. After biomyth comes bioporn. (It would be nice to enjoy it for what it is but that’s impossible when it exists to kill interest in anything not designed for looks.) It’s good to see you following up on biomimicry interior homeostasis because comfortable interior environments seems to be what it’s all about, or rather, should be all about. Do you know the ‘thermal comfort zone’ for ants/termites? Or is it all about their queen? Her eggs? Their fungus?

      (I was thinking more about leafcutter ants and their famous fungus. The ecosystem obviously works but, having had three million years to naturally select, it’s a shame the ants are stuck with such a high-maintenance fungus that objects to the wrong kind of leaves. It seems like the ants are slaves to the fungus.)

      1. davergp

        I am very unsure about the thermal comofort zone of ants and termites. I assume from where they live that they can survive a range of temperatures (from 40+ deg C at least to probably below freezing), which is largely due to thier other adaptation, exoskeletons. Think of them like space suits: they are reflective, prevent moisture loss, pressure differences etc. It’s a biological template that I have a feeling has come up in NASA a few times at least.
        That said, ‘comfort zone’ is a real human concern. We really can tolerate a huge range for relatively extended periods but we operate best/prefer a small range, which varies with location, prior experience etc. To label both cases ‘comfort zone’ seems to both confuse matters and suggest an almost cartoon anthropomorphisim to a situation that is purely biological. Not to get angry about it obviously, but just to be clear :)
        As for the slaves to the fungus thing, yes, totally. It’s kinda sad, but if you want to anthpomorphise a bit more, ever had a job you’ve hated, but had to keep up with for survival? ;p The survival range for the fungus IS something that’s quantified in various papers, I’ll try and drag the full references out when I re-start the research in this field, but I think Klienedam and Tschinkle have both mentioned it in various spots, and seems to be a situation where it starts whithering/dehydrating/not chemically productive at 30+ degrees, which then brings in a holistic veiw of interior comfort: is humidity pertinant? Do ants/termites manage the nest with a view to air temperature alone, or as a way of manipulating relative humidty and condensation levels etc? If anyone reading this is confused check this out: http://en.wikipedia.org/wiki/Psychrometrics. The TL;DR is with different air temperatures, the same MASS of water behaves differently. This is research I’ve never been able to track down re: termites/ants, but if any research student is reading this here is a PhD topic idea gratis. You’re welcome, just email me a copy of the paper when you’re done ;p

      2. Graham McKay Post author

        I see what you mean about how easy it is to go all anthropomorphic. I have had, of course, more than one job I didn’t particularly like but did anyway in order to survive. I plan to be more careful – both with the jobs and with the terminology. Terms like “comfort zone” are as irrelevant as statements like “aren’t they clever!” when what the ants are doing is programmed not by logic but by instinct, and instinct is programmed by biology. But whether it’s mastery or slavery, I find the levels and degrees of interdependence between ants and fungus and habitat fascinating and, like you and many others, am trying to work out what could work for us. I’m interested in making the environment within buildings more comfortable (within reason) and using less energy to do it. Thanks for offering to look for me, but I won’t really need to know about optimum temperatures for ant-cultivated fungus production – at least not per-se. I think you’re right in humidity probably being important. Having lived once in a place with humid summers, I’ve seen fungi flourish under certain combinations of temperature and humidity – usually in the shoe cupboard. But we humans also have our preferred combinations of temperature and humidity. Maybe ants have “arrived at” some simple way to regulate them both for the sake of their continued survival. Unlike the ants, our immediate survival won’t depend upon it, but it would be great if we could do something similar.

  3. John Mele

    I completely agree, no laugh, with you about the biomimicry (love the term) that some, smug, “environmentalist” architects are embracing. I think beautiful architecture, can, and often does seem to have an aesthetic harmony with it’s immediate environment by selecting certain materials and often leaving much of the ecosystem around the new structure intact. BUT. this fu-fu movement of elite, snooty, we’re better than you because we care people that increasingly inhabit architectural thought is a shame. We tend to learn a lot more about the ways in which more primitive societies used materials in their HVAC-less worlds 500 years ago then by studying termite mounds!
    I posted a brief, but critical question about the movement on my website. Here’s the link: http://building-architecture.com/?p=1322 Consider linking to it if you like!

    1. Graham McKay Post author

      Hello John, That’s basically the theme of my latest post. the content is not all that new but it follows on from what you said about people coming up with good solutions to not dissimilar problems 500 years ago – or although in this case more like 2,500 years!

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