BIOMIMICRY
"The solutions are all around us", sounds cliché, I know but this can’t be any further from the truth. Nature in itself is self-reliant meaning it can sustain itself without human interference. For us humans however everything we do depends on nature even the very air we breathe. Rather than ravaging and destroying nature there are better ways in which people are using nature to improve lives. As the planet struggles with climate change and the need to live more sustainable lives there could be no better way to address this than by looking at things from natures perspective.
This brings me to the concept of biomimicry. According to the biomimicry Institute, biomimicry can be defined as an approach to innovation that seeks sustainable solutions to human challenges by emulating time-tested patterns and strategies. In simple terms its copying natures shape, processes and structure.
Basically, the idea here is that nature has already stood the test of time,3.8 billion years to be exact. Within that time animals, plants and microorganisms have become experienced engineers. They know what works, what doesn't and most importantly, what lasts on earth. To me it’s like having the exam answers right in front of you, you just have to know where to look. In this series we will look at some of the groundbreaking innovations that have been influenced by nature and the science behind it.
The Eastgate building
Termites might not be the most majestic creatures, but they build impressively tall skyscrapers — towers of dirt that can top 30 feet. (If humans built a tower the same number of times our height, it would top out around 3,600 feet; the world’s current tallest building, the Burj Khalifa, is around 3,000 feet tall.)
These small insects have been the inspiration behind the design of buildings of the future.
In the capital of Zimbabwe, a building called Eastgate Centre holds nearly 350,000 square-feet of office space and shops. It uses 90 percent less energy than a similar sized building next door.
In the 1990s, Mick Pearce, the building’s architect, took his inspiration from mounds built by fungus-farming termites he saw on a nature show. The insects created their own air conditioning systems that circulated hot and cool air between the mound and the outside. Architect Mick Pearce collaborated with engineers at Arup Associates to design Eastgate, which uses 90% percent less energy for ventilation than conventional buildings its size, and has already saved the building owners over $3.5 million dollars in air conditioning costs.
The science behind it
Scientists used high-resolution scanning technology and computer and physical simulations to examine the microscopic structure of the external walls of African termite nests. In slabs that look solid to the naked eye, the team found a network of tiny, interconnected pores. Through principles of basic physics, these pores regulate ventilation, humidity and possibly temperature, within the mound and nest. These natural structures are what influenced the design of eastgate building.
There are around 2,600 species of termites, and only about two dozen infest and destroy buildings. Many more are highly social builders aiming to protect their queens and ensure the survival of their colonies.
Carbon dioxide must exit so they don’t suffocate in their underground nests, and oxygen must enter. The mounds termites build above nests are the lungs that make this breathing possible. The vents allow in air cooling the mound and hot air escapes through the top chimneys. This keeps the mound cool and allows for free flow of air. The same design concepts are what were used in the design of the building. In addition, the building’s exterior is built in slabs reducing its exterior surface area which in turn reduces the amount of heat absorbed by the building.
But there are different types of mounds. Termites that farm fungus build structures with chimneys and openings that work like windows. The structures of non-farming termites, like the ones the researchers collected in Senegal and Guinea, have no apparent openings to the naked eye.
But the pores are there, because the mounds are made from stacking pellets of sand mixed with spit and soil. Small spaces form inside these pellets and larger spaces, between them. Previous work with CT scans showed the small pores in the outer walls of these nests.
But with micro-CT scanners, the team saw deeper inside, with greater resolution and revealed the connections between smaller pores and bigger ones. That this microstructure was practically the same regardless of whether it was built of sand in dry Senegal or clay in wet Guinea suggested structure, not material, might be the key to ventilation.
When the team mimicked strong winds in simulations, structures without the larger pores couldn’t breathe as well and accumulated more carbon dioxide. The researchers also drenched mound walls in water to mimic heavy rain. The big-pore-small-pore structure dried out faster.
The vents allow in air cooling the mound and hot air escapes through the top chimneys. This keeps the mound cool and allows for free flow of air. The same design concepts are what were used in the design of the building. In addition, the building’s exterior is built in slabs reducing its exterior surface area which in turn reduces the amount of heat absorbed by the building.
The eastgate building is a clear example that natures designs can go a long way into influencing the human world. As we look more into biomimicry next week we will explore how the mantis shrimp is helping scientists develop more durable material as well as a mantis shrimp robot built by the American army.
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