Among the around 2,000 known types of termites, some are environmental engineers. The hills worked by certain genera — for instance, Amitermes, Macrotermes, Nasutitermes, and Odontotermes — arrive at up to eight meters high, making them a portion of the world’s biggest natural designs. Normal determination has been working on the ‘plan’ of their hills for a huge number of years. If humans visited termites and considered their methods, what lessons might they gain as architects and engineers?
Researchers demonstrated in a new study published in Frontiers in Materials that termite mounds can instruct us on how to create interior climates for our buildings that are comfortable and do not have the carbon footprint of air conditioning.
Dr. David Andréen, a senior lecturer at the bioDigital Matter research group at Lund University and the study’s first author, stated, “Here we show that the ‘egress complex,’ an intricate network of interconnected tunnels found in termite mounds, can be used to promote flows of air, heat, and moisture in novel ways in human architecture.”
“We anticipate that future building walls made with emerging technologies such as powder bed printers will include networks similar to the egress complex. These would allow air to be moved about using embedded sensors and actuators that use very little energy.”
Dr. David Andréen, a senior lecturer at the bioDigital Matter research group of Lund University,
Mounds of Macrotermes michaelseni termites from Namibia were studied by Andréen and his co-author, Dr. Rupert Soar, an associate professor at Nottingham Trent University’s School of Architecture, Design, and the Built Environment. States of this species can comprise in excess of 1,000,000 people. The termites cultivate symbiotic fungus gardens for food at the center of the mounds.
The egress complex was the focus of the research: a dense, lattice-like network of tunnels with a width of 3 to 5 millimeters that connects wider conduits inside and out. This extends over the mound’s north-facing surface, directly exposed to the midday sun, during the rainy season (November to April). Outside this season, termite laborers keep the departure burrows hindered. It is thought that the complex maintains adequate ventilation while allowing excess moisture to evaporate. But how does it function?
Termite Hill in Bangalore, India Credit: D. Andréen
Andréen and Soar looked into how the arrangement of the egress complex makes it possible for flows to be oscillating or pulse-like. They put together their examinations with respect to the checked and 3D-printed duplicate of a departure complex section gathered in February 2005 from nature. This piece was 4cm thick with a volume of 1.4 liters, 16% of which were burrows.
A speaker drove oscillations of a CO2-air mixture through the fragment to resemble wind, and a sensor tracked the mass transfer. They discovered that oscillation frequencies between 30 and 40 Hz resulted in the greatest airflow; moderate at frequencies somewhere in the range of 10 Hz and 20 Hz; and at frequencies between 50 and 120 Hz, the lowest.
The researchers came to the conclusion that the complex’s tunnels interact with the wind blowing on the mound in a way that improves mass transfer of air for ventilation. Wind motions at specific frequencies create choppiness inside, whose impact is to convey respiratory gases and abundant dampness away from the hill’s heart.
A fragment of the Macrotermes michaelseni termite egress complex scanned in three dimensions. Credit: D. Andréen and R. Soar.
“When ventilating a building, you want to maintain the delicate balance of temperature and humidity created inside without preventing the movement of stale air outward and fresh air inward,” say D. Andréen and R. Soar. This is an issue for most HVAC systems. Because of differences in concentration between the two sides, we have a structured interface here that enables the exchange of respiratory gases. So, the inside conditions stay the same,” Soar said.
The authors then used a series of 2D models to simulate the egress complex, which ranged in complexity from straight tunnels to a lattice. They filmed the mass flow and drove an oscillating body of water, which was made visible by a dye, through the tunnels using an electromotor. Surprised, they discovered that for the ebb and flow to penetrate the entire complex, the motor only needed to move air back and forth a few millimeters, which corresponds to weak wind oscillations. Importantly, the layout had to be sufficiently lattice-like for the necessary turbulence to occur.
Termite mound in Namibia’s Waterberg Credit: D. Andréen
Buildings that live and breathe The authors conclude that the egress complex can enable termite mounds with weak winds to be ventilated by wind power.
“We envision that building walls from here on out, made with emerging innovations like powder bed printers, will contain networks like the departure complex. These will make it conceivable to move air around through installed sensors and actuators that require just little measures of energy,” said Andréen.
“When we can design structures as complex as those found in nature, construction-scale 3D printing will only be possible,” Soar concluded. The departure complex is an illustration of a muddled construction that could tackle different issues all the while: keeping solace inside our homes while controlling the progression of respiratory gases and dampness through the structure envelope.”
“We are on the verge of moving toward construction that resembles nature. It may be possible for the first time to design a building with real life.”
More information: Termite-inspired metsamaterials for flow-active building envelopes, Frontiers in Materials (2023). DOI: 10.3389/fmats.2023.1126974. www.frontiersin.org/articles/1 … ts.2023.1126974/full
