There are many animals and plants that have developed very advanced structures and skills that have served as inspiration for innovations in the design of architectural structures. Termites are an example. Their nests have been studied as effective examples for ventilation and thermoregulation, but aspects remain to be clarified. New research, published by Science Advances, has combined multiscale X-ray images with three-dimensional flow field simulations to investigate the impact of the architectural design of the nest walls on CO2 exchange, heat transport and water drainage.
An example of sustainability
The key is the pores of its outer walls that allows good thermal insulation and rapid drainage of rainwater, thus restoring ventilation and providing stability to the structure. In their study, scientists from Imperial College London, the University of Nottingham and CNRS-Toulouse conducted an X-ray scan of several termite mounds from Senegal and Guinea to measure the walls and corridors. Thus they were able to calculate the thickness of the internal and external walls and also determine the structure of the internal tunnels that termites used to move around the mound. They discovered that the nest walls have large and small micro pores to help with ventilation.
In fact, the Eastgate building in Harare, in Zimbabwe, is based on a similar system of vents well located within elaborate ducts, groups of tall chimneys that exchange heat and solar panels. The pipelines would channel the air through the building, while the chimneys would extract heat from the occupants and machinery during the day, ventilating and cooling the building after dark.
There are two types of termite nests: fungal growth and fungal growth. In the first case, termites grow fungi as food in the inner chambers of nests and fungi. For the survival of the millions of termites that live in the chambers, the CO2 emitted by fungi must dissipate into the atmosphere. This is mainly achieved by exchanging gases through external openings at the millimeter scale on the outer wall of the nest. Termites open and close these openings frequently in response to the amount of CO2 accumulated. In the outer wall, in addition to the openings at the millimeter scale, there are smaller pores that could also assist in ventilation.
This process is more complicated in closed nests without fungi, which do not have large openings on a millimeter scale in the outer wall and lack specific aeration tunnels. It is unknown if the outer wall is porous, if the pores are connected and permeable. And if so, how do they contribute to air circulation or ventilation? The answer would be very useful in the design of sustainable buildings.