Termite mounds could hold clues to passive climate control, according to new research. Seven scientists scrutinized African termite mounds to see how they keep their homes cool in the sun while maintaining a uniform concentration of carbon dioxide (CO2). Researchers have looked at south Asian termite mounds in the past, but those are often more shaded; they say uncovering the secrets of African termite mounds could lead to energy-efficient building ideas.
Termite mounds are impressive not only because the creatures that construct them are so small, but because they naturally maintain a comfortable temperature – no air conditioner necessary. Researchers led by Samuel Ocko, a Massachusetts Institute of Technology graduate student, dug further into climate control in termite mounds, specifically those of the Macrotermes michaelseni termite in Namibia. Their mounds can be around 10 feet high, with millions of workers residing inside.
Ocko and his team measured air velocities and temperatures in the mound over 35 days in Namibia’s autumn and found even though temperatures outside the mound changed by 27 to 36 degrees Fahrenheit, inside temperatures only varied by 15 degrees Fahrenheit. The termites drew on the sun more than wind to achieve climate control. According to IFLScience, convection from the temperature gradient between outside the mounds and their centers drove smooth airflow.
During 24 hours, CO2 levels stayed around five percent. The mounds have holes that can be up to 0.2 inches in diameter, which IFLScience said creates an array of tunnels and allows for gas exchange. They said the mounds also lean towards the equator.
CO2 levels vary more in Indian mounds during the day, while temperatures remain even. African mounds have large thermal gradients between the center and the sun-facing side. The researchers said in their paper abstract that even though African and Indian mounds differ, they can harness periodic solar heating for ventilation; they said the system functions like as an external lung.
The Journal of Experimental Biology published the research this year. Ocko was joined by scientists at institutions in the United States, Sweden, and the United Kingdom.