The old model, popular in architecture writing, held that metabolic heat from the colony and its fungus creates a steady updraught pulling fresh air through the base. Direct tracer and flow measurements by Scott Turner, Rupert Soar and colleagues at Macrotermes mounds gave a different picture.
The thin outer flutes of the mound warm faster than the central chimney during the day and cool faster at night. That difference reverses the internal circulation twice in twenty-four hours: warm air rises in the flutes by day and sinks by night, so the whole structure oscillates. Gas exchange with the outside happens largely by diffusion through the porous wall, driven by these oscillations rather than by a one-way draught.
The nest below houses the fungus comb of Termitomyces, which digests plant material the termites collect and returns it in a digestible form, in a partnership similar in principle to that of leafcutter ants but evolved separately. The mound itself is a ventilation organ, not living space: the colony occupies chambers beneath it.