How earth tubes work

An earth tube is simply a length of smooth pipe buried below the frost line. Fresh air is drawn in through a screened intake, travels through the pipe, and exchanges heat with the surrounding soil along the way. By the time it reaches the building, it has moved toward the ground's steady temperature.

What makes a good loop

A few details matter: enough pipe length and diameter for the airflow you want; a gentle slope so condensation drains rather than pools; a screened, weather-protected intake; and burial deep enough to reach stable ground. Active systems use a quiet inline fan; passive systems rely on stack effect.

None of it is exotic — it's the same corrugated and smooth-wall pipe used for storm drainage, put to a smarter use.

Model a Sophab + earth tubes →