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Treat earth tubes with caution

Earth tubes pull ventilation air through buried pipes to pre-cool or pre-warm it. Poorly built ones collect condensation and grow mould, contaminating the air you breathe.

How

1. Know the claimed benefit. Natural Resources Canada describes tubes buried below the frost line; a Toronto field study warmed winter air by up to 14.3 C and cooled summer air by about 6.8 C.
2. That article does not cover moisture. The condensation and mould risk comes from builders' field experience, so treat drainage and cleaning as essential.
3. Avoid earth tubes in humid climates and on sites with a high water table.
4. If you build one, slope it continuously to an accessible drain or sump and pressure-test joints for air and water tightness.
5. Provide cleaning access and a filter at the intake.
6. Compare against an HRV or ERV and a glycol ground loop, which give similar benefits without passing air through buried pipe.
7. Remember it cannot be fixed easily once backfilled.

Safety: Mould in a supply air path is a health hazard. Inspect and clean regularly or decommission if odours appear.

Sources

1. My Earth Tube Story. Green Building Advisor, accessed 2026-11
2. New energy efficient way to heat and cool buildings (earth tubes). Natural Resources Canada, accessed 2026-11

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