I'd like to see how these compare with other earth-based construction methods (still used in many parts of the world, including developed countries [1]). My guess is that the voids improve the insulation, but reduce the compressive and shearing strength, but this may be mitigated by the round shape and the internal "triangular" structure.

In any case, it's an interesting experiment that should provide good data and observations toward a more "complete" house prototype.

[1] https://www.lemoniteur.fr/photo/le-pise-ressort-de-terre-a-l...