Root vegetables (carrots, beetroot, potatoes) layered in boxes of dry or lightly damp sand, kept cool and dark, prevents individual vegetables from touching, sprouting, or rotting each other, extending usable storage by months without refrigeration. Distinct from the general ventilated dry pantry: a specific technique for a specific food category, documented on Low-tech Lab (a distinct evaporative-cooling variant, the Zeer pot, now its own entry: the zeer pot).
Note: Cost, carbon and footprint are rated against the other options for this same need, not in absolute terms.
No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.