Passive
One of 3 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.
Somewhere the panel gets winter sun, which is the hard part in the season the stove is wanted. A balcony or a south window may be enough at 100 W
A dense block heated by a small solar panel through the day, which goes on radiating for hours after sunset. Feet on the cube, blanket over the lap. The preindustrial version held embers from the fire; the electric one carries no risk of carbon monoxide or fire, and its thermal mass is what turns an intermittent solar supply into evening warmth.
Compare building and maintaining complexity, as well as efficiency where possible.
| Solution | Build skill | Upkeep burden | Efficiency |
|---|---|---|---|
| Hot water bottle | None | 2 | N/A |
| Electrically heated table (kotatsu) | Basic | 4 | N/A |
| Solar-powered foot stove (heat cube) | Intermediate | 3 | N/A |
Build skill and upkeep burden are proxies (lower burden = simpler to maintain); the efficiency column is this sub-function’s ranking, 1 = best. “N/A” where an axis isn’t rated here.
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.