Value Village ／ Everyday know-how
This answer is a draft. It stays unpublished until legal review and source verification are complete.
The heated low table with a quilt is one of the most photographed objects in Japanese homes. Outside Japan it reads as cosy furniture; inside Japan it is a heating strategy born of houses that were, until recently, barely insulated.
| Item | Typical figure |
|---|---|
| Heater output | 300–600 W (thermostat-controlled, so actual draw is lower) |
| Running cost (Tokyo, 31 yen/kWh, 5 h/day) | roughly ¥15–50 per day |
| Compared with a 1,000 W fan heater, 5 h/day | roughly ¥155 per day |
[Verify] Insulation-standard figures with MLITT's housing survey; electricity rates change — recalculate costs at publication.
It heats what is under the quilt. This is the point: head cool, feet warm is comfortable at a lower room temperature, and that is where the saving comes from.
It is the main cause of kotatsu-related harm: dehydration, low-temperature burns from prolonged contact, and in older units overheating. Manufacturers and the National Institute of Technology and Evaluation (NITE) advise not sleeping under it.
The modern electric type has a flat heater unit with a guard; old charcoal or "hori-gotatsu" (sunken pit) types still exist in rural houses and have carbon monoxide risk. Do not improvise one.
The kotatsu-gake is a quilt sized to reach the floor on all sides and made of flame-retardant or at least non-synthetic-fluff fabric. Laundry drying on or against the heater unit is a known fire cause (NITE case reports).
Sales remain steady, and compact one-person kotatsu for small flats and remote work are a growth segment. It pairs well with a sensor-controlled thermostat and a cheaper room temperature.
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https://ondankataisaku.env.go.jp/coolchoice/warmbiz/
https://www.mlit.go.jp/jutakukentiku/house/jutakukentiku_house_tk4_000103.html
https://www.nite.go.jp/jiko/chuikanki/
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
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