Lowtech Graph lists low-tech options for every need of a home. Here you can compare them, find tutorials to build them, and link them together into a circular system. Why low-tech?
Personal heating (heating people, not spaces)
Warming the occupant directly rather than warming the volume of air around them, so the room can be allowed to stay cool. Radiant and conductive sources put heat where a body actually is: under a table, against the feet, against the skin. Historically this was the normal way to be warm in winter, and it uses a small fraction of the energy that heating a whole house to a comfortable air temperature does. Distinct from zoned conditioning, which still heats air but in fewer rooms.
Ranked by how much of the heat produced reaches a person rather than the room. A source in contact with the body loses almost nothing on the way; one under a blanket loses a little; one radiating into open air loses most of it. Absolute output is not the axis here, because these are all small: a device delivering 50 W to someone's feet can replace a kilowatt of space heating, and that substitution is the point.
Solutions
Hot water bottle: A sealable container of hot water in a textile cover, held against the body. It works indoors and out, needs nothing but water that has already been heated, and
Electrically heated table (kotatsu): A low table with a heat source underneath and a thick blanket draped over it, as in the Japanese kotatsu. The blanket traps the warmth around the legs of whoeve
Solar-powered foot stove (heat cube): A heavy block warmed by a small solar panel during the day, that you rest your feet on with a blanket over your lap. The block stores the day’s heat and keeps g
Box-bed with thermal curtain: A bed enclosed like a cupboard, closed with a curtain in cold weather. Only the small space around the sleeper needs to stay warm, and their own body heat does
Insulating furniture (hooded chair, folding screen): Furniture that shelters the person rather than the room: a high-backed chair with a hood, a folding screen behind the seat. It blocks draughts and shields you f