Scandinavians know a thing or two about burning wood efficiently. Can't speak for Sweden or Finland, but new wood stove installations in Norway are mandated to

Scandinavians know a thing or two about burning wood efficiently. Can't speak for Sweden or Finland, but new wood stove installations in Norway are mandated to generally have complete combustion and be efficient in combustion and heat transfer. There's lots of local manufacturers with a long history, e.g. Jøtul. Their stoves are generally >80% efficient. E.g. https://www.jotul.no/produkter/ved https://www.jotul.no/produkter/ved Newly-constructed city apartments are generally heated by centrally installed air-to-air or water electric heat pump, but single family homes are usually built with a modern wood stove for flexibility, atmosphere and redundancy. Older homes and apartments also very commonly (>50%) have a wood-fired heat source, and government mandates ensure that they have practically always been upgraded to modern specs.