Many of Japanese houses are not comfortable in winter in comparison with North America and the European house. Because high humidity and a high temperature of the summer were severe in Japan, ventilation is considered, and the Japanese house is built.
In other words it’s a house with many gaps. And it keeps the room of the winter very cold necessarily. The conventional heating in Japan is bonfire in the room. When the airtightness of the room is high, the heating method is in danger of the carbon monoxide poisoning. And fresh air must be introduced into the room for combustion consistently.
Therefore, the body faced with fire is warm, but backs are always cold. Even if stoves were imported later from the West, a tendency about the Japanese heating did not have the change. The Japanese is still a partial heating thought. The radiators installed under the window, central heating and the use of a thick insulation material spread in Sweden.
Many Japanese have wrong heating knowledge now in the room of the personal space other than a public place. Therefore, the Japanese room is colder than Sweden 🙂