Beauty of Tatami - insulation effectiveness

It feels that when you touch a tatami in summer somehow coolly and feel it somewhat warmly in winter.
It is because tatami has insulation effectiveness.

Because straw in a tatami floor has a lot of cavities, and a facing side of tatami which is covered with rush grass has a shape such as a sponge that it can contain a large quantity of air.
This air plays role that it seems to be a wall and intercepts heat.
Outside hot air is hard to come in a room in summer, and indoor warm air is hard to escape outside in winter, and this is the insulation effectiveness of tatami.
It could be said that tatami is suitable flooring in Japan where the difference of heat and cold is big.

Therefore, it is more effective to spread an electric carpet on tatami than on flooring in winter.