The conventional modern way of building for northern climates often involves synthetic insulation and some kind of mechanical heating -- an energy-intensive and inefficient way to live out the winter. For the Ainu, the indigenous people of Japan, the traditional way of winter-proofed building is called "chise," referring to a home that is built with earth, clad with bamboo and sedge grasses, with radiantly heated floors and interiors kept warm by a central hearth that is never allowed to go out.
In stark contrast with modern expectations based on "static environmental engineering of the 20th century," Kuma describes how this house's dynamically heated interior environment was created:
We wrapped a wooden frame made of Japanese larch with a membrane material of polyester fluorocarbon coating. Inner part is covered with removable glass-fiber-cloth membrane. Between the two membranes, a polyester insulator recycled from PET bottles is inserted that penetrates the light. This composition is based on the idea that by convecting the air in-between, the internal environment could be kept comfortable because of the circulation.
The house's interior is kept warm by the continuously-burning central fireplace, which warms up the ground, which in turn slowly but surely radiates heat throughout the day and night, thanks to its high thermal mass. The structure's translucent walls allow for natural daylighting, so occupants wake up to bright sun and sleep when it goes down.
Most interestingly, the house's interior glass fiber cloth lining is removable, allowing researchers to test how different components will affect the thermal qualities of this so-called "membrane house." This is a fascinating example of how modern building conventions don't always hold up and are still evolving, as Kuma notes that
We do not treat insulation within the thickness of heat-insulation material only, which was a typical attitude of the static environmental engineering in 20th century. What we aim at is a dynamic environmental engineering to replace it for this age. That we utilize the radiant heat from the floor is part of it, and it has been verified that you could spend several days in winter here without using floor heating.
More over at Kengo Kuma & Associates.