How do wooden houses protect people from the cold?

A house protects one from the cold in two ways: First, by preventing loss of heat by convection, by eliminating the flow of air from the outside in and vice-versa, and by preventing loss of heat by conduction, by preventing the loss of heat through the walls. A house eliminates draughts by being air-tight. Wooden houses can be made reasonably airtight if the lumber is well cut. Wood, however, does transmit heat fairly easily, so to make a wooden house effective in cold weather, the walls should be doubled, creating an air pocket between inner and outer walls. This form of insulation can prevent loss of heat by conduction. Even fancier forms of insulation will do this more effectively. But even for the most efficient house it is essential to have a heat source inside the house to replenish heat lost in these two ways.