In Kouvola, there was Finnish Housing Fair in summer 2019. A Talo Aito-house is a modern wooden ecolocigal house. In the sauna building, there is a glass Liune interior door to increase the brightness and bring extra space. 

Liune door leaf slides inside a normal-sized partition wall. So it does not need that thick of a wall, just an ordinary one is enough. It creates more space because it doesn't need to turn. Building with Liune is efficent and controlled.