See the Future in Ancient Japanese Architecture [View all]
Japanese homes are beautifully designed -- and while I think I'd like some rooms with designated purposes, the ideas here are very adaptable to a simple, frugal, energy efficient home. I particularly like sliding doors so that you can easily expand or contract room size.
http://www.lifeedited.com/see-the-future-in-ancient-japanese-architecture/
While there’s a time and place for innovative space-saving solutions, sometimes the way forward requires a little looking back. A perfect example of this is the traditional Japanese home, a space-saving layout that works as well today as it did 400 years ago.
Unlike western homes, which typically have designated rooms for specific purposes (e.g. living, dining and family rooms), traditional Japanese homes center around a large living space called a washitsu that serves as any and all rooms (excepting the kitchen, toilet and genkan). Many modern Japanese homes still include a washitsu, though they are now accompanied by several western-style rooms as well.
Subdivision of the main room is achieved with shōji, translucent paper walls, or fusuma, thicker, impermeable walls, both of which move along wood rails on the floor and ceiling. Opening and closing these walls can dramatically alter the size and utility of the room.