Sleeping lofts are a great way to maximise space. I really like this cabin with it's one legged ladder but I don't know that I think much of that 'safety rail'. Do you like it? Not the rail, silly - the cabin and sleeping loft!
earth-sheltered homes are far less impacted by extreme outdoor air temperatures than a normal house. most earth-sheltered houses "blend" the building into the landscape and tend to be less maintenance.