Houses for self-sufficient living

   The modern three or four bedroom house with 2000 square feet of 
   living space is a real 20th century luxury.  And like most 
   luxuries it brings with it a real burden --- a burden of high 
   mortgage (or rent) payments and high utility bills.  How big a 
   house does one really need?  How much floor space does one 
   really need?  How much floor space do the smallest house 
   trailers have?  How much floor space did the log cabins of 
   bygone years have?  How about the one-room huts of people 
   living in third world countries?  Do they perhaps have about a 
   tenth as much living space as our modern 2000 square foot 
   house?  What would be the cheapest way to build a house with 
   300 to 400 square feet of living space?  How much would it cost 
   to build a super-insulated house measuring 16 feet by 24 feet 
   using standard construction with exterior plywood for the 
   exterior and drywall for the interior?  How long would it take 
   to build a house like this?  How would it be to live in such a 
   house?