About eight years ago my middle son wanted to build a club house with me and his brothers...so we talked about how big and what it would have in it...ya know kids...we ended up with a little "house" instead of a kids clubhouse...I had a friend of mine that teaches building trades at a local vocational school teach us how to properly build this thing...

It has heating and AC, tv/dvd, frig, cable and internet...couch bed...everything a typical house has but it's 20'X 20' that's 400 square feet that is so well insulated you could heat it with a candle if you wanted to...When the kids are grown and moved I may rent it out as a tiny apartment...

and of course it's powered by my solar power from the house...