That is so cute and underground houses are very efficient - they stay an even temperature year round. I lived in a community most of my life that encouraged alternative housing - most people I know built their own houses - some are really interesting - most people I know are off-the-grid - meaning they have solar or water wheels and wind generators for power - I lived that way for many years - you get used to it and you can still have all the conveniences without the power bill. There was talk of building straw houses - but I think they are better suited to a dryer area like the desert. Bravo to these people for thinking out of the box.