I had this idea about an underground house. Not an original idea I am certain! However I had a small twist on it. It would be cool if the house were built off site!? The plots of land then could be prepared at the same time as the houses themselves were created offsite. Once the ground work was completed the houses could be delivered to site in sections of 2 or 4 and then lowered into the plot. I suppose there would potentially be issues with hooking up the various mains but I am sure this could be worked around. the only thing you would have to get used to is having no real windows. However we could get round the light issue in two ways. You could have light holes that mean daylight is reflected into the house anyway and the other cheeky thing you could do is simulate windows with some sort of mirror trickery. I am sure it would make for a very warm cosy house.