That is a great idea, it follows along with Geo thermal heat exchange which is a great way to heat and cool the home as the ground is a constant temperature underground. The idea is a good one, but also cost prohibitive. A friend of mine knows a lot about houses and how to mitigate the temperature changes. It Requires walls at least 18 inches thick from what research he has done. Digging a large hole in the ground and building your house there and filling in around it would be the ideal way to keep a house cool, but comes with its own problems, like drainage.

I'd still like to know if any one has any idea how the cooling effect works with Negtropic energy, and if no one does then I will have to experiment myself.