I think it would make for an excellent hide away since it would probably be difficult to see or find if one did not know it was there. It looks - IMO - not only cool but green. I like it.

More pics of the interior would have been appreciated.

This is an interesting take on a partially underground house.
My biggest issue I have with this structure versus building a "square box": the length of the perimeter walls and the associated extra costs.

Definitely stylish, and we could use more of that in Austin where generic suburbs have been growing at alarming rates. I love the pool and separate living, sleeping space. I'm not sure viewing ant mounds would be considered a bonus, the fire ants here are mean. But my main worry is that the hottest days of the year in Austin are also the most humid. That place could get pretty damp if it's cooled through the walls and floor and not by a forced air system that traps the condensation.

I get to observe ant colonies from my house as well. Mostly in the kitchen.

So what is the advantage of not having a covered walkway between the two sides?

Looks neat but not very practical. Washing windows inside and out would become a full time job. Roof bracing looks a little weak unless there is some heavy metal concealed. The space in the middle could hold about three truck loads of blowing leaves and catch tons of snow. Worse yet where would all the melting snow water go. Under the doors? Not quite enough protection from a tornado and could be a nightmare of flying glass. But the neighborhood peeping Toms should enjoy it. Where was the garage?

These ventures will continue to be expensive "one-offs" until someone makes a successful multi-home development. In parts of the country with extreme weather. a community with connecting tunnels and a small shopping center would make this very attractive.

Somehow, ther "Green" aspects seem to fall flat when it's a house that must have cost several million dollars to build. I like the overall configuration, but it feels a bit like living in a museum store. Needs earthy touches to dispell that sterile atmosphere.

Glazey, it sounds like the heating system is designed to dump heat into the ground, not primarily into water. That said, a big shallow pool will move a lot of heat into the air even in the most humid regions - just ask the guys at the cryogenics department in NHMFL, Tallahassee, FL.
Bob, last I checked, tornadoes, snow, and huge piles of leaves were not big problems in Austin, but this house looks at least as well equipped to deal with them as the standard design. I say that having just shoveled my way out of three feet of snow last week.