I'm wondering how efficiently a system could operate that relied on passive solar, earth sheltered, wind-driven heat pumps.
Probably about as efficient as a totally passive solar house.
However, at some point you have to draw power from something, (for nocturnal illumination and for refrigeration.)
The use of solar cells and battery energy storage seems expensive and inefficient. I was just reading about solar dynamic systems, which concentrate the sunlight onto a mechanical dynamo. You still have to deal with batteries, but the investment and physical profile is smaller.
Another advantage is that you could arrange for thermal energy storage, which can actually be used in many food preparation procedures.
Internal household efficiencies could be boosted by using heat pump technology to remove excess heat from refrigeration chambers and transfer it to a water-heating function.
Essentially, we should design our houses as if each one were isolated on an asteroid. Then the next step would be upgrading our communications capabilities to the point where travel was almost unnecessary.
Picture a new high-tech internet, where you could "videoconference" to work together and solve problems. There is very little that most of us do that could not be done equally well by an immersive communication technology.
This opens up the possibility of new immersive entertainment venues as well. One could establish a connection to his favorite science fiction scenario, and enjoy role-playing to his heart's content.
With a suitable android robot available at your house, your doctor (plumber, handyman, maid, et cetera) could also make house calls.
My mother lived "off the grid" for years. It's not that expensive -- if you make the accomodations. Lighting with electric lamps is greatly minimized (as is brightness); use low-power appliances (TV); use propane fridge, and run the generator once in a while as needed.
My sister's current house is also still off the grid, I believe. (For the same reason: too expensive to get power run out that far.) They've made many of the same accomodations.