Multiple U's vs. Global model roof with wooden frame holding it up

Without a finished global model book what's an earthship sailor to do? Become an intern like Dan Richfield? http://www.youtube.com/watch?v=iI9LInmNfpE and hire EB staff during your build? He's got great practical details in his videos that EB kind of glossed over. I like the multiple U design. It's got more thermal mass for a cold climate. In a sunny cold climate we need to collect as much sun energy in thermal mass as we can get. Admittedly the weaknesses that I can tell are: you can't overhang the roof at all over the greenhouse, and the front of the U sidewalls are vulnerable, and the transition from the main roof to the greenhouse can be straight as I want, but it's a little trickier. I want multiple U's with 1st greenhouse glass like the packaged earthship, which became the global model. I was worried if I put up 9 courses of tires and then dig the little foundation for the non-weight bearing 1st greenhouse glass that it's going to cause the dirt under those front tires to weaken, but we'll be putting concrete in there anyway. They run that footing all the way to the sidewalls on the packaged earthship. Even one of the "existing earthships" in the back of volume 1 implemented it. We definitely need the 1st inner greenhouse in Mongolia in my opinion.

Solar, Solar, Solar...

We're living in Mongolia. Though it can get below -40F/-40C for brief periods in winter, it has on average 233 full days of sunshine and usually isn't cloudy. This makes it perfect for exploiting solar applications (solar PV panels, solar water heater, solar oven, solar toilet, etc.). A solar system must be one of the most expensive components of an earthship. My rough estimate is that the most expensive items are the insulation and windows and the solar system, and maybe the roof. The great thing is if I use a combination of solar applications, that it reduces the requirements of the solar PV panels and battery system, reducing the cost by thousands of dollars. 

I found this web site http://planetaryrenewal.org/ipr/lifesupport.html and they have some similar ideas, but different ones, though lacking details. Their solar water heater is just 2 8-10" 20' long pipes with reflectors. They brought up the point of the system freezing. That's definitely an issue here. They say "Breadbox water heaters have too little surface area compared with storage volume." I think the earthship solar water heaters are breadbox style. Now I have to research what will freeze here. I would imagine anything will freeze here in winter, especially metal pipes. OK, these are in a box with glazing. My impression is these pipes are better than having somebody weld a stainless steel box locally. It's got to be a totally insulated box. Ha Ha. I bet the piping will break in winter. Should this be at the bottom of the face? I can just see our earthship face full of all kinds of solar reflectors.

Straw Bales for thermal wrap insulation - maybe not

So far everything I've read is that it's too hard to keep straw bales dry underground, even if you encase them in concrete and plastic and clay. Concrete may develop little cracks, then when the moisture gets in it's history. I think the harder insulation is more expensive. In Mongolia the main way of building is with concrete. They build a concrete slab wall, then glue insulation (usually something like cheap styrofoam) and then cement over it. I saw this on Russian style high rises close up. Usually they're selling the cheap styrofoam. The harder insulation costs more.

2 great developments in keeping earthships warm are the thermal wrap with the insulation http://earthship.net/Comfort-in-Any-Climate/Thermal-Wrap-turbo-charge-your-earthship-dp2 and the "double front face" as seen on The Phoenix. http://earthship.net/Comfort-in-Any-Climate/double-frontface-Comfort-in-Any-Climate-dp4 http://www.flickr.com/photos/earthshipkirsten/sets/72157600792202122/

The double front face keeps more buffer zones from outside. If I had that, I would have full confidence to go with "no backup heating." I don't know if we can afford it. All it is though is the trusses with the frame and tires and all the glass and the extra roof. That's all. If I'm convinced it's within budget, I just might do it. It's not complicated except for the roof transition and the truss supports, except that I'm up in the air to install it all. Thanks to Brian Simpson for encouraging me to go for it. 

But just like the inner Chukchi tent was warm enough, the inner sanctum of a fully insulated thermal wrap with tires has got to be a lot warmer than that Chukchi inner tent at -60 outside.

I'll keep looking for more info on straw bales underground, but right now it seems like they're not going to be waterproof enough to prevent rotting. Also, thick concrete around them costs money, even if it did work.