Evacuated tubes? Nope, new one on me, but it'll make a nice research project for tomorrow. Luckily my job allows me some free time due to computer lethargy (centralized programs used by thousands of people, lots of lag time on the server side) to research personal things while waiting for the computer to catch up. Multitasking rocks :D.

The fellow that put that site up suggested building the solar wall at 90 degrees instead of 70 degrees to help limit summertime exposure, that combined with an overhang that will cover the top half of the panel in summer and none in winter might be plenty for this. Might have to play with the roof on this, perhaps design the overhang so that it allows a flap to be extended to cover more or less of the panel, much like a jetliner's flaps extend out? Such a setup could even be computer controlled. It wouldn't take much power or a very heavy overhang to do this, perhaps enough to cover from 40 to 60 percent of the panel in the summer. So far as dumping the excess, I'm figuring the large water tank would be more than enough to help moderate the temp. Such a large mass of water would take time to heat up and cool down.

I am also a geothermal fan, but only on a commercial scale. I used to be hot on those ground loop heat pumps, till I discussed it with an HVAC contractor. He said his customers who have bought them usually wind up having to replace the ground loop within 3 years or so. While the ground loop tubing is under warranty, that warranty is parts only, not labor. They have to use a special kind of glue, in layman's terms, to install the loop so that it will properly transfer heat with the ground, and it's almost impossible to get it back out. His customers usually wind up replacing the ground loop system with a high SEER heat pump for the same amount of money as the ground loop repair, and get an entire new system. I deal with the guy on a high performance automotive board and his shop is somewhere down in Louisiana, so there was no ulterior motives on his discussion of them.

Wow, those evac tubes look great! Much better than what I was planning to use. Course, more expensive, but looks like they'd work a lot better so might reduce the need for a wood fired boiler (not that I'd ever want to not have a backup). Thanks for the tip!

Totally untrue. Must be anti-straw bale nuts. You don't treat the bales, you plaster/stucco them to keep out mice. They don't burn--they might smolder for days if a fire somehow started. I know numerous people who have built them, are building them, or live in them. I would seriously consider straw bale if I were building a new home.

I must be a nut because I looked at something you support and decided it wasn't the best way to go? Call me squirrel poo then. If you like the idea of a straw bale house, by all means build one. I don't like the idea of one, so I won't.

Incidentally, plaster is no barrier to mice. Don't know about stucco.

Edit - Did a little searching, looks like it's not the easiest thing to get approval for. New Mexico is the only state that allows it. Go here for more information on straw bale housing, very informative article that shows potential problems and cures, and the direction of straw bale housing. Pretty surprising info.

I still plan to build with cement though.

There is no problem building straw bale homes in Minnesota or Wisconsin. Historically mice aren't a problem. Don't badmouth something you don't know anything about--and I was referring to whoever told you these untruths about strawbale as "nuts", not you personally. But you shouldn't be spreading rumours and half truths as the gospel.

But, to get back more on-topic, I have been talking to a few homeowners and builders who have been having problems with blown-in fiberglass as attic insulation and are finding that it doesn't pack down enough when blown in to prevent infiltration, and some folks are experiencing freezing through a foot of fluffy fiberglass because of its porosity. They are finding that blown cellulose is giving better results in the real world, because it packs down a bit and isn't as loose. For walls, in a stud wall, I would seriously consider one of the foams or sticky fiberglass or cellulose products to fill all the voids.

Wow, touchy! I admit to not looking closely at straw, but I'd hope that someone interested would look into it themselves, not take what they see on a message board as gospel. I didn't look closely at it because I'm not using it, end of story. I looked at it more due to your post, still not using it. :D But, if someone came to me talking about it, I might not try to talk them out of it anymore.

Blown in fiberglass wasn't my first choice, it was what was in the house when I bought it. It's not recommended to put cellulose on top of fiberglass, and I wasn't about to pay to have the whole house cleaned out and cellulose put in. This house is as insulated as I plan to make it as 2 years from now, I'm out of it. The insulating guy did say that he's having a hard time getting blown fiberglass though, said that the insulation companies are moving to cellulose for their main product.

WisJim -

I think straw-bale is great *if* you have the real-estate to burn.

I was thinking that anything you blew in should have a "spray cover" to keep it one place after it's blown in. But maybe that would lead to condensation. Maybe a netting would be more appropriate.

Last year we looked into the Nasa-Style "Foam Roof". I know it would have gone a long way to solving our problem, but it is based on petroleum products, so the cost was pretty high last year. Here is an example :

https://www.socalfoam.com/

EDIT : It was between $6K to $10K for our < 1000 sqft flat roof, depending on the thickness.

We were also a worried about toxicity/allergy issues. Technically, it's inert, so it shouldn't be a problem. But, you probably wouldn't know until after you experience health problems.

CarloSW2