Google Group: Earthship Building and Design

I've made several posts about third greenhouse glazing angles, electric car batteries used with solar PV panels, etc. http://groups.google.com/group/earthships_en?hl=en

Bicycle wheels for windmills

This is a bit of a diversion again, but could be a cheap way to supplement power off-grid using bike wheels. I got this off the icebike email list. 

http://www.exacteditions.com/exact/browse/409/460/6594/2/11/0/

The quality way to do this is to use a Shimano dynamo hub on an old beat up rim and just step the power up to 12v. This appealed to me being a cyclist. It would be great to find ways to recycle old bike parts. It would add more outer space landing look to your earthship.

Dynamo bike hubs and battery packs

The concept isn't exactly new and neither is this product, but the Busch & Müller "e-werk."

http://www.ecovelo.info/2009/09/05/e-goodies-from-busch-ller/

This collects electricity from a dynamo bike hub into a battery. It's one way to decrease reliance on a home solar PV system and enable earthship off-grid living for small appliances like charging cellphones and other small DC devices. This would require not only this device, but a dynamo hub, so the whole package could cost as much as $250.

I've already read "Water From The Sky", but wasn't clear about details for our location. Many of the details, like the silt catch, were designed with Taos, NM in mind and need some adjustment. Taos has a frost depth of 18" (0.45 meters). I'm dealing with a frost depth of supposedly 1.9 meters as some say. They have that pic of a wonderful silt catch on top of a cistern. In Taos it can get cold, but the average high in January is above freezing. Even then they said it could possibly freeze up a little. If it froze a little there in January, It would definitely freeze in Mongolia, where rivers are completely frozen blocks of ice until the end of March.

So I was dealing with the situation that even if I have a well insulated cistern that it has an opening. I can't even close it for the winter, because as we use water inside, it has to relieve pressure. They also say in that book that metal funnel shaped silt catches will eventually rust and develop holes, so they suggested plastic tubs filled with pebbles as an alternative. The tubs were close to 18" deep. So even if some cold winter air got down through the tub into the cistern, the water is quite a big mass and warm below the frost depth line, even insulated.

I was frustrated when looking at Dan Richfield's 18" cistern riser, because I doubted they had a 2 meter version of that, even if I took 2 1 meter risers. We will check out the water tank places locally. (We know where they are.) Then it occurred to me that I could simply get 2 industrial strength new plastic garbage cans and stack them on top of the cistern opening and do some sealing to prevent dirt from entering the cistern.

Since I want to build in a cold arid climate where 80% of the precipitation is in about 4 summer months, I don't need to be concerned about collecting any snow melt, and need a very large capacity. I wanted to build tire cisterns. If I collect water off the roof and it falls through 2 meters of silt catch, and I want to have the bottom of the cistern at or above the ground floor in the house. That leaves 1 meter or less height fully below the frost depth and above the floor. Most of the large capacity tire cisterns are tall and wide. If I built one cistern, it might need to be extremely wide of 10 meters or more and it would be hard to put a strong lid on it that wouldn't collapse.

I was looking for a cistern design that was 1 meter high or less and large capacity. Eventually it occurred to me that I could use tires behind the thermal wrap in a multiple U design using the smaller tires often found on Asian cars 195 or less, which are considered to be too small for earthship tire walls in the dwelling place. Each U could be maybe 2 meters in width with a common (greenhouse analogy) area to drain towards the center. This way I could easily secure a strong cistern top with rebar and cement over each U. Since 2 tall garbage cans could easily hold the largest storm, I could have one entry point over one U, and perhaps have another insulated cover with a pipe riser from another point to inspect the contents or even climb into the cistern if necessary.

So far this sounds great, because not including piping to/from the cistern there is almost no cost besides cement, sand, 2 big garbage cans and maybe the other riser with an insulated cap to gain entry. It would take the labor to pound hundreds of tires, though.

So, the idea is: put the 1 meter high cistern with 2 meters of earth over it. It would be completely insulated on the inside. It would have a riser of 2 or more pebble filled plastic garbage cans as a silt catch. Even though air could find it's way down into the cistern, I'm hoping that the water won't freeze. 

Let's say one cistern U is 1 meter (3.28 ft.) tall, 8 feet long towards the north, 6 feet wide (U sidewall to sidewall) not including tires. Even though U's might be curved and lose space the juncture between each cistern U will compensate for that. These are adjustable. We could easily make them 10 feet if we're short on capacity. 6 feet wide will give up a strong roof over each U. I figured one of these will contain about 1100 gallons. 

UB gets about 10" of precip. a year. Maybe less. The airport reported 25" one year. Some places like weather.com report as low as 7-8". If we built a 2000 sq. ft. (large) roof, what is the likely maximum amount of water the roof could produce at 10"? I figured about 12,000 gallons. If we tried to contain the entire year's worth of rainfall, how many 10' long cistern U's would we need? 11.2. If we say a tire is 2' wide and we have 10 walls between 11 tire cistern U's, this would have to be 88 feet long including the tires.

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.