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.

How to keep warm - a lesson from the Chukchi's

This guy sleeps in a Chukchi dwelling. He says it reached -60 at night. At the beginning of the clip he stands in what looks very similar to a Mongolian ger. Then there's a tent made of reindeer skins inside the ger. He says it's -30 outside and close to -30 inside. Inside the inner tent there is no blanket or sleeping bag, but only a candle and his body heat. How could he "stay warm as toast"? A dwelling inside a dwelling and body heat. In the previous minutes (in part 10) he was in another Chukchi ger with a fire where they were cooking. Even though he sleep well, they admitted it was a "difficult life" there reindeer herding.


So what can we learn? He slept comfortably through -60 in a tent inside a tent and nothing more except 2 candles and body heat. When he first entered, the ger was cold, about as cold as outside. The inner tent wasn't big, but it wasn't small. Air locks? Insulation and a little thermal mass and sunlight should go a long way in an earthship.

Thermal Wrap - Use Straw Bales underground as insulation?

The global model earthship has that very nice development of putting insulation behind the tires about 4 feet or so. This is very much needed in a cold climate like Mongolia where it can be -40F or below in winter. The rammed earth in the tires has thermal mass, but heat can escape beyond the tires. The frost depth in Mongolia is something like 3 meters deep. A water line has to be that deep to avoid freezing in the coldest times in winter. In Mongolia rivers are ice blocks in winter until early April. I saw some people, like Dan Richfield's Earthship Blog , put the insulation down to the flat level. I would put the insulation deeper than the flat level at the floor. 

I wondered if straw bale could be substituted for expensive insulation. The obvious risk is that the straw gets wet and doesn't work as insulation and rots. While reading, somebody said that straw covered with clay, then 1cm coating of cement after a few stacked bales. If we did a thick wall of straw, coated and waterproofed with plastic over it all, that would have to be sufficient. Then I would do insulation on the top cap that runs back to the roof and completely cover the straw bale wall.


On the global model the roof is north facing. That means the water is coming back to the gutter into cisterns right near the straw bale insulation wall, so it must work. If the cisterns overflow, they should drain with a pipe to the front of the earthship, not into the cracks of the straw bale.

The savings on insulation should be substantial of a few thousand dollars. If we feel that the straw bales somehow failed, it is possible to dig up most of the wall and replace it anyway, since it's behind the house in the berm. So I feel confident on using this approach.  

Solar Ovens - 2

I thought more about solar ovens. This morning is a very sunny day in late July in Mongolia suitable for cooking. Though our current apartment is not an earthship, it has windows facing directly south. At 9AM the sun was directly east and didn't reach even in the corner of the windows, though it was full sunshine outside. 

So in order to use a solar oven, it has to be facing the sun probably outside unless there is wide window almost facing directly to the sun with a table of some sort. If you have regular windows that are about 1 meter wide, it still would be challenging to catch nearly full sunlight indoors over the course of an hour. With very wide earthship windows maybe it's very likely in the middle of the day until afternoon, but not if it's 7AM or even 5PM in summer, unless it works at low level with non-direct sunlight. The obvious solution is to carry it outside. 

One guy on youtube has a cardboard box on a cart. He got temps as high as 290F with ordinary aluminum foil and a cardboard box around 19F. That means with quality materials it might have been hotter. There was another youtube video of a woman in Michigan who cooked caserole in late December in a pot. It worked throughout the whole day. In Mongolia it can easily be -30F outside in January, thought usually not at noon. It could be below 0F for a week or 2. From late October to early April it's basically below freezing 99% of the time. One point is that to cook and even try to use an oven outside, you have to go outside when it's -20F or even 0F. But if it's warm months and we're in an earthship and we go outside in the front yard, it's entirely possibly for most meals, except cooking french fries. Also, if the cook is not enthusiastic about it, it might not work if the cook has habitual ideas about cooking. But if it's January not only is the cooking time more limited, but even if you can cook outside in -20F, but you have to go outside to attend to it. Also, there will be cloudy times when we need to cook that we need an alternative. Even during the day, and even if it worked well enough in -30F (let's say very good model), there will be dark cloudy moments and times at 11PM when people want to cook. We just need different stoves. Hopefully we can run a little off the solar batteries like say 30 minutes a day to augment or use propane gas or a regular wood/coal stove.

This aspect is solved in my mind. If we move, then maybe we'll take the door frame we bought recently and make a solar pizza oven like in that video.

Solar ovens

I realized I needed to learn more about solar power and PV panels. This will work great for lights, computer(s), charging things like cell phones, etc.. The main issue seems to be cooking. Mike Reynolds seems to prefer natural gas to cook and get solar heated warm water a little hotter. It wasn't clear to me how costly such a system would be. For months we've been getting by on one electric heating element. (The electric stove my wife's Mongolian relatives let us borrow stopped working. Folks I'm an American living in Mongolia hoping to get land and build an earthship.) On the bottom it says 1200w. My desktop computer says 500w. I understand that to mean it consumes 1200 watts of power in one hour (on high?). My laptop says something like 220w. Maybe 500 watts for the desktop is some kind of peak power load and actual consumption is much lower. 

I debated: Could one (or 2) heating elements be served by a solar system? I'd have to do the numbers. Mongolians traditionally cook everything over a fire (or stove), like soup. Web sites are warning that it puts too much demand and that this is not the best way. On the other hand some high draw appliances that you run for 2 minutes seem to be OK, so maybe the issue is if you could cook soup for a whole hour, then have to cook other stuff too, or 2-3 items at the same time. But if I'm on the computer for 6 hours, nobody seems to think that's a problem in the solar power web sites. Once I get solar panels, I'll try to see how long it takes to drain the batteries to see how bad it is. 

Then it occurred to me to check out solar ovens, which are hardly mentioned in the Earthship Biotecture literature, though mentioned in a recently posted Guatemala video. I haven't seen these function in real life. Actually I didn't see much of any of this stuff work in person. I don't recall knowing anybody in person relying mainly on solar panels for household needs. I started checking out various solar ovens. It seems they need a little attention. They need to face the sun. It seems they don't fry. It seems the better the reflective material is and the better seal it has in the chamber, the better it will work. I'm 100% sold on the concept and want to build one in the face of earthship wherever the kitchen area is. I was impressed with people on youtube taking simple boxes with aluminum foil and glass getting water to boil. I'm living in Mongolia now. It can get very cold in winter, but it's often sunny. Multiple cloudy days are rare. I saw one site Climatological Information for Ulaanbaatar, Mongolia that calculated the average sunny hours per day for UB over 30 years. Throughout the year, UB got 7.65 hours of "Daily Sunshine Duration" every day on average. Let's assume throughout the year that on average there are 12 hours of daylight, then based on their data (there is varying data out there and what "sunshine" is exactly is open to debate), UB gets something like 233 whole days of 12 hours of "sunshine." Actually this makes Mongolia a suitable place for earthships, because there is lots of open land getting lots of sunshine. 

So, I want to exploit as MUCH SOLAR potential as possible, so PV panels, a solar oven, and try a solar toilet. I realize that it is not always sunny, so if it's night time or dark, then we'll just use an alternate method, like a gas stove. We have a small camping type gas stove. Here many stores sell the little cans. My opinion is the gas stoves are too expensive to run here for most people everyday. They might be good enough in a pinch. I will test running a single heating stove element off solar batteries or research that more just in a pinch, like if we cook at 11PM, not everyday. I'm pleased with all the youtube videos I've seen. 

What are other ways to cook off grid in an earthship? Mongolians typically use wood and coal burning stoves. UB has a terrible air pollution problem due to this use. I'd rather not contribute to bad air pollution. I can see burning garbage paper and wood. In winter we may have to have a stove. I hope not. Maybe if we minimize the use to late at night, but I'd like to avoid that if possible. Just adjusting and cooking and eating during sunny hours might work somewhat. At some point we have to cook during night time. My opinion is that natural gas is somewhat too expensive and is NOT a renewable resource, though it burns clean. This is not 100% resolved in my mind, except that I am planning 100% on getting a decent solar oven.

Discussing various points of earthship building

I'll be posting comments here about the pluses and minuses of various earthship techniques as I try to design my own earthship. http://mongoliaearthship.blogspot.com/  Feel free to correct or comment.