Here’s the first post in a series on permaculture analysis. This is where we kill sacred cows by ruthlessly checking our subject using permaculture design. Today I’ll cover the natural building technique of Earthships.
I intend for these posts to break assumptions and “taken-for-granted” truisms for everyone, including myself.
Note: This post may contain affiliate links that give us a small commission at no cost to you. See the Disclosures page for more info.
Also, if you like getting free tools, sign up for the tool giveaway in the sidebar. Matt from The Tool Merchants gives away free tools every month.
Based in facts, or falsehoods?
Changing one’s opinion on deeply held beliefs because of contradicting facts is psychologically one of the hardest things people can do.
The concept of unfalsifiability is a big part of political and religious views. See here for a longer article on the topic.
It means people hold tighter to beliefs in the face of conflicting information, and go even farther in their own beliefs.
In permaculture, we must use the facts (regardless of our own beliefs) to make good design decisions. So let’s get to the facts and burst some bubbles!
Essentially, an Earthship is an earth-sheltered passive solar home that tries to provide most human physical needs.
They have water harvesting, sewage treatment, food production, power production, heating and cooling, and are (usually) built with natural or recycled materials.
Usually they are an uncomplicated single story, and built with packed dirt, cement, and cob (clay, straw or other binding agent, and sand).
Novices without vast amounts of construction knowledge can build them, to vary degrees of completion and quality.
Exterior walls are often built by packing dirt into used tires, though this is not strictly required. Builders use tires many times because they are very cheap or free.
Any dense material that stores heat could be used, like earthbag, stone, or concrete.
Because Earthships use earth, adobe, or cob for the walls, they are generally fire-resistant. The exception is the wood beams and framing for supporting the roof and front glass wall.
They commonly use aluminum soda cans and mortar in non-load bearing interior walls.
Most incorporate artistic decoration (bottle glass wall, cob sculptures, decorative colorful tiles, etc.) and are very common in New Mexico, the home of the first Earthships.
You find Earthships most often in rural off-grid situations where access to power and water/sewer is cost-prohibitive or impossible and building codes are more relaxed.
Water and power
Earthships use thermal mass to store heat and cool, and use thermal differential to let hot air rise and pull in cool air.
They also prefer heavy insulation on every side except the south, as well as the roof. This slows down the rate of heat transfer, which keeps you more comfortable year-round.
Usually, toilets flush with greywater collected from sinks and showers, while the roof catches water (rain, snowmelt, condensation) then gravity-feeds it to a cistern water tank.
Greywater also waters the interior greenhouse, which supplies food to the residents.
Separate from greywater, blackwater flushed from toilets travels to the septic anaerobic digester, then to non-edible plant filled cells (often concrete). These plants process the waste further and uptake the nutrients that would otherwise be wasted.
Power generated from wind turbines and solar panels stores in batteries (commonly placed in a special room on the roof).
Heating and cooling
Heating and cooling happens by southern orientation of the “U” or horseshoe-shaped Earthship that collects solar heat during the day through large windows. These windows angle to take most advantage of the low winter sun, and limit summer overheating.
This heat stores in the thermal mass of walls and floors, which radiates out at night to heat the home.
Growing up in a passive solar house, I can attest to the sun’s warmth from tile and bricks on a cold night. We also used thermal curtains backed with foil over the windows to keep heat in at night.
In the summer you use shade curtains to avoid heating the mass.
Some Earthships also use an “earth tube” – a pipe buried under the berm into the house – to cool the air by passive convection.
In a perfect world, you use no external grid power or liquid fuels (propane, diesel/gasoline, fuel oil) to heat or cool the Earthship.
First, let’s measure the Earthship against the prime directive:
The only ethical decision is to take responsibility for our own existence and that of our children.
-Bill Mollison, from Permaculture: A Designer’s Manual
By building a house that helps us be highly self-reliant, we can provide our own needs without relying on external systems of support.
So it is possible to fulfill this ethically responsible decision with an Earthship style house.
Now let’s look at the 3 ethics that guide our permaculture decisions.
Note: These three ethics have equal importance. And only having two out of the three right won’t cut it.
Ethic #1: Care of the Earth
Does the Earthship care for the earth?
By using natural materials, reducing your reliance on and use of public utilities, growing your own food, and processing your own waste, it certainly reduces the waste and energy required for humans to live.
It also doesn’t necessarily require clear-cutting forests, monoculture industrial factory farms, or dumping sewage into rivers.
This reduces pollution of the environment, and helps provide a clean space to live in.
It usually includes worn-out tires, which I don’t like (more on this drawback later). On one hand, this does remove them from landfills. On the other hand, it puts them in your house.
I can think of lots of things from the landfill I don’t want in my house, so using tires isn’t a plus in my book.
Overall though, the Earthship design can be more environmentally friendly than other building methods.
So let’s give it the benefit of the doubt and say that an Earthship design fulfills the first ethic.
Ethic #2: Care of People
Does the Earthship design care for people?
One of a human critical survival needs is shelter. It should protect from heat and cold, and at least not detract from supplying their other needs. If possible it should help supply them.
Because the Earthship is built with low-cost recycled or natural materials, it also helps humans in another way: not having a mortgage.
This only true if you do most of the work yourself. If you have to hire labor to pack tires and build the rest of the house, you might want to look at another building method.
Most homeowners have a mortgage on their house. And most people will keep upgrading houses, and so will keep having a mortgage.
Not being in slavery to debt gives you financial freedom, and building an Earthship could help you in this respect.
It can also produce food from its integrated greenhouse. The size is too small to produce all the food a family needs, but it can help offset the grocery bill.
So yes, an Earthship can care for people, if you can keep the costs down.
Ethic #3: Return of Surplus
Does the Earthship support the previous two ethics? Does it cycle excess energy back into the system?
Like I’ve already talked about, an Earthship takes care of water harvesting, waste processing, shelter, power generation, and food production.
This ethic is more about the human interaction and behavior with the system, and so in some sense it doesn’t apply to a static design.
But in other ways, it does what the ethic is asking.
Food-wise, if you produce more than you consume, you should process and store it away to be used later. Or you could sell or give it away (only if you desire). This isn’t collectivism or communism.
If nothing else you could turn that over-production into compost.
This will increase your social or financial, or material capital, and so should benefit the system as a whole.
Because the Earthship design should produce and not consume vast resources, it may be used as a tool to help fulfill the third ethic.
Returning and cycling excess energy back into the system is what makes the system able to keep going. We commonly call this sustainability.
Despite all the possible benefits, the default Earthship design is not perfect. The devil is in the details, as they say.
The Earthship must orient properly, as well as building the front glass at the proper angle for your latitude.
Considering that many non-professionals build Earthships, if the orientation and angling is not done correctly, you will get suboptimal performance.
In addition, they require correct installation of walls, waterproofing, insulation, plumbing, and electrical systems. This is no different from constructing any other home, but novices are more likely to get something wrong.
Of course, professionals are not immune to mistakes either. The important thing to remember is to build correctly without shortcuts.
Also realize that education with experience is your best hedge against errors.
Another claim made by the Earthship founder and the website is that they work in any climate.
It is more accurate to say they can work anywhere, if you modify the design to account for the climatic factors like excessively colder, hotter, or wetter than their origination in New Mexico.
Also, it’s somewhat quibbling, but Earthship is a trademarked name. Technically it’s illegal to build one unless you bought the plans from the originator.
Unlike permaculture, which Bill Mollison wanted to never get trademarked or copyrighted, Earthship Biotecture, a company founded by the originator, Mike Reynolds, trademarked “Earthship”.
Dirt-packed tires are generally not approved in structural building codes, so you might be in for a struggle with the local building inspectors.
For me, another drawback is that I’m not fond of using tires to build a house. Retaining walls, sure. Concrete-filled pipe stand, yep. Kid’s tire swing, yes.
Garden beds, iffy but probably not. House, nope.
I’ve heard several stories of Earthships becoming toxic and unlivable from the tire decomposition off-gassing. This happened to the now-deceased actor Dennis Weaver, for one.
To be fair, this doesn’t happen in (or at least isn’t reported for) most Earthships, but it happens often enough for concern.
What happens is that the tires continue settle and break down, releasing odorless gasses that make occupants sick.
The Earthship proponents fix is to add vents and replaster every year to make sure that there are no cracks anywhere in the living area. This seems to me a Bad Idea to trust that there is no gas leaking anywhere from a tiny missed crack.
Packing dirt into tires is also an extremely labor-intensive and tiring way to build.
Mike Renyolds, the creator of Earthships, wrote a manual for building them.
He has commented that Earthships are “hard to mess up”, but anecdotal tales abound about how difficult the Earthships are to build.
One lady in Taos, NM tried to build hers, and after wasting $20000 she gave up. She thought it would work if she hired Mike Reynolds but doing it yourself was too hard.
Despite the claims, Earthships are also not best-suited to every climate with a “cookie-cutter” design. Earthships in very cold or wet climates will perform poorly unless changes are made to deal with these climatic variations.
Some Earthships in Europe have moisture and mold problems, and deep soils not separated from the home can tend to remove heat and cause excessive heating costs.
For proper heating, Earthships also need a good number of solar days, which is plentiful in New Mexico but are lacking in the Northwest US or Europe.
If this sunshine is lacking (especially in the winter), it is wise to include another heat source like a rocket mass heater.
The earth tube idea for air cooling seems to work OK in a dry climate, but in a humid climate just brings in moldy, smelly air.
Free heating and cooling?
As far as the free heating and cooling claims go, the facts don’t always bear out the claims.
In an ideal world, heating and cooling would be free. Since neither you nor I live there, we have to deal with the fact that TANSTAAFL. Or for you non-Heinlein-readers, “There ain’t no such thing as a free lunch.”
Many people in cooler climates must use supplemental heating to keep the Earthship warm. Wood heat (sometimes a rocket mass heater as mentioned above) is commonly used.
As show in the example above of 95°F inside summer temperatures, Earthships also have a tendency to get too hot in the summer.
Earthships built without sufficient (significant) insulation under the floor and in walls can see poor thermal performance.
The problems can include summer cooling as well. Earthships can get too hot, especially in hot summer areas like Texas and Australia.
One Earthship in New Mexico whose construction was managed by the creator of Earthships was getting to 95°F inside. This was during the summer with all window shades up.
Unfortunately, the outside temperature was cooler at only 90°F.
This spectacular failure from the birthplace of the Earthship is quite concerning to me. It is just one fact of many that makes me unwilling to recommend them as a preferred natural building method.
One improvement to an Earthship is to integrate solar hot water (AKA solar thermal). This is one of the best ways to cheaply heat water, as well for floor/space heating. See this page for tons more info on solar heating.
No utility bills
Part of most people’s living off-grid is the monetary and time cost of maintaining and periodically replacing batteries to store the generator electricity.
Batteries can last between 5 and 10 years, depending on care and conditions. They are not inexpensive to purchase or replace, and replacements must be factored into the cost of ownership.
In addition you will need the other components of off-grid power systems, like a charge controller, inverter, and wiring/breakers to connect it all together.
Dividing up the cost of this system over the expected life can show you how much it will cost.
It could be just like having utility bills!
Another promoted benefit is the elimination of burning fossil fuels. However, the Earthship website talks about using a gas water heater, gas for cooking, and gas or fireplace for heating. Here and as exampled above in the overheating incident, it seems the claim of “no utility bills” is at least overrated if not misleading.
Money IS an object
One possible solution to the battery replacement issues are nickel-iron batteries. Once called Edison batteries, they are now available again after a long absence from the market. While they are expensive per amp-hour, they have a very long expected life.
This is usually around 50 years, though some batteries made 100 years ago are still running! See ironedison.com for one such supplier.
So now let’s look at the cost per square foot. Where I live, the average cost of home building is around $120 per square foot.
The “Global Earthship” model, a one-bedroom, one-bath Earthship, costs around $225 per square foot, or about $300K.
Tire-packing is so tiring and labor-intensive that if not doing all the work yourself or finding free labor, this is a big cost adder.
People have successfully built their own Earthships at a lower cost, with free labor and recycled materials. But it’s still not cheap, especially if you want all the off-grid systems in place as well.
One article I read mentioned a cost range of between $50K and several million dollars depending on size and amenities, with a (wild?) guessed average of $150K.
Another thing to know is that building an Earthship on average takes two years in Taos, NM.
So make sure you have alternate housing while building your new Earthship.
So it is possible to build an Earthship correctly and have a low-cost passive solar home that you don’t have to pay a mortgage on.
Earthships are an interesting natural building method from the 1970s.
They are an earth-sheltered passive solar home with integrated greenhouse, water collection system and sewage treatment.
They can have issues if not properly modified for the site or well-designed and built, and can have high labor costs.
The Earthship design only passes the prime directive and ethics test if it is well-designed and built.
This caveat is no different from the failures when improperly using a technique like swales, herb spirals or hugelkultur, though the cost is possibly much higher.
What you don’t want to do is commit a “type 1 error” that costs a lot of time and money to fix.
Frankly, I don’t recommend Earthships as a building method, especially for people unfamiliar with good construction techniques who want to build one themselves.
There are more recent, better passive solar designs that have fewer issues.
http://www.greenbuildingadvisor.com/blogs/dept/musings/earthship-hype-and-earthship-reality -> and read the comments
OK, that’s all folks! Do you have any questions or comments about natural building, permaculture design or anything else? Ask your question down below and let’s talk! You can also use the contact form, or email me at info at thepermaculture dot life.
FREE Lazy Gardener's Guide to Homestead Management
What to plan, do, and buy each month to keep your sustainable homestead on track.
Never forget important tasks again, and get lots of stuff done!
And you get our latest content by email. We usually publish new stuff twice a week.