3D Printed Earthships
Fringe science + fringe science = ?????
There’s a lot of very detailed writeups about earthships, including the original Michael Reynolds book itself which I’m reading right now.
Here’s a crash course:
- An earthship is like an ocean ship in that it’s a 100% (or as close to as possible) self contained unit. It generates its own power, water, temperature, foods and disposes of its own wastes.
- The idea generally is to be as eco friendly as possible, and also effective with building / living, so there’s a lot of cleverness with using less energy through better architecture, using grey water to feed plants instead of dumping it immediately, that sort of thing.
- The primary design is around these U shaped rooms, which are built with rubber tires tamped with dirt and stacked like bricks. This is three-fold: tires are often free and we can’t get rid of them fast enough as garbage products, tires are rubber and therefore move with the earth without cracking like concrete might (more on that in a bit) and they’re easy for the lay person to do work on and make something sturdy — they’re about 300 pounds when filled which is the upper limit of something humans can effectively work with sans machinery.
- The other primary idea is that passive heating and cooling as the most efficient when you have thick thermal mass around you: berms of dirt instead of open walls that leak energy to the air even with insulation. So, the design puts a big greenhouse to the south (facing the sun) and the other three walls are solid to regulate temperature to the earth constant.
And so on, I think that’s the main points.
The upside to all of this is that it attracts the budget minded: tires are free, there’s no insulation or lumber bought, you just have to do a lot of manual labour and you can build yourself a house. More about that in The Middle.
The downside is that you have to pound hundreds of tires with dirt which is a ton of work that, let’s be honest, probably sucks and probably isn’t a great selling feature to your more average, traditional homebuyers.
So how do we take the benefits of earthship design (thermal mass, recycling systems, generally budget minded ideals) and also not use tires.
Maybe purists would say that ceases to become an earthship; I guess I would argue we build yachts different than we build barges and those are both ocean ships. But, it doesn’t matter. I’ll call them brenships if you want.
3D Printing
Yeah, the buzzword baby of the 2010’s, but hear me out:
The floorplan of an earthship is very careful and deliberate: the depth of a room is based on the height of the windows allowing sunlight in, the width of a room is based on a) beam widths for roofing and b) maximum volume of air, for thermal reasons (though in general the earthship is heating mass instead of air, which is more efficient). Then the top is arched to barricade against the force of the north berm’s packed earth.
So we have these U shaped rooms for a reason.
The major downfall of 3D printed houses, currently, is that it’s really tricky to cut out doors and windows without the support to print the top layer. It overhangs and falls, so that’s no good.
But an earthship pointedly does not make holes in the tire walls. It’s both bad for thermal loss and also hard to engineer if the goal is that you’re having laypeople build their own brick wall with minimal skill / danger.
The other downside of 3D printed houses is insulation: you have relatively thin concrete walls that are standing against the outside air and of course have terrible R values. Some designs add spray foam insulation inside, or air pockets in the print itself (which is rather neat and future-y, actually) but in the end it’s still not what it should be for energy efficiency.
Fortunately, the earthship design doesn’t care: the walls are packed with earth on the outside — they’re intended to never be insulated. The tire (or concrete) wall is basically just a retainer like a foundation wall, carving out a vertical space so your room isn’t a slumping burrow. That’s basically it.
This design is perfect for printing.
The main downside to concrete as Reynolds describes it is that it cracks — it’s too rigid to float on the earth herself, and so instead of fighting the natural expansion and subtle movements of the ground, we should build the houses to ride them out. Rubber tires allow this in a way that concrete tries to fight.
But, this book was also written 30 years ago, and his concrete mixtures didn’t seem all that sophisticated — we can make ductile concretes now and engineer the perfect combinations of binding agents and various things in a way that his “3 parts sand, 1 part cement” recipes just couldn’t handle.
Also, since we’re printing the concrete, it has to have certain amounts of flow and ductility for that process, so it’s a more engineered thing to begin with and adding characteristics to that shouldn’t be too much burden.
Understandably, now we’re adding machinery to a world where it was explicitly attempting to make something dead simple, but I feel like people will understand the benefits of a robot making everything for you instead of pounding dirt into hundreds of tires all day in the hot sun. I realize some people will still make this tradeoff for free labour, but if we’re middle-ifying these designs we’re allowed to throw a bit of money to save a lot of work.
In Summary
As I wrote about in The Middle, I feel like there’s this middle ground between taking these cleverly designed buildings and applying modern technologies and abilities in a way that comes out greater than the sum of those parts. We’re not just adding but multiplying ideas together.
Obviously houses are poorly designed today, I’m fighting my house right now even, as I have to run a loud and energy expensive AC unit to cool the bedroom someone put on the 2nd floor facing south-southwest. It’s offensive to me that we should have to use those sorts of bandaid solutions to keep a room comfortable when we can instead just design it slightly better. Be a tiny bit more intentional and thoughtful with our architecture.
3D printing is still in its infancy. I’m probably one of the stodgiest people in the industry regarding the “it’ll fix everything!” optimism of popular science, but I do think it’s rather convenient that earthships have a great design with some drawbacks that can be covered by the strengths of 3D printing while also covering the weaknesses of that process. It’s just sort of perfect, right?
I’ll continue to think on this, but it’s something that came to mind as I was reading the book and wanted to express it here as well.
Let’s make cool stuff.
