Earthships demonstrate a way to live in harmony with the planet by encountering natural resources without defeating them. Imagine living in a home that costs you nothing to heat or cool. Imagine Earthships!
An earthship is a passive solar home made out of natural and recylced materials. It is off-grid, getting it’s power from the sun and wind, it’s water from the rain and the snow, and it re-uses, contains, and treats its own waste water with hydroponic.
We call the compilation of all these integrated systems Biotecture.
The major building component of an earthship is used automobile tires, filled and compacted with earth to form a rammed-earth brick, encased in steel-belted rubber. These bricks and the resulting load-bearing walls are virtually indestructible. The three-foot thick massive walls and the method of incorporating them into the earth create living spaces with thermal dynamic that results in a stable room temperature.
Recycled cans and bottles are used as filler when packing out tire walls. They are also used like little bricks to form interior non-structural walls. A matrix of cement is formed which is the strength of these walls. The cans and bottles serve no structural or insulative purpose; they simply are a method of forming concrete walls in a low-tech way, using recycled materials instead of more cement and wood.
The thermal-mass construction of the tire walls works with passive-solar gain to create a warm living environment even on a freezing day. A stable mass temperature of 58 degrees trapped in the walls needs a little solar gain to temper up to 70 degrees or whatever your comfort zone is. The lower winter sun shoots deep into the house charging the dense massive walls and the dense floors which in turn release that warmth back into the room when the air temperature of the room starts to drop. Alternately, summer sun does not enter farther than the planter itself.
In addition to the thermal cooling properties of these earth homes, passive ventilation systems assist in maintaining a comfortable temperature. Dormer windows, skylights, and doors can be opened to allow the natural convection of fresh air. Insulated shades against the glass face keep out the hot summer sun and the heat inside on cold winter evenings.
For extremely hot climates a cooling tube can be added. In this case, the incoming air is channelled through a tube and buried 8 feet in the earth, tapping into the cool earth temperature, and drawing cooled air into the house.
There’s a limit to the amount of fresh water on the planet. In order to conserve and protect this precious resource we have developed unique catch water and grey water systems that work together to extend the use of a given amount of water.
Earthships efficiently use fresh water by using it four times. Rain and snow is caught on the roof and funneled into a cistern. This fresh water is prepared by the water-organizing model. This unit consists of a panel of filters and a DC pump which pushes the water into a conventional pressure tank. As water is needed it is filtered, pumped, and pressurized for household use.
Water that drains from the sinks and shower passes through a grease and particle filter, then into a grey water treatment plant where plants flourish from the water. This interior water treatment sill is potentially a food producer, a source of beautiful and fragrant flora, and an oxygen producer in addition to functioning as a cleaner for the grey water.
The extra water not used by the plants drops into a reservoir at the far end of the planter where a pump sends the cleaned grey water to fill the toilet tank for flushing. Used toilet water (known as black water) is flushed outside for treatment in a conventional septic tank. The septic tank we use is solar heated and glazed with a south facing window which enhances the anaerobic breakdown process. The unit functions like a regular septic tank with a line out to a conventional leechfield(?) and an alternative series of rubber-lined planter cells which feed the exterior landscaping while further cleansing the water.
Hot water is attained from self contained solar water heaters with gas on demand water heaters as a backup. The solar hot water is usually mounted onto the systems area and built into the shape of the building.
The systems are packed into a room containing all of the equipment needed to run the earthship except for the cistern which, ideally lies very close to this area. We call this area the Systems Package. The water organizing module, pressure tank, grey water pump panel, batteries, and the power-organizing module are all kept in this small room called the systems package.
An Earthship’s power is generated by the sun and wind. Solar panels and windmills collect energy which is sent to and stored in a bank of batteries located on top of the cistern.
Expanding upon the work of Michael Reynolds, inventor of the Earthship, I would say that a more sustainable and efficient way to harness energy for your Earthship home might be the utlization of Biogas for power using table scraps, and even human waste to generate likely enough energy to meet all your home’s energy needs.