Earthships, which I will hereafter refer to as earthhomes, are a concept introduced in the 1970s, of using waste tires, glass bottles, and cans to create a structure that would be minimally impacting of the environment; off the grid and making its own water, heat and cooling. Exterior walls are constructed of earthfilled tires to provide thermal mass cooling and heating and interior walls are constructed of a honeycomb of empty cans and glass bottles. They are artistically beautiful and the houses appear to rise out of the earth as if by natural commandment.
I have some concerns with earthships, not the least of which is that the term is trademarked and only legal to use if the structure is designed by Michael Reynolds or Earthships Biotecture. I live and breathe them everyday here in Taos, NM and I listen to my friends and clients frustrate about how their homes do not function as designed.
Pros (in theory, but only works in some climates, see notes below)
Energy efficiency: the buildings utilize solar and/or geothermal heat, cooling and hot water, and provide rain and greywater harvesting.
Self-sustainability: grow veggies inside, use and reuse water, and minimize impact on the environment.
Ease of construction: anyone can build an earthhome. If you can pound dirt, you can do it!
Recycling: all the materials, except the clays, come from used products that would otherwise fill up a landfill. Unfortunately, the steel cans and glass bottles they were recycling with almost no recycle cost in the 1970s are not nearly as available today.
Cons
There is actually NO cost savings in designing and building an earthhome over a conventional home or other type, unless you can perform 100% of the work and obtain all the products yourself. Plan on $150 per square foot, minimum.
What they do not tell you is that once the earthhome settles, the breakdown of the rubber tires, which by nature was already in process, now happens in an enclosed environment. Which means, the gas expelled by the tires as they disintegrate collects in the walls, and then suddenly the walls start “farting” from time to time, farting toxic vapors that make people sick. And it is not easy to control whether the gas is expelled inside or out. Choose your poison - poison your self or your environment.
In a humid environment, earthhomes, being within the ground, collect water along their interior wall surfaces, forming a vertical pool for molds and algaes to grow, and often secretly, within the walls of your planting areas, so that (usually) edible plants are infected or overwatered.
In a dry environment, like New Mexico, it is not physically possible to collect enough rainwater to support the house. Many who have earthhomes have to get in their cars, drive 30 minutes to town each way, and buy water just to survive, let alone wash dishes or laundry. The result is that the people that live on the mesa are identified by their tendency to be constantly dirty and having their own special brand of body funk.
Because earthhomes are not designed in concert with the land around them in most cases, and landscaping is just not a concern, they tend to have hot and cold spots. In the summer the galleries at the south wall, where the slanted windows are, are stiflingly hot and humid. The heat is not sweltering in winter, but neither is it comfortable. Also in the winter, because there are not many windows in the north-side rooms, which include ALL of the living spaces, the north ends of the rooms stay at or near earth temperature, that being about 50 degrees. So you have to have a sweater in part of the house and then you strip to your skivvies to pass through to another part of the house and then need your sweater again to settle into that room.
I have never seen a solidly built, leakless, or easy to repair design. The roofs ALWAYS leak.
The pumps to run the greywater and rainwater harvesting mechanisms are LOUD.
They are considered “experimental architecture” and building codes are not designed for experiments. Many locations do not even allow them.
Financing for experiments is rarely available. You will have to find a very special kind of banker to even consider this investment.
It is very challenging to resell an earthhome.
It is very, very challenging to obtain insurance for an earthhome.
Every piece is custom constructed and therefore comes with custom time and custom cost. If you are a do-it-yourselfer, that is great. If you are on a budget, that is not.
Followup
Because I love the look and ability to do-it-yourself qualities of earthships, and I do believe that these projects work in some areas, I offer this advice…
In a temperate or hot environment, with regular rainfall of over 50 inches per year (that falls on the ground – places like Tucson have nearly 80 inches of rain per year, of which 11 hits the ground after evaporation), with plenty of trees, if you are definitely considering landscaping, and are willing to battle the city or county, insurance companies, and banker for your ability to build it, an earthhome might be a good investment. You must live in a place where the home can: be elevated off the valley floor, have excellent access to ventilation (too much can be controlled with trees), have an open face to the south, and have near constant humidity of less than 60%. Slanted windows are NOT a good idea in any environment and shading will be required on south-facing windows. It is critical that a good passive solar designer or architect be involved to make the earthship right for your region. Prepackaged kits will just NOT work for all environments. Cool environments and those with constant humidity set earthhome type architecture up for failure. A viable, proven alternative to the pressed earth in the tires, for those of you who have off-gassing concerns, is adobe. Rammed earth and earthbags are also viable options.
Definitely use the ideas from earthships, including wetlands for greywater harvesting, recycled bottle and can walls, and good passive design techniques as part of your design. Earthship, for all their faults, are a GREAT please to start and find some really wonderful ideas.
