Post on 05-Apr-2018
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Tools of the Trade: Sustainability
Final AssignmentAn investigation into the differences in water consumption between
earthships and conventional suburban households
by Markolf von Ketelhodt
Image 1: Source : Epa : united states environmental agency
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Table of Contents
Final Assignment........................................................................................................................................1
An investigation into the differences in water consumption between earthships and conventional
suburban households.........................................................................................................................1
Image 1: Source : Epa : united states environmental agency...........................................................1
Foreword....................................................................................................................................................3
Introduction................................................................................................................................................4
Earthships...................................................................................................................................................5
Water Consumption....................................................................................................................................6
Table 1: Mexico Water Withdrawal & Precipitation Statistics.........................................................6
Graph 1: Water Withdrawal by Sector..............................................................................................7
Comparison between the water consumption of Conventional Houses and that of Earthships.................8
Table 2: Water Used per Activity for different methods..................................................................9
Graph 2: Bar Chart Comparison between Conventional and Water Saving Methods....................10
Illustration 1: Cross section of Earthship........................................................................................13
Table 3: Water Usage per activity of Conventional Households and Earthships...........................15
Graph 3: Earthship vs Conventional Households water consumption per activity........................15
Conclusion and Evaluation......................................................................................................................16
References:...............................................................................................................................................18
Appendix..................................................................................................................................................18
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Foreword
Throughout human history, never has there been a time where many of us live a life of plenty.
Through the rapid evolution of technological innovation the standard of living has increased
tremendously in almost all countries, arguably at different degrees. However, all this progress came
with a darker side that seems to increase at parallel with industrialisation, namely pollution and waste.Natural systems do not produce waste the same way we humans do. The waste of a tree, becomes the
food for countless organisms and eventually decomposes into nutrients and fertilizers for new plants.
Only recently have humans in the industrial age begin to realize that continued linear production of
products and consequential dumping of waste poses fundamental problems. These problems not only
negatively impact the environmental systems, but the very foundation that our civilization is built upon.
There is only a limited amount of time where one is able to recklessly cut down the rainforests, exploit
natural ecosystems and burn non-renewable fossil fuels. The reason for this are now becoming
increasingly intuitive for individuals to understand. Because of globalization and expansion of industry,
we have reached a point of realization that we live on a finite planet with finite resources. The
traditional way of recklessly exploiting natural resources has to come to an end, not only for the sake of
the environment, but for the sake of humanities well-being altogether. What then, are available
alternatives that we can adopt to function under more sustainable circumstances? The obvious point of
reference are the very systems we are currently destroying; the systems that function naturally.
Initiatives to implement such holistic modes of production have been developed and implemented to
some degree in the modern industrial civilization, with terms and practices such as 'recycling' and
'cradle-to-cradle' becoming ever more popular. However, many aspects of our modern life continue to
be inherently unsustainable. Even the 'patch-work' solutions to these problems, such as 'recycling' can
often be more wasteful in terms of energy use, than simply disposing the waste in conventional ways. If
the very nature of the socio-economic system that we have created is inherently unsustainable, then
even many of the tools we are attempting implement are simply not enough to right the many wrongs
of our system. Infinite economic growth, for all countries, can simply not occur on a planet with finite
resources. And this is especially true when a large portion of economic growth is fuelled by a rapidlydepleting non-renewable resource called oil.
It is clear that a fundamental paradigm shift is required to rethink the way we live our lives and
run our economies, which is perhaps a task to big for any government, organization or collective
governing body to undertake. What then can be done? The problem of course is that modern society
functions within a complicated web of a costly, inefficient and resource hungry infrastructure. The
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water that we drink, is often bottled in a different country than the one we call our home. The electricity
we - often wastefully - use is obtained through burning non-renewable fossil fuels, hydro-power which
requires a construction of a dam and flooding of a valley, nuclear power and other forms of electricity
generation which causes numerous environmental problems, economic challenges and has even results
in wars between nations. The majority of the food we eat is farmed in industrial-style mono-crop farmsand often requires hectares of land, the majority of our freshwater, and is sprayed with pesticides and
genetically modified, then 'fed' with artificial oil-based fertilizers. Then once its harvested, it must be
shipped and trucked over large distances until it reaches our plates. The hidden costs of our food is
almost incalculable, especially if you include the environmental impact of soil depletion, increase of
water toxicity due to the pesticides and fertilizers as well as the health costs involved with fighting
multiple-resistant bacteria that become immune to the antibiotics we use in livestock farming. These
hidden financial and environmental costs do not only apply to the realms of food production, but are
scattered throughout the industrial 'eco-system' (economic system) that we rely on.
Introduction
The aim of this paper is to introduce the reader to a means of living that can co-exist with the
current socio-economic structures in place today, but that is able to circumvent many of the
degenerative outcomes that result from the current system. The concept of an Earthship is at the heart
of one of the most sustainable initiatives and solution to the complex problems of the modern era. It
solves the problems associated to water scarcity, electricity production and use, food production andwaste disposal and recycling, all of which are encapsulated in the design and construction of a single
building called the Earthship. This paper will elaborate on the workings of such a building and how it
reduces its ecological footprint on a number of levels. To fully grasp the scope of the earthships
potential, it will be compared with conventional suburban households in regards to the many 'hidden'
costs of maintaining - and living in such buildings. At the end of this paper the reader will not only
have a clearer understanding of the problems associated with conventional housing and living practices,
but will develop an understanding and appreciation of alternative possibilities concerning sustainable
housing which not only shelters its inhabitants but is able to provide small-scales of food production,
waste management and other features that regular houses do not provide they rely on external
facilities to provide these services. Furthermore, this paper aims to show that if the concept of
earthships becomes fully utilized and replaces conventional suburban housing, that the stress on
modern infrastructure will be vastly reduced. Due to the limited scope of this investigation only water,
one aspect of housing is studied and compared in more detail. Quantitative arguments, in regards to
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water consumption will be used to strengthen the case and highlight the differences between
conventional housing and earthships. The two countries that are studied in this investigation concerning
water usage are the United States and Mexico.
Earthships
The concept of earthships has been developed over the past three decades by architect Michael
Reynolds. Earthships are passive-solar autonomous houses that are primarily build using natural or
recycled materials. Each building is designed to capture rainwater from its roof, produce its own
electricity using solar panels, processes its own waste through 'biocells' and produces a large amount of
food products for its inhabitants. The main building blocks of an earthships are discarded tires that are
pounded by hand and sledge hammer with earth to create a almost 200kg brick. These are not only
solid structures to build walls with, but they function as thermal mass, capable of storing and releasing
heat, through which they are capable of naturally regulating the indoor temperature. These principles
function much like a caves, that never get hotter, or colder than the outside environment. The thinner
walls of the interior are build using old soft-drink cans or plastic bottles plastered together to form a
light weight strong and durable wall. Using tires, plastic bottles, and tin cans as building materials
represents one the most effective form of recycling.
These buildings are all designed with sustainability in mind. Compared to conventional houses,
they do not rely on, or burden the national electricity grid, water services, waste disposal services and
to some extent the production and transportation of food. Furthermore, the earthships usage ofelectricity and water are designed in such a way to minimize and save every available kilojoule or drop
of water. For instance, where conventional houses require vast amounts of electricity to heat water and
their living rooms, earthships are designed to trap the natural heat of the sun, as well as using it to heat
water. Water is also used very differently than in conventional housing and these differences will be
discussed more in detail in the following chapters. Another key feature of the earthships is that they can
be designed and customized so that they can function in any climate. The birth of the first earthships
was in the desert of New Mexico, in close proximity to a small town called Taos. Here the summers can
get extremely hot, and the winters extremely cold, yet the inhabitants of earthships require no heating
or cooling systems, because the buildings are designed to allow maximum penetration of the sun into
the buildings during the winter months, and limits the amount of sun light warming the building during
the summer months. Furthermore, passive ventilation is also built into the structures to help regulate
temperatures. The key aspects and sustainable features are not completely unique to earthships. Solar
panels are generating power on conventional homes as well. However, earthships are one of the very
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few buildings that aim to be completely self-sustaining and as energy efficient as possible. One of the
most interesting distinctions between earthships and conventional houses can be made by investigating
the water usage of the two buildings. Investigating the differences between conventional houses water
consumption and that of an earthship will provide the best indications of how much more sustainable
and efficient these earthships are. This investigation will also postulate what it would mean in terms ofwater consumption, if every average household in the United States was replaced by an earthship.
Water Consumption
Fresh water is one of the most crucial natural resources life requires to exist on this planet. In
our industrial age this resource is being aggressively exploited at a much faster rate than it is being
replenished. This has tremendous implications on a number of different aspects of industry, domestic
and international prices of fresh water, structural implications of groundwater harvesting and even
affects international relations. A shocking case study that emphasizes one of the many implications of
uncontrolled fresh water harvesting is the situation of Mexico city. The mega metropolis of Mexico
City has been sinking into the ground due to the excessive depletion of the aquifer that lies beneath the
city. The sinking of the city does not occur evenly and results in many buildings collapsing (800 to
date) or tilting dangerously from their vertical axis. The city has condemned over 50 new structures
since 2006 because they are unsafe to live in. The cities main cathedral and the Sagrario Church
required 6 years and $33 million dollars to restore and preventing collapse. More than 380 fissures
have opened up and cracks appear on the surface, one of which a foot deep and longer than a mile inlength.1These and many other problems associated with the depletion of the water resources, coupled
with the constant threat of earthquakes makes Mexico City a costly project of restoration and
maintenance. These are all hidden costs of unregulated and excessive aquifer depletion. Most of these
problems could have been avoided if the depletion of the aquifers was more strictly monitored and
other methods of water harvesting, such as rain water harvesting would have been utilized.
To further investigate the problems associated with the depletion of aquifers and what potential
rainwater harvesting offers, the following data will be used:
1 http://seattletimes.nwsource.com/html/nationworld/2016310507_mexicosinking25.html
Table 1: Mexico Water Withdrawal & Precipitation Statistics
Mexico Unit 1988-1992 1993-1997 1998-2002 2003-2007 2008-2012
Average precipitation in volume (10^9 m3/yr) 1477 1477 1477 1477 1477
Agricultural water withdrawal (10^9 m3/yr) 62.5 56.1 60.57 61.2
Industrial water withdrawal (10^9 m3/yr) 6.9 7.22 7.4
Municipal water withdrawal (10^9 m3/yr) 9.6 11.16 11.2
Total water withdrawal (10^9 m3/yr) 72.6 78.95 79.8
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The table presents the data concerning water withdrawal for different sectors, as well as
precipitation for Mexico. It was obtained from the Aquastat database and the complete dataset can be
found in the appendix. The raw data as found on the Aquastat database poses a slight problem
concerning the validity of the data. For instance if we look at the 'average precipitation in volume'
variable, we find that the value of 1477 (10^9 m3/yr) is constant for the past 20 years. This of coursereflects a estimate of how much precipitation occurs, but does not reflect the reality. But for the sake of
this research assignment this data will be used, with the acknowledgement of certain inconsistencies
that can be found in any data set one comes across. The main point of this acknowledgement is that any
conclusions drawn in this assignment are only partially validated due to the uncertainty of the data.
Nonetheless, we can clearly see that total water withdrawal of all sectors in Mexico is about 5%
(79.8/1477) of the average annual precipitation. This shows that there is no lack of renewable water
falling from the sky each year. Essentially all of Mexicos water needs could theoretically be satisfied
using water from precipitation instead of natural aquifers. A problem concerning collection and
entrapment of precipitation as well as the distribution of it is rather obvious, which makes a complete
replacement of freshwater through precipitation very difficult to almost impossible. This becomes
increasingly relevant once you consider the information that the following pie diagram presents:
With 77% of all water withdrawal being attributed to the agriculture it becomes obvious that the
thirst of the farming sectors can not be quenched with rainwater harvesting techniques alone. However,
Graph 1: Water Withdrawal by Sector
77%
9%
14%
Water Withdrawal by Sector
Mexico
Agricultural water withdrawal
Industrial water withdrawal
Municipal water withdrawal
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the other thing the jumps out is that municipal water withdrawal is the second largest recipient of fresh
water. The FAOSTAT database definition of the Municipal water withdrawal is the annual quantity of
water withdrawn primarily for the direct use by the population, which includes renewable freshwater
resources as well as potential over-abstraction of renewable groundwater or withdrawal of fossil
groundwater and the potential use of desalinated water or treated waste water
2
. In the case of MexicoCity we can clearly identify that their primary source of freshwater is the fossil groundwater that has
been extract faster than it is replenished causing numerous problems. Although the municipal category
encompasses numerous buildings and facilities of the civilian population, a large amount of the water
consumed can be attributed to family households. Focusing on individual houses is important in the
context of this investigation, because its at individual households where rainwater harvesting can be
most effective specifically in the design of earthships.
The following part of this paper focuses on the differences between the water consumption of
conventional suburban households and that of earthships. The reason why earthships are being
compared to suburban conventional households is that they are more easily comparable than comparing
an earthship with say an apartment building in a city. Earthships are alone standing, solitary buildings
and are best compared to their equivalent counterpart of conventional communities.
Comparison between the water consumption of ConventionalHouses and that of Earthships
In order to compare the water consumption of both models, it is vital to form a coherent
appreciation of how much water the average household requires in conventional buildings. It is
impossible to get data for the exact amount of water each household uses, in each state or country.
Therefore this paper focuses on the average water consumption of a household in just one of the states
of the US. The state in question is Washington and the data was obtained from the Washington
Suburban Sanitary Commission and indicates how much water is used for a specific household activity.
No further information is given concerning how many people live in an average household nor was it
possible to find any additional meta-data on the website.3
The table on the following page is complied using information given by the WSSC, and is
manipulated into SI form in order better aid in this investigation.
2 FAOSTAT, Aquastat, Resources, Water:http://www.fao.org/nr/water/aquastat/data/popups/itemDefn.html?id=4251 ,28.03.2012
3 Washington Suburban Sanitary Commission: http://www.wsscwater.com/home/jsp/content/water-usagechart.faces
http://www.fao.org/nr/water/aquastat/data/popups/itemDefn.html?id=4251http://www.fao.org/nr/water/aquastat/data/popups/itemDefn.html?id=4251http://www.fao.org/nr/water/aquastat/data/popups/itemDefn.html?id=42518/2/2019 Final Assignment ToTS
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[Original values were converted manually from gallons into litres,
and are averages where necessary, see original table in the Appendix]
These figures will be used to get the general appreciation of how much water the average
household uses in the United States. Although this may differ from state to state, this paper assumes
that suburban houses in other states and countries use on average the same amounts of water than those
in Washington. The table shows two categories of how water is used in Washington; there is the
'Conventional' method, and the 'Water Saving*' method. The third 'grey' column represents the
calculated average between the 'conventional' and the 'water-saving' methods water consumption. The
estimates in the (AVERAGE) column will be used at a later stage to compare water usage betweenconventional houses and earthships. But before this can commence, it is important to describe in detail
the data manipulation that was undertaken in order to get these estimates, as well as do some
rudimentary data interpretation. This will help justify the data manipulation that took place.
For now, we shall concentrate on the two 'original' categories of the table, namely the
'conventional' and the 'water-saving' methods. The original estimates were not only converted from
gallons into litres, but in some cases, an average was taken between two estimates, in order to acquire
one value that is easier to work with. For instance, for the activity of 'Toilet (per flush)' the original
table provided the estimated amount of water being used for the 'conventional' method to be between 5
and 7 gallons. In order to convert these into workable SI values, I first converted each estimate
separately and then calculated the mean between the two values, which for the case of flushing toilets
the 'conventional' way is 45.43 litres per flush. This was done for all estimates that provided a range
rather than a concise value. Further more, concerning the estimates of water used for showering, the
meta-data on the website does not provide any explanation if these estimates are per person or per
Table 2: Water Used per Activity for different methods
ActivityLiters Used Liters Used Liters Used
(Conventional) (Water Saving*) (AVERAGE*)
Toilet (per flush) 22.72 9.47 16.095
Shower (per day) 386.1 136.32 261.21
Bath (full tub) 162.77 132.49 147.63
Laundry Machine (full load) 227.12 158.99 193.055
Dishwasher 56.78 33.12 44.95
Dish Washing by hand 113.56 56.78 85.17
Shaving 75.71 13.25 44.48
Brushing Teeth 37.85 9.47 23.66
Washing Hands 7.57 5.68 6.625
TOTAL 1090.18 555.57 822.875
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household. In fact, the original table indicates how much water is used 'per minute' in a shower, as
opposed to 'per day'. These estimates differ from the conventional shower to the water saving shower
(conventional shower = 32.18L/min and water-saving shower = 11.36l/min). Also, the meta-data
provided describes that a conventional shower takes between 7-10 minutes, where as a water-saving
shower takes between 12-15 minutes, which is a rather odd phenomena. Regardless of this, for thepurpose of this investigation I shall assume that the average household requires 12 minutes to shower,
which is about 3 minutes per person for a four people home. Because the other estimated amounts of
water used for the other activities presented in the table are 'per day' estimates, it was important to
convert the 'per minute' shower estimates into 'per day' estimates as well. The following bar chart
indicates how much water each household activity requires, on average each day, for both the
conventional and water-saving methods:
The bar chart on the previous page clearly indicates the differences in the amounts of water
being used between the two methods and also highlights which activities require the most amounts of
water. Clearly, showering in the conventional way requires the most amount of water compared to any
other activity and method . However, we also find that in the water-saving method, showering requires
less water than the laundry machine, which is not the case for the conventional method. These
differences are important to identify, specifically if we want to compare the water consumption of
conventional households (both 'water-saving' and 'conventional') with that of earthships.
Furthermore, Table 2 indicates the total amount of water being used for both types of water
Graph 2: Bar Chart Comparison between Conventional and Water Saving Methods
Toilet (per flush)
Shower (per day)
Bath (full tub)
Laundry Machine (full load)
Dishwasher
Dish Washing by hand
Shaving
Brushing Teeth
Washing Hands
0 50 100 150 200 250 300 350 400 450
23
386
163
227
57
114
76
38
8
9
136
132
159
33
57
13
9
6
Comparison between Conventional and Water Saving Methods(each activities water use (litres) for the average household)
Liters Used (Conventional)
Liters Used (Water Saving*)
Water Used (Litres)
Ac
tiv
ity
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using scenarios. The 'conventional' water usage requires approximately 1090.18 litres of water a day,
compared to the 'water-saving' houses that require about half (555.57 litres) of the water the former
uses. Because there are two different types of water usage evident in conventional housing and the
quantity used differs quite substantially, it remains a difficult process in comparing these estimates with
earthships, that have a completely different methodology of managing the water usage. One possibilityto circumvent this problem is to calculate the average water usage between the 'conventional' and the
'water-saving' methods in order to have one estimate viable for the comparison between earthships and
conventional suburban households as opposed to having two. This is why the third grey column
(AVERAGE) was added into Table 2. In the 'average' column we find that the total amount of water
being used is approximately 822.88 litres a day.
From this point on, the investigation will focus on the 'AVERAGE' litres of water used in
conventional housing. A more extensive and longer report would avoid such simplification of the data.
Nonetheless, the average total of 822.88 litres of water used in a household is a rather conservative
estimation, considering that this does not even include the out door water use for gardening, washing
cars, swimming pools etcetera.
Now that the technicalities regarding the data manipulation have been addressed, and the
interpretation of the data has taken place, it is time to compare the water consumption of conventional
households with that of earthships. In conventional housing each activity uses new/additional fresh
water from the pipes. What sets the earthship apart in this aspect is that it relies solely on rain or snow
water harvesting to meet the water requirements of the household. The roofs of earthships are designed
to channel every drop of rainwater and even dew through a silt catching filter into large underground
cisterns which store up to 4000 litres of water each. Many earthships have multiple cisterns in order to
trap as much water as possible during wet periods, so that they have enough water during drier periods.
The cisterns are designed to gravity feed a WOM (water organization module) which filters out bacteria
and contaminants, and makes it suitable for drinking. The WOM consists of a number of filters and a
DC pump which is powered by the solar panels on the roof. The pump is used to push the water
through the filters and into a conventional pressure tank to create normal household water pressure.
Conventional houses on the other hand, rely on water utilities to provide them with fresh water,
and different utility companies rely on different methods to providing fresh water to a thirsty
population. This paper has earlier demonstrated the problems associated with the conventional
management and supply of fresh water. The problems describe with Mexico City is one extreme
example which discussed most of the hidden costs associated with conventional methods of obtaining
and distributing fresh water. The earthships method of trapping rain water is a far more
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environmentally friendly and sustainable approach of acquiring fresh water. It needs to be stressed that
rainwater harvesting is not unique to earthships, nonetheless it remains an important difference between
earthships and conventional houses. Furthermore, the plumbing of earthships is designed to reuse a lot
of the waste water from different activities. Waste water can be distinguished between two categories;
grey water and black water. Grey water is the waste water generated from domestic activities, such aswashing dishes, washing hands, dishwashers, the waste water from showers etcetera, which can be
recycled on site. It differs from black water or toilet water that requires special sewage treatment. The
earthships plumbing is design in such a way that all of the grey water is recycled in a number of
different ways. Before the grey water can be reused, the earthships plumbing is designed to channel it
through a grease and particle filter and then into a rubber lined botanical cell. The botanical cell is
essentially a flowerbed inside (and/or outside) the living room of an earthship, which is comprised of
multiple layers. The bottom of such a cell is comprised of large rough gravel and rocks, which allows
water to pass through. On top of this layer, there is a layer of smaller gravel and sand, which divides the
larger rocks with the soil on top of it, which encourages plants (even edible plants) to grow. Throughout
the botanical cell oxygenation, filtration, transpiration and bacteria encounter all take place and help to
cleanse the water(Reynolds, 2000) through natural mechanism. The filtration of the grey water is
primarily achieved by passing the water through a mixture of gravel and plant roots. The plant roots
add oxygen to the water, remove nitrogen and absorb some of the water, which transpires through their
leaves. Natural bacteria will grow helping the plants fixate nitrogen and nitrates and further help
cleanse the water. The botanical cells floor is slightly sloped in order to gravity-pull the grey water
from one side to the other. Once it reaches the end of the cell it is directed through a peat moss filter
and then collects in a small reservoir or well. This semi-filtered grey water, although unfit for primary
reuse such as drinking or showering, can/and is used to flush conventional toilets or to water the
gardens. The main precautions that are necessary for the 'healthy' functioning of such a natural filtration
systems, is of course not to pollute them with toxins. In a conventional home, there are no immediate
consequences to the home owner when pouring dangerous chemicals down the drain. In an earthship,
this is discouraged, because if you pour something like paint thinner down your grey water drain, it will
not be healthy for the plants in the botanical cell. There are however, a number of biologically
degradable soaps, shampoos and cleaning agents that can be used in these systems. This, however
requires the conscious use of chemicals by the home owners of an earthship. This may seem limiting to
conventional home owners, but in terms of sustainability and environmental consequences, this
limitation may be viewed as negligible. Furthermore, earthships often have botanical cells placed both
indoors and outdoors. For the process of the grey water coming from sinks and showers an indoor
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botanical cell is used, and the outdoor botanical cells are used to process the grey water from washing
and dish washing machines as well as the over flow of the processed black water. Depending on the
size of the earthship, as well as the number of toilets it has, the grey water of washing machines and/or
dishwashers can also be processed indoors. To prevent flooding the indoor botanical cells, calculations
need to be made before hand to determine how many people will live in the earthship and use the toiletwhich will flush out the excess grey water.
The black water or toilet water, is non-reusable waste water and is sent to a outdoor solar-
enhanced septic tank which stores the sun's heat in its concrete mass to help anaerobic processes to
break down the solids. The excess semi-filtered black water over flows and is channelled into an
outdoor landscaping plant bed that is similar to the indoor botanical cells. This is also where the grey
water from washing and dishwashers end up in, if the indoor botanical cell is too small to process these
amounts of grey water. The following schematic illustrates the use of water in an earthship as well as
many of its other unique features that make it one of the most sustainable houses ever designed:
An earthship provides a small scale sewage treatment facility that is modelled after natural
decomposition and recycling processes. Furthermore, the flexibility of the earthships design allows it to
be connected to traditional utilities for water and waste management. However, this is often only done
in areas where there is either too little natural rainfall to satisfy the water needs (which rarely is the
Illustration 1: Cross section of Earthship
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case) or in areas of extreme climate, where outdoor temperatures are too cold to process the black water
waste. However, because of the ongoing innovation in the design of earthships, even these difficulties
are now overcome. In extremely cold climates such as Norway, earthships are designed with a double-
greenhouse, in which the outer green houses encapsulates the black water treatment botanical cells, and
the inner green house functions as the conventional grey water treatment botanical cells that allow foredible plants to be grown. These greenhouses also function as an crucial aspect of the interrior climate
control system, regulating temperature and humidity. Waste in an earthship is no longer seen as waste,
but as nutrients for other purposes. All this is not to say that an earthship does not produce any
chemical waste at all. Batteries need to be exchanged and disposed of every few years, so do light
bulbs, but the extent to which the waste is managed and disposed of is extremely reduced compared to
conventional houses.
The task of quantifying all of the sustainable features of earthships and comparing them with
conventional housing will prove to be a too large scope for this investigation. Solely concentrating on
the usage of water simplifies this task to a great degree. To compare the water usage of earthships with
conventional households a number of assumptions need to be made. Because earthships, much like
conventional houses differ in size and scope, I will assume that they require the same amount of water
for each activity as the 'average' conventional household does. This information is encapsulated in the
'grey' column of Table 2. The major difference of course lies in the fact that earthships require no
additional new water for flushing the toilets, but instead use grey water for this task. Furthermore,
earthships require no additional water for watering out door plants during dry periods, because their
waste water full fills this task. According to the WSSC the average household in requires between 630-
1860 gallons (2000-7000 litres) of water an hour for out door activities (see Appendix for table).
The other main difference between earthships and conventional houses, is that only a few
conventional houses actually make use of water saving devices, while a majority of them use the
conventional way. The exact ratio between how many houses use 'conventional' and 'water-saving'
methods is unknown, but the term 'conventional' indicates an implicit normality to the term, hence it is
rather likely that the majority of conventional households use the 'conventional' method of using water.
This further emphasizes the conservativeness of the estimated 'average' household usage. Nonetheless,
the water use in earthships is radically reduced because all earthships are designed to use low flow
show heads, low water use washing machines and other water saving devices. Therefore it can be
assumed that the water usage of the average earthship is similar to the 'water-saving' methods that some
conventional households have. In order to compare earthships with conventional houses, the estimates
of strictly 'water-saving' methods are attributed to the earthships and the calculated 'average' water
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usage, will be attributed to conventional households. These presumptions should be justified
considering the extensive descriptions and analysis offered on the previous pages.
The following table presents the assumed water consumption of earthships and the calculated
average water consumption of conventional households:
The following bar chart visualizes the information from the table and helps with comparing the
amounts of water being used per activity between earthships and conventional households:
Graph 3: Earthship vs Conventional Households water consumption per activity
Toilet (per flush)
Shower (per day)
Bath (full tub)
Laundry Machine (full load)
Dishwasher
Dish Washing by hand
Shaving
Brushing Teeth
Washing Hands
0 50 100 150 200 250 300
16
261
148
193
45
85
44
24
7
0136
132
159
33
57
13
9
6
Earthship vs Conventional Household
(comparrison of water consumption per activity)
Conventional Household
Earthship
Litres of Water
Ac
tiv
ity
Table 3: Water Usage per activity of Conventional Households and Earthships
ActivityLiters Used Liters Used
(Conventional Household) (Earthship)
Toilet (per flush) 16.10 0
Shower (per day) 261.21 136.32
Bath (full tub) 147.63 132.49
Laundry Machine (full load) 193.06 158.99
Dishwasher 44.95 33.12
Dish Washing by hand 85.17 56.78
Shaving 44.48 13.25
Brushing Teeth 23.66 9.47
Washing Hands 6.63 5.68TOTAL 822.89 546.1
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The one difference between the earthships water consumption and the 'water-saving' estimates
of conventional households, is that the earthship requires no additional water to flush toilets, because it
uses filtered grey water. This lowers the earthship water consumption by approximately 9.5 litres a day,
compared to the 'water-saving' estimates of conventional households. This may not seem like much, but
9.5 litres a day equate to 3467.5 litres a year, which are solely used for flushing a toilet.The graph on the previous page illustrates that the majority of the water used in earthships is
attributed to laundry machines. Another interesting thing about these graphs and the data provided by
the WSSC is that they indicate differences in water consumption between shaving, brushing teeth and
washing dishes by hand for different methods of water consumption. It seems in an earthship you use
less than half the water for shaving, than what you would use in a conventional household. These
differences cannot solely be attributed to physical water-saving devices, but are probably determined
by the way individuals use the water themselves. After all, leaving the tap running while shaving and
brushing teeth requires a lot more water than if you only use the tap when washing off the shaving
cream or tooth paste once your done. These differences in behaviour undoubtedly have a significant
influence on the water consumption of a household and are rather difficult to capture in a statistical
value or estimate.
Conclusion and Evaluation
Regardless of the many implications surrounding the data, and the many assumptions that were
necessary to arrive at a conclusion, this investigation has been able to provide a framework in which toestimate the differences in water consumption between earthships and conventional households. A
conservative estimate of the amount of water being used in conventional households is around 823
litres a day, which equates to a little over 300,000 litres a year. In comparison, earthships only use an
estimated 546 litres a day, equating to a little under 200,000 litres a year. This is 1/3 reduction of water
consumption by a single household. Furthermore, if you take into account that these 200,000 litres used
by earthships do not come from underground fossil water aquifers, large dams, or other conventional
fresh water sources, but from harvesting water from rain and snow fall, it becomes clear how much less
pressure is put on the environment.
The United States of America has a little over 300 million inhabitants, who live in
approximately 125 million houses. Not all of these house are alone standing 'conventional' households,
but if only one fifth (25 million) of these houses were replaced by earthships, that all harvest their own
rain water and take care of their own sewage, the US would save approximately 2.5 trillion litres of
water a year. Many of the technologies concerning water-saving can be implemented into conventional
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households as well. However, what sets the earthship apart, is that its efficiency in water use, is not its
only characteristic. The efficiency of its water management and recycling processes is just a fraction of
what earthships are capable of in terms of sustainability. Their electricity use is just as impressive as its
efficiency in reducing the amount of water it requires. More all-encompassing research needs to be
undergone in order to fully appreciate the benefits of earthships in quantitative terms. Nonetheless, thisinvestigation aimed to demonstrate one aspect of the effectiveness of the intelligent design of
sustainable housing. Earthships are just one of the more effective and impressive alternative sustainable
housing solutions, the use waste as building materials, and natural processes for electricity production
and water management. One of the more pressing issues concerning earthships is that their design will
be hard to incorporate into existing cities and high rise buildings. But there would be no problem in
replacing every single suburban household with an earthship, or retrofitting existing houses with the
technological mechanisms that make the earthship so sustainable. The only thing hindering the
expansion such efforts is the lacking appreciation of societies need for a sustainable revolution.
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References:
1. Seattle Times, Mexico City copes with that sinking feelinghttp://seattletimes.nwsource.com/html/nationworld/2016310507_mexicosinking25.html
2. FAOSTAT, Aquastat, Resources, Water:http://www.fao.org/nr/water/aquastat/data/popups/itemDefn.html?id=4251 , 28.03.2012
3. Washington Suburban Sanitary Commission:http://www.wsscwater.com/home/jsp/content/water-usagechart.faces
4. Earthship Information: http://www.appropedia.org/Earthship, 28.03.2012
Appendix1. FAOSTAT raw data:
Mexico Unit 1988-1992 1993-1997 1998-2002 2003-2007 2008-2012
Total population 87523 95441 102634 109221 112033
Rural population 24264 24874 25317 25200 25173
Urban population 63259 70567 77317 84021 86860
Average precipitation in volume (10^9 m3/yr) 1477 1477 1477 1477 1477
National Rainfall Index (NRI) (mm/yr) 1199 1171 1052
Agricultural water withdrawal (10^9 m3/yr) 62.5 56.1 60.57 61.2
Industrial water withdrawal (10^9 m3/yr) 6.9 7.22 7.4
Municipal water withdrawal (10^9 m3/yr) 9.6 11.16 11.2
Total water withdrawal (10^9 m3/yr) 72.6 78.95 79.8Municipal water withdrawal as % of total withdrawal (%) 13.22 14.14 14.04
Total water withdrawal per capita 707.4 722.8 712.3
Municipal water withdrawal per capita (total population) 93.54 102.2 99.97
Produced wastewater (10^9 m3/yr) 9.4 13.34
Treated wastewater (10^9 m3/yr) 1.92 2.596 3.11
Direct use of treated wastewater (10^9 m3/yr) 0.28
United States of America Unit 1988-1992 1993-1997 1998-2002 2003-2007 2008-2012
Total population 258276 272643 288467 302285 307687
Rural population 62009 59932 58320 56230 55394
Urban population 196267 212711 230147 246055 252293
Average precipitation in volume (10^9 m3/yr) 6885 6885 6887 6887 7030
National Rainfall Index (NRI) (mm/yr) 1020 1005 938.7
Agricultural water withdrawal (10^9 m3/yr) 194.7 195.6 196.5 192.4
Industrial water withdrawal (10^9 m3/yr) 207.1 210.1 213 220.6
Municipal water withdrawal (10^9 m3/yr) 60.67 62.31 63.95 65.44
Total water withdrawal (10^9 m3/yr) 462.5 468 473.4 478.4
Municipal water withdrawal as % of total withdrawal (%) 13.12 13.31 13.51 13.68
Total water withdrawal per capita 1791 1717 1641 1583
Municipal water withdrawal per capita (total population) 234.9 228.5 221.7 216.5
Produced wastewater (10^9 m3/yr) 76.75
Treated wastewater (10^9 m3/yr) 48.71
Direct use of treated wastewater (10 9 m3/yr) 1.284
(1000 inhab)
(1000 inhab)
(1000 inhab)
(m3/inhab/yr)
(m3/inhab/yr)
(1000 inhab)
(1000 inhab)
(1000 inhab)
(m3/inhab/yr)
(m3/inhab/yr)
http://seattletimes.nwsource.com/html/nationworld/2016310507_mexicosinking25.htmlhttp://www.fao.org/nr/water/aquastat/data/popups/itemDefn.html?id=4251http://www.wsscwater.com/home/jsp/content/water-usagechart.faceshttp://www.appropedia.org/Earthshiphttp://www.fao.org/nr/water/aquastat/data/popups/itemDefn.html?id=4251http://www.appropedia.org/Earthshiphttp://www.wsscwater.com/home/jsp/content/water-usagechart.faceshttp://seattletimes.nwsource.com/html/nationworld/2016310507_mexicosinking25.html8/2/2019 Final Assignment ToTS
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2. Washington Suburban Sanitary Commission Data Tables:
3.