Since the Potter's are disconnected from the urban grid, they have to supply their own electricity and water supply which allows for alternative solutions to housing.
Thermal Energy
The Potter House employs two methods of thermal energy: first, through the use of a wood stove and, second, through the use of passive solar gain. Both of these heating methods require minimal amounts of energy and draw from renewable resources. The conventional method of procuring thermal energy requires the use of a furnace which is a redundant and wasteful use of energy, once these other two methods of energy production are employed. The Potter's Earthship has an extensive row of large green house windows fronting the South side of the building; therefore, passive solar gain can be achieved because heat is readily absorbed into the building. Since the structure is not very deep, light and heat can penetrate quite extensively into the house. The Potters feel their house remains at an adequate temperature in the summer months with gains from their passive solar heating during the daytime and the heat emanating from the mass of the building during the night (the tires filled with earth radiate the heat absorbed during the day). Solar Power is used to heat the water needed for the Potter's hot water. In the winter months, the stove is used more often but the principle of mass heating still applies; the earth filled tires still absorb the heat from the wood burning oven and radiate it throughout the day. A conventional wall system only prevents warm air from leaving the house, while the mass heating absorbs and utilizes the heat throughout the day. The reintroduction of the wood burning stove, leads the Potter's house towards a more family oriented dwelling, one that promotes community over isolation.
Solar Panels
The Potter's rely on four solar panels to fuel their house with the electrical energy they require to live comfortably. The Potter's do not use light bulbs during the day as their large windows facing south provide ample light, thereby, decreasing the demand on electrical energy.
Solar Panels are composed of Photovoltaic cells which are comprised of silicon (a semiconductor) which is a material that allows electrons to be energized when exposed to the sun. Consequently the electrons are freeded from their atoms. Electric current can now flow through the material since the electrons are free. Therefore "the current flows in one direction (like a battery), and thus the electricity is generated". This resultant energy is then transformed through a charge controller that prevents the overcharging of the battery, allowing for longer life. Now the electricity traces through the Potter's nickel cadmium battery, which is a deep-cycle battery, that maintains long life by releasing more of is saved energy and outputting minimal current for a longer duration. Since harmful chemicals were something the Potters wanted to avoid, they invested in the nickel cadmium batteries, which can be discharged completely without any harm to the environment. After the battery the electricity is then guided via an inverter, converting the energy into alternating aurrent (AC) loads for the Potters use of ordinary appliances. Other sections of electricity do not get guided through the inverter and become direct current (DC) providing life for the Potter's light bulbs.
Detailing scientifically how solar panels transfer sunlight into electricity is an important issue to understand since this is the Potters only source of electricity. The panels function by using silicon as a semiconductor to transfer the ulta violet rays into usable electricity. Since pure silicon conducts electricity poorly, its electrons are not free to move about. To give silicon a greater conductivity impurities such as phosphorous and boron are added. As a result phosphorous gives the silicon a negative charge and boron imbeds a positive charge to present the silicon with an electric field. This electric field acts as a diode allowing and even pushing the electrons from the positive to negative side.8 Photon's then interact with this electric field to produce an electron flow which provides a current, which causes a voltage. With both current and voltage, we have power, which is the product of the two.
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This technology is not a new revolution for the photovoltaic effect was first observed in 1839 by Edmund Becquerell, a French Physicist. Silicon cells then became more practical in "1953 when scientists developed methods to diffuse certain desirable impurities into the silicon" In 1954 Bell Telephone Laboratories produced single-crystal silicon photovoltaic which converted 6% of the sunlight striking it into electric energy. This efficiency has been greatly improved since with amounts such as "30% of the sunlight being converted into energy." As technology and time move forward the cost, efficiency and acceptance of solar power for everyday living will become a greater force.
Grey Water System
The Potter's grey water system is based upon the basic concept of reusing water. Since the Potter's have constructed a self-sufficient home, they need a well from which they can draw their water. This seemingly limited water supply drives the Potter's efficiency in using water in a limited fashion. The kitchen sink and the shower are the two areas around which grey water system is based. Both the sink and shower drain into separate planters located to the west of each facility. This water, which is fed into the adjacent planters, is very nutritious for small trees and large plants. As the water passes through the planter the plants, gravel and soil help filter the water. This is because the water from the sink is a "tremendous collector of organic matter" and the shower water supplies oils and grim from the human body, which is quite advantageous to the growth of plants. With this constant supply of water and sunlight, the plants grow very quickly and produce bountiful amounts of grown food. Since the Potter House is occupied mostly by only two people, there is not enough water consumption to warrant an external grey water tank. Instead, they just need an overflow pipe which drains outside when the water rises too high in the planter. An additional well is placed at the end of the planter, where the exit pipe makes a U-shape extension so that the planter can be drained by a small pump in case of blockage. Very simple materials are used in the construction of this grey water system, like the filter bucket, which is an ordinary plastic bucket with holes drilled in either side. The overall structure of the planter consists of a water proof liner filled with medium-size rocks, followed with another layer of smaller rocks on top, then a third layer of smaller pebbles on top of these rocks with, fourth, the addition of coarse sand, and then finally, covered by topsoil on the topmost layer. This layering of rock and sediment material constitutes a solid base for the plants so that the large quantities of water which pass through the planter do not wash away the dirt. This grey water system is efficient because it passes the water through two cleaning systems leaving very little waste and, at the same time, acting as a crucial advantage towards the production of food throughout the same process.
Solar Toilet
The Potters' solar composting toilet is yet another example of the devotion to the principles of sustainable architecture. In addition to administering a system that recycles all of their urinary and fecal waste into valuable fertilizer, the toilet does not tax the house's energy resources, by using direct solar energy to power the compost process.
The toilet used by the Potters operates much the same as an outhouse would. They sit on a seat over an open hole, and their urine and excrement falls down a chute into a large chamber, not into a bowlful of drinking water. The wastes are not whisked away by gallons of water through a system of pipes into large septic tanks. Its liquids are not contaminated by chlorine and returned to our drinking water supply, its solids are not buried in landfill, contaminating groundwater sources. Instead, the waste, the biodegradable toilet paper, and the sawdust that the Potters manually toss down the chute to prevent odours is naturally composted in the composting chamber.
The toilet has been built contiguous to an outside wall, to allow for natural ventilation of the toilet stall, and at a slight elevation from the rest of the house, so that the composting chamber can be easily accessed from the outside of the house. The composting chamber opens up to the south side of the house, so that it receives direct rays of sunlight, which serve to heat the composting humanure to a temperature that will kill off any and all of the disease-causing bacteria that it harbours. This means that in short order (a matter of a few months), the manure will be safely converted into humus, which can be used to nurture the Potters' beautiful indoor vegetable garden.
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