Passive Solar Heating and Cooling

The living spaces of these homes are wrapped on three sides with rammed earth mass walls. This mass acts like a battery, storing radiant heat and direct solar gain within it, releasing this heat as the building cools at night and as the temperatures drop during the winter. In addition, wrapping the east, north and west sides of the buildings in earth berms enables the interiors of the buildings to tap into the stable temperature of the earth's surface, the end result being a daily and seasonal temperature far more stable than conventional housing with average low winter interior temperatures around 60° F (15.6° C). By adding thermal shades which are closed in the evening on the glazed south face, more warmth can be retained.

Passive Ventilation System

Operable vent windows located on the front face and operable skylights at the back of the room are opened allowing natural ventilation. To increase ventilation, the number of vent windows can be increased, and the height of the skylight box can be raised to create a stronger draw. This natural ventilation system ensures that indoor air is healthy.

Insulation

Insulation is an important factor in the performance of these thermal mass buildings. The roof has batt and urethane insulation with an insulative value of R 70. Skylights are triple dome and the glazing is double paned 1” insulated. External doors are of insulated sandwich construction fitted in draft-tight frames.

Photovoltaic Electrical System

These buildings produce their own electricity with a prepackaged photovoltaic power system. This power unit is a pre-designed, pre-built "components"called the Power Organizing Module (POM). It can be installed and hooked up to by any electrician. Pre-designing reduces the need for specialists, therefore lowering the cost. The basic POM unit works with 120 Watt solar panels which can be pole mounted or attached to the front of building. The 8 volt - 6 B/220 Amp. 2.5 K or 4K inverter can be expanded to 8 or more 120W panels and 16-20 batteries. The Earthship power system can be expanded to accommodate larger families and can be supplemented with wind turbines where applicable.

Reduction in Energy Usage

This rammed earth, passive solar structure has "designed down"mechanical systems, enabling its residents to live off of a relatively small solar power system. The idea is to incorporate the most efficient and low energy use equipment and appliances reducing the overall electrical needs. There are no electrical heating demands because of the passive solar design. The glazed south sides of the building admit daylight, eliminating the need to use electrical lighting in the daytime.

Energy Efficient Appliances

All built-in lighting is 24V DC using super-efficient light bulbs. The pumps for the water system are 24V DC, and the most power consumptive appliance, the refrigerator, is a super insulated 24V upright or chest type fridge. The oven is gas because an electric oven is a burden to a photovoltaic system. With the power inverter, most other conventional appliances and tools can be used on this system.

Water

The buildings collect their own water from a unique metal roof, silt catch and cistern system and treat their own sewage through greenhouse technology that allows contained flush toilets. Like the "designed down"power system, the water system in this building reduces the overall water requirements of its inhabitants. Data and calculations that determine how much water a conventional home uses should not be used in determining how much water the occupants will need because this building will use each gallon of water four times.

Catch water systems elicit low water consumption and go hand-in-hand with gray water and black water treatment systems that cleanse and reuse water.

Rain Water Catchment and Storage

This building is designed with a coated metal roof and gutter system that transports rain and snow melt to the ends of the building passing through a funnel which filters large debris and directs the water into two cisterns. These cisterns have the capacity to store 5,000 gallons of water each (more cistern storage may be added as necessary). The cisterns are buried in the earth barmy maintaining stable temperature and away from sunlight therefore reducing the growth of algae.

Pumps and Filters

Water caught on the roof and stored in the cistern flows with gravity pressure to the water organizing module (WOM). The WOM is pre-designed component consisting of four filters (one for drinking water), a 24V pump and pressure gauge. As the water passes through this unit it is filtered and pumped to a pressure tank for household use. From there it is distributed as cold water to the kitchen and bathroom.

Interior Gray Water Treatment

The gray water treatment planter is a lined, contained indoor planter that receives the once-used water from sinks, tubs and washing machines. This water passes through a grease and particle filter to remove large debris so as not to clog up the treatment system. After this filter, the water is taken through a long pathway of pit run pumice to create natural cleaning similar to a mountain stream running and tumbling through rocks and gravel. Also, a certain type of bacteria actually houses itself in the "caverns"of the pumice. This bacteria attacks the bacteria in the gray water. This pathway of pumice is placed in the bottom of a planter designed to hold water.

The planter is designed with baffles to create the longest possible travel distance through the pumice. Above the pumice, the planter is filled with sand and topsoil to accommodate the plants. The plant roots bring oxygen down into the water. This combination of travel through pumice and oxygenation by plant roots cleanses the water to the point where it looks and smells clean. It is not clean enough to drink, but it is clean enough to be used for growing plants both inside and out, as well as to flush your toilet.

Another function of these containment and treatment planters is that the plant roots will suck up a large part of the water. This is called transpiration. The planter is designed to allow maximum travel of the water, and at the same time provide enough plants to absorb most of the water. The more "jungle", the more water will be absorbed by the plants. Twenty square feet of planter per plumbing fixture is recommended as a minimum size.

Food Growing

The water is used twice in a planter creating indoor vegetation and making it possible to grow foods year round.

Gray Water Flush Toilet

At the end of the planter, the treated gray water is stored and ready to be used to flush the toilet, eliminating the need to use fresh drinking water to flush the toilet. The toilet is the third use of the water. After the toilet is flushed, this "black water" sewage is sent out to the outdoor contained black water treatment system.

Black Water Contained Treatment System

Conventional flush toilet systems consume vast amounts of precious fresh water, mix it with human waste and end up putting a large quantity of it back into the earth where it can contaminate future freshwater supplies. By separating gray water from black water, Earthships substantially reduce the volume of water that would end up in public sewage or a septic tank. By using treated gray water to flush the toilet, the overall water need is again reduced. To take this one step further, the contained black water treatment system cleans and uses the waste water so that no waste water leaves the site.

Solar Septic

The black water leaves the building and passes through the solar septic tank which accelerates the anaerobic process by heating the waste with solar energy. The solids break down and are later washed through with the liquid waste. The liquid waste then enters the fully lined bed and travels through layers of gravel, pumice, soil and roots where it is absorbed by plants and cleaned.

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