Autonomous building
An autonomous building is a hypothetical building designed to be operated independently from infrastructural support services such as the electric power grid, gas grid, municipal water systems, sewage treatment systems, storm drains, communication services, and in some cases, public roads. The literature mostly refers to housing, or the autonomous house.
Advocates of autonomous building describe advantages that include reduced environmental impacts, increased security, and lower costs of ownership. Some cited advantages satisfy tenets of green building, not independence per se. Off-grid buildings often rely very little on civil services and are therefore safer and more comfortable during civil disaster or military attacks. For example, off-grid buildings would not lose power or water if public supplies were compromised.
History
1970s
In the 1970s, groups of activists and engineers were inspired by the warnings of imminent resource depletion and starvation. In the United States, a group calling themselves the New Alchemists were famous for the depth of research effort placed in their projects. Using conventional construction techniques, they designed a series of "bioshelter" projects, the most famous of which was The Ark bioshelter community for Prince Edward Island. They published the plans for all of these, with detailed design calculations and blueprints. The Ark used wind-based water pumping and electricity and was self-contained in food production. It had living quarters for people, fish tanks raising tilapia for protein, a greenhouse watered with fish water, and a closed-loop sewage reclamation system that recycled human waste into sanitized fertilizer for the fish tanks.Around 1975–1977, Australian architect and lecturer at University of Sydney School of Architecture, Col James, in collaboration with urban designer, architect, artist, and university tutor Nick Hollo, designed and built an autonomous house on university grounds, in collaboration with students. This taught self-build sustainability to hundreds of students.
1990s
The 1990s saw the development of Earthships, similar in intent to the Ark project, but organised as a for-profit venture, with construction details published in a series of three books by American architect Mike Reynolds. The building material is tires filled with earth. This makes a wall that has large amounts of thermal mass. Berms are placed on exposed surfaces to further increase the house's temperature stability. The water system starts with rain water, processed for drinking, then washing, then plant watering, then toilet flushing, and finally black water is recycled again for more plant watering. The cisterns are placed and used as thermal masses. Power, including electricity, heat and water heating, is from solar power.Some 1990s architects such as William McDonough and Ken Yeang applied environmentally responsible building design to large commercial buildings, such as office buildings, making them largely self-sufficient in energy production. One major bank building in the Netherlands was constructed to be autonomous and artistic as well.
2000s
In 2002, British architects Brenda and Robert Vale wrote:It is quite possible in all parts of Australia to construct a 'house with no bills', which would be comfortable without heating and cooling, which would make its own electricity, collect its own water and deal with its own waste...These houses can be built now, using off-the-shelf techniques. It is possible to build a "house with no bills" for the same price as a conventional house, but it would be smaller.
Advantages
As an architect or engineer becomes more concerned with the disadvantages of transportation networks, and dependence on distant resources, their designs tend to include more autonomous elements. The historic path to autonomy was a concern for secure sources of heat, power, water and food. A nearly parallel path toward autonomy has been to start with a concern for environmental impacts, which cause disadvantages.Autonomous buildings can increase security and reduce environmental impacts by using on-site resources that would otherwise be wasted. Autonomy often dramatically reduces the costs and impacts of networks that serve the building, because autonomy short-circuits the multiplying inefficiencies of collecting and transporting resources. Other impacted resources, such as oil reserves and the retention of the local watershed, can often be cheaply conserved by thoughtful designs.
Autonomous buildings are usually energy-efficient in operation, and therefore cost-efficient, for the obvious reason that smaller energy needs are easier to satisfy off-grid. But they may substitute energy production or other techniques to avoid diminishing returns in extreme conservation.
An autonomous structure is not always environmentally friendly. The goal of independence from support systems is associated with, but not identical to, other goals of environmentally responsible green building. However, autonomous buildings also usually include some degree of sustainability through the use of renewable energy and other renewable resources, producing no more greenhouse gases than they consume, and other measures.
Disadvantages
First and fundamentally, independence is a matter of degree. For example, eliminating dependence on the electrical grid is relatively easy. In contrast, running an efficient, reliable food source can be a chore.Living within an autonomous shelter may also require sacrifices in lifestyle or social opportunities. Even the most comfortable and technologically advanced autonomous homes could require alterations of residents' behavior. Some may not welcome the extra chores. The Vails described some clients' experiences as inconvenient, irritating, isolating, or even as an unwanted full-time job. A well-designed building can reduce this issue, but usually at the expense of reduced autonomy.
An autonomous house must be custom-built to suit the climate and location. Passive solar techniques, alternative toilet and sewage systems, thermal massing designs, basement battery systems, efficient windowing, and the array of other design tactics require some degree of non-standard construction, added expense, ongoing experimentation and maintenance, and also have an effect on the psychology of the space.
Systems
Water
There are many methods of collecting and conserving water. Use reduction is cost-effective.Greywater systems reuse drained wash water to flush toilets or to water lawns and gardens. Greywater systems can halve the water use of most residential buildings; however, they require the purchase of a sump, greywater pressurization pump, and secondary plumbing. Some builders are installing waterless urinals and even composting toilets that eliminate water usage in sewage disposal.
The classic solution with minimal life-style changes is using a well. Once drilled, a well-foot requires substantial power. However, advanced well-foots can reduce power usage by twofold or more from older models. Well water can be contaminated in some areas. The Sono arsenic filter eliminates unhealthy arsenic in well water. However drilling a well is an uncertain activity, with aquifers depleted in some areas. It can also be expensive.
In regions with sufficient rainfall, it is often more economical to design a building to use rainwater harvesting, with supplementary water deliveries in a drought. Rain water makes excellent soft washwater, but needs antibacterial treatment. If used for drinking, mineral supplements or mineralization is necessary.
Most desert and temperate climates get at least of rain per year. This means that a typical one-story house with a greywater system can supply its year-round water needs from its roof alone. In the driest areas, it might require a cistern of. Many areas average of rain per week, and these can use a cistern as small as.
In many areas, it is difficult to keep a roof clean enough for drinking. To reduce dirt and bad tastes, systems use a metal collecting-roof and a "roof cleaner" tank that diverts the first 40 liters. Cistern water is usually chlorinated, though reverse osmosis systems provide even better quality drinking water.
In the classic Roman house, household water was provided from a cistern, which was a decorative feature of the atrium, the house's main public space. It was fed by downspout tiles from the inward-facing roof-opening. Often water lilies were grown in it to purify the water. Wealthy households often supplemented the rain with a small fountain fed from a city's cistern. The impluvium always had an overflow drain so it could not flood the house.
Modern cisterns are usually large plastic tanks. Gravity tanks on short towers are reliable, so pump repairs are less urgent. The least expensive bulk cistern is a fenced pond or pool at ground level.
Reducing autonomy reduces the size and expense of cisterns. Many autonomous homes can reduce water use below per person per day, so that in a drought a month of water can be delivered inexpensively via truck. Self-delivery is often possible by installing fabric water tanks that fit the bed of a pick-up truck.
It can be convenient to use the cistern as a heat sink or trap for a heat pump or air conditioning system; however this can make cold drinking water warm, and in drier years may decrease the efficiency of the HVAC system.
Solar stills can efficiently produce drinking water from ditch water or cistern water, especially high-efficiency multiple effect humidification designs, which separate the evaporator and condenser.
New technologies, like reverse osmosis can create unlimited amounts of pure water from polluted water, ocean water, and even from humid air. Watermakers are available for yachts that convert seawater and electricity into potable water and brine. Atmospheric water generators extract moisture from dry desert air and filter it to pure water.