Encyclopedia > Autonomous building
Autonomous building
Autonomous buildings have several advocates. Members of the Green movement approve because the buildings usually minimize environmental impact. Businessmen sometimes install them to increase profit. Advocates of emergency preparedness also favor them, because they make civil society less fragile. Most autonomous systems are used in areas far from networked systems.
The usual argument in favor of autonomous buildings attempts to show that the distribution networks have larger inefficiencies (i.e. a cost of continuing waste) and capital expenses than simply providing the service with the building. The usual counter-argument is that those inefficiencies and capital expenses are easily borne in urban concentrations.
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Food production is a part of many autonomous homes, though not of many commercial buildings. Most such enthusiasts desire only the security of potential independence from the world food-production network. They usually use high-intensity vegetable gardening. A few advanced projects (see below) have included hydroponics and fish farms.
Pebble-bedded container-based hydroponics produces vegetables as intensively as any other method, often with far less work than dirt farming, because weeds are efficiently suppressed, and no bed preparation is required.
Another high density, low-work approach is forest gardening, in which perennial, compatible edible species are planted in 'canopies': tree, shrub, ground-cover, climbing-vine, and rhizome (root). The density of food plants is said to be so high that wild plants have trouble invading.
Most food-production experiments have used vegetable farming because it can support an adult from as little as fifteen square meters of land.
Water is the most important utility. There are many methods of collecting and conserving it.
Most desert and temperate climates can be assured of more than 25cm (10 inches) of rain per year. This means that a typical one-floor bungalow or ranch house with a greywater system can supply its year-round water needs from its roof. In the most extreme areas it will require a cistern of 30 cubic meters. Many areas average a half inch of rain per week. These can use a cistern as small as ten cubic meters. It can be convenient to use the cistern as a heat sink or trap for a heat pump or air-conditioning system; however this limits its usefullness for drinking water.
Greywater systems reuse wash water to flush toilets, water lawns and gardens. Greywater systems roughly halve the water use of most residential buildings, at the expense of a sump, greywater pressurization pump and secondary plumbing.
In a drought, water could be delivered each month, or as needed. Fabric water tanks can be purchased that fit the bed of a pick-up truck.
In some areas, it is difficult to keep a roof clean enough to assure that the water collection is sanitary for drinking. Commercial reverse osmosis systems provide good quality drinking water. Some persons might choose to attach devices to remineralize drinking water, or drink bottled water.
Water makers are available for yachts that convert seawater and electricity into potable water and brine.
Sewage handling is not attractive, but it is essential for public health. Many diseases are transmitted by poorly functioning sewage systems.
Composting or packaging toilets make it economical and sanitary to throw away sewage as part of the normal garbage collection service. They also reduce water use by half, and eliminate the difficulty and expense of septic tanks, which are designed to eliminate excess water from sewage.
State of the art home sewage treatment systems use biological treatment, usually beds of plants and aquaria, that eliminate nutrients and bacteria and convert greywater and sewage to clear water. This odor and color-free reclaimed water can be used to flush toilets and water outside plants. When tested, it approaches standards for potable water. In climates that freeze, the plants and aquaria need to be kept in a small greenhouse space. Good systems need about as much care as a large aquarium.
A big disadvantage of living sewage treatment systems is that if the house is empty, the sewage system starves to death.
Storm water presents problems in servicing new and existing neighbourhoods.
Paved areas and lawns or turf do not allow for much precipitation to filter through the ground to recharge aquifers. This can cause flooding and damage in neighbourhoods, as the water flows over the surface towards a low point.
Typically, elaborate, capital-intensive storm water management systems are engineered to deal with storm water. In some cities, such as much of the old City of Toronto[?] the storm water system is combined with the sanitary sewer system. In the event of heavy precipitation, the load on the sewage treatment plant at the end of the pipe[?] becomes too great to handle and raw sewage is dumped in to holding tanks, and sometimes into the lake.
Autonomous buildings can address precipitation in a number of ways:
If a water-absorbing swale for each yard is combined with permeable concrete streets, storm drains can be omitted from the neighbourhood. This can save more than $500 per house by eliminating storm drains. One fine way to use the savings is to purchase larger lots, which permits more amenitiies at the same cost. Permeable concrete is an established product in warm climates, and in development for freezing climates. In freezing climates, eliminating storm drains can often still purchase enough land to construct swales instead, which still provides more land for homeowners.
A green roof captures precipitation and uses the water to grow plants. It can be built into a new building or used to replace an existing roof.
Using a solar roof, solar cells can currently (2001) provide electric power. Solar roofs are far more cost-effective than retrofitted solar power.
Most areas that lack sun have winds. In these areas, to generate its own power, a house would need a small wind turbine, five meters or less in diameter. On a thirty meter tower, it can provide enough power to supplement the solar power on cloudy days. Commercially-available wind-turbines use sealed, one-moving-part AC generators and passive self-feathering blades for years of operation without service.
The largest advantage of wind-power is that larger wind turbines have a lower per-watt cost than solar cells, if there is wind. However location is critical, because some locations lack sufficient wind for an economical installation. In the Great Plains of the United States a ten meter turbine may be able to supply enough energy to heat and cool a well-built all-electric house.
Batteries need to be replaced every few years. In many areas, battery expense can be eliminated by attaching the building to the electric power grid and operating the power system with net metering. Such a building is less autonomous, but more economical and sustainable.
In areas that lack access to the grid, battery size can be reduced by including a generator to recharge the batteries in extended low-power times. Auxiliary generators are usually run from bottled gas, or sometimes diesel.
Recent advances in passively-stable magnetic bearings may someday permit inexpensive storage of power in a flywheel in a vacuum. Well-funded groups are also working to develop a "regenerative fuel cell", a device that can generate hydrogen and oxygen when power is available, and combine these efficiently when power is needed.
Passive solar heating can heat most buildings in even the coldest climates.
Modern krypton or argon-insulated windows permit normal-looking windows to provide most of the heat without structural weakness. The basic tricks are that the windows must face the prevailing sunlight (usually south), and the building must incorporate thermal mass to keep it warm in the night.
If small amounts of gas, oil or wood heat are available for the coldest nights, a properly designed slab, or basement cistern can inexpensively provide the thermal mass. In cold climates, construction costs can be as little as 15% more than new conventional buildings. In warm climates (less than two weeks of frosty nights), there is no cost impact.
A small supplementary heater can reduce the required amount (and expense) of thermal mass substantially. A popular system for ultra-high-efficiency houses is a central hydronic air heater that recirculates hot water from a water-heater. Whether the water-heater is gas or electric depends on local prices.
Houses designed to cope with interruptions in civil services generally incorporate a wood stove, or heat from diesel fuel or bottled gas.
The windows must be shaded in summer. Eaves can be overhung to provide the necessary shade. These also shade the walls of the house, reducing cooling costs.
The basic trick is to cool the building's thermal mass at night, and then cool the building from the thermal mass during the day. It helps to be able to route cold air from a sky-facing radiator (perhaps an air-heating solar collector with an alternate purpose) or evaporative cooler directly through the thermal mass. On clear nights, even in tropical areas, sky-facing radiators can cool below freezing.
If a circular building is aerodynamically smooth, and cooler than the ground, it can be passively cooled by the "dome effect." Many installations have reported that a reflective or light-colored dome induces a local vertical heat-driven vortex that sucks cooler overhead air downward into a dome if the dome is vented properly (a single overhead vent, and peripheral vents). Some persons have reported a temperature differential as high as 15F between the inside of the dome and the outside. Buckminster Fuller discovered this effect with a simple house design adapted from a grain silo, and adapted his Dymaxion house and geodesic domes to use it.
Refrigerators and air conditioners operating from the waste heat of a diesel engine exhaust, heater flue or solar collector are theoretically possible using the same principles as a gas refrigerator. A truck-trailer refrigerator operating from the waste heat of a tractor's diesel exhaust was demonstrated by NRG Solutions, Inc. 11385 Shipley Road Johnstown, OH 43031, for EPA contract No. 68D98131. NRG developed a hydronic ammonia-gas heat-exchanger and vaporizer, the two essential new, not-commercially-available components of a waste-heat-driven refrigerator.
A similar scheme (multiphase cooling) can be by a multistage evaporative cooler. The air is passed through a spray of salt solution to dehumidify it, then through a spray of water solution to cool it, then another salt solution to dehumidify it again. The brine has to be regenerated, and that can be done economically with a low temperature solar still. Multiphase evaporative coolers can lower the air's temperature by 50F, and still control humidity. If the brine regenerator uses high heat, they also partially sterilise the air.
If enough electric power is available, cooling can be provided by conventional air conditioning using a heat pump.
Telephone and network service will probably be purchased.
Network service could be provided by a cooperative of neighbors, each operating a router as a household appliance.
Wireless routers operating a radio-based protocol such as IEEE 802.11b can commoditize information services into products that can be purchased, and minimize long-distance infrastructure, and its costs and vulnerabilities.
Simple simulations show that even quite high-density developments can still provide web and e-mail services using radio-based protocols. This is already being done to some extent (much to the chagrin of some commercial network service providers.)
Satellite internet service also can provide high-speed connectivity to remote locations, but as of early 2002, most of these services are limited in which types of network hardware and operating systems they support. They are also not yet on-par with the costs of cable modem or DSL service providers.
Modern office buildings are largely self-sufficient in heat, and could be self-sufficient in water and sewage. A major bank building (ING's Amsterdam headquarters) in the Netherlands was constructed to be autonomous, and artistic as well.
Food refrigeration, water heating and cooking can be electric, if perfect autonomy is needed. The battery costs are very high.
A small source of auxiliary heat and power permits all the storage systems to be less expensive and provides a backup option (for comfort) when something breaks.
In most areas, bottled gas is more convenient for these services, and can provide auxiliary heat, refrigeration and (with a generator) power for exceptional conditions (extended foggy conditions, etc.) A wood stove or an efficient fireplace could provide homey heating in wooded areas.
Some persons concerned about civil upsets advocate diesel-fuel-based systems, because then the building's auxiliary services and vehicles can be operated from a single fuel. Diesel stoves, heaters, water heaters and generators are commercially available.
Refrigerators operating from waste-heat may soon be comemrcially available. A refrigerator similar to a gas refrigerator could theoretically be operated from many sources of waste heat. See the section above, about air cooling.
In ancient Roman houses, the center of the rich man's atrium house was a cistern, fed from the roof during rain, and purified by water lilies. Sewage services were the street, obviously unacceptable in a modern city. Heat was by braziers, and a central fire.
Dymaxion house
In the 1950s, Buckminster Fuller's Dymaxion house used most of the above principles to operate without city services other than telephone and road. Notable inventions included a "fogger" to reduce water use when cleaning people, a packaging toilet, a vacuum turbine for electric power and a very clever bathroom. See the Wikipedia article for more information.
New Alchemists
In the 1970s, a group of activists and engineers that called themselves the "New Alchemists" believed the warnings of imminent resource depletion and starvation. The New Alchemists were famous for the depth of research effort placed in their projects. Their dedication, and the depth of their work is still impressive.
They designed a series of "bioshelter" projects, the most famous of which was the "Ark Bioshelter" for Prince Edward Island. They published the plans for all of these, with detailed design calculations and blueprints. Later research reports followed-up on the results.
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.
The Ark used quite conventional construction techniques. This may be an advantage, because these techniques are very refined.
In 2002 the successor organization to the New Alchemists still had a web page up as the Green Center (http://www.fuzzylu.com/greencenter/index.htm).
Earthships (http://www.earthship.org)
This is a more recent effort, very similar in intent to the Ark project. All the details are different; in particular, the Earthships are clearly a "for profit" effort. The depth of research is harder to evaluate, because most of it is held as proprietary information.
The building material is tires filled with earth. This makes a wall that has large amounts of thermal mass (see earth sheltering). 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.
The emphasis on gardening is to provide some degree of autonomy in food.
Bottled propane is used to round out energy needs. This is a sensible choice- it is clean, and saves a lot of construction that would otherwise be needed to chase diminishing returns in electricity and heating.
- "Natural Capitalism" by Amory Lovins and the Rocky Mountain Institute. The section about the banana plant in the Rocky Mountains is especially amusing.
- Also see "A Fuller Explanation" by Amy Edmondson, one of B. Fuller's later adjuvants; an online copy is available here (http://www.angelfire.com/mt/marksomers/40).
- The Buckminster Fuller Institute (http://www.bfi.org) is still in existence. B. Fuller left thousands of pages of notes to the university where he last taught.
- There is a section on Autonomous Houses (http://reality.sculptors.com/cgi-bin/wiki?Autonomous_Houses) in the on Reality Sculptors (http://reality.sculptors.com/cgi-bin/wiki) wiki, including links to a mailing list which frequently discusses autonomous design considerations.
- Designs for a geodesic dome version of an Autonomous House can be found at http://reality.sculptors.com/~salsbury/House/
See also: eco-village
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