An autonomous building is a building designed to be operated independently from infrastructural support services such as the electric power grid, municipal water systems, sewage treatment systems, storm drains, communication services, and (in some cases) public roads.
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 building is an idea of western civilization in the 20th century. Inhabitants of cabins, huts and yurts through most of history were off-grid whether they liked it or not.
First and fundamentally, independence is a matter of degree. Complete independence is very hard or impossible to attain. For example, eliminating dependence on the electrical grid is one thing, and growing all of your own food is a more demanding and time-consuming proposition.
This section includes some minimal descriptions of methods, to give some feel for such a building's practicality, provide indexes to further information, and give a sense of modern trends.
Water is the most important utility, and is fast becoming a scarce resource. There are many methods of collecting and conserving water, and use reduction is usually quite cost-effective.
Sewage handling is not attractive, but it is essential for public health. Many diseases are transmitted by poorly functioning sewage systems.
Drainage systems are a crucial compromise between human habitability and a secure, sustainable watershed. Paved areas and lawns or turf do not allow much precipitation to filter through the ground to recharge aquifers. They can cause flooding and damage in neighbourhoods, as the water flows over the surface towards a low point.
Since electricity is an expensive utility, the first step towards conservation is to design a house and lifestyle to reduce demand. Fluorescent lights, laptop computers and gas-powered refrigerators save both electricity and money.
Passive solar heating can heat most buildings in even the coldest climates.
Solar water heaters are widely useful because they can save large amounts of fuel. Also, small changes in lifestyle, such as doing laundry, dishes and bathing on sunny days, can greatly increase their efficiency.
Earth sheltering or annualized passive solar systems substantially reduce the cooling needed by a building. In temperate climates several feet below the earth the average temperature ranges from 4 °C (40 °F) in North Dakota to 26 °C (80 °F), in Southern Florida. Annualized passive solar buildings often have buried, sloped water-tight skirts of insulation that extend 6 m (20 ft) from the foundations, to prevent heat leakage between the earth used as thermal mass, and the surface.
Food production has often been included in historic autonomous projects to provide security. Skilled, intensive gardening can support an adult from as little as 15 square meters of land. Some proven intensive, low-effort food-production systems include hydroponics, and forest gardening.
Telephone and network service will probably be purchased.
If considering a system for the economics, run the numbers with real utility prices. Most utilities have prices 5-10% below the amortized price of the mass-produced rural systems they replace (e.g., electricity will be just below the fuel costs and amortization of a generator powered from natural gas). However, many people pay for utilities from after-tax income, so even the simplest home-based utilities can be 15-45% more efficient by creating untaxed value. Clever purchasing (e.g. in internet co-ops) can cut capital costs.
