Appropriate technology is a movement (and its manifestations) encompassing technological choice and application that is small-scale, decentralized, labor-intensive, energy-efficient, environmentally sound, and locally autonomous. It was originally articulated as intermediate technology by the economist Dr. Ernst Friedrich “Fritz” Schumacher in his work Small is Beautiful. Both Schumacher and many modern-day proponents of appropriate technology also emphasize the technology as people-centered.
Appropriate technology has been used to address issues in a wide range of fields. Well-known examples of appropriate technology applications include: bike- and hand-powered water pumps (and other self-powered equipment), the universal nut sheller, self-contained solar lamps and streetlights, and passive solar building designs. Today appropriate technology is often developed using open source principles, which have led to open-source appropriate technology (OSAT) and thus many of the plans of the technology can be freely found on the Internet. OSAT has been proposed as a new model of enabling innovation for sustainable development.
Appropriate technology is most commonly discussed in its relationship to economic development and as an alternative to technology transfer of more capital-intensive technology from industrialized nations to developing countries. However, appropriate technology movements can be found in both developing and developed countries. In developed countries, the appropriate technology movement grew out of the energy crisis of the 1970s and focuses mainly on environmental and sustainability issues. Today the idea is multifaceted; in some contexts, appropriate technology can be described as the simplest level of technology that can achieve the intended purpose, whereas in others, it can refer to engineering that takes adequate consideration of social and environmental ramifications. The facets are connected through robustness and sustainable living.
Building and construction
In order to increase the efficiency of a great number of city services (efficient water provisioning, efficient electricity provisioning, easy traffic flow, water drainage, decreased spread of disease with epidemics, …), the city itself must first be built correctly. In the developing world, many cities are expanding rapidly and new ones are being built. Looking into the cities design in advance is a must for every developing nation.
Adobe (including the variation called Super Adobe),
Compressed earth block,
and/or other green building materials could be considered appropriate earth building technology for much of the developing world, as they make use of materials which are widely available locally and are thus relatively inexpensive.
The local context must be considered as, for example, mudbrick may not be durable in a high rainfall area (although a large roof overhang and cement stabilisation can be used to correct for this), and, if the materials are not readily available, the method may be inappropriate. Other forms of natural building may be considered appropriate technology, though in many cases the emphasis is on sustainability and self-sufficiency rather than affordability or suitability. As such, many buildings are also built to function as autonomous buildings (e.g. earthships, …). One example of an organisation that applies appropriate earthbuilding techniques would be Builders Without Borders.
The building structure must also be considered. Cost-effectiveness is an important issue in projects based around appropriate technology, and one of the most efficient designs herein is the public housing approach. This approach lets everyone have their own sleeping/recreation space, yet incorporate communal spaces e.g. mess halls, latrines, public showers, …
In addition, to decrease costs of operation (heating, cooling, …) techniques as Earth sheltering, Trombe walls, … are often incorporated.
Organizations as Architecture for Humanity also follows principles consistent with appropriate technology, aiming to serve the needs of poor and disaster-affected people.
Natural ventilation can be created by providing vents in the upper level of a building to allow warm air to rise by convection and escape to the outside, while cooler air is drawn in through vents at the lower level.
Electrical powered fans (e.g. ceiling fans) allow efficient cooling, at a far lower electricity consumption as airconditioning systems.
A solar chimney often referred to as thermal chimney improves this natural ventilation by using convection of air heated by passive solar energy. To further maximize the cooling effect, the incoming air may be led through underground ducts before it is allowed to enter the building.
A windcatcher (Badgir; بادگیر) is a traditional Persian architectural device used for many centuries to create natural ventilation in buildings. It is not known who first invented the windcatcher, but it still can be seen in many countries today. Windcatchers come in various designs, such as the uni-directional, bi-directional, and multi-directional.
A passive down-draft cooltower may be used in a hot, arid climate to provide a sustainable way to provide air conditioning. Water is allowed to evaporate at the top of a tower, either by using evaporative cooling pads or by spraying water. Evaporation cools the incoming air, causing a downdraft of cool air that will bring down the temperature inside the building.
Appropriate technology has been applied extensively to improve agricultural production in developing countries. In the United States, the National Center for Appropriate Technology operates ATTRA (attra.ncat.org), a national sustainable agriculture assistance program.
Water and sanitation
As of 2006, waterborne diseases are estimated to cause 1.8 million deaths each year while about 1.1 billion people lack proper drinking water.
Water generally needs treatment before use, depending on the source and the intended use (with high standards required for drinking water). The quality of water from household connections and community water points in low-income countries is not reliably safe for direct human consumption. Water extracted directly from surface waters and open hand-dug shallow wells nearly always requires treatment.
Appropriate technology options in water treatment include both community-scale and household-scale point-of-use (POU) designs.
The most reliable way to kill microbial pathogenic agents is to heat water to a rolling boil. Other techniques, such as varying forms of filtration, chemical disinfection, and exposure to ultraviolet radiation (including solar UV) have been demonstrated in an array of randomized control trials to significantly reduce levels of waterborne disease among users in low-income countries.
Over the past decade, an increasing number of field-based studies have been undertaken to determine the success of POU measures in reducing waterborne disease. The ability of POU options to reduce disease is a function of both their ability to remove microbial pathogens if properly applied and such social factors as ease of use and cultural appropriateness. Technologies may generate more (or less) health benefit than their lab-based microbial removal performance would suggest.
The current priority of the proponents of POU treatment is to reach large numbers of low-income households on a sustainable basis. Few POU measures have reached significant scale thus far, but efforts to promote and commercially distribute these products to the world’s poor have only been under way for a few years.
On the other hand, small-scale water treatment is reaching increasing fractions of the population in low-income countries, particularly in South and Southeast Asia, in the form of water treatment kiosks (also known as water refill stations or packaged water producers). While quality control and quality assurance in such locations may be variable, sophisticated technology (such as multi-stage particle filtration, UV irradiation, ozonation, and membrane filtration) is applied with increasing frequency. Such microenterprises are able to vend water at extremely low prices, with increasing government regulation. Initial assessments of vended water quality are encouraging.
Whether applied at the household or community level, some examples of specific treatment processes include:
Porous ceramic filtration, using either clay or diatomaceous earth, and oriented as either cylinder, pot, or disk, with gravity-fed or siphon-driven delivery systems. Silver is frequently added to provide antimicrobial enhancement
Intermittently operated slow-sand filtration, also known as biosand filtration
Chlorine disinfection, employing calcium hypochlorite powder, sodium hypochlorite solution, or sodium dichloroisocyanurate (NaDCC) tablets
Chemical flocculation, using either commercially produced iron or aluminum salts or the crushed seeds of certain plants, such as Moringa oleifera. Recent work has shown even table salt (NaCl) is effective at removing high-activity clays for solar water disinfection.
Irradiation with ultraviolet light, whether using electric-powered lamps or direct solar exposure such as with the SODIS method
Mixed flocculation/disinfection using commercially produced powdered mixtures
membrane filtration, employing ultrafiltration or reverse osmosis filter elements preceded by pretreatment
Some appropriate technology water supply measures include:
Deep wells with submersible pumps in areas where the groundwater (aquifers) are located at depths >10 m.
Shallow wells with lined walls and covers.
Rainwater harvesting systems with an appropriate method of storage, especially in areas with significant dry seasons.
Fog collection, which is suitable for areas which experience fog even when there is little rain.
Air wells, a structure or device designed to promote the condensation of atmospheric moisture.
Handpumps and treadle pumps are generally only an option in areas is located at a relatively shallow depth (e.g. 10 m). The Flexi-Pipe Pump is a notable exception to this (up to 25 meters). For deeper aquifers (