A shared library of methods, designs and discoveries that groups of
people can build, run and maintain themselves — for energy, food,
water, shelter, tools and exploration. Knowledge, not products.
Many sound ideas never travel far, because nobody stands to profit
from promoting them. Meanwhile, some of the most heavily promoted
ideas are exaggerated, untested or plainly false. This page tries to
sit firmly on the evidence side of that divide. Each entry links to
the research, field data or engineering documentation behind it,
states how strong that evidence is, and says plainly what the method
does not do well.
Entries are judged on three questions: Is there verifiable,
independent documentation that it works as described? Can a household,
village or neighbourhood group build and maintain it without depending
on a single company? And are its limits and hazards understood well
enough to state honestly?
Ground rules
Nothing here is for sale. No product promotion, no affiliate links, no shops. Where a design is linked, it is an openly published plan, manual or paper.
Every entry has verifiable sources. Claims link to specific papers, field reports or technical manuals — never to a homepage or a sales page.
Every entry carries an honest evidence label (see the legend below), and a section on what the evidence does not show.
Safety notes are included where relevant. Read them before building anything.
Try at your own risk; check local laws and building codes. Structures, fuel-burning appliances, electrical systems and water supplies are regulated in most places for good reasons. Consult qualified local people where lives or health are involved.
Widely demonstrated over years, in regular use, with independent peer-reviewed or institutional evidence (for example WHO, FAO, national standards bodies).
Demonstrated
Working installations or field trials are documented, but evidence is thinner, more variable between sites, or contested on some points.
Promising
Peer-reviewed results are encouraging, but results vary widely or the method is not yet proven at practical scale.
Historical / Revisit
Documented in the past, then largely dropped. Worth re-examining with today’s materials and knowledge — but not a ready-to-use technology.
Energy · Exploration
Mechanochemical engine: turning a salt gradient directly into motion
A 1960s Weizmann Institute engine in which collagen fibres shortened in strong salt solution and lengthened again in fresh water, turning a pulley with no heat, combustion or electricity.
Evidence status: Historical / Revisit
How it works
Muscle converts chemical energy straight into mechanical work, with no
heat engine in between. Aharon Katchalsky (later Katzir) spent decades
asking whether simple materials could do the same: in 1950 he and
colleagues showed that a polyacrylic-acid gel swells and shrinks when
its acidity changes (Kuhn, Hargitay, Katchalsky & Eisenberg, Nature 1950),
and he had described muscle-like gels for a general audience in
Scientific American, “Muscle as a Machine” (Katchalsky & Lifson, March 1954).
At the Weizmann Institute in Rehovot, Itzhak Steinberg, Avraham
Oplatka and Katchalsky then built an engine around cross-linked
collagen fibre. Dipped in a concentrated lithium bromide solution the
collagen contracts forcefully; washed in water or a dilute solution it
relaxes. Running a loop of fibre over pulleys that sit partly in each
bath turns that cycle into continuous rotation
(Steinberg, Oplatka & Katchalsky, “Mechanochemical Engines”, Nature 210:568–571, 1966;
US patent 3,321,908, granted 1967).
The “fuel” is the free energy released as the strong and weak
solutions mix.
It worked. The principle is sound physics and the engines ran. The patent reports a 50 mm-radius compound pulley turning continuously at 13 revolutions per minute (US 3,321,908).
Efficiency figures: we could not find a published measured efficiency for the 1960s collagen engines that we could verify, so we do not quote one. The theoretical ceiling is set by the free energy of mixing the two solutions; real cycles capture only part of it. For scale, modern descendants using synthetic hydrogels report about 1.6% energy efficiency and up to 13.3 joules per gram of dry gel per cycle (Bui et al., Polymers 2021); an MIT group modelled more than 5% for an ideal process using river-water and seawater salinities and measured over 10% thermodynamic efficiency in the lab with optimised gels (Zhang, Lin, Zhao & Karnik, Journal of Applied Physics 2020).
Very low power density. The fibre can only contract as fast as salt diffuses into it — the Weizmann group itself studied these “diffusion-controlled contractions” (Oplatka & Yonath, Biopolymers 1968). The machines turned slowly, like a clock rather than a motor.
Demanding fuel. The 1966 engine used roughly 11 M lithium bromide against a bath of 0.3 M or less. A later patent by Dan Urry names “large concentration gradients and uncommon salts and denaturants” as the collagen engine’s major disadvantage (US 5,032,271, 1991). The mixed solutions must be re-separated — which takes energy — unless a natural gradient (river meeting sea, salt lake, brine) is available.
Why it never spread: slow, diffusion-limited motion
(and so little power for the size of the machine), plus reliance on
concentrated special salts, left it unable to compete with electric
motors and heat engines.
Katchalsky, the programme’s driving figure, was killed in the
1972 Lod Airport attack.
We have seen reports of US defence interest in the work but could not
verify them from a primary source, so we make no claim about it.
Why revisit it: the same principle can in principle run
on the natural salinity difference where rivers meet the sea, and the
2020–2021 studies above show synthetic gels doing work with ordinary
sodium chloride at river-water and seawater salinities. Mechanical
salinity engines remain a research topic, not a usable power source
— but they are a good example of a sound idea left half-explored.
What it takes
Currently a bench-scale experiment: a cross-linked fibre or gel
loop, pulleys, two baths, and the ability to make and measure salt
solutions. Best suited to school, university or makerspace
exploration, not to meeting a household’s energy needs.
Safety
Concentrated lithium bromide is an irritant and harmful if swallowed
(PubChem hazard summary).
Use eye protection and gloves; keep away from children. Ordinary
sodium chloride is the safer choice for gel experiments.
Using sunlight alone — in clear bottles, or in a simple reflective cooker — to make biologically contaminated drinking water much safer.
Evidence status: Established
How it works
SODIS (solar water disinfection): clear water is poured into
transparent PET or glass bottles of up to about two litres and left in
full sun. Ultraviolet light and warming together inactivate many
disease-causing organisms; exposure times range from about 6 to 48
hours depending on sunlight and the organism
(McGuigan et al., Journal of Hazardous Materials 2012).
Solar pasteurisation heats water in a dark container inside a
solar box or panel cooker. Bacteria and rotavirus in naturally
contaminated water were inactivated by about 60 °C; reaching
65 °C gives a safety margin, well short of boiling
(Ciochetti & Metcalf, Applied and Environmental Microbiology 1984).
A reusable indicator — a small tube of wax that melts at about
69 °C — shows when the water has been pasteurised
(PACE action sheet 25).
What the evidence shows — and its limits
A 2020 meta-analysis of 10 randomised trials (5,795 children) found SODIS reduced childhood diarrhoea risk by 38% (risk ratio 0.62). The authors caution that risk of bias and large differences between studies prevent definitive conclusions (Soboksa et al., BMJ Open 2020).
Across lab and field studies, SODIS achieved a mean reduction of about 3.6 log (roughly 99.97%) for bacteria, but somewhat less for protozoa, with wide variation (Rao et al., Environmental Science & Technology 2025).
Limits: SODIS treats small volumes, needs clear water and strong sun, and does nothing against chemical contamination (arsenic, nitrates, fluoride, pesticides). As the 2025 review stresses, laboratory performance means little unless a method is used consistently and correctly every day.
Solar cookers for food work well physically, but a randomised trial in Senegal found no measurable effect on smoke exposure or health, largely because the ovens were under-used and misused alongside existing stoves (Beltramo & Levine, Journal of Development Effectiveness 2013).
What it takes
SODIS: clean, undamaged clear bottles and a sunny surface (a metal sheet
or roof). Solar pasteurisation: cardboard or wood, foil or other
reflective material, a dark pot, a clear heat-resistant bag or glazing,
and a temperature indicator. No special skills; a few hours to build a
panel cooker.
Safety
The SODIS manual says water more turbid than 30 NTU must be settled
or filtered first, and that bottles need two consecutive days of
exposure when the sky is more than half cloudy. Neither method removes chemical pollutants. Store treated water
in the same clean container to avoid recontamination. Reflectors can
cause eye injury and burns — avoid looking into concentrated light.
A box of carefully graded sand in which a living biological layer removes most bacteria and parasites from household water — built locally from concrete or plastic, with no chemicals or power.
Evidence status: Established
How it works
Water trickles slowly through fine sand; a
biologically active layer (the schmutzdecke) forms near the top
and, together with straining and adsorption in the sand, removes
pathogens. The household biosand filter, developed by David Manz at the
University of Calgary in the 1990s, adapts this to a single container
filled by hand, with a standing water layer that keeps the biological
layer alive between uses
(CAWST Biosand Filter Manual, 2009).
What the evidence shows — and its limits
A cluster-randomised trial in rural northern Ghana found 60% less diarrhoeal disease in households given a plastic biosand filter, and a 97% reduction in E. coli in filtered water. The authors note it was short (four months), unblinded and relied on self-reported illness (Stauber et al., Int. J. Environ. Res. Public Health 2012).
Pooled across studies, sand filters reduced bacteria by about 1.9 log (about 99%). Virus removal was high in lab studies but only about 1.7 log in the few field studies (Rao et al. 2025).
Limits: the biological layer can take up to 30 days to form, so a new filter does not reach full performance at once; it does not reliably remove viruses or chemical contaminants; and stored water can be recontaminated. Many programmes pair it with chlorination or SODIS for that reason.
What it takes
A reusable steel mould, cement, washed and sieved sand and gravel of
specific sizes, a diffuser plate and a lid. Building requires careful
sand preparation and some masonry skill, so one trained local workshop
can serve many households. The concrete design filters slowly — the
manual’s check is a flow of 0.4 litres per minute or less — and
should be used at least once a day.
Safety
Test the water source for chemical hazards (arsenic, fluoride, nitrates)
where these are common — sand filtration does not remove them.
Follow the manual’s maintenance steps. The manual recommends disinfecting filtered water
as well — especially while the biological layer is still forming.
Zaï pits and half-moons: harvesting rain on degraded dryland
Hand-dug planting pits and crescent-shaped earth basins, filled with manure or compost, that catch scarce rain and bring crusted, barren Sahelian soils back into production.
Evidence status: Established
How it works
Zaï are small pits, conventionally about 20 cm across and
10–15 cm deep, dug into hard, crusted ground in the dry season;
half-moons are larger semicircular basins with an earth bank on the
downhill side. Both break the surface crust, trap runoff and concentrate
water and organic matter where the seed is planted. The practice is
traditional in the West African Sahel, particularly Burkina Faso, and
has since been adapted as far away as Kenya
(Kimaru-Muchai et al., Journal of Agriculture and Rural Development in the Tropics and Subtropics 2020).
What the evidence shows — and its limits
On a degraded, crusted soil in northern Burkina Faso, half-moons with compost or manure produced 900–1,600 kg of sorghum grain per hectare — 20 to 39 times the yield of half-moons without any amendment (Zougmoré, Zida & Kambou, Soil and Tillage Research 2003).
The same study carries the key lesson: catching water alone was not enough. Once the water constraint was removed, poor nutrients became the limit; the organic matter is essential.
In semi-arid Kenya, zaï raised sorghum yields by 25–58% over conventional planting in two short-rain seasons, but gave little benefit in a season with dry spells of around 70 days (Kebenei et al., Frontiers in Sustainable Food Systems 2021).
Limits: digging is heavy, slow dry-season labour, and adoption studies, including in Kenya, identify labour demand as a major obstacle (Kimaru-Muchai et al. 2020). It also depends on having manure or compost to put in the pits.
What it takes
Hand tools (a heavy hoe or pick), organic matter, seed, and many
person-days of work per hectare — well suited to work parties and
shared labour arrangements. No purchased inputs are required.
Safety
Ordinary precautions for heavy manual labour in heat: water, shade, rest and rotating tasks.
Regrowing trees on farmland from the living stumps and roots already in the ground, by selecting, protecting and pruning the shoots — credited with re-greening millions of hectares in Niger.
Evidence status: Established
How it works
In much of the dry tropics, cleared fields still hold living root systems
that keep sending up shoots, which are cut or grazed every year. In FMNR,
farmers choose a few strong stems on each stump, protect them and prune
them, letting them grow into trees spread across the cropland. The trees
shelter crops from wind, add leaf litter and yield fodder, firewood and
food. It is largely an organisational practice: it depends on agreements
about grazing and on who may cut and use the trees
(Chomba et al. 2020).
Positive crop-yield effects were found at moderate tree densities (about 15–40 trees per hectare in Niger).
Limits, stated by the same review: quantitative evidence is sparse and comes mostly from two regions of Niger; commonly quoted cost figures are expert estimates rather than measured; and insecure land and tree rights are a key barrier. In Niger, adoption grew after forestry officials reduced interference and tree-tenure rules changed — showing how much depends on who controls the trees.
What it takes
A pruning knife or saw, knowledge of local tree species, and — most
importantly — agreement among neighbours and herders about protecting
young growth. No nursery, seedlings or irrigation are needed.
Safety
Low risk. Check local rules on tree cutting and ownership before pruning or harvesting.
Earth and plant-fibre building: compressed earth blocks, straw bale, hemp-lime
Walls made largely from local subsoil or agricultural by-products, with far less cement and fired material than conventional construction — now recognised in some building codes.
Evidence status: Established
How it works
Compressed earth blocks are made by pressing damp subsoil, often with
a small proportion of cement or lime, in a hand-operated or powered press;
they are cured, not fired. Straw bale walls stack baled straw —
a farm by-product — and coat it inside and out with thick plaster.
Hemp-lime (“hempcrete”) is a non-load-bearing insulating
infill of hemp stalk core mixed with a lime binder, cast around a frame.
What the evidence shows — and its limits
In an Ethiopian study, compressed blocks with as little as 6% cement exceeded 2 MPa compressive strength, used less than half the cement of hollow concrete blocks, and could save up to 2 tonnes of CO2 per 100 m² of wall (Shiferaw, Buildings 2025). Suitable soil must be tested; not every soil works.
Plastered straw bale walls have withstood two hours of direct flame in fire tests modelled on the ASTM E119 standard (Garas, Allam & Mamdouh, WIT Press 2009).
Straw bale (2024 International Residential Code, Appendix BJ) and hemp-lime (Appendix BL) now have model-code appendices in the United States, though each jurisdiction decides whether to adopt them. Three framed hemp-lime wall assemblies each passed a one-hour ASTM E119 fire test in 2024–2025 (Natural Building Alliance, code update summary).
Limits: moisture is the main enemy. Straw is considered safe below about 15% moisture content and at risk of decay above about 25%; one monitored wall with a severely exposed face did decay (Lawrence, Heath & Walker, Construction and Building Materials 2009). Earth walls need protection from driving rain and rising damp. Hemp-lime is not structural.
What it takes
Earth blocks: suitable subsoil, a block press (manual presses are
built in local workshops), some cement or lime, and soil-testing know-how.
Straw bale: dry bales, timber for frames and roof, and large volumes of
lime or clay plaster. All three are labour-intensive and well suited to
group building days, but structural design should involve someone with
experience.
Safety
Earthquake zones: unreinforced earth masonry performs very
poorly in earthquakes and has caused many deaths. Follow a seismic design
guide such as the EERI/IAEE
earthquake-resistant adobe tutorial (Blondet, Villa García & Brzev, 2003)
and local codes. Lime is caustic: wear eye protection and gloves.
Loose straw is highly flammable before it is plastered. Check local
building codes and permits before starting.
Orienting, glazing and shading a building so that the sun heats it directly, with heavy walls that store daytime warmth and release it in the evening.
Evidence status: Established
How it works
Passive solar design combines equator-facing windows, thermal mass
(masonry, earth, concrete or water), insulation and roof overhangs
sized so that low winter sun enters while high summer sun is blocked
(Whole Building Design Guide, “Passive Solar Heating”).
A Trombe wall is a thick, dark masonry wall placed just behind a sheet of
glass: it absorbs sunlight during the day and radiates the heat into the
room hours later.
What the evidence shows — and its limits
At the Zion National Park Visitor Center (Utah, USA), monitored by the US national renewable energy laboratory, the Trombe wall supplied 20% of annual heating and was a net heat gain on 149 of 151 heating-season days. Its average efficiency — heat delivered divided by sunlight striking it — was 13% (Torcellini & Pless, “Trombe Walls in Low-Energy Buildings: Practical Experiences”, 2004).
Limits found in the same study: even when shaded by overhangs, the walls added summer cooling load; and furniture or cabinets placed against a Trombe wall cut the heat it delivered by over 40% in an earlier house. Poor design can make a building too hot in summer.
Results depend on climate, latitude and careful design; a design that works in one place can overheat or underperform in another.
What it takes
Mostly design knowledge rather than special materials: a sun-path
assessment of the site, ordinary masonry and glazing, insulation, and
correctly sized overhangs. Adds little material compared with a
conventional building of the same size.
Safety
Plan summer shading and ventilation to avoid overheating, which is a health risk in heatwaves. Follow local building codes for glazing and structural walls.
Small water turbines on streams or springs that generate electricity day and night wherever there is a suitable site.
Evidence status: Established
How it works
Part of a stream is diverted through a pipe down a slope to a turbine,
then returned to the stream. Available power depends on two things:
the vertical drop (“head”) and the flow. As a worked example from a
US agricultural extension guide, about 2.4 litres per second falling
30 m (5 cubic feet per minute, 100 feet) gives roughly 700 W in
theory and about 425 W of usable electricity after turbine, belt and
alternator losses; typical overall efficiencies are 50–70%
(NCAT/ATTRA, Micro-Hydro Power: A Beginner’s Guide to Design and Installation).
“Pico-hydro” usually means systems under 5 kW.
What the evidence shows — and its limits
Unlike sun and wind, a stream can run around the clock, so even a small turbine can supply steady power. Pico-hydro can be among the lowest-cost options for remote villages when equipment is standardised and locally made (Williams & Simpson, Renewable Energy 2009).
Nepal has a long record of community-owned, community-operated micro-hydro plants. A study of the project process found the typical failure points were weak specification of civil works, manufacturing quality, poor construction and trained operators leaving (Butchers, Williamson & Booker, Sustainability 2021).
Limits: it only works where there is enough drop and dry-season flow — output must be planned around the lowest flow of the year. Water rights, fish passage and environmental permits apply in most places.
What it takes
A suitable site; months of flow measurements; pipe, an intake with a
screen, a turbine (which can be locally manufactured), a generator and
controller; and electrical
skills. A village scheme also needs an agreed way to run and maintain
it and to share the power.
Safety
Generator voltages can kill; involve a qualified electrician for wiring and
earthing. Pipelines under high head carry great pressure. Intakes and
channels can be a drowning hazard for children. Check water-use and
environmental permits.
Locally built small wind turbines (the “Piggott” design)
An open design for hand-built wind turbines with wooden blades and a home-made permanent-magnet alternator, refined over decades for off-grid use and built in many countries.
Evidence status: Demonstrated
How it works
Hugh Piggott, living off-grid on the Scoraig peninsula in Scotland,
developed a turbine that can be made with basic tools: hand-carved
wooden blades, a welded steel frame and an axial-flux alternator made
by casting magnets and coils in resin. A hinged tail turns the rotor
out of strong winds to protect it. More than 1,000 have been built in
over 25 countries
(Leary, Piggott & Howell, Wind Engineering 2021).
What the evidence shows — and its limits
Field measurements of seven locally made turbines found that real output varied considerably between machines, but over-performance was as common as under-performance against the designer’s predictions. Tuning one machine raised its energy yield by up to 156% (Leary, Piggott & Howell 2021).
Limits: output is far less predictable than solar panels; small turbines need a genuinely windy, unobstructed site. Maintenance is the known weak point — one unmaintained turbine in the trial lost 10–15 mm off its blade edges in 3–4 years. The same paper notes that the predictability of solar panels is why they now dominate small off-grid systems; small wind earns its place mainly at windy sites, often alongside solar.
What it takes
Timber, steel, a welder, resin, copper wire and strong neodymium
magnets, plus a tower, batteries and a charge controller; welding,
woodworking and electrical skills. Building is well suited to group
workshops.
Safety
Towers fall and blades fail: raise and lower towers with a tested method,
keep people clear, and never climb a turning turbine. Strong magnets can
crush fingers. Battery banks store a lot of energy and can cause fires;
install fuses and follow electrical codes.
Two clay pots with wet sand between them: water evaporating from the outer pot cools the inner one and keeps vegetables fresh for days longer, with no electricity.
Evidence status: Demonstrated
How it works
Evaporating water absorbs heat. A smaller pot sits inside a larger
unglazed pot; the gap is filled with sand kept wet, and the top is
covered with a damp cloth. As water evaporates through the outer
wall, the inner chamber becomes cooler and much more humid than the
surrounding air — conditions that slow wilting and spoilage of
vegetables.
What the evidence shows — and its limits
In a multi-year study in Mali with the World Vegetable Center and Mali’s Institut d’Economie Rurale, coolers kept contents about 5–7 °C below the outside temperature on average in the dry season, cut the daily peak by more than 8 °C, and held humidity above 80–90% against an ambient 40%. Shelf life increased by 50% to 600% depending on the vegetable — for example, eggplant from 3 days to more than 15 (MIT D-Lab, Clay Pot Coolers: Preserving Fruits and Vegetables in Mali, 2016–2021).
Limits: it works well only in hot, dry climates; in humid air, evaporation and cooling are small. It is not a refrigerator: it is not cold enough to store meat, milk or medicines safely. It needs daily refilling with water and holds modest volumes.
What it takes
Two unglazed clay pots of different sizes (or a pot inside a dish),
sand, a cloth and water to keep the sand wet. Local potters can make
the pots.
Safety
Use for fruit and vegetables only — not for meat, fish, dairy, cooked food or medicines that need refrigeration. Keep standing water covered to avoid mosquito breeding.
A sealed tank in which manure and food waste break down without air, producing a cooking gas and a liquid fertiliser.
Evidence status: Established(technology); long-term use often fails — see limits
How it works
Bacteria digest organic matter in the absence of oxygen and release
biogas — mostly methane with carbon dioxide — which is piped to a
stove. The digested slurry is a usable fertiliser. Common household
designs are a fixed brick or concrete dome, a floating steel drum or a
flexible plastic bag, fed daily with dung and water
(FAO, Biogas Technology: A Training Manual for Extension, 1996).
What the evidence shows — and its limits
Replacing smoky wood fires helps. In a small Kenyan comparison, 43% of women cooking with biogas reported breathing problems versus 71% of women using biomass; lung-function differences were not statistically significant (Dohoo et al., Journal of Environmental and Public Health 2012).
Many digesters stop working. Of about 41.9 million household digesters in China by 2015, an estimated 40–60% remained operational (Rasimphi, Mulaudzi & Tinarwo, Frontiers in Energy Research 2026). The review traces failures less to the technology than to the system around it: operation, maintenance, governance and financing.
A steady daily supply of dung and water (cattle dung is the most common feedstock); bricks, cement and pipe for a fixed
dome, or a heavy-duty plastic bag; a gas stove. Masonry skill for
construction and a nearby trained person for repairs. Gas production
virtually stops when the surrounding temperature falls to about 10 °C, so it
suits warm climates best (FAO manual above).
Safety
Biogas is flammable and can explode when mixed with air in an enclosed
space; it can also contain hydrogen sulphide, which is toxic. Never
enter a digester or slurry pit — the gases inside can be fatal.
Keep flames away from the tank, check pipes for leaks, cook in a
ventilated space and fence the slurry pit.
Charcoal made from crop residues or wood and dug into soil — useful in acidic, nutrient-poor tropical soils, but not the universal soil improver it is often claimed to be.
Evidence status: Promising(strong in some soils, little effect in others)
How it works
Heating biomass with little oxygen (pyrolysis) leaves a porous, stable
charcoal. Added to soil, it can raise pH like lime, hold nutrients and
water, and lock away carbon for long periods.
What the evidence shows — and its limits
A global meta-analysis found biochar raised crop yields by an average of 25% in the tropics, but had on average no effect in temperate regions. The tropical gains came mainly from liming and added nutrients in acidic, low-fertility soils (Jeffery et al., Environmental Research Letters 2017).
Limits: results depend heavily on the soil, the feedstock and how the char is made. Making it in open, smouldering pits produces heavy smoke.
What it takes
Dry crop residues or wood waste, a simple kiln or retort, and water to
quench it. Because much of the tropical yield gain came from nutrients,
mixing the char with compost or manure before use makes sense.
Safety
Fire and burn risk; smoke is harmful to breathe — work outdoors, away from homes, and follow local burning rules. Fine char dust is an inhalation hazard: wet it before handling.
Rice: alternate wetting and drying — and the SRI debate
Letting rice paddies dry out periodically instead of keeping them flooded saves around a quarter of the irrigation water with little or no loss of yield when done carefully.
Evidence status: Established(alternate wetting and drying); the wider SRI package is contested
How it works
In alternate wetting and drying (AWD), the field is re-flooded only when the
water level falls a set depth below the soil surface, checked with a
simple perforated tube pushed into the ground
(IRRI Rice Knowledge Bank fact sheet).
The System of Rice Intensification (SRI), developed in Madagascar,
combines non-flooded water management with young seedlings planted
singly and widely spaced, and organic matter.
What the evidence shows — and its limits
A meta-analysis of 56 studies (528 comparisons) found that “mild” AWD — never letting the water drop more than 15 cm below the surface — cut water use by 23.4% with no significant yield loss in most conditions. Harsher drying cut yields by 22.6% (Carrijo, Lundy & Linquist, Field Crops Research 2017).
SRI is contested. Supporters report large yield gains; agronomists reviewing the empirical record have argued that SRI does not consistently out-yield good conventional practice (McDonald, Hobbs & Riha, Field Crops Research 2006). Its water-saving component is the best-supported part.
Limits: AWD needs control over when water arrives — hard in shared canal systems where farmers cannot choose their timing — and yield losses were larger on soils with high pH or low carbon.
What it takes
A length of perforated pipe per field, a ruler, and agreement among farmers sharing an irrigation channel.
Safety
Low risk. Coordinate with neighbours on shared water to avoid conflict and unintended drought stress.
Vertical mesh panels on foggy, coastal mountain ridges that capture droplets from passing fog and channel them into tanks — drinking water with no pumps or power.
Evidence status: Demonstrated
How it works
Wind pushes fog through a fine polyethylene (Raschel) mesh stretched
between poles. Droplets collect on the threads, merge, run down into a
gutter and flow by gravity to storage. A standard test collector is
1 m² of mesh; working collectors are typically about 4 m high and
10 m wide
(Klemm et al., Ambio 2012).
What the evidence shows — and its limits
Operational projects typically yield 3–10 litres per square metre of mesh per day as a yearly average; a Chilean site averaged about 6 over 14 years. In Tojquia, Guatemala, 35 large collectors averaged around 6,300 litres a day (Klemm et al. 2012).
Fog water tested in several studies met WHO drinking-water standards for ions and heavy metals, though local testing is still needed.
Limits: it only works where fog is frequent — usually where an ocean meets a mountain range. Several projects declined after handover because they were not maintained. A 2018 review finds the main obstacles are not technical but institutional: weak policies and local institutions, limited local expertise, and costs that are assumed rather than analysed (Qadir et al., Water 2018).
What it takes
Measurements with a 1 m² standard test collector to confirm the
site first; then poles, cables, shade-cloth-type mesh, gutters, pipe and a
storage tank. Simple construction; the real work is organising
ongoing maintenance.
Safety
Test the water before drinking (especially near roads, industry or farms). Secure poles and cables against high winds. Keep storage tanks covered and clean.
Shared, freely licensed designs for farm implements and workshop machines that farmers and community workshops build, adapt and repair themselves.
Evidence status: Demonstrated(varies by project — see below)
How it works
Instead of buying proprietary machines that only the manufacturer can
repair, farmers co-design tools with engineers, publish the plans under
open licences, and teach each other welding and fabrication. Improvements
are shared back, so every builder benefits.
What the evidence shows — and its limits
L’Atelier Paysan (France) is a cooperative that develops farmer self-build techniques and publishes a library of more than 200 tool and equipment plans under a Creative Commons non-commercial licence (L’Atelier Paysan plan library). Researchers studying it note that “open source” must be judged case by case — how far each tool is genuinely shareable varies (Chance & Meyer, Techniques & Culture 2017).
Open Source Ecology’s Global Village Construction Set aims at 50 open industrial machines. Honest status: by 2014 twelve had been prototyped and four documented, and the full set remains unfinished. Its compressed earth block press was, in 2011, the first of its designs built by an independent group (overview of the project’s progress). Treat it as an ongoing design effort rather than a finished toolkit.
Limits: plans do not build themselves — welding, machining and safe operation take training. Quality varies between builds, and most designs have no independent performance testing.
What it takes
Access to a metal workshop (welder, angle grinder, drill press), steel stock and standard parts, and an experienced fabricator to teach. Shared community workshops make this far more practical than going alone.
Safety
Welding and grinding cause burns, eye injuries and fume exposure: use proper eye, hand and respiratory protection and ventilation. Home-built machines with moving parts need guards. Check road and safety rules before using self-built equipment on public roads.
This library does not host remedies or treatment instructions. Health is
an area where promotion often outruns evidence, and where mistakes harm
people directly. Instead, below are links to approaches that individuals
and communities can take up themselves and that have held up in
controlled studies. Every link goes to a public-health body, an
independent evidence review, or a peer-reviewed study — none of
them sells a product (one exception, a nonprofit publisher, is noted).
Please read first. None of this is medical advice, and
none of it replaces care from a qualified clinician. The evidence behind
each item is about specific groups of people in specific settings; it may
not apply to you. Check with a clinician before starting something new if
you have a health condition, take medicines, are pregnant, or are caring
for a child. Anyone in crisis or danger should seek urgent help.
Mental health that communities can offer each other
The Friendship Bench (Zimbabwe). Trained lay health
workers, many of them older women, offer structured problem-solving
talk on a bench outside a clinic. In a randomised trial in Harare,
people who received it had fewer symptoms of depression and anxiety
six months later than those who received enhanced usual care
(Chibanda et al., JAMA, 2016).
Problem Management Plus (PM+). A five-session
psychological help programme that trained non-specialists can deliver
in communities facing adversity. The WHO manual is open to download
(WHO, PM+ manual).
Doing What Matters in Times of Stress. An illustrated
self-help guide to managing stress
(WHO).
Mindfulness-based cognitive therapy for people who have
had repeated episodes of depression. It is taught in groups by trained
teachers. Across nine trials, it lowered the risk of relapse over
60 weeks compared with not receiving it
(Kuyken et al., JAMA Psychiatry, 2016).
People should not stop antidepressants without medical guidance.
Movement and connection
Exercise for depression. A review of 218 trials found
meaningful reductions in depression, with walking or jogging, yoga and
strength training among the most effective. The certainty of most
findings was rated low to moderate
(Noetel et al., BMJ, 2024).
Exercise to prevent falls in older people. Exercise
programmes reduced the rate of falls by about 23%
(Cochrane review, 2019).
Yoga for chronic low back pain. The review found small
to moderate improvements in function, with low- to moderate-certainty
evidence. Mild side effects, mostly more back pain, were somewhat more
common than without exercise
(Cochrane review, 2017).
Social connection. Across 148 studies, people with
stronger social relationships were more likely to survive over the
study periods. These are observational studies, so they show a strong
association rather than proof of cause
(Holt-Lunstad et al., PLoS Medicine, 2010).
Care that families and community health workers can provide
Kangaroo mother care. Continuous skin-to-skin contact
and breastfeeding for low-birthweight babies whose condition is stable.
Compared with conventional care, it reduced the risk of death
(Cochrane review, 2016).
It is started under the guidance of health workers.
Oral rehydration solution for diarrhoea, which prevents
many deaths from dehydration in young children
(WHO fact sheet).
Community health workers. WHO guidance on selecting,
training, supervising and supporting them
(WHO guideline, 2018).
Hesperian HealthWiki. The full text of
Where There Is No Doctor and related community health guides
is openly readable online
(Hesperian HealthWiki).
Hesperian is a nonprofit; it also sells printed copies, which you do
not need in order to use the guides.
Vitamin and mineral supplements
For most people who eat a reasonably varied diet, the best trials find
that everyday vitamin and mineral supplements do little measurable good.
Heart disease and cancer. The US Preventive Services
Task Force reviewed the trials in 2022. It found the evidence
insufficient to say multivitamins help prevent heart disease or cancer,
and it recommends against beta-carotene and vitamin E for that
purpose
(USPSTF, JAMA, 2022).
The strongest positive result is small. In a trial of
about 14,600 male doctors followed for 11 years, a daily multivitamin
lowered total cancer by about 8%, with no clear effect on prostate or
colorectal cancer
(Physicians’ Health Study II, JAMA, 2012).
An editorial in a leading medical journal summed up the
evidence under the title “Enough is enough: stop wasting money on
vitamin and mineral supplements”
(Guallar et al., Annals of Internal Medicine, 2013).
Not always harmless. Some supplements have caused harm
in trials: beta-carotene raised lung cancer in smokers
(ATBC trial, NEJM, 1994),
and vitamin E raised prostate cancer risk
(SELECT trial, JAMA, 2011).
In the United States, supplements are linked to an estimated 23,000
emergency department visits a year, many from weight-loss and energy
products
(Geller et al., NEJM, 2015).
Labels are often wrong. US law does not require
supplements to be approved for safety or effectiveness before they are
sold
(US Food and Drug Administration).
When researchers tested 30 supplements sold to “boost
immunity”, 17 had inaccurate labels; in 13, listed ingredients
could not be found at all
(Crawford et al., JAMA Network Open, 2022).
Supplements recalled for containing banned drugs were often still on sale,
with the drugs still in them, months later
(Cohen et al., JAMA, 2014).
Real exceptions. Some people do benefit, usually because
of a specific need: folic acid before and in early pregnancy to prevent
neural tube defects
(USPSTF, JAMA, 2023);
vitamin B12 for people who eat no animal foods, since plant foods contain
none unless fortified
(NIH Office of Dietary Supplements);
and a diagnosed deficiency, treated with a clinician. These are the
situations to ask about, rather than a daily routine for everyone.
A case of a manufactured need. Supplements show how
marketing can create a felt need that the evidence does not support. When
income depends on selling more, the incentive is to persuade healthy
people that they are missing something, and many spend money every month
on products that, for most of them, do little or nothing. A community
that shares reliable health information, and makes nourishing food
accessible to everyone, takes away much of the pressure behind it.
Herbal medicine
A plant that genuinely affects the body can also interact with medicines.
St John’s wort, for example, outperformed placebo for major
depression in trials, though results varied between countries
(Cochrane review, 2008),
but it can interact in dangerous, sometimes life-threatening ways with a
variety of medicines
(NIH National Center for Complementary and Integrative Health).
Doses, preparations and contamination also vary widely, and
“natural” does not always mean safe
(NCCIH, “Using Dietary Supplements Wisely”).
For what the evidence says about a particular herb, the
NCCIH “Herbs at a Glance” fact sheets
summarise the trials and list known safety concerns. Talk to a clinician
before taking anything.
Suggest an innovation
Know of a method, design or discovery that belongs here — or a
correction to an existing entry? Send it to
community.forum@worldintransition.net with:
What it is — a plain description of how it works.
Sources — links to specific papers, field reports, test data or open build documentation. Claims without verifiable sources cannot be listed.
Your connection to it — whether you developed, sell, research or simply use it. A connection does not disqualify a suggestion, but it must be stated.
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Every suggestion is reviewed against the ground rules before anything is
posted, and labels can move up or down as evidence changes. Nothing
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