The heat crisis is usually read as an air-conditioning problem. That reading is wrong for most of humanity.
For the middle 50 percent — roughly four billion people above extreme poverty but below the income that buys a modern air conditioner — the binding constraint is not how efficient an AC unit is, but whether a household can afford any cooling at all.
The electric fan is the only technology that converts a single dollar of income and a single watt of electricity into cooling at the scale these people need. A fan costs about $20 to buy against several hundred dollars for an air conditioner, and it draws roughly a twentieth of the power — enough to run on the weak grids and off-grid solar systems where most of the exposed population actually lives.
This report makes the case for treating the fan as public-health infrastructure. It maps the heat problem, the cooling gap, the physics and economics that favor the fan, and the policy levers — subsidy, procurement, standards, finance, design — that would turn a $20 device into the single highest-leverage climate adaptation available to the largest block of humanity.
The heat problem is already here
Heat exposure is no longer a forecast. In 2000 roughly 200 million people lived in cities that saw at least one month of 35°C average maximum heat. By 2050 that number reaches 1.6 billion, by 2075 it is 2.2 billion, and by 2100 up to 3.9 billion — nearly a billion of whom will endure six months or more of such heat every year.
Three forces compound at once: population growth concentrated in the hottest regions, urbanization that intensifies the heat-island effect, and climate forcing that adds up to 4.7°C of warming on high-emission pathways. South Asia and sub-Saharan Africa carry the heaviest burden, but no continent is untouched; this report's geography is deliberately global.
The health toll is already measurable. An estimated 489,000 heat-related deaths occurred each year between 2000 and 2019 — 45 percent in Asia and 36 percent in Europe. Exposure is the input; cooling is the response. The only question that matters is which cooling technology can actually reach the people being exposed.
Air conditioning is out of reach for billions
Air conditioning is one of the most concentrated technologies on Earth. Across the 2.8 billion people living in the hottest parts of the planet, only about 8 percent own an air conditioner, against more than 90 percent of households in the United States and Japan. In India the figure is roughly 5 percent, in Indonesia roughly 9 percent, and across much of sub-Saharan Africa it sits below 5 percent.
The gap is closing in one direction only. On current trends two-thirds of the world's households could have an air conditioner by 2050, and space-cooling energy demand would more than triple — consuming as much electricity as China and India use today. Cooling already accounts for about a fifth of electricity in buildings worldwide and a tenth of all global electricity.
Read plainly, an AC-first adaptation path asks the world to triple a technology that most of the exposed population cannot yet afford, and to pay for it on grids that already strain in the heat. The "cold crunch" is also a cost crunch — and it is the middle of the income distribution, not the top, that is left outside.
Why the fan wins: physics, energy, cost
The fan does something the air conditioner cannot: it scales. A fan moves air across the skin and accelerates the evaporative and convective cooling the body already does for free. For healthy adults this is effective below roughly 40°C — the threshold the WHO and the Global Heat Health Information Network set for safe fan use. Above that, a fan can add heat rather than remove it, and in very humid conditions its benefit shrinks because sweat stops evaporating. Those limits matter. They also leave a vast operating range: the conditions under which most of the middle 50% actually lives.
The economics are equally asymmetric. A typical fan draws 15 to 100 watts; a room air conditioner draws 500 to 2,000 watts — roughly twenty times as much. A fan costs $15 to $40; an air conditioner costs $300 to $800 before installation. And the two are complements, not rivals: an air conditioner set to 27°C with a fan running feels about 4°C cooler, cutting cooling electricity by up to 70 percent. A fan runs on a weak grid, a solar panel, or a battery; an air conditioner demands stable, high-capacity power. For the middle 50%, that difference is the whole argument.
The middle 50%: a market and a mandate
Who exactly is the middle 50 percent? The World Bank draws the lines: about 700 million people — 8.5 percent — live below $2.15 a day, and about 3.5 billion, 44 percent, live below $6.85 a day; its prosperity benchmark sits at $25 a day. Between the floor of extreme poverty and the ceiling of the affluent tiers sit roughly four billion people. They are not the poorest; they are the largest single block of humanity, and they are precisely the group that can afford a $20 fan but not a $500 air conditioner.
SEforALL slices the same population from the cooling side. Its Chilling Prospects analysis finds 1.2 billion people — one in seven — at high risk from lack of access to cooling, and a further 2.39 billion in the lower-middle tier, living on under $10 a day, who can reach a fan but not efficient AC. Together they are 3.6 billion people with inadequate cooling, and the 2.39 billion lower-middle tier is the market and the mandate in a single number: the largest underserved cooling population in history, and the group a fan-first strategy exists to serve.
The fan-first strategy has five parts
Fans are cheap, but their diffusion is not automatic. The strategy that scales them has five parts, and each has already been proven elsewhere.
Efficiency. Brushless DC fans cut electricity consumption sharply against conventional AC-motor fans, and minimum-energy-performance standards — the approach CLASP's Efficiency for Access program applies to off-grid fans — lift the whole market at once.
Power. Pairing fans with rooftop or community solar, plus batteries, keeps cooling running through the blackouts that arrive with every heatwave. A fan draws little enough to live on the same panel that already lights a home.
Finance. Pay-as-you-go and micro-financing let households buy cooling in the same small increments they buy mobile-phone service — the model that already electrified off-grid solar across Africa and South Asia.
Manufacturing. Local production and repair keep prices low, cut import dependence, and create jobs in the communities that need cooling most. A fan that can be repaired locally is worth more than an AC that cannot.
Design. Shade, cross-ventilation, and reflective roofs lower indoor temperatures by 4 to 10°C before a fan ever spins, which widens the range where a fan alone is enough.
None of these is exotic. The cooling sector has simply not borrowed what mobile money and off-grid solar have already proven at scale.
Policy and diffusion levers
Subsidies for efficient cooling should target the middle 50 percent, not just the poorest households. That is where the air-conditioning default is most likely to take hold — and where a subsidy can still steer a household toward a fan, or a fan-plus-efficient-AC pairing, rather than an oversized unit that locks in decades of high energy use.
Bulk procurement by governments and NGOs compresses unit prices the way it did for vaccines and solar lanterns. Urban heat-resilience plans should stock cooling centers with fans and fold fan access into heat action plans, alongside hydration and safe-heat messaging. Standards and labeling give buyers and procurers a floor they can trust, and public awareness campaigns correct the persistent myth that a fan is useless when it is in fact the highest-value cooling device most households will ever own. Each lever is cheap; combined they convert a consumer good into an arm of public health.
Three regions, three entry points
South and Southeast Asia show the strategy at full load. The region combines humid heat, low air-conditioning penetration, and the world's largest lower-middle class. India and Indonesia, at roughly 5 and 9 percent AC ownership, are the ground zero where a fan-first path can prevent hundreds of millions of households from locking into grid-straining AC by default. Heat action plans in the region already treat fans as a frontline intervention.
Sub-Saharan Africa faces a different binding constraint: electricity. With the lowest electrification rates of any region and the fastest growth in extreme heat, its entry point is the off-grid solar fan sold on pay-as-you-go — the same channel that delivered off-grid lighting. Here cooling access is a rural energy problem as much as a heat problem.
Latin America adds the urban dimension. Heat islands in fast-growing cities, often in informal settlements with unreliable power, make shading and cool roofs as important as the fan itself. Its middle-income urban households sit exactly on the fan-versus-AC decision line, where subsidy and standards have the most leverage.
| Region | Heat exposure growth | AC penetration | Binding constraint | Entry technology |
|---|---|---|---|---|
| South & Southeast Asia | Very high | ~5–10% | Affordability | Grid fan + heat action plans |
| Sub-Saharan Africa | Very high | <5% | Electricity access | Off-grid solar fan (PAYG) |
| Latin America | High (urban) | ~10–20% | Urban heat island | Fan + shading / cool roofs |
The economics and the scale
The arithmetic favors the fan at every turn. A $500 air-conditioning budget buys cooling for one household; the same money buys fifteen to twenty-five fans, or more through bulk procurement. Cooled by fans, the 3.9 billion people projected to face extreme heat would draw a fraction of the electricity an AC pathway demands — avoiding the tripling of cooling energy that is otherwise on the way.
The health value compounds. Less heat stress means fewer deaths and less of the productivity loss that arrives when a workforce can no longer work in the heat — a channel that, in the wet-bulb literature, shows up in economic output years before it shows up in the death toll. And a fan-first market is a manufacturing market: billions of units, a repair economy, and a solar-fan ecosystem that employs people in the very regions being cooled. The device is cheap; the system it unlocks is not.
What should happen next
- GovernmentsSubsidize efficient fans and fan-plus-AC pairings for the middle 50%, and set minimum energy performance standards for fans so the whole market rises.
- CitiesStock cooling centers with fans and fold fan access into heat action plans, alongside hydration and safe-heat messaging.
- Development financeFund bulk procurement and off-grid solar-fan programs at scale, and track cooling access as a health outcome rather than an appliance count.
- ManufacturersBuild brushless-DC fans engineered for hot-humid climates at the lowest price points, and stand up local repair ecosystems.
- FinanciersExtend pay-as-you-go and microfinance to fans, priced like mobile service, so the middle 50% buys cooling in increments it can afford.
The wrong tool for the wrong population
The cooling crisis is being answered with the wrong tool for the wrong population. Air conditioning will remain essential — for the affluent, for the hottest and most humid extremes, for hospitals and the elderly. But for the middle 50 percent of humanity, the decisive question is not when they get an air conditioner; it is whether they get any cooling at all in the decade when the heat arrives fastest. The fan answers that question today, at a price and an energy draw the grid can actually bear.
Treat cooling access as a fan problem, not an air-conditioner problem. The binding constraint for the middle 50% is not how efficient an air conditioner is but whether a household can afford any cooling at all — and the fan is the only device that converts a single dollar of income and a single watt of power into relief at the scale billions require. Measure every cooling investment by that conversion.
References
- IEA (2018), The Future of Cooling: Opportunities for energy-efficient air conditioning. iea.org/reports/the-future-of-cooling
- IEA (2018), press release, "Air conditioning use emerges as one of the key drivers of global electricity demand growth." iea.org/news
- SEforALL (2022), Chilling Prospects 2022: Tracking Sustainable Cooling for All. seforall.org/chilling-prospects-2022
- World Health Organization, Heat and health fact sheet. who.int/news-room/fact-sheets/detail/heat-and-health
- Global Heat Health Information Network, Keep Cool guidance. ghhin.org/keep-cool
- Jay, O., et al. (2021), "Reducing the health effects of hot weather and heat extremes: from personal cooling strategies to green cities," The Lancet 398(10301): 709–724.
- Malik, A., et al. (2022), "The potential for indoor fans to change air conditioning use while maintaining human thermal comfort during hot weather," Lancet Planetary Health 6(4): e301–e309.
- Zhao, Q., et al. (2021), "Global, regional, and national burden of mortality associated with non-optimal ambient temperatures," Lancet Planetary Health. pubmed.ncbi.nlm.nih.gov/34245712
- World Bank (2024), Poverty, Prosperity, and Planet. worldbank.org/en/publication/poverty-prosperity-and-planet
- Pavanello, F., et al. (2021), "Air-conditioning and the adaptation cooling deficit in emerging economies," Nature Communications 12:6460. nature.com/articles/s41467-021-26592-2
- H Heuristics (2026), Human Exposure to Extreme Heat dashboard. hetr.hheuristics.com