This story was produced and published by National Geographic through a reporting partnership with the United Nations Development Programme.
It’s 11 a.m. on a mid-May morning in the village of Koumi, Burkina Faso, and Sanon Mousa has almost finished the annual maintenance on his three-room house. He has replaced termite-ridden roof supports with freshly cut beams. He has applied a layer of reinforcing mud to the walls, some of which are a yard thick and more than 100 years old. After replenishing the thatch and sacrificing a goat to the memory of his ancestors, all that will remain is for his female relatives to apply layers of rainproofing to the exterior.
“The mud will keep us cool. The motor oil, clay, and cow dung will keep us dry,” Mousa says. “We’ve perfected this.”
Mousa, a 50-something retired school librarian with a slight paunch and a serious demeanor, is proud of his work. That doesn’t mean living in it is his first choice, though. When we met, two brothers in the village had recently been killed in their sleep when a mud wall collapsed on them.
In recent years, Mousa has watched as his wealthier neighbors, in this verdant strip of the country’s southwest, have rebuilt their own homes in concrete. He has smarted at what he sees as a symbol of his relative poverty. Despite considerable debt and consecutive failed harvests of the crops he relies on to pad his pension, he’s sorely tempted to borrow money and abandon mud.
Holding court inside a crumbling mud meeting house—and with Mousa sitting uncomfortably to his side—Sanu, the village chief, is furious.
“This is our heritage,” he says. “For thousands of years, these houses gave us a good life. Why would we change when we most need them?” He has mandated mud construction in the village core in a bid to preserve the old ways. But fewer and fewer people are abiding by his instructions. Painfully, that includes his own sons.
“I guess this is modernity,” Sanu says. “Maybe we can’t fight it anymore.”
Concrete on the rise
Across Sahelian Africa, there are thousands of villages like Koumi—and in the dozens I’ve visited in several countries, concrete is ascendant. Architects, officials, and villagers confirm the trend: People are discarding traditional materials, mostly mud, in favor of concrete, as soon as they can afford it. As living standards increase making concrete more accessible, some of the world’s hottest, poorest landscapes are rapidly morphing from brown to cinder block grey.
In scores of interviews this year across Burkina Faso and Morocco, villagers and city dwellers were near-unanimous in their preference for concrete over mud, the only building material many had ever known. They see concrete as sleek, clean, and above all, less likely to collapse during extreme rainfall. As a concrete advertisement outside Koumi puts it, ‘Concrete is a Strong Material for Strong Men.’
But as climate change makes a hot region even hotter, a growing coterie of architects, tribal chiefs, and government officials insist that concrete construction is anything but a sign of progress. Mud has a high thermal mass and hence a long lag time, which means that heat only slowly penetrates adobe walls, before dissipating as outside temperatures cool in the evening. By contrast, thin concrete cinder blocks, with their hollow recesses, allow for the swift passage of heat, rapidly warming house interiors.
Mousa’s house is a case in point: On the day photographer Moises Saman and I visited, the temperature inside was in the mid-20s Celsius (mid-70s Fahrenheit), a good 14ºC or so cooler than outside.
Proponents of mud brick are motivated in part by a desire to preserve Sahelian heritage and identity. For all mud’s recent association with poverty and backwardness, this region has produced enduring, globally significant architecture from mud brick—in neighboring Mali, Timbuktu’s city center or the crenellated Great Mosque of Djenné are good examples. In Burkina Faso too this regional patrimony is a source of pride.
But the mud-brick revivalists also have a grander ambition. On a continent that accounts for just four percent of global emissions, yet is hit hard by climate change, they’re trying, as world powers fiddle, to take ownership of some of the solutions. In beating the heat, these architects suggest, homegrown, nature-based traditions could be every bit as important as foreign technology and expertise.
“It’s a matter of time, it’s a matter of belief. It’s a matter of political will,” says Francis Kéré, a Burkina Faso-born architect and globally renowned proponent of eco-sensitive architecture. “But there’s a lot of accumulated knowledge now. In 10 years, you’re going to be surprised by our success.”
A refuge for the sweaty
It’s at least 45ºC (113ºF) in the shade by the time we arrive in the northern town of Kaya, but well under 30ºC inside Clara Sawadogo’s latest project, a half-built clinic: You’d be hard pressed to break a sweat. The vaulted earth ceiling cocoons the cool. The stone and mud brick walls deflect the sun. Angled toward the prevailing north winds and surrounded by lush greenery, the site is already enticing enough for dozing stray dogs.
Sawadogo is one of the young, environmentally savvy architects trying to re-popularize mud. She’s got plenty of talking points. The material is essentially free, or at least locally available for a fraction of the cost of concrete, which requires several ingredients and which, in Burkina Faso’s case, are mostly imported. At the adobe pits that dot the outskirts of many large villages, teams of youthful laborers lever mud from the ground, compress it into rectangular cookie cutter-like fittings, and then sell each air-dried brick for 40 CFA apiece, about a tenth of a U.S. cent.
“People tell me: It’s the 21st century. Stop using mud,” Sawadogo says, gesturing at her design. “But look at this. What’s not modern about this?”
Mud construction contributes little to global warming–unlike concrete. The manufacture of cement, a key ingredient of concrete, accounts for around five percent of global CO2 emissions. And concrete tends to be a gateway, once people can afford it, to another fossil-fuel guzzling invention: Air conditioning. Worldwide, both the electricity and the coolants required by air conditioning are a growing source of greenhouse emissions.
The greatest selling point of mud in Burkina Faso, where temperatures seldom dip much under 30ºC (86ºF), is that it makes the heat tolerable even without air conditioning.
In Boromo, roughly a three-hour drive west of Ouagadougou, the capital, Ilboudou Abdallah has recently rebuilt his part-concrete, sheet metal-roofed house in mud. “I can’t tell you what a joy it is being able to spend time inside the house now without suffering,” he says. The Association La Voûte Nubienne, an international NGO, helped with construction, one of a record 5,000 houses it built in Burkina Faso in 2020.
In Tiébélé, a commune along the Ghanaian border where most residents have long since turned to concrete, many of them have taken to returning to their old, ornately painted mud houses at night. Some appear to regret ever having abandoned them.
“They see the comfort that they said ‘no’ to before,” says Bayeridiena Abdou, a farmer who lives inside the mud-only local chief’s compound. “They’re sneaking back.”
In clinics from Leo to Bobo-Dioulasso, doctors report a roughly fivefold increase in heat-related admissions and deaths over the past decade. Some doctors suspect that a disproportionate number of these patients are men and women who’ve rebuilt in concrete but lack the means to artificially cool their new houses.
“The reality is that cement construction is simply sexy,” says Francis Kéré. “But it's bad sex because you don't have the materials you need. It is not producing comfort.”
Dangerous to live in?
But mud-brick buildings have one major drawback.
In District 9, a poor and populous sector of northern Ouagadougou, most of the houses were built of mud. Then came the summer of 2020, one of the strongest rainy seasons on record. The unprecedented rains tore through people’s ceilings, soaking their meager possessions and penetrating the oil and cow dung rainproofing that’s no match for such torrential downpours. Soon after, flood waters inundated the neighborhood in up to 20 inches of fast-flowing sludge. By the time the waters eventually receded, at least a dozen people were dead and over 2,000 mud houses had been reduced to soggy ruins.
Meeting in an upscale bakery near the city center, Siméon Toe, a career builder of both concrete and mud, says there’s no understating the extent to which the population has lost faith in traditional materials.
“There is a real fear,” he says. “A fear that meets the stereotypes of mud as the poor person’s material and that drives people to concrete.” As if to underline his point, three interviewees at a nearby granite quarry specifically identified a desperate desire to rebuild in concrete as their main reason for tolerating their work’s brutal heat, horrific air quality, and grueling—but well-paid—labor.
“Sleeping in heat is better than dying in collapsing mud,” Oumar Oukongo reasons.
Yet, as an industry veteran who’s witnessed Ouagadougou’s transformation from an all-mud town to a city with concrete-and-glass apartment blocks and elaborate highway overpasses, Toe has little doubt that concrete would have expanded its foothold, building collapses or not. People have become more individualistic, fueling a desire for large-windowed, low-maintenance structures, which mud can’t usually provide. Urbanization as well as jihadi violence have torn millions of people from the extended families that they traditionally relied on to build their mud houses for free.
Meanwhile, rampant deforestation of the trees needed for traditional roofs is reducing Burkina Faso’s woodland by up to 600,000 acres a year, according to forestry officials. Rampant desertification is making the soil sandier and less suitable for mud brick. Together, these challenges are adding to mud’s costs and complications—and hurting its competitiveness with concrete.
“A house, like a human, needs a lot of care,” said Reine Zongo, another young eco-sensitive Burkinabe architect. “But in these conditions that care is not always there.”
An uncertain future
Francis Kéré is in a reflective mood when I call him in July. This year’s rainy season was every bit as bad as the last, destroying dozens of buildings across Burkina Faso, including a school, which collapsed on a classroom of children, and part of the Grand Mosque of Bobo-Dioulasso, one of the most celebrated buildings of its kind in the Sahel. The subsequent bad press has only reinforced the clamor for concrete, no matter the cost.
But even as the setbacks have multiplied, Kéré and other mud advocates have been hard at work trying to rehabilitate the material’s image. They’re finding ways to protect mud buildings from downpours—by adding broader, metal canopy roofs that project more than a yard out from the walls, for example, or by mixing small portions of cement into the mud bricks to fortify them.
And by developing more advanced supply chains, they’ve learned to match some of concrete’s inherent advantages. In an industrial park outside Ouagadougou, Mahamadou Zi’s workers cut, condense, and then sell millions of standard size compressed earth bricks—providing the reliable supply and ease of construction that attracts clients to concrete. “I remember how cool my grandfather’s house was,” Zi says. “I wanted to make it simpler for others to replicate this experience.”
Through a rigorous emphasis on not cutting corners with a material that is unforgiving of shoddy construction, architects hope to limit the building collapses that are damning them all by association. At her construction site in Kaya, Clara Sawadogo says she has had to be so exacting in erecting the vaulted roof that 15 of her original 25 masons quit, citing the difficulty of the work.
“It’s not just about the materials,” Kéré says. “It’s what you do with them, and many have reduced it to mediocrity, like fast food.”
Ultimately, though, Kéré wonders if, after being fed a steady diet of half-truths about mud’s dangers and concrete’s promise, wary citizens simply need more examples of what well-built mud architecture can offer. Around Koudougou, 60 miles west of Ouagadogou, he has tried to create something of a showcase. At the Lycée Schorge high school and at the Burkina Institute of Technology, a technical college, hundreds of students learn—and thrive, according to their teachers—under multi-layered and overhanging roofs, between earthen walls, and surrounded by floor-to-ceiling windows. At a nearby mud-brick orphanage, supervisors report fewer fights, fewer mental health issues, and higher test scores.
To one 18-year-old computer science student, who gave his name as Nataniel and who has never lived in a home with electricity, it’s almost as if these places are air-conditioned.
“We were told mud was bad,” he says. “We were told we needed to work to escape this. But I would be happy to live in something like this.”