Traditional building materials are cooler, cheaper, and require less energy for manufacturing. But persuading Burkina Faso villagers to insist on using soil is not easy.

This story was produced and published by National Geographic through a reporting partnership with the United Nations Development Program.

It was 11 a.m. in the morning of mid-May in the village of Kumi, Burkina Faso, and Sanon Moussa had almost completed the annual maintenance of his three-bedroom house. He replaced the termite-infested roof supports with newly cut beams. He applied a layer of reinforced mud to the walls, some of which were one yard thick, and were more than 100 years old. After putting thatch on his ancestors and sacrificing a goat to commemorate his ancestors, all that is left is for his female relatives to coat the outside with a rain layer.

"Mud will keep us cool. Motor oil, clay and cow dung will keep us dry," Moussa said. "We have perfected this."

Mousa is a 50-year-old retired school librarian with a small belly and serious expression. He is proud of his work. But this does not mean that living in it is his first choice. When we met, two brothers in the village were recently killed by the collapse of a mud wall in their sleep.

In recent years, Moussa has witnessed his wealthy neighbor rebuilding his home with concrete in this verdant area of ​​the southwest of the country. He felt smart about what he thought was a symbol of his relative poverty. Although he was heavily in debt and the crops he relied on for pensions continued to fail, he still wanted to borrow money and discard the mud. 

The court was held in the crumbling mud conference hall-Moussa sat uncomfortably beside him-and the village chief Sanu was angry.

"This is our legacy," he said. "For thousands of years, these houses have given us a good life. Why should we change when we need them most?" He asked for soil construction in the village core to preserve the old ways. However, fewer and fewer people follow his instructions. The pain is that this includes his own son.

"I think this is modernity," Sanou said. "Maybe we can't fight anymore."

Throughout Sahel Africa, there are thousands of villages like Koumi—concrete is on the rise in dozens of villages in several countries I have visited. Architects, officials and villagers confirmed this trend: as long as they can afford it, people will abandon traditional materials, mainly mud, and use concrete instead. As living standards improve and concrete becomes more accessible, some of the hottest and poorest landscapes in the world are rapidly changing from brown to cinder block gray.

In dozens of interviews in Burkina Faso and Morocco this year, villagers and urban residents almost agreed that concrete, not soil, is the only building material known to many people. They believe that the concrete is smooth and clean, and most importantly, it is unlikely to collapse during extreme rainfall. As Koumi's concrete advertisement outside said, "Concrete is a powerful material for strong men."

But as climate change makes hot areas even hotter, more and more architects, tribal leaders, and government officials insist that concrete buildings are by no means a sign of progress. Mud has a high thermal mass, so the lag time is very long, which means that the heat will only slowly penetrate the adobe wall, and then dissipate as the external temperature decreases at night. In contrast, thin concrete cinder blocks with hollow grooves allow rapid heat transfer, which quickly warms the interior of the house.

Mousa's house is a good example: on the day the photographer Moises Saman and I visited, the temperature inside was about 20 degrees Celsius (about 70 degrees Fahrenheit), which was about 14 degrees Celsius lower than the outside.

The supporters of mud bricks are partly motivated by the desire to protect the heritage and identity of the Sahel. Although mud has recently been associated with poverty and backwardness, the area has been used mud bricks to build enduring, globally significant buildings-in neighbouring Mali, Timbuktu’s city centre or Djeene’s large jagged mosque is very popular. Good example. In Burkina Faso, the heritage of this region is also a source of pride.

But mud brick revivalists also have greater ambitions. On a continent that accounts for only 4% of global emissions, they are hit hard by climate change, and they are trying to master some solutions like the world's major powers. These architects suggested that local, nature-based traditions may be as important as foreign technology and expertise in resisting high temperatures.

"It's a matter of time, it's a question of faith. It's a question of political will," said Francis Kéré, a Burkina Faso-born architect and a world-renowned supporter of ecologically sensitive buildings. "But now a lot of knowledge has been accumulated. In 10 years, you will be surprised by our success."

When we arrived in the northern town of Kaya, the temperature in the shade was at least 45ºC (113ºF), but in Clara Sawadogo's newly designed semi-built clinic, the temperature was much lower than 30ºC: it is difficult for you to sweat. The vaulted earth ceiling makes the coolness a cocoon. The stone and mud brick wall deflected the sun. The site faces the prevailing north wind and is surrounded by lush greenery, which is enough to attract stray dogs to doze off.

Sawadogo is a young, environmentally-savvy architect trying to repopulate soil. She has a lot to say. This material is basically free, or at least available locally at a fraction of the cost of concrete, which requires multiple components, and in the case of Burkina Faso, these components are mainly imported. In the adobe pits scattered on the outskirts of many large villages, a group of young laborers pried the soil from the ground, compressed it into rectangular biscuit knife-shaped accessories, and sold each air-dried brick for 40 CFA, which was about one US dollar. point.

"People tell me: it's the 21st century. Stop using mud," Salvadorgo said, pointing to her design. "But look at this. What's so unmodern in this?"

Unlike concrete, mud construction contributes little to global warming. Cement is a key component of concrete, and its production accounts for approximately 5% of global carbon dioxide emissions. Once people can afford it, concrete is often the gateway to another invention that consumes fossil fuels: air conditioning. Worldwide, the electricity and coolant required for air-conditioning are both sources of increasing greenhouse gas emissions. 

The biggest selling point of Burkina Faso's mud is that even without air conditioning, the temperature is rarely lower than 30ºC (86ºF), but it can tolerate high temperatures.

In Boromo, about 3 hours west of the capital Ouagadougou, Ilboudou Abdallah recently rebuilt his semi-concrete sheet metal roof house with mud. "I can't tell you how happy it is to be able to spend time in the house now without pain," he said. The La Voûte Nubienne Association, an international non-governmental organization, helped build a house, one of its record 5,000 houses built in Burkina Faso in 2020.

In Tiébélé, a commune along the border with Ghana, most of the residents there have already switched to concrete, and many of them are used to returning to their old, whitewashed mud houses at night. Some people seem to regret giving up on them.

"They saw the comfort of saying'no' before," said Bayeridia Abdu, a farmer who lives in the mud-only compound of the local chief. "They sneaked back." 

In clinics from Leo to Bobo-Dioulasso, doctors reported that the number of hospital admissions and deaths related to high temperature has increased approximately five-fold in the past ten years. Some doctors suspect that there are a disproportionate number of men and women among these patients. They rebuilt with concrete, but lacked artificial methods to cool the new house.

 "The reality is that concrete buildings are simply sexy," Francis Kéré said. "But this is bad sex because you don't have the materials you need. It doesn't create comfort."

But mud brick construction has a major disadvantage.

In District 9 of the poorly populated area in northern Ouagadougou, most houses are built of clay. Then comes the summer of 2020, which is one of the strongest rainy seasons on record. Unprecedented rain broke through people’s ceilings, soaked their meager property, and penetrated into the rain-proof layer of oil and cow dung, which is unmatched by the downpour. Soon after, the flood flooded the community with up to 20 inches of fast-moving sludge. When the sea finally receded, at least a dozen people died, and more than 2,000 mud houses were reduced to wet ruins.

Meeting at a high-end bakery near the city center, Siméon Toe, a professional builder of concrete and clay, said that the extent to which people have lost confidence in traditional materials made no secret.

"There is a real fear," he said. “A fear fits with the stereotype of soil as a material for the poor and drives people to turn to concrete.” As if to emphasize his point, three interviewees at the nearby granite quarry specifically pointed out that they are eager to rebuild concrete as they endure the work. The main reasons for the extreme heat, terrible air quality, and hard but well-paid labor.

"It's better to sleep in the heat than to die in the collapsed mud," Oumar Oukongo explained.

However, as an industry veteran who witnessed Ouagadougou’s transformation from a muddy town to a city with concrete and glass apartment buildings and well-designed highway overpasses, there is almost no doubt that concrete will expand it. A foothold, regardless of whether the building collapses or not. People have become more personalized, fueling the desire for large windows, low-maintenance structures, which soil usually cannot provide. Urbanization and jihadist violence have separated millions of people from their large families that traditionally rely on building mud houses for free.

At the same time, according to forestry officials, rampant felling of trees needed for traditional roofs has reduced Burkina Faso's woodland by as much as 600,000 acres each year. Rampant desertification is making the soil more sandy and less suitable for mud bricks. Together, these challenges increase the cost and complexity of the mud, and undermine its competitiveness in concrete.

“Houses are like people and need a lot of care,” said Reine Zongo, another young architect who is sensitive to ecology in Burkina Faso. "But in this case, care is not always there."

When I called him in July, Francis Kéré was in a heavy heart. This year’s rainy season is as bad as last year. Dozens of buildings across Burkina Faso were destroyed, including a school that collapsed in a children’s classroom, and one of the most famous buildings, a part of the Great Mosque of Popodioulasso. Similar to the Helle region. Regardless of the cost, the subsequent unhealthy pressure will only intensify the demand for concrete.

But even if the frustration has multiplied, Kéré and other mud advocates have been working hard to try to restore the image of this material. For example, they are looking for ways to protect mud buildings from downpours—for example, by adding wider metal canopy roofs that protrude more than a yard from the walls, or mixing a small portion of cement into mud bricks to strengthen them.

By developing a more advanced supply chain, they learned to match some of the inherent advantages of concrete. In an industrial park on the outskirts of Ouagadougou, workers at Mahamadou Zi cut, condensed, and sold millions of standard-size compressed adobe bricks—providing reliable supply and ease of construction to attract customers to use concrete. "I remember how cool my grandfather's house is," Zi said. "I want to make it easier for others to replicate this experience."

By strictly emphasizing not to cut corners with materials that cannot tolerate low-quality construction, the architect hopes to limit building collapse through association. At the construction site in Kaya, Clara Sawadogo said that she had to be so strict in building the vaulted roof that 15 of her original 25 masons resigned due to work difficulties.

"It's not just about materials," Kéré said. "This is what you did to them, and many people have reduced it to mediocrity, such as fast food."

In the end, though, Kéré wondered whether, after accepting the half-truth of a stable diet about mud hazards and concrete promises, vigilant citizens just need more examples of what a good mud building can provide. Around Kudougou, 60 miles west of Ouagadougou, he tried to create some display opportunities. At Lycée Schorge High School and Burkina Polytechnic Institute (a technical college), hundreds of students learn and thrive in an environment with multiple overhanging roofs, earth walls, and floors surrounded by floors. Ceiling windows. At the nearby mud-brick orphanage, the supervisor reported that the number of fights had decreased, mental health problems had decreased, and test scores had been higher. 

For an 18-year-old computer science student, his name is Nataniel. He has never lived in a home with electricity. It's almost like these places are air-conditioned.

"We were told that the mud was not good," he said. "We are told that we need to work hard to get rid of this situation. But I will be happy to live in such a place."

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