- The modern construction industry is built on cement, with factories and public buildings, commercial space and apartment buildings, and homes fashioned out of it. But cement production is helping destabilize the climate, and has poor durability. Bioarchitects in Mexico think they have a solution.
- They’re reviving traditional clay adobe building techniques used since the 16th and 17th centuries in Mexico and the U.S. Southwest, to give birth to a new cutting-edge school of bioconstruction aimed at reducing the ecological footprint of the cement-hungry construction sector.
- Bio-buildings are built from natural materials, are long-lasting, energy-efficient, healthier, and often with better earthquake resistance. Built with local materials by locally trained workers, with their walls easily recycled at the end of a building’s life, bio-buildings can be part of a circular economy, benefiting humanity and nature.
- Bioconstruction could radically cut construction sector carbon emissions by curbing cement production. But bioconstruction faces an uphill battle against outdated building codes, and a huge, well-entrenched cement and construction industry, whose companies are often large contributors to political campaigns in Mexico and other countries.
Every morning, when Laura Alba arrives at her office in the Imagina cultural center on the outskirts of León in central Mexico, she feels good vibes — and that’s not only because she loves her job leading a nonprofit that educates the city’s poor children.
“This is a beautiful place where I have a lot of magical moments,” she says of the building where she works, despite its being located in one of the most dangerous neighborhoods of León, a city of 1.7 million in Guanajuato state.
Imagina is housed in a literally groundbreaking edifice: It’s a big, multistory facility, constructed mostly from locally dug clay adobe, and is the first modern public building in Mexico engineered using bioconstruction techniques.
Harmony as a principle
The spacious cultural center is an eye-catcher, with its pinkish adobe walls seeming to rise right out of the earth, its two red domes reaching gracefully skyward, and its roof partly covered in solar panels. Its big round windows, open pattern handmade brick walls, and soaring arched entryway all invite natural sunlight, reducing electricity use.
It’s a feel-good space inside too, with excellent ventilation and pleasant temperatures maintained without air conditioning year-round. The center is flanked by a kitchen garden, flower garden, and an edible forest. The building also boasts composting toilets.
But the key to what makes this public space revolutionary, is that it was constructed not out of modern society’s ubiquitous cement, but of local materials: clay adobe, wood and brick. In fact, all 3,500 square meters (about 37,700 square feet) are meant to serve as a bold demonstration of bioconstruction principles.
But Imagina is far more, Alba says. “The building is important because of its sustainability, but also because of its social impact on the community.” This seamless integration of architecture and purpose is indicative of bioconstruction, a holistic building technique that aims to achieve a circular economy, minimizing waste and benefiting people.
“Harmony is the key principle,” declares Peter van Lengen, Imagina’s lead architect. “Buildings need to be in harmony with the surrounding nature and community.”
This implies not only the use of local, eco-friendly materials, but also the recruiting and training of a cadre of local craftspeople. After receiving a crash course in building with clay, 130 newly trained bricklayers from the city’s El Castillo neighborhood were hired to complete the two-year construction project.
While this form of adobe architecture is a several-centuries-old tradition in Mexico, nowadays it’s been almost forgotten, with only a few workers left who remember how it’s done. But this isn’t a big problem, van Lengen says. “Everybody can learn how to do it.”
And van Lengen should know. He’s the son of Johan van Lengen, whose Barefoot Architect’s Manual became famous in the 1980s. It’s a tome nowadays recognized as the bioconstruction bible.
Dreaming of a new era of construction
When the building of Imagina was completed in 2016, its inauguration was a huge social event, attended by the state governor, city mayor, and also those who built it, including a proud group of young former substance abusers. “They were weeping when they were handed over a diploma for their participation,” Alba recalls. “Thanks to the diploma, many of them have found work elsewhere.”
Imagina’s completion was a dream come true for van Lengen too. “I thought it would be the beginning of a new era of bioconstruction,“ he says, because the 2016 grand opening nearly coincided with a crucial moment in international diplomacy, coming less than a year after the historic Paris climate agreement was reached.
Bioconstruction was seen then as a way to reform and transform the building and construction sector — a climate killer that accounts for roughly 40% of global CO2 emissions .
A significant amount of this carbon release is due to “the building material, especially the cement,” van Lengen says; the cement industry is responsible for an estimated 8% of all global emissions .
The Portland cement production process , devised in 1825, begins today with the large-scale quarrying of limestone (calcium carbonate) and silica-bearing minerals such as clay. These react chemically within giant industrial kilns, whose high heat, in excess of 1,500° Celsius (2,732° Fahrenheit), make huge energy demands. The resulting “clinker” is mixed with gypsum, ground to a fine powder, and when water and aggregates like gravel are added becomes concrete — the most commonly used human-made material on Earth.
The cement industry produces 2.8 billion metric tons of CO2 emissions worldwide each year. Along with its massive energy demand, it’s also notorious for high levels of air pollution dangerous to human health, with cement plants in the U.S. and elsewhere often sited in low-income areas. Much of the more than 4 billion metric tons of cement produced annually goes into conventional concrete buildings.
Enchanting a broader public
At the Imagina opening, the state governor’s wife, Maria Eugenia Carreño, who then presided over Guanajuato’s social assistance department, fell so much in love with the new building that she later sent a group of young professionals for training with the cultural center’s construction team. Her hope was to copy the Imagina model in other Mexican cities, though that was not to be. Van Lengen confidently moved ahead, and his company, Tibárose , continues to thrive, with offices in both Mexico and Brazil.
Others, too, are riding the bioconstruction wave and educating a new generation of bio-builders. “It started in the ’70s with hippies, then I worked a lot for NGOs in rural communities, and nowadays I receive a lot of doctors and engineers, usually concerned about their ecological footprint,” says Alejandra Caballero. “Today, we receive more people from diverse backgrounds interested in bioconstruction.”
Caballero, a gray-haired woman who always wears overalls, is the director of Mexico‘s most famous bioconstruction school, the Proyecto San Isidro , situated on the outskirts of the picturesque village of Tlaxco, a short drive east from Mexico City.
Her school consists of half a dozen clay buildings — dormitories with bathrooms, a kitchen, and a green-roofed library — each with a unique design, using and displaying different bioconstruction methods.
Universities don’t teach it
Young architects have begun doing internships with Caballero to learn directly from her. One of them is 30-year-old Carla Godinez, who when Mongabay interviewed her was just finishing the exterior of a newly built cottage by smoothing out the wet clay walls with a mason’s trowel. “I would like to include bioconstruction in my portfolio because I see my clients’ interest growing,” Godinez says.
“Universities hardly offer courses in bioconstruction,” she adds. “And the normal knowledge of architecture is not of much use [in bioconstruction] because you build with completely different materials with completely different properties.”
There are a lot of traditional secrets that must be learnt: For instance, when building a bathroom with clay, or sealing an external wall, it must be made water-resistant. That requires a 2,000-year-old plastering technique called Moroccan stucco, which requires the mixing of adobe with lime in precise proportions, and then polishing with agate or obsidian stones. The result is a smooth, marbled, water-repellant surface.
Bioconstruction isn’t fast. It takes patience and some level of artisanal finesse. Finishing an adobe bathroom requires days if not weeks, not merely a few hours of tiling, as for a modern bathroom. But because its building techniques can be learned by anyone, it can often be done more cheaply, making the costs for a bio-house similar to those of a conventional home.
The poisoned narrative of the three little pigs
Bioconstruction has many other advantages apart from a smaller ecological footprint. As seen with Imagina, bioconstruction requires hands-on skill, not heavy machinery, so it creates lots of jobs and therefore a healthier, more resilient local economy. Bioconstruction can also be used as an exercise in community building, as was done at Imagina. It can also lower the long-term costs of heating and air conditioning, in some environments reducing them to zero.
Unlike many badly aging modern buildings, bioconstruction can also last for centuries. To illustrate that point, one need look no further than the clay city of Chan Chan in northern Peru or Arg-e Bam in Iran, a trading center on the famous Silk Road. Bam was built in the third century entirely of mud clay bricks and the trunks of palm trees. In German cities, one can still find beautifully conserved timber clay construction from the Medieval period. In Asia, parts of China’s Great Wall are made of clay.
But change comes hard to human societies. And ours is no different, where building with cement has become a go-to “tradition.” Modern construction companies also cast many doubts on clay buildings and are hard to fight, van Lengen says.
There is, for instance, the famous old children’s fable of the three little pigs and the hungry wolf that destroys the straw house of the first pig, then the wooden house of the second, only to be stymied by the third house, made of brick and mortar.
“[E]very kid knows [this story] and associates natural materials with being poor and unprotected,” van Lengen says, referring to the phenomenally popular Walt Disney short cartoon The Three Little Pigs, which premiered in 1933. But that’s based on a myth, he says. In fact, bioconstruction today has come a long way with its well-tested building techniques such as straw bale, timber frame and clay adobe, showing that these more natural materials and methods are at least as strong and durable as brick and mortar — while being far better for the environment.
Caballero also vigorously debunks the unqualified belief regarding cement’s strength: “About 70% of the conventional houses in Mexico are auto-constructed, without proper supervision by an expert,” she says. “Usually, people don’t use the correct mixture for the cement [when making it themselves], which is lowering the resistance of the material.” This can prove deadly during an earthquake.
Possibly the most terrifying example of concrete failure was seen in Haiti’s 2010 earthquake, when more than 200,000 people died, as many houses collapsed because of bad homemade cement or static construction errors.
“Clay houses can also collapse,” Caballero admitted. “But usually, they crack first which gives you enough time to escape.”
The slow shift to bioconstruction
Mexico’s government is aware of the problems with modern construction and recently started a program called CEELA , financed by the Swiss government, which aims to make modern houses more energy-efficient and climate-friendly.
CEELA is training architects and construction workers, and advising authorities on incorporating new building standards. But van Lengen calls the program unambitious: “A few solar cells on the roof and an energy-saving refrigerator do not solve the basic problem,” he states.
He calls some modern “climate-friendly architecture” trends depressing and misguided: “In order to be more energy efficient, Germany started to oblige constructors to seal windows, which is very harmful to human health,” he points out. During the COVID pandemic, architects realized that poorly ventilated buildings can be “sick buildings” that more easily spread infectious disease within.
Bioconstruction also suffers from the realities and misperceptions of today’s conventional home building and real estate markets: When considering bioconstruction, “Owners are afraid of high maintenance costs, about not being able to resell the house, and credit or financing that is hard to obtain,” says van Lengen.
But, notes Caballero, those fears arose relatively recently. Bioconstruction with adobe was very popular in Mexico until the revolution there in the 1920s. “After that, the new governments wanted to be modern, and we lost our tradition,” she says. And yet, adobe Catholic missions, some enduring since the 16th and 17th centuries, still dot the Mexican and U.S. Southwest landscape today.
An entrenched conventional construction industry
Another problem is the absence of proper regulations for bioconstruction and, worse, laws hindering them.
In most U.S. states, for example, construction materials must contain a minimum of 10% cement, but that can be lethal when combined with adobe. In 2013, Mexican architect Mauricio Rocha built a school of fine arts in Oaxaca. He decided to build with clay, but inexperienced with bioconstruction, mixed it with reinforced concrete. At the first earthquake, the building cracked and had to be demolished.
Caballero has another explanation for the ongoing marginalization of bioconstruction: the economic power of the cement industry . “Politicians love huge construction projects such as bridges, highways, hydroelectric plants,” she says.
Even though cement gradually disintegrates and loses its structural integrity with age, causing collapses of bridges and buildings around the world, it hasn’t lost its dominance. In Mexico, that control is probably helped along by generous political party donations by huge, often oligopolistic companies such as Cemex or Cruz Azul.
This may also be one reason why Imagina remains the only public building in Mexico built using bioconstruction techniques. “Clay is freely available, and up to now, there isn’t any Mexican company commercializing it and making profits,” van Lengen says.
But the conventional construction model is even strong in poorer communities where big cement and construction companies play no role. In small Mexican and U.S. towns, the mayor’s family, or those politically connected locally, often own the local retail hardware store, stocking cement sold by the bag.
“Maybe we need a president’s son who is a bioarchitect so that the sector will finally develop,” jokes van Lengen.
Banner image: Arg-e Bam in Iran, a trading center on the famous Silk Road, known to be the largest adobe building in the world. Image by Diego Delso via Wikimedia Commons.
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