Mud buildings are remarkably good at keeping us cool in summer and warm in winter, and withstanding extreme weather. In the search for more sustainable buildings, architects are returning to this overlooked, age-old construction material.
In Yemen’s ancient walled city of Sana’a mud skyscrapers soar high into the sky. The towering structures are built entirely out of rammed earth and decorated with striking geometric patterns. The earthen buildings blend into the nearby ochre-coloured mountains.
Sana’a’s mud architecture is so unique that the city has been recognised as a Unesco World Heritage site.
“As an outstanding example of a homogeneous architectural ensemble reflecting the spatial characteristics of the early years of Islam, the city in its landscape has an extraordinary artistic and pictorial quality,” Unesco writes in its description of Sana’a. “The buildings demonstrate exceptional craftsmanship in the use of local materials and techniques.”
Even though the buildings in Sana’a are thousands of years old, they remain “terribly contemporary”, said Salma Samar Damluji, co-founder of the Daw’an Mud Brick Architecture Foundation in Yemen and author of The Architecture of Yemen and its Reconstruction. The ancient structures are still inhabited today and most remain private residences.
Damluji said it is easy to see why these mud buildings have not lost their appeal – they are well-insulated, sustainable and extremely adaptable for modern use. “It is the architecture of the future,” said Damluji.
Architects around the world are reviving raw-earth construction as they seek to construct sustainable buildings that can withstand extreme weather events such as flash floods and intense heat. Could this ancient form of architecture influence the design of our future homes and cities? Could this back-to-basics technique provide an important solution to the climate crisis?
Construction’s climate problem
The construction industry accounts for 38 percent of global carbon dioxide emissions. The building sector has an important role to play if the world is to meet its goal of reaching net zero by 2050 and keep global temperature rise below the critical threshold of 1.5C.
Swapping concrete for less polluting materials is critical to achieving our climate goals, scientists warn. Concrete, a staple of modern construction, has a huge carbon footprint. Building with concrete accounts for around 7 percent of global CO2 emissions – substantially more than the aviation industry which is responsible for 2.5 percent of emissions. Worldwide 4 billion tonnes of cement, the key component of concrete, is produced each year.
“We cannot live in these concrete jungles anymore,” said Damluji. “We have to consider the environment and biodiversity. We cannot construct in isolation.”
Mud could be the perfect sustainable alternative to concrete, according to Damluji. Constructing with mud has a very low impact on the environment and the material itself is fully recyclable, she said.
The city of Djenné lies in the Niger delta region of central Mali. Founded in 800 AD, it became an important meeting place for traders travelling from the Sahara and Sudan. Djenné is known for its magnificent earthen architecture, especially its Great Mosque which is the largest mud building in the world, standing almost 20m (66ft) tall and built on a 91m-long (300ft) platform.
Every year the residents of Djenné gather together to repair and reclay the mosque, supervised by a guild of senior masons. These master builders are revered for their expertise and artistry in Malian society, said Trevor Marchand, emeritus professor of social anthropology at London’s School of Oriental and African Studies and author of The Masons of Djenné.
“Master builders are recognised for their supernatural powers to bring protective elements to the buildings and people who live there,” said Marchand.
The re-claying is an important symbol of social cohesion, said Marchand. “Everyone takes part. Boys and girls mix the mud, women bring the water and masons direct the activity.
Djenné’s mud architecture is constantly changing as residents re-clay, repair and rebuild their homes.
“There is a dynamism to it,” said Marchand. “Mud is very malleable and it responds to the changing demographics of a home.” If the family grows, buildings can easily be added to the home and if it shrinks, buildings are left to decompose and turn back into soil.
Sustainable construction
The ancient building practice is inspiring modern-day architects, such as Serbian Dragana Kojičić, who specialises in raw-earth construction.
“Our ancestors were really clever and really practical – they used what they had around them,” said Kojičić. “The earth was everywhere and it could be used for everything: walls, floors, ceilings, stoves and even roofs.”
Kojičić, who completed her training at the Centre for the Research and Application of Earth Architecture, restores and builds earthen houses across Serbia, reviving ancient building methods. “Mud is contagious – it is love at first touch,” she said. You don’t need to wear any protective gear when handling the material, she adds. “With earth, you can just play.”
Anna Heringer, an Austrian architect who creates buildings using natural materials such as mud and bamboo, agrees. “It is a wonderful feeling to touch the earth,” she said. “You don’t need any tools to build with it, you just use your hands.”
Heringer has been working with mud for almost 20 years and has designed many notable earthen buildings, including the METI handmade school in Rudrapur, Bangladesh, for which she received the Aga Khan Award for architecture in 2007. “Mud is a very inclusive material; poor and rich can build with it,” she said.
The METI handmade school was built entirely with local materials, such as mud, straw and bamboo, and constructed by a team of local builders, craftsmen and the students themselves.
“Earthbound materials such as loam and straw are combined with lighter elements like bamboo sticks and nylon lashing to shape a built form that addresses sustainability in construction in an exemplary manner,” the Aga Khan jury said.
“Mud is the champion of future sustainable construction,” said Heringer. “It is the only material we can recycle as often as we like, without using any energy,” she said. “It actually gets better the more you use it.” It’s a bit like a dough, Heringer said – as you work with it, the material changes and responds.
But using mud for construction should be done in a sustainable way and should not reduce land availability for growing crops, said Marchand. “It can be a solution, but only on a certain scale,” he said, noting that the global population is expected to reach 9.7 billion people by 2050, mounting pressure on land.
BBC