Deep in Yemen’s most remote valley lies the city of Shibam. Surrounded by palm groves, and flanked by the steep cliffs leading up to the Yemeni highland on both sides, the city of 2,000 inhabitants hardly seems impressive. Just a handful of high-rise residential buildings, not so different from the Soviet-style blocks found across the Arab world.

Yet  these buildings don’t date from the 20th century, or even the late 19th century. They were built almost five centuries ago, and have remained largely unchanged since.

On a dustless day, the white finish of its walls can be seen from miles away. The city, one of the few to be designated a UNESCO World Heritage site in its entirety, appears to rise from the plains. Its 500 houses reach an astounding 100 feet in height, almost as high as Chicago’s  first skyscrapers. Perhaps most remarkable of all is the fact that the city was built using nothing but mud.

From a historical point of view, this is an incredible piece of engineering. But does the city also hold the key to a more sustainable architecture? Salma Damluji, the world’s foremost expert on Arabia’s traditional architecture, thinks the city’s use of mudbrick – bricks that have been dried in the sun rather than fired – is a key technique developed to cope with challenges posed by the harsh climate.

A close up of the "skyscrapers". Image: Aiman Titi/Wikimedia Commons.

Mudbrick has a higher heat capacity and lower conductivity than concrete, which means it slows the rate at which the temperature within the building changes. It’s also cheap to produce - labour costs are the only real costs involved - and it’s eco-friendly. Not only does the production of sun-dried bricks involve no polluting emissions, the bricks are also reusable.

And, unlike fired bricks, the physical structure of dried bricks does not change during the drying process. Without its white protective layer, a wet brick simply becomes mud.

In Shibam, climatic considerations manifest themselves in more than just the building material. Wooden windows provide privacy, refract glare and promote air circulation with their low placement, and small ventilation holes near the ceiling. Narrow streets and open plazas further enhance this air circulation on a city level. Thus, the architecture of Shibam reveals a complete approach to urban planning, fine-tuned to the city’s climate and social structure.

Although Shibam’s skyline probably forms its pinnacle, mudbrick architecture is widespread in the Middle East. One of its greatest champions was the Egyptian architect and intellectual Hassan Fathy (1900 – 1989), whose architectural philosophy took great inspiration from the socialist politics of Egypt’s anti-colonial hero: Gamal Abdel Nasser.

James Steele, in his biography of the architect, writes that, “On the one hand, Fathy respected and admired European traditions, while on the other hand he resented them as part of a colonial legacy that had threatened Egypt’s identity.”

Spurred on by discomfort with European models of architecture and urban planning, Fathy researched a wide range of architectural traditions native to Egypt. Though he was greatly impressed by both Pharaonic and Islamic monumental architecture, he was more directly influenced by the vernacular architecture of rural Nubia, an area covering the south of Egypt and the north of Sudan.

It was in Nubia where he first encountered mudbrick. “Once convinced of the long history, durability and cultural applicability of mudbrick, as well as its low cost and environmental advantages,” Steele writes, “Fathy saw no reason why it should not be used on a wider scale.”

Towards the end of his life, he was widely recognised for his development of an architectural philosophy that integrated modern technology with the demands of local culture and nature, winning the Aga Khan Award for Architecture in 1980.

And yet it appears that his work failed to make a lasting impact on architecture in the Middle East. No large scale projects involving traditional building methods exist, and even Shibam is under threat.

While decades of political instability and the current war between Houthi rebels and the Saudi-backed government forces have largely passed by the remote valley, Shibam’s architecture has been in decline since the nationalisation of many of its buildings. Although the buildings are rented out to their original owners, a lack of ownership has made their inhabitants reluctant to invest in the considerable maintenance costs. Without regular maintenance, crucial experience with traditional building methods risks being lost forever.

In close up. Image: Jialiang Gao/peace-on-earth.org/Wikimedia Commons.

And local tradition is crucial. When Oxfordshire organic farmers Lutfi and Ruby Radwan, inspired by the mud brick architecture of Saudi Arabia and Senegal, built Willowbrook Farm, they decided to use similarly eco-friendly methods. However, Britain’s climate is, unsurprisingly, not quite dry enough for sundried bricks.

“Instead, we built using the traditional British method of mixing the cob and building up directly in a continuous lump,” Lutfi says. “We admire Hassan Fathy’s work, but it didn’t influence us greatly. More importantly I had visited a number of mud buildings in Britain to see how local issues were dealt with.”

“Mudbrick architecture is more sustainable and cheaper if one factors in the environmental costs,” he continues. “Materials and labour can usually be sourced locally, so it benefits a local economy rather than relying on inputs from outside, which also affects energy costs involved in transportation.

"Plus, its environmental impact is minimal. These traditional methods are certainly a viable alternative to less environmentally sustainable modern methods.”

Sustainable, local architecture. With a shortage of 3.5m affordable homes reported in the Middle East and North Africa, perhaps an affordable, durable and eco-friendly solution lies in the traditions of a forgotten Yemeni valley.