What if there was a building material that was easily obtainable, environmentally sustainable, and inexpensive?
Well, there is. Just look down—you’re literally standing on it. Earth.
Soil as a building material is utilized in sun-dried mud brick (adobe) structures, rammed-earth walls, wattle and daub buildings, and in a variety of other construction techniques that vary from culture to culture and region to region. According to the United Nations, an estimated 30 percent of the world’s population lives in houses made of earth, and earth remains a prevalent building material in many parts of Africa, Asia, and Central and South America. The UNESCO World Heritage List includes more than 200 earthen sites.
Although this seemingly modest material has been used in construction for millennia, people often perceive it as something found solely in developing countries, as a local form of architecture. This is far from the truth. You can find earthen structures of almost every architectural type throughout the world, ranging from ancient archaeological sites to modern buildings. You see earth in large complexes and historic centers, in individual buildings, and in the form of decorated surfaces.
Consider the beautiful neighborhoods of Santa Fe, New Mexico, old and new, made of mud brick. The oldest public building in the United States still in use is the Palace of the Governors in Santa Fe, built in 1610 and today part of the New Mexico History Museum. The walls of the Alhambra Palace in Granada, Spain, are largely constructed of rammed earth; the palace’s name, from the Arabic Al Hamra, meaning red, is in reference to the color reflected by earthen walls at sunset. In Mali, the Old Towns of Djenné, including the Great Mosque, are made from earth formed into djenné ferey—cylindrical bricks shaped by hand—and the transmission of knowledge for this construction method is passed from father to son guided by the bareyton, a mason’s guild.
What about Earthquakes?
Earthquakes—especially the 2003 quake in the ancient Iranian city of Bam that destroyed more than 70 percent of the earthen buildings and killed much of the population—have earned earthen structures the reputation of being structurally unsound. But many of the fallen structures had previously survived for more than 500 years in this earthquake-prone region. Placed on the UNESCO List of Heritage in Danger the following year, Bam has since been the subject of a restoration project that is still ongoing.
It’s also important to note that modern materials such as concrete, which in many developing economies signifies progress, can also fail, as demonstrated by the 1971 collapse of the brand-new Sylmar hospital during the San Fernando, California, earthquake; the collapse of the Ponte Morandi bridge in Genoa in 2018; and just last year, the Champlain Towers South condominium in Surfside, Florida. Understanding the materials and construction techniques, as well as conducting ongoing maintenance, are key to ensuring a building’s longevity and structural integrity, no matter its building materials.
To address seismic safety in historic earthen structures, the Getty Conservation Institute (GCI), in a project with the Ministerio de Cultura del Perú, the Escuela de Ciencias e Ingeniería of the Pontificia Universidad Católica del Perú, and the University of Minho, has developed an innovative seismic retrofitting approach. (The Seismic Retrofitting Project is a component of GCI’s Earthen Architecture Initiative, an effort to support the field of earthen architecture conservation through laboratory research, field projects, training, conferences, and publications.) This new approach combines traditional construction techniques and materials with high-tech analysis—all to design and test easy-to-implement seismic retrofitting and maintenance programs that will improve the structural performance and safety of earthen buildings while minimizing loss of historic building material.
The seismic retrofitting of the small 17th-century Church of Santiago Apóstol in Kuñotambo in the Peruvian Andes, one of four case studies for this project, has been completed, and the focus now turns to a much larger structure, the cathedral in Ica, Peru, constructed in 1759. The new seismic retrofitting approach is intended to be widely applicable across Latin America—where the majority of historic structures are constructed of earthen materials—and detailed information on it is available through a series of free downloadable publications in English and Spanish.
Indeed, the entire field of earthen architecture conservation has grown tremendously in recent decades. This is reflected in the development of a series of international conferences devoted to the preservation of earthen architecture, the first of which was held in 1972 in Iran. With each conference the number of participants, along with their geographic and professional diversity, has increased. Academics, scientists, architects, and conservation practitioners, united by their interest in earthen architecture, now convene every few years to discuss chemistry, soil science, seismology, hydrology, structural engineering, archaeology, sustainability, and more as they pertain to earthen architectural heritage. In June this year, Santa Fe will host the next such conference, Terra 2022, organized by the GCI, the National Park Service, Vanishing Treasures Program, and the University of Pennsylvania Stuart Weitzman School of Design.
The Old and the New
Existing earthen heritage is an important resource for conservators, as are local craftsmen who bring an enormous capital of skill and expertise in traditional construction techniques and use of materials. Built heritage also shows us how to adapt to a given context, and inspires ideas for how earthen materials can be used in a modern context.
Consider the windcatcher, a traditional architectural element that captures cool breezes and redirects them downwards, either into the home or into underground storage rooms to refrigerate perishable foods. Earthen windcatchers have been in use for millennia in the Middle East and North Africa, as well as in Pakistan and India. Yazd, in Iran, popularly known as the City of Windcatchers, was added to the UNESCO World Heritage list in 2017. The windcatchers, together with the courtyards and thick earthen walls, create a pleasant microclimate in this hot desert city. Neglected by modern architects in the latter half of the 20th century, windcatchers have been rediscovered and adapted by architects in the early 21st century as a way to increase ventilation and cut power demand for air conditioning. Windcatchers used in the buildings of the University of Qatar, Doha, are a good example.
Senegalese architect Nzinga Mbouphas been pushing for earthen materials to make a comeback, arguing that they reduce pollution from cement factories and electricity production and also keep people cool. She has noted that it really resonates with people when she reminds them that their grandmother’s mud house in the village was always the coolest.
While interest in new earthen architecture is continuing to grow—in part because of concerns related to the environment, sustainability, and equity—it hasn’t yet gone mainstream. CRATerre, the Center for Research and Application of Earth Architecture, part of the School of Architecture of Grenoble, France, offers the only master’s degree in earthen architecture in the world. Few architecture programs even expose future architects to this material. In many parts of the US, local building codes can make it illegal or prohibitively expensive to build with earth. And there are no lobbies or manufacturing industry groups that support earthen materials as there are for concrete, lumber, and steel. Still, earth is the only building material not yet industrialized, even though it is readily available and can potentially contribute to sustainable and equitable development.
This is slowly changing, and recognition is building. On November 24, 2021, the winners of the 2021 edition of the TERRAFIBRA Award were announced during the inauguration of the TerraFibra architecture exhibition in Paris. Under the patronage of the UNESCO Chair for Earthen Architecture, Building Cultures, and Sustainable Development, 40 buildings conceived, built, or rehabilitated with earth, plant fibers, or both were recognized. Projects include a public school in Zanskar, one of the most remote places in India; the Terre Centre on the campus of Kunming University of Science and Technology in China, as a space to carry out long-term artisans’ training and showcase the achievements of new seismic resistant earth construction; and the Xewa Sowé Child Care Center, in Benin, West Africa, built with the help of the local community.
The TerraFibra award celebrates and promotes the aesthetic properties, construction advantages, and environmental benefits of these types of buildings to a global audience. The local know-how and cultural traditions that have inspired these projects provide a foundation for a modernity that acknowledges our different identities.
Today more than ever, such approaches are needed to respond to the cultural homogenization and globalization threatening the values, origins, and expressions of countless communities.
