Abstract

Earthen architecture has been used as a construction material in most of the world for millennia. According to the United Nations, approximately one third of the world population and half of the population of developing countries live in building constructed of earth. This presentation makes a basic SWOT (Strengths, Weaknesses, Opportunities, Threats) analysis of earthen architecture in an attempt to explain why this material, possessing many positive qualities, is often maligned or underestimated and dismissed as a construction material associated with poverty, especially in the rural areas of Latin America. This paper emphasizes the importance of maintenance and the preservation of the local socio-cultural knowledge system associated with earth construction.

EARTHEN ARCHITECTURE – VALORIZATION AND UNDERESTIMATION

Norma Barbacci

Robert A.M. Stern Visiting Professor , Yale School of Architecture

April 13, 2020 Lecture

I would like to start with a disclaimer. I am not a technical expert on earthen construction but an advocate or a fan if you will. As part of my work at World Monuments Fund (WMF) in Latin America, we helped conserve many important Pre-Columbian monuments built of earth, but I also witnessed the loss of the tradition of earth construction and the growing prejudice against a material that was in my mind, perfectly suited for the region’s climate, economy and heritage. So I decided to learn more about it, and this is what I found out…

1. EARTHEN ARCHITECTURE IN THE WORLD

Earth as a building material, because of its abundance and accessibility, has been used successfully from Afghanistan to Argentina, and from Mali to Mexico, for thousands of years.

The fertile regions that made possible the development of the Neolithic Agricultural Revolution invited human beings to build their settlements from the alluvial soils, rich in sand, silt and clay, mixed with straw from agricultural crops, and gave birth to the first solid and durable building material: sun-dried mudbricks.

According to United Nations statistics, approximately one third of humanity and possibly half of the population of developing countries live in earth buildings. From humble houses in Puno, Peru, to buildings with ten or more floors in Yemen, earthen architecture has been used to build homes, churches, mosques, palaces, fortresses, pyramids, barns, defensive walls and all types of structures, many of which have survived for centuries and even millennia in drier climates.

In Africa, Djenné-Djennó in Mali, one of the oldest villages in Sub-Saharan Africa, was built of adobe around 250 B.C. and the Great Mosque of Djenné, is considered the largest earth building in the world. In southern Morocco, the Berbers developed an earth architecture known as “ksar” or castle, which consists of a walled and dense enclosure located on the edge of the arable land, which is considered a model for bioclimatic adaptation in architecture.

Ksars in Morocco and Great Mosque of Djenné

In America, almost all Pre-Columbian cultures used earth in their constructions, especially in Peru, Mexico and the Southwest of the United States, but also in all those regions where hot and dry weather favored the use of this material.

Sechin Bajo, Huaca de la Luna, Huaca Ventarron, Chan Chan (Peru)

In Peru, Sechin Bajo (Ancash), is one of its oldest earthen sites, built of adobe in the 4th millennium B.C. Huaca Ventarron (Lambayeque), was built of blocks of yapana or dried alluvial mud in the 4rd millennium B.C. Huaca de la Luna (La Libertad), a ceremonial Moche pyramid was built of millions of adobe blocks and covered with polychrome friezes in the first millennium A.D., and the Chimu city of Chan Chan, a World Heritage Site, is considered the largest Pre-Columbian city in South America.

In Mexico, the core of the Pyramid of the Sun in Teotihuacán was built of compacted earth, between 300 and 900 A.D., while in the Sierra Nevada of Santa Marta, Colombia, the traditional homes of the indigenous Arhuacos, known as urakais, were made of quincha or wattle and daub.

Teotihuacan (Mexico), Urakais (Colombia)

During colonial times, indigenous earth construction systems continued to be used, enhanced by new European techniques, so the architecture built between the 16th and 18th centuries was mostly made up of quincha, tapial or rammed earth and mudbrick structures, combined with other materials such as stone and wood. Only from the 19th century, industrialized materials begun to be used in urban settings and, in the 21st century, these systems began to displace traditional earth architecture in rural areas.

In Asia, one of the first expressions of architecture and the first surviving earth structures are found in Anatolia, Turkey, at the archaeological site of Çatalhuyuk. This Neolithic settlement was built with adobe bricks, between 7500 and 5700 B.C., by a society of collectors, farmers and shepherds.

In China, the first structures of the Great Wall were built of earth almost 3000 years ago, and in the Fujian Province there are thousands of rammed earth structures built by the Hakkas between the twelfth and twentieth centuries, known as tolou or tolos.

In Japan, the earth construction system known as tsuchikabe (mud wall), consisting of a combination of clay, earth, sand and rice straw, was used from the 7th c. on the construction of temples, palaces and houses. The biggest threat to traditional Japanese wooden architecture is fire, so the tsuchikabe system became popular in the country as a fireproof system.

In Europe, some of the oldest settlements, located in Thessaly, Greece, were built of mud bricks, wattle and daub, and stone, as early as the 7th millennium B.C.

In Italy, the first Etruscan temples as well as the first monuments of the Roman Republic (4th and 3rd centuries B.C.) were constructed of adobe. Vitruvius, in his (1st century B.C.) treatise on architecture, discusses how to protect mudbricks (although discourages the use of wattle-and-daub), while in the Iberian Peninsula, earth construction techniques, introduced by the Romans, were later improved by the Arabs.

Spanish “palomares”, Vitruvius, Spanish cliff dwellings, Etruscan houses (ceramic & drawing).

During Medieval times, earth was used as fill in wooden constructions. Between the 15th and 19th centuries the rammed earth or terre pisé technique was widely used in France and was especially popularized in Paris by the architect François Cointeraux in the 18th century.

In the Middle East, the regions of the Mediterranean Levant, which today include Lebanon, Syria, Palestine, Israel, Jordan and parts of Iran and Iraq, were the cradle of great ancient cultures which excelled in the art of earthen construction since the 8th millennium B.C.

In Iran, the predominant construction system from prehistory to the present is earth, and in Yemen, the city of Shibam, known as the "Manhattan of the desert," has adobe buildings of 9-10 stories, dating back almost 1600 years ago.

The universal value of earthen architecture is evident and deserves the recognition, protection and conservation of the international community. In 2011 approximately 10% of the UNESCO World Heritage sites were earthen monuments or sites and 25% of the list of World Heritage in Danger was made up of this type of construction - threatened by floods, earthquakes, industrialization, urbanization, modern construction technologies, disappearance of traditional construction practices, etc. For this reason, UNESCO established the World Heritage Earthen Architecture Program (WHEAP) with the objective of improving the conservation and management of earth architecture in the world.

2. EARTH, AN IGNOBLE MATERIAL?

The following Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis attempts to explore the reasons why earthen architecture, possessing such good material qualities, such longevity as a construction technique, and such wide geographical distribution, is underestimated in many parts of the world, with a particular focus in Latin America.

2.1 Strengths

In terms of strengths, raw earth is an ecological material, since it is natural, it does not have to be industrially transformed, it consumes less energy and water than the manufacture of cement and other materials, it does not require transportation since it is everywhere, it is completely recyclable and does not generate waste during its construction or at the end of its useful life.

It is economical and its construction and maintenance techniques are relatively simple and do not require complex knowledge or equipment, therefore it is accessible to almost every nation in the world.

If it is well built and receives continuous maintenance, it can be resistant even against earthquakes and floods.

In Peru, the destruction by an earthquake in 1609 of the stone and brick vaults of the old Cathedral of Lima generated a technical debate between builders concerned with structural stability during earthquakes, and resulted in the use of new construction systems of greater lightness and flexibility such as vaults made of earth with cane frameworks; the reduction in the height of the walls and the increase of their thickness; the introduction of wooden reinforcements and especially; the requirement to maintain the structures after each earthquake. These recommendations proved to be effective as long as maintenance was carried out

More recently, an evaluation conducted by the Catholic University of Peru (PUCP) of the adobe houses reinforced with cane and asphalt, built in 1973 by the government, in the community of Cayaltí, Chiclayo, indicated that after 25 years they had resisted the onslaught of El Niño phenomena without major damage, as long as they had received maintenance.

Also, the report of the Earthquake Field Investigation Team (EEFIT) of the Institute of Structural Engineers of the United Kingdom, on the results of the earthquake of August 15, 2007 that devastated the central coast of Peru, mentions that the adobe houses that were reinforced by the Catholic University or the Japan International Cooperation Agency (JICA) before the disaster, in the cities of Guadalupe, Zúñiga and Huangáscar, performed satisfactorily during the earthquake, while all other adobe houses in the surrounding area suffered medium to severe damage or collapsed.

It is healthy since it does not contain toxic elements, it does not pollute the environment in any of its stages and its manipulation is not dangerous.

Earth constructions are comfortable and contribute to the quality of life of their occupants since they have a great thermal inertia: adobe absorbs heat during the day and releases it slowly during the night. Poured earth walls have less thermal conductivity than concrete and brick. This feature is especially important in the Andes where temperatures can drop to -22º C. Earth construction also offers sound insulation and helps control humidity by acting as a sponge.

It is a versatile material with many construction techniques that range from mudbrick (adobe), rammed earth (tapial), wattle-and-daub (quincha), cob walls, etc. Each region has its own systems and they could be adapted to diverse needs. The basic earthen material can be improved with the use of local natural reinforcement products which are often waste materials, which can get recycled this way.

Furthermore, it is a flexible system since it can be built in stages and it can be expanded, reformed and improved during rebuilding.

2.2 Opportunities

Regarding opportunities, as I mentioned before, a significant percentage of the world's population lives in earthen structures and, because of its wide geographical distribution, any improvement in the material or construction techniques can have a great worldwide impact.

Building with earth offers the opportunity to express cultural identity through its design, use of local materials and community maintenance activities.

In Burkina Faso, the royal complex of Tiébelé, a group of mud constructions painted with geometric motifs, is maintained through a communal effort where the tradition of mud plaster and surface decoration is transmitted from generation to generation.

In the Great Mosque of Djenné, the epicenter of the cultural and religious life of Mali and a UNESCO World Heritage site, wooden beams located throughout the exterior are both decorative and structural and also function as scaffolding for the re-plastering of the mosque during the annual festival called Crepissage de la Grand Mosquée or Plastering of the Great Mosque, in which the entire community participates, accompanied by music and singing. Despite the pressure to change certain aspects of the mosque such as replacing the earth construction with concrete, the sand floor with tiles or eliminating music during the maintenance festival, the Djenné community has struggled to maintain their material and intangible cultural heritage intact.

The availability and low cost of earth as a construction material means that it has great potential to contribute to poverty alleviation and sustainable development.

Hassan Fathy, the visionary Egyptian architect, recognized as a pioneer in sustainable and participatory architecture, was convinced of this and wrote the book: "Architecture for the Poor: An Experiment in Rural Egypt" in 1976, in which he describes his plan to build the adobe city of New Gourna, Egypt. New Gourna was built between 1945 and 1948 near Luxor, using mudbricks, the native technique that Fathy learned in Nubia, and traditional Egyptian architectural elements such as enclosed courtyards and vaulted ceilings. Fathy worked with the villagers to adapt their designs to their needs and taught them to work with adobe, supervised the construction of the buildings and encouraged the revival of old crafts such as lattice designs to decorate and ventilate the buildings.

Francis Kéré, an architect based in Berlin and a recent visiting professor at Yale, grew up in Gando, a rural settlement in Burkina Faso that had no school or medical services. After studying architecture in Europe, Kéré returned to his hometown to build a school together with the community. As a result of his work, Gando revived the ancestral tradition of earth construction techniques and now has schools and homes of good quality and contemporary design, perfectly adapted to the climatic conditions of the region.

In Neuquén, Argentina, the lack of housing and the difficulty of accessing mortgage loans forced many to look for construction alternatives that relied on their own labor. Since 2010, the Plottier Agricultural Professional Training Center No. 1 offers a workshop on earthen construction to 40 to 70 people per year. The premise of the workshop is that by building their house with their own hands, the owners can reduce construction costs by up to 80% compared to a commercially built house.

In Puno, Peru, the putucos or trulli of adobe and straw are examples of sustainable architecture, accessible to people of limited resources. In 2014 the Ministry of Culture declared the ancestral knowledge in the construction of putucos as Cultural Heritage of the Nation.

In Mali and Burkina Faso, the Djenné and Kassena communities mentioned before, by preserving their tradition of maintaining their earth structures, are developing an important economic resource, thanks to tourism.

Finally, given the imminent threat of climate change and global warming, earth construction offers a better alternative to concrete, which according to the Chatham House report of the Royal Institute of International Affairs, the concrete industry is responsible annually for 8% of CO2 (carbon dioxide) emissions in the world. On the other hand, earth constructions have better thermal qualities and therefore require less energy to heat or cool.

So then, given all these wonderful properties, how can we explain that raw earth is not considered a "noble" material such as concrete and brick?

2.3 Weaknesses

Because, as with any material, there are some weaknesses.

Earth constructions are sensitive to moisture and therefore require protection from rain, water penetration by capillarity and salt crystallization; they are sensitive to wind erosion; and structurally, only work well in compression, require a load distribution since they do not admit point loads, and in seismic areas, require reinforcement, especially at the angles and the connection between walls and foundations. Because of these vulnerabilities, earth is considered a “non-engineered” material.

Earth construction requires continuous maintenance, and deteriorated mud dwellings can offer an ideal habitat for insects that transmit diseases such as the Chagas disease which causes blindness (caused by triatoma dimidiata popularly known as vinchuca), or for parasitic vegetation.

2.4 Threats

The most common threats consist of natural disasters such as earthquakes and floods, and those generated by man, such as prejudice, loss of the ancestral knowledge of traditional construction techniques, lack of maintenance and inappropriate interventions.

2.4.1 Earthquakes

In the city of San Juan in Argentina, where 98% of the buildings were built of unreinforced earth, the earthquake of January 1944 destroyed 80% of the city.

In Chile, the earthquake of February 2010 damaged a large part of the country's earthen architecture, including 30% of the buildings declared National Monuments.

In Guatemala, in response to the damage suffered by adobe homes due to earthquakes in 2012, 2014 and 2017, adobe ceased to be the main housing construction material in the country, to be replaced by concrete block. Adobe was listed as a construction risk material, associated with poverty.

In Peru, earthquakes stronger than 6 megawatts, that occurred throughout the 20th century have caused the collapse of thousands of earthen buildings.

However, it is worth mentioning that the UNESCO (CERESIS) report of the devastating 2007 earthquake indicate that the earth structures that collapsed were those of poor construction quality, had walls that were too thin or too high, had a high percentage of openings, or had roofs that were too flexible or too heavy. Collapses occurred mainly due to the lack of adhesion between walls and roofs.

In the case of the Church of the Company of Jesus in Pisco (Peru), the building had been rebuilt in 1704 after its predecessor was destroyed by an earthquake in 1687, based on the recommendations developed after the collapse of the Lima Cathedral, mentioned before. The church resisted the earthquakes of 1746, 1877 and 1942, without being destroyed, but the cumulative effects of these seismic movements required maintenance and restoration interventions which in 1960 introduced the use of cement to reinforce vaults and walls. In addition, the church’s surrounding area was paved with cement and asphalt which, together with the plastic paint used as a finish on the walls, contributed to the trapping of moisture within the earthen structure, resulting in the crystallization of salts and the softening of the adobe. The added lack of maintenance and the attack of termites and fungi to the wooden elements, also contributed to the collapse of the church in the 2007 earthquake.

2.4.2 Floods

In 2015, several rainy days and sandstorms, not experienced in 40 years, destroyed 700 adobe homes in a refugee camp in the Sahara Desert, Algeria, where water dissolved the adobe like lumps of sugar, apparently, for not containing straw.

In March 2019, floods destroyed thousands of earthen houses in Herat province, Afghanistan.

In Peru, floods are a recurring phenomenon during the rainy season in the mountains, between the months of November and April. El Niño (ENSO: El Niño Southern Oscillation) contributes to aggravate these disasters, which especially affect the country's earthen architecture. For example, in March 2017, the flooding of the Huarmey River left this Ancash municipality flooded, without electricity or water for a week, and according to interviews with the victims, the government’s aid was insufficient and came too late.

2.4.3 Prejudice

Much of the world's earthen architecture is considered “popular architecture” or “vernacular” because it is of local, native, indigenous, or traditional origin, which automatically gives it a common, folkloric character, a “not being special” that diminishes its value and limits its fair appreciation. According to Graziano Gasparini, a Venezuelan architect and historian: “traditional popular architecture is fragile and breaks in the face of the emergence of more convenient new solutions. The traditional is valid until new options arise.”

The destruction of earthen architecture through earthquakes and floods usually sparks a vociferous public questioning of its capacity to resist natural disasters, and many times, authorities with a short-term vision, issue laws or decrees such as those promulgated in the wake of the earthquakes in Costa Rica (1910), Argentina (1944), or Peru (2007) by which the material became the scapegoat. In my opinion, because it is easier to blame the material, than to explain the conglomerate of bad practices that include failed public construction policies, uncontrolled development, lack of sanitation, lack of investment, poor building supervision, inadequate planning and disaster prevention, inexperienced builders, lack of maintenance, marketing of the cement industry, etc.

In a study conducted by the Ricardo Palma U. in communities of Puno, Peru, its residents indicated that as soon as they receive a higher income, the first thing they do in their homes is to replace the thatched roof with a corrugated metal one because it is considered a more durable material, easier to install and a symbol of modernity, although in practice this material only generates heat losses in the coldest hours of the night. Also, despite recognizing that the adobe-built enclosures are warmer than those of stone or metal, these residents indicated that if they had more money, they would replace the adobe with brick, since this is a material used in the city, and therefore associated with a higher economic stratum.

According to the Peruvian historian, Elizabeth Kuon: “Due to sociological problems that are structural in our country, now adobe is ceasing to be the favorite construction material for farmers. The ‘noble materials’ as they now call concrete, is what is used because it means economic status and therefore social status and a sign of prestige in rural communities, which is why the wonderful small and warm two-story adobe houses, are being replaced by a new landscape of ‘modern’ materials such as colored polycarbonate, colored glass, tiles, etc.”

2.4.4 Loss of Ancestral Knowledge

Another major threat to earth construction is the loss of ancestral knowledge of how to build and maintain this type of buildings.

In the Argentine Northwest, near the Quebrada de Humahuaca a World Heritage Site, the transfer of the knowledge of how to choose the earth, prepare it, let it “sleep” for several days, spread the straw, prepare the area, “cut” the adobe, let it dry and stack it; is part of the daily work of family life, passed along with other tasks, such as preparing the land to sow the seeds, spinning the wool to weave blankets or shelling corn to prepare food. It is these customs and daily tasks, particular and typical of the community, that over time generated the identity of the region, and the character of a recognized intangible heritage. This knowledge, unfortunately, is being lost because of the massive insertion of new materials, or the influence of "modernity" or the new cultural patterns brought by outsiders settled in the region.

In Chile, Cristian Heinsen, regarding his work at the Altiplano Foundation in Arica and Parinacota, says that “when someone arrives in a community asking who knows how to work with earth, most likely no one will respond. The adobero of the community, tired of the disregard for his inherited knowledge, will remain silent expectant and distrustful, as if that someone was interested in locating a treasure. For Heinsen, “the valorization of earth as a constructive element coincides with the vindication of indigenous or ancestral cultures and with the decolonization of knowledge.”

In Latin America, for the most part, earthen architecture construction is not taught in technical schools or universities, there are not enough norms and regulations written, and it hardly appears in the books of structures or technology.

2.4.5 Lack of Maintenance

The lack of preventative conservation is a symptom of the loss of the culture of maintenance in general, but it specially affects earthen construction because of its susceptibility to water and earthquakes.

In several examples mentioned before, we saw that many of the collapses caused by seismic movements occurred in structures that had not received proper maintenance. The cumulative effect of earthquakes requires constant maintenance, otherwise, it eventually results in partial or total collapse. As I mentioned, earthen constructions can offer a habitat for insects and invasive vegetation but only when they are riddled with cracks and holes. A well-preserved adobe or rammed earth wall can be as much or more sanitary than a concrete or brick wall.

2.4.6 Inappropriate Interventions

Most of the damage in earthen structures is caused by interventions carried out with incompatible criteria and materials, applied with the goal of “reinforcing” or “improving” the material or its design. Many times when an earth structure deteriorates, some builders accustomed to iron, concrete, lime and cement, decide that the solution is to incorporate these types of materials to give it solidity. Thus abandoning the basic concepts of continuity, homogeneity, adhesion - in terms of construction - and of unity, texture and color, in the visual and morphological sense.

A common intervention is the replacement of mud plaster with a cement one, especially in the lower parts of the walls where the wall is most exposed to use. This creates an impermeable layer that traps the moisture rising by capillarity, causes the accelerated deterioration of the mud wall and eventually, when the cement coat falls due to lack of adhesion, it drags with it, parts of the original wall.

The introduction of openings and additions of incompatible materials such as concrete blocks or reinforced concrete can cause detachment and separation, or “hammering” during earthquakes, and contribute to the loss of the structural unit of the construction.

Finally, deterioration due to lack of maintenance or failures caused by inappropriate interventions contribute to a poor perception of the material. This process is a vicious cycle that results in the replacement of a viable, economical and locally accessible construction tradition, with other technologies and materials that not only require a greater investment, but because of their industrial production and need for transportation leave a greater carbon footprint.

In contrast, seismic reinforcement, installation of adequate drainage infrastructure, use of appropriate restoration designs and techniques and continuous maintenance, are key to the sustainability of earthen constructions, especially in seismic or flood-threatened areas.

3. LEGISLATION

Legislation may be a threat or an opportunity for the preservation of earth building systems, depending on the intention and scope of the regulations. However, although there have been significant advances in recent decades, earthen architecture is neglected in many local and regional development plans.

In Argentina, although adobe is still used as a construction material, it is illegal in several regions, especially in seismic areas. However, ten years ago, environmentalists, architects and civil engineers started researching alternative construction techniques with low environmental impact, using earth, straw, cane and waste materials. This work resulted in the establishment of public ordinances that enable, regulate and promote these types of constructions in several cities.

In Chile, in 2003, when the Altiplano Foundation started to restore historic churches in Arica and Parinacota, the message from the Academy and the Government was to conserve the shape of the buildings, but replacing its original earth material with another ‘noble’ or modern material, that complied with the strict norms of construction safety. Years later, and in response to the massive damage caused by the 2010 earthquake, the Chilean Government developed in collaboration with Peruvian experts, a new Technical Standard (Minvu NTM 002) to regulate the restoration and structural consolidation of earth constructions in Chile, but new construction with this material is not yet legalized.

In Costa Rica, following the earthquake of 1910 that devastated the city of Cartago, the government launched a Presidential Decree to prohibit the construction of adobe in the city, and by not including regulations on how to restore or reinforce this type of construction, many were demolished.

In Peru, a country that has pioneered the development of earthquake-resistant design standards, the Technical Standard E-080 issued in 1985 and revised in 2006 and 2017, regulates reinforced adobe constructions. The law’s objectives are to regulate the design of buildings of social interest and low cost that can resist seismic actions. This Peruvian standard has served as the basis for other technical regulations in the world such as in India and Nepal.

4. PRESERVATION OF EARTHEN ARCHITECTURE

Natural processes dictate that perishable construction materials such as earth, wood and paint, be consumed by the sun, rain, bacteria, insects or are violently decimated by earthquakes, hurricanes or torrential rains. In other words, conservation goes against the dynamics of nature itself. To these natural threats we must add those anthropogenic such as wars, development pressure, architectural fashions and, unfortunately, ignorance.

Construction methods now considered traditional, such as earthen architecture, were the result of decades or centuries of trial and error processes through which the combinations of materials and constructive details that proved to be the best and most appropriate to the local reality survived. Architecture converted into heritage remains architecture and therefore the construction logic mentioned above remains an important factor in its preservation.

The processes of architectural creation continue during the useful life of the structure, as well as changes in the needs and tastes of users, the availability of new materials or the disappearance of others, some historical challenges worsen, or new threats need to be addressed. Built heritage is a living and changing subject whose preservation is not governed by the same rules as movable or museum heritage.

A basic principle of conservation in any constructive typology is to use materials and technology compatible with those that it was built of, and this principle is even more important in the case of earthen architecture. Incompatible interventions such as concrete or brick additions in earth constructions, often produce negative results such as in the city of Bam, Iran, razed by the 2003 earthquake, or in the Pisco Cathedral, destroyed by the 2007 earthquake, or in the Gingerbread Houses of Haiti, affected by the 2010 earthquake.

Furthermore, constant maintenance is key in long-term conservation, especially in earthen constructions. Some important examples of participatory maintenance, mentioned before are the Great Mosque of Djenné in Mali and the Royal Court of Tiébelé in Burkina Faso. These traditions, which constitute an intangible heritage in itself, not only help to preserve the material cultural heritage, but also contribute to the generation of economic resources through cultural tourism.

However, the spirit of this shared or communal work dedicated to the conservation of monuments that are of great importance to the community, should also be applied to the maintenance of houses, deposits or fences built of earth. It is this vernacular, self-constructed, common and utilitarian architecture, which is an integral part of many cultural landscapes, that is most threatened and in danger of disappearing. Its current “preservation by neglect” cannot be sustained for much longer.

5. CONCLUSIONS

What can be done to preserve and promote earthen construction in areas where this type of construction is most appropriate for geographical, climatic or economic reasons?

Should we promote structural and seismic reinforcement techniques such as compressed earth blocks (CEBs), the use of geotextiles or nylon ropes, galvanized steel trusses or tensors, or stabilization with lime or polymer fibers?; or promote new and more efficient earth construction techniques such as prefabricated quincha?; or build houses of adobe reinforced with sea weed?; or build structures of earth contained in bags (Nader Khalili)?

In any case, low cost, availability and durability of the proposed reinforcement materials should be prioritized in their selection, as well as the avoidance of “greenwashing” which some contemporary earthen architecture projects tend to do (i.e. Musée Régional de la Narbonne Antique, France - uses rammed earth with slightly less cement than concrete).

Furthermore, many contemporary earthen architecture projects, consisting of either new construction or seismic reinforcement, are generally led by international support agencies, governments or academic researchers (PUCP, JICA, etc.), which in many cases fail to create long-standing or entrenched local capacity. Undoubtedly, more research is needed but also more participatory processes, long-term national policies and effective knowledge transfer programs.

Since earthen constructions require constant renovation and maintenance, and its preservation is not simply about conserving the physical or material object, but mainly about the preservation of its construction and maintenance techniques, the local socio-cultural knowledge system of this type of construction becomes an intangible heritage asset that requires valorization, documentation and promotion.

6. ACKNOWLEDGMENTS

To A.J. Artemel, Cristian Heinsen, Eduardo Gamboa, Frank Sanchis, Graciela Viñuales, Isidora Larraín, Lisy Kuon, Marcelo Magadán, Oscar Centurión, Ramón Gutiérrez, Ricardo Morales, Robert Aréstegui, Silvia de los Ríos, Sofía Rodríguez Larraín and Víctor Marín for their generous contributions to this paper, and to World Monuments Fund and Yale University for the use of their images.

7. REFERENCES

Aranda, Yolanda, Suárez D., Edgardo. (2014). Análisis experimental para determinar la productividad térmica en la tierra vertida. 14º Seminario Iberoamericano de Arquitectura y Construcción con Tierra (SIACOT). San Salvador, El Salvador: Imprimatic S.A. pp. 76-79.

Beltrán, Lina C. (2007). La tradición cultural de los sistemas constructivos en tierra en Iberoamérica. Arquitectura en tierra, Apuntes vol. 20, núm. 2. pp. 179-181. Bogotá, Colombia: Facultad de Arquitectura y Diseño, Pontificia U. Javeriana.

Blondet, Marcial, Vargas, Julio, Tarque, Nicola (2005). Reflexiones sobre la normatividad para la construcción sismo resistente de edificaciones de adobe. Primer Congreso-Taller Internacional para la normalización de la Arquitectura de Tierra. Mexico,Tampico: Universidad Autónoma de Tamaulipas.

Canziani, José. (2012). Arquitectura Monumental de Adobe en el Perú Prehispánico: su temprana evolución histórica y los retos de conservación. Terra 2012. Lima, Perú.

Cherradi Akbil, Faissal. (2012). Arquitectura de tierra en el sur de Marruecos. Terra 2012. Lima, Perú.

Del Huerto, Josefina, Sosa, Mirta. (2012). El Saber Construir con Tierra- Patrimonio Intangible del Noroeste Argentino. Terra 2012. Lima, Perú.

Garzón, Lucia. (2012). Aporte de la quincha pre-fabricada en Colombia: Análisis de la tecnología en aspectos ambientales y energéticos. Terra 2012. Lima, Perú.

Gasparini, Graziano (2009). Escuchar al Monumento. Caracas, Republica Bolivariana de Venezuela: Editorial Arte.

Gayoso, Magaly, Pacheco, Orlando. (2014). Vivienda alpaquera altoandina. Caso de estudio tipológico en Puno, Perú. 14º Seminario Iberoamericano de Arquitectura y Construcción con Tierra (SIACOT). San Salvador, El Salvador: Imprimatic S.A. pp. 88-94.

Gioberchio, Graciela (2016). Aprueban la construcción en adobe en diferentes ciudades del país. Clarín.

Giuliani, F. et al. (2008). El Terremoto de Pisco-Perú, 15 de Agosto de 2007. Lima, Perú: CERESIS/UNESCO.

González, Georgina. (2018). Con las manos en el barro para llegar a la casa propia. LMNeuquen.com.

Guillaud, Hubert (2003). An approach to the evolution of earthen building cultures in Orient and Mediterranean regions: What future for such an exceptional legacy ?. Al-Rāfidān: Journal of Western Asiatic Studies. Tokio: Kokushikan Daigaku. Iraku Kodai Bunka Kenkyūjo.

Hassel, B. Ivón, Kitamori, Akihisa, Kiho, Jung, Komatsu, Kohei. (2013). Prefabricated mud wall units based on a traditional Japanese building system: Lateral in-plane performance in terms of connection, and crack development using digital speckle photography. International Journal for Research and Development.

Hernández Salazar, Ileana. (2014). Restauración de Arquitectura de Tierra en Zonas Sísmicas. Valencia, España: Universidad Politécnica de Valencia.

Hurtado, Pedro. (2012). Aprendiendo del pasado: los muros de adobe y bóvedas de entramados de tierra de la iglesia la Compañía de Pisco- Perú frente a los terremotos. Terra 2012. Lima, Perú.

Mendoza, Olga. (2012). Arquitectura de tierra tradicional en Japón frente a los desastres naturales. Terra 2012. Lima, Perú.

Pastor, Diana (2018). El adobe no es pobreza, es resiliencia. Entremundos.

Quiun, Daniel, Cadillo, Antonio. (2012). Inspección de estructuras de adobe construidas en programas de vivienda desarrollados hace más de veinticinco años en el norte de Perú. Terra 2012. Lima, Perú.

Rivero, Santiago. (2007). El uso masivo de la tierra como material de construcción en Colombia. Arquitectura en tierra, Apuntes vol. 20, núm. 2. pp. 354-363. Bogotá, Colombia: Facultad de Arquitectura y Diseño, Pontificia U. Javeriana.

Rodríguez Romo, Fernando. (2003). Conservación de Tipologías Constructivas Tradicionales. Valencia, Republica Bolivariana de Venezuela: INDUVAL Instituto de Desarrollo Urbano del Centro de Valencia.

Sánchez, Mauricio. (2012). Criterios de intervención y obras de emergencia de los monumentos nacionales de chile dañados por el terremoto del 2010. Terra 2012. Lima, Perú.

Sharma, Tara. (2012). Guardians of the Earth: Cultural Dimensions of Earthen Architecture in Ladakh. Terra 2012. Lima, Perú.

Taucer, Fabio (Ed.). (2008). 2007 August 15 Magnitude 7.9 Earthquake near the Coast of Central Perú. Earthquake Field Investigation Team (EEFIT) Field Mission, 5-12 SEPTEMBER 2007 / Final Report. Luxembourg: Office for Official Publications of the European Communities.

Vargas, Yalmar. (2012). Actualización del patrimonio arquitectónico de tierra de las comunidades indígenas en Colombia. Terra 2012. Lima, Perú.

Viñuales, Graciela (2009). Restauración de Arquitectura de Tierra. Buenos Aires, Argentina: CEDODAL.