Building with earth is often seen as backward and primitive in developing countries. And yet earth buildings are cheaper and in many ways more sustainable than energy-intensive concrete or brick buildings, and the problems associated with earth buildings can be solved with the help of modern science and technology. One project that clearly shows this is the METI Handmade School in the village of Rudrapur in Bangladesh. The school was designed by architects Anna Heringer and Eike Roswag and built together with the local villagers. This project took the locally available materials and techniques, and by improving them and using them in a new way, it created a new interest in earth building while benefitting the local people.
The school is run by a local NGO called Dipshikha that has several education programs aimed at people in different stages of their lives. Although METI Handmade School is the more famous one, the Dipshikha campus in Rudrapur actually has also another earth school, called DESI, that is part of the same project and was built three years later. While METI is a primary school, DESI is a school for teaching technical skills to older students and some teachers also live there. The school also has a garden where students grow plants and food.
Evolution of traditional materials
Earth is one of the most easily accessible building materials and people have developed many different ways of building with earth. Because it’s a naturally available material, earth has a much smaller carbon footprint than concrete and it also produces no waste once demolished. In this project cob – a mixture of earth, clay, straw and water – was used and it was applied in layers, letting each layer dry before applying the next layer. The resulting earth walls of METI and DESI schools are thicker and heavier than traditional earth houses in Bangladesh, which means the walls have a larger thermal mass. Thermal mass is very good at regulating indoor temperatures and keeping a more stable indoor temperature as outdoor temperatures fluctuate during the day.
One of the main problems with earth buildings is that earth structures erode over time and the traditional earth buildings found in Bangladesh are far from optimal in this case. Mixing straw with the earth, as was done in this project, makes the material more stable and durable and slows down the erosion. In DESI school there also pieces of bamboo sticking out from the walls and these slow down rainwater runoff and the subsequent erosion. Unlike the traditional earth houses, the schools also have a masonry foundation that adds stability, and there is a locally available plastic moisture barrier between the bricks and the earth walls, which protects the walls from moisture from the ground and further increases the lifespan of the building.
Traditional earth houses have roofs made of straw, and in tropical climates this straw keeps heat out of the house by insulating the roof – the part most exposed to sun – from solar heat. At the same time, the overhanging roof also shades the walls and windows and door openings. The straw also lets air flow through it, improving the ventilation. Newer earth houses often have a roof made of corrugated steel sheeting, which can make the house unbearably hot if the steel ceiling is left exposed and the roof is not well ventilated.
In METI Handmade School the roof is made of steel but there are colorful sari fabrics hanging below the ceiling. These not only change the whole space by adding color and creating a different feeling, the saris also block the heat from the steel from radiating directly into the room. There is also a ventilated gap between the steel and the saris, and as the air in this space heats up, it causes an updraft and ventilates the classroom below.
The classrooms rely on cross-ventilation, and the upper floor in particular is very airy with a light bamboo construction. These walls have openings with shades made of woven bamboo and by opening and closing these shades, the amount of air and sun entering the room can be regulated. When the shades are closed, air still flows in and out through the gaps but solar heat radiation is mostly blocked. The gaps also let in daylight, and even when most of the shades are closed there is enough daylight coming into the classroom. This type of bamboo cover also help filter some of the dust from the outdoor air. One problem with this openness though is acoustics since the noise from each classroom can easily be heard in other classrooms and outside.
The classrooms on the bottom floor have a very different feeling with heavy earth walls. These classrooms only have a few openings scattered around the walls, and these cannot be closed, but even they provide enough daylight. The small size of the windows means that the thickness of the earth wall is enough to shade the openings. The bottom floor is used by the younger students and the classrooms include playful “caves” inside the earth walls. The different classrooms of METI show how flexible earth can be in creating different type of spaces.
Improving rural life through architecture
The METI Handmade School project produced more than just a building, and the involvement and education of the local people was an important part of the process. Almost all the work was done by local unskilled labour who thus learned new skills in the process. The students also took part in the construction and they are also responsible for cleaning and maintaining the buildings. The architects also did a housing project with the community, showing how they can improve their own earth houses.
Since DESI was designed for teachers to live in, the building has a higher status than METI and this meant more money could be used for the project. Instead of using the extra money for more expensive materials, the extra money went into detailing and craftsmanship. A part of the bamboo facade has a pattern made with local weaving techniques and this meant that the extra money went directly to the local people instead of industries. The increased use of industrialized products such as plastic means that the local craftsmen have less and less work, but this project gave them new ideas for how they can use their skills.
Overall, the way earth and bamboo have been used in these two schools is professional and sophisticated, which is important for raising the status of these materials. Traditional earth buildings in Bangladesh only have one floor, but METI and DESI schools show that earth can be used to build multi-story buildings as well. This is particularly important in Bangladesh as it is one of the most densely populated countries in the world, and there is a need for buildings to expand vertically in order to leave more land available for agriculture, especially during uncertain times of climate change. In fact, lack of arable land is forcing a lot of people in Bangladesh to migrate into urban areas which is creating an enormous pressure on the cities. What this project shows is that by taking traditional techniques and skills and using them in a new way, it is possible to build more sustainable rural communities.