Building without burdening the planet

Chris Simoens
17 July 2019
Four young architects went to Burundi to learn how to use local materials for building. They now apply this form of 'circular architecture' in Belgium. Discover their story.



Four young adventurous architects, who founded the companies BC Architects & Studies and BC Materials: Wes Degreef, Ken De Cooman, Nicolas Coeckelberghs and Laurens Bekemans.




In Burundi, they learned what circular architecture entails: local materials, respecting the environment, working with the local community.




We need to build differently: our current way of  building produces too much CO2, while local, bio-based CO2-neutral methods are available.

We all studied architecture at the Sint-Lucas campus in Brussels: five years filled with learning, drawing plans, building scale models, … The program was fascinating, but by the time we graduated, we had still not touched a single brick. We believed this was a shortcoming.

We felt a real need to be involved in the building process, to learn a different approach. And the right opportunity arose! One of us knew a small NGO that worked with an NGO in Burundi, more specifically in Muyinga, the capital of the province that bears the same name.


A school for deaf children

In Muyinga, they wanted to build a school for deaf children, as there was only one such school in the whole of Burundi. The idea was to build the library first. It sounded like a great idea to us, so we offered to build it ourselves.

After an exploratory trip, we started looking for funds: through Rotary Aalst, the province of West Flanders, crowdfunding, ... Eventually, we set out on our adventure in 2012, with a budget of 20,000 euros and the theoretical knowledge we had acquired, but without any practical experience at all.

In Burundi, we worked mainly with master builder Salvator, a skilled expert who had built the local cathedral and worked mainly for local NGOs. He was familiar with the traditional building methods.

What was the best approach? 20,000 euros does not get you far: imported building materials turned out to be too expensive. In fact, we could not even afford industrial materials from Burundi’s capital.


A group of Burundians is digging a well for the foundations of the library.
© BC Architects

Materials for the poor

The only option was to use local materials. Salvator showed us that there were many possibilities. Nearby, there was a quarry where clay was used to make bricks that were then dried in the sun. The caveat: these bricks were only used for the ‘poor’, so people were not interested in using them for public infrastructure or NGO buildings.

The local bricks were not only rather expensive, they also contributed to deforestation, requiring lots of wood in the baking process. These were therefore not an option.

We decided to thoroughly investigate an area of five kilometres around the building site to see what was available. We found Eucalyptus trees and sisal plants, which provide fine wood and solid fibres respectively, while solid natural stone could be found a little further along the valley. A local tile factory could provide us with a local fired roof and floor tiles, among other things,. We also conducted tests on the various types of local earth available, to establish the different characteristics: grain size, different fractions, cohesion, …

Miraculously, in a lost corner, we found an old stone press that our local NGO partner had received from the Belgian NGO, even before the genocide in the 1990s. We managed to refurbish the machine so that it could press fine clay bricks using only the power of a lever. After leaving these to dry for two weeks in the shade, they turned into very strong bricks, even stronger than the local sun-dried, handmade, unpressed clay stones. On top of that, they looked very neat, and quite different from the ‘material for the poor’.



The Burundian brickworkers are busy with brickwork.
© BC Architects

Down to work

At last, we could set to work. In Burundi, the whole community gets involved: residents, the master builder, bricklayers, and of course ourselves, together with a few trainees. We wished to avoid using bulldozers to prepare the construction site. Instead, we cleared trees and bushes with the help of many villagers. The earth was then sieved, moistened to achieve the right humidity and pressed into bricks.

We used clay mortar, a mixture of clay and a more sandy fraction from 100 meters away, to lay the bricks. Local natural stones were selected for the retaining walls and foundations, while the inner walls were covered with clay-based plaster from the valley.

We used the cut Eucalyptus trees to make roof beams and furniture. From the sisal fibres, we wove a hammock that could serve as a reading corner for the children.



A number of children are reading in the library.
© BC Architects


We also adopted a 'bio-climatic' approach: we adapted the design of the building to the environment and the construction site. This was also something we learned from the local population. We took into account aspects such as solar orientation, prevailing rain, vapour permeability of the materials and spontaneous 'cross-ventilation' to create a perfect indoor climate without having to resort to air conditioning or filter systems. 

At the top of the library, for example, we made some holes in the wall to allow the rising heat in the building to be easily conveyed outside. In addition, the clay bricks slowly store the heat during the day and release it slowly at night, so that it remains fairly cool during the day and still pleasantly warm when nights are more chilly.  

After eight intense months, the library was ready, followed by the sanitary block, the classrooms, the desks, … Gradually, we became less involved and the local NGO took over.

Thanks to master builder Salvator, the local community and the general Burundian culture, we received excellent training. We learned more about the impact of building than we ever had during our architectural studies. The result was a school building for deaf children that showed the local community that 'material for the poor' can be beautiful and is suitable for use in public infrastructure. A win-win situation all round.

The finished biology class in the hangar.
© Thomas Noceto

Fort V in Edegem

After Burundi, we realised similar projects in Morocco and Ethiopia, according to the same principles: working together with the local community, respecting the environment, using local materials, adapting to local architecture, … Involving the local community ('building together') is so important because you cannot realise innovative projects all alone. After all, no one is an expert in everything.

The question then arose: could this also work in Belgium? A useful test case for us was Fort V in Edegem, one of the fortress parks around Antwerp that has a large military barracks, or rather hangar, in the middle. The plan was to build a biology classroom in the hangar, where local schools could go for practical biology lessons.

We began by looking for local materials. Two trucks of free earth - clay from Boom – were offered by a nearby quarry owned by Wienerberger, a manufacturer of lightweight bricks. To plaster and insulate the walls, we used 'hemp shives' from the Netherlands and Wallonia, mixed with different mortars. The design was inspired by the barracks, featuring large arches, among other things.

In order to involve the community, we had to come up with a different formula than in Burundi, where everything happens spontaneously. For this reason, we organised open days and workshops in Fort V. During a first (three-week) workshop we made 19,000 clay bricks with a powerful hydraulic press. First, the supplied clay had to be fully dried and powdered. Afterwards, the clay powder was mixed with different types of sand and brought to the right level of humidity in order to press into stones. The workshop also included several lectures.

Subsequently, the building was constructed by professional bricklayers. During a second workshop, we mixed the hemp with the different mortars, which was then applied to the walls in layers.

The biology classroom is located in the hangar and has no roof. In a later phase, the roof over the rest of the hangar will be removed, in order to create a hortus conclusus or enclosed garden.



Multiple rows of stacked bricks while in the background workshop participants press bricks.
© BC Architects

CO2 positive

In short, we found out it is possible to work in Belgium according to the principles that we learned in Burundi. The result is a building that tells a story, you can see the handiwork of those who helped to construct it, for example in the plasterwork.

Moreover, the building is CO2-positive. Indeed, the press consumes green electricity and mortar hemp extracts 1.34 kg of CO2 per kg from the air! In doing so, our biology classroom takes net CO2 from the air.


Growing interest

We are pleased to see that there is growing interest in circular architecture. For example, we were invited to the Venice Architecture Biennale and the Oslo Architecture Triennale to demonstrate circular architecture projects. We notice the growing interest in Belgium in our workshops, which are immediately full. One of our current projects is Usquare in Ixelles, the conversion of a military complex into an interuniversity research centre for social transition (ULB-VUB).

Circular architecture is also extremely useful. We have a great deal of earth at our disposal from large construction sites which is still considered as waste. For that reason, we founded BC Materials, which produces clay, masonry and clay plaster using the earth from major Brussels construction sites.


Also watch the videos about the 2 construction projects

Circular economy Architecture Burundi
Back Globetrotters
About the same theme - Article 3 /4 A happier life thanks to waste