A Swiss start-up wants to build sustainable homes for everyone

Gnanli Landrou and Thibault Demoulin from Oxara at their “workshop” at the Zurich Polytechnic School. Together with a fellow architect, they want to build concrete houses without cement. swissinfo.ch

Two materials experts and an architect want to revolutionize the construction industry with their cement-free concrete made from clay excavation materials. A technique aimed primarily at developing countries.

This content was posted on June 21, 2019 – 17:00

« I hopeexternal link» comes from « Ossara », which means commune in Kabiyé. This language takes its name from a people who live in particular in Togo. “This name is very important to us”, explains Gnanli Landrouexternal linkhimself a Togolese and founder last fall of the start-up Oxara.

With Thibault Demoulinexternal linkalso a specialist in materials, welcomes us, smiling, in a large workshop of the Escola Politécnica Federal (EPFZexternal link), on the heights of the Hönggerberg in Zurich. All that is missing is the architect Daria Ardantexternal linkalso a member of the Oxara team, whose two colleagues salute the care she brings to the smallest detail.

Landrou and Demoulin arranged the samples on two tables: uncemented concrete slabs and cylinders. A test tube with water, clay excavation material and a bottle of white powder complete this mini-exhibition. Its building material is made of these three elements and offers an alternative to conventional concrete. They’ve been working on this for years and want to revolutionize the construction industry in a sustainable way.

Water, additive developed by Oxara and clay excavation material. The three ingredients of cementless concrete offered by the start-up. swissinfo.ch

Concrete is the most used building material in the world. But to turn it on, you need cement, the production of which consumes a lot of energy and emits a lot of CO2. Another problem is the scarcity of resources: making concrete requires cement, but also tons of sand and gravel. For many, concrete is simply too expensive.

“The concrete developed by Oxara is 90% more respectful of the environment and 60% cheaper”, says Gnanli Landrou. Environmentally friendly as it does not contain cement and can be produced with clay excavation materials. It is simply the earth that is removed by digging up building land, but it must be clayey. Currently, we are content to transport it to landfills. “More than 90% of the materials we use for our concrete come from the ground”, continues our interlocutor. This makes Oxara’s solution significantly cheaper.

The fact that the building remains accessible is particularly close to the heart of Gnanli Landrou. “Oxara wants everyone to be able to build a house. Even the poor.” The United Nations Human Settlements Program (UN-Habitatexternal link) considers that, by 2050, Africa will need thousands of hospitals and schools, as well as millions of affordable homes.

A house worthy of the name for everyone: this is Oxara’s ambitious goal. Here, a slum in Nairobi, Kenya. Keystone / Ben Curtis

This basic idea of ​​sharing her invention motivated Oxara to enter the Together we are better contest.external linkcreated by the Department for Development and Cooperation (SDCexternal link) and the Secretary of State for Economic Affairs (SECOexternal link). “We are looking for innovative projects, initiatives and ideas from young Swiss that can contribute to sustainable development and the fight against poverty in developing countries,” explains project manager Barbara Hell. More than 90 files were sent and the five best projects were awarded this Friday at the Swiss Development Cooperation Annual Conference. Hope is one of them!

The start-up will use the 10,000 francs award for a pilot project in Africa. She wants to collaborate with the NGO Earth Enableexternal link in Rwanda. It is already building special floors for the local population, which can be cleaned. Because dirty floors are veritable nests of mosquitoes and other parasites, which promote the spread of diseases.

“With the Earth Enable technique, it takes four weeks for the house to become habitable”, explains Gnanli Landrou: three weeks for the construction and drying of the clay foundations and one for finishing. The mix of materials supplied by Oxara dries faster and forming a slab before pouring takes less time than packing it in the traditional way.

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Gnanli Landrou is keen to emphasize that he does not go to Rwanda to tell people what they need. “I see that a local NGO is working on the same issue as Oxara. I present to them our technique, which is faster, greener and more sustainable, but they are the ones who decide if they are interested in collaborating.”

Gnanli Landrou looks at her watch. The next meeting is approaching. Static testing, material development: this is the foundation on which Oxara wants to build. The startup is just getting started. Currently, the young associates are working on patent issues and business development – ​​entirely new territory for the three of them.

One more final question: where will Oxara be ten years from now? The question makes them both laugh. In fact, it keeps them busy. “We were still talking about it this morning,” says Thibault Demoulin. And Gnanli Landrou explains: “I hope that in ten years we will be building houses for many people in many countries”.

Swiss Development Cooperation Annual Conference

We can no longer imagine development cooperation without collaborations with partner governments, companies, multilateral organizations, Swiss, international and local NGOs, or without universities and research institutes. The role of formal and informal networks – including youth networks – is becoming increasingly important. This year, the Annual Conferenceexternal link of Swiss development cooperation is dedicated to these new partnerships. It takes place today, Friday, June 21, in Fribourg.

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