Vertical green wall

For this challenge, CDEC chose a different design than scaffolding. CDEC worked with a Swedish partner (Butong) who had developed living walls that are easy to maintain and allow many different plants to be grown in a small space. We chose to work with him because of his experience with biochar as a substrate.

In February 2023, at a biochar event in Nantes, France, we met our partner Butong from Sweden, who helped us design this green wall.
We wanted to show that it is possible to mix concrete and plants and add value to facades with a green wall. The advantage of a green wall is that it requires less space for the plants to grow, thanks to its vertical position.

The use of biochar in the substrate improves plant growth. The biochar reduces the weight of the wall and therefore the pressure on the structure. The biochar is also very useful in keeping the substrate moist due to its high porosity.

Why using biochar in green walls?

For this challenge, CDEC chose a different design than scaffolding. CDEC worked with a Swedish partner (Butong) who had developed living walls that are easy to maintain and allow many different plants to be grown in a small space. We chose to work with him because of his experience with biochar as a substrate.

In February 2023, at a biochar event in Nantes, France, we met our partner Butong from Sweden, who helped us design this green wall.
We wanted to show that it is possible to mix concrete and plants and add value to facades with a green wall. The advantage of a green wall is that it requires less space for the plants to grow, thanks to its vertical position.

The use of biochar in the substrate improves plant growth. The biochar reduces the weight of the wall and therefore the pressure on the structure. The biochar is also very useful in keeping the substrate moist due to its high porosity.

This project will therefore investigate whether biochar can help to make green walls more visually attractive.

Benefits of biochar for green roofs

  • Significant increase in water retention
  • Extended life of the green wall
  • Reduced weight of wall cladding
  • Suppliers of green walls


Few non-green wall manufacturers use biochar in their products. We finally found one company, Butong, based in Sweden, who use 20% biochar in their substrate. They also use concrete in the structure of their green walls.

We needed to find the right location that was well lit, could support the load of the green wall and was close to a water source (preferably rain). We vacillated between 3 locations (3 arrows on the first picture). In the end we chose the blue and orange bottlenecks because the red bottleneck was too exposed and too far from the water source.

The green wall is on the south-west wall of the new building (owned by the IFSB) in Bettembourg, Luxembourg.

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