Like its mosses, BESIX Clean Air is growing

24 November 2020

As the global population steadily increases and more of us will find ourselves living in densely populated areas at some point in our lives, so does the need to transform these in green and healthy environments. This is also reflected in the growing regulation of construction projects, in which sustainability plays an increasingly important role.

In response to that, BESIX has developed a natural, air purifying technology that can be integrated into building blocks of various infrastructures.

Mosses x technology = (clean air)²

BESIX Clean Air develops panels that make use of mosses to improve air quality in places such as tunnel mouths, car parks, industrial sites and in densely populated areas such as schools and public buildings.

The decision to include mosses is because of their capabilities to reduce the concentration of fine particles, known as PM10 & 2.5 present in the air.

Concretely, the polluted air is actively drawn in by fans built into the panels and blown through a membrane and a layer of moss. The air filtered by the moss is then returned to the ambient atmosphere, minus the fine particles.

By combining the plant’s natural qualities with technology, BESIX Clean air is able to locally reduce fine dust concentrations and improve the overall air quality.

Up to 43% cleaner

Based on studies from the University of Antwerp (UA) & University of Liège, moss significantly contributes to the product’s filtration performance. Moreover, moss species are known to be more robust towards the seasonal changes of the climate compared to vascular plants, making it an ideal candidate for the application of this product.

In August 2019, BESIX Clean Air’s panels were tested at the Faculty of Applied Engineering Sciences of the University of Antwerp. The test consisted in monitoring the rate of fine particles (i.e. PM10 & 2.5) captured by the panels through a scientifically valid methodology. The study revealed an average filtration efficiency of 43.1 % for PM10 and 22.8 % for PM2.5. These results are beyond expectations and indicate that the concept has a significant effect on the air quality nearby dense traffic roads in populated areas.

For cities that are cleaner, greener, cooler and quieter

Besides improving the overall air quality, BESIX Clean Air’s moss vegetation has a series of additional advantages that address today's environmental challenges.

The concept does not only provide a green and esthetic character to the environment, it equally offers a creative solution to tackle the Urban Heat Island effect (UHB). The panels create more reflective surfaces and will shade streets and paved areas. Finally, the mosses are capable of absorbing noise. Up to 8-10 dB (DLα) has been registered and the panels conform to the Dutch A2/3 standard for noise reducing walls.

A successful pilot project

The BESIX Clean Air panels were first spotted along the future national road N434 (RijnlandRoute), in the Netherlands. In July 2019, a 30 meter long moss wall with 45 m² active surface was put up near a service road of the construction site. The aim was to protect workers from environmental fine dust. In addition, it served to validate theoretical results and to measure more precisely the technical performance of the panels.

A validation it certainly was, as the measurements during the third quarter showed an average air filtration efficiency of 11 % (PM10) and 18 % (PM2.5). As for measuring the panels’ technical performance, the team found that precise monitoring could be achieved via sensor technology, as well as remote steering through the internet.

To bring this pilot project to a good end, the BESIX Clean Air team collaborated with the University of Antwerp, COMOL 5, Innoviris (Brussels innovation agency), the University of Liège and Achilles Design. Internally, the team relied on expertise within BESIX Group and worked closely together with BESIX Environment, a department of the group specialised in the environmental field, in particular the water and energy sectors.

Taking it to the next level

This project was launched in 2018 under the BESIX Unleash program. This program supports innovation initiatives with the aim to eventually develop and commercialise marketable and sustainable solutions and products in the building ecosystem, ConTech or PropTech.

Today, BESIX Clean Air is successfully prospecting the possibility to cultivate moss species in BESIX’ moss growing plant in Bilzen (Belgium). The acquired knowledge enables the team to present an even stronger and comprehensive solution in this field.

In order to accelerate the venture’s growth, BESIX is looking for a new equity provider to take a substantial share. For more information, contact Karl Hautekiet ( or Peter Van den Mooter (