To reduce the impact of building construction on our environment, Celloz produces roofs made from a bio-based raw material. Half of this material comes from recycled paper, including paper that cannot be re-used by the paper industry. This start-up, a 2017 Circular Challenge finalist, provides roofs with low environmental impact that are referenced and are due to go on sale in 2020 in Leroy Merlin stores. According to Jean-François Ruffenach, the founder of Celloz : 
"Circular Challenge is one of very few competitions that brings real added value to start-ups. Two days of discussing the project with experts from different fields, preparing for the pitch with the support of teams of professionals as well as a top-quality jury composed of big names from organisations that support innovation and the environment, venture capitalists and paper industry specialists."