The project Nuage Vert is based on the idea that public forms can embody an ecological project, materialising environmental issues so that they become a subject within our daily lives. A city scale light installation onto the ultimate icon of industrial pollution – the cloud generated by a coal burning power plant - alerts the public: Every night from 22-29 February 2008, the vapour emissions from the Salmisaari coal burning power plant in Helsinki, Finland were illuminated with a high power green laser animation. The laser drew an outline of the moving cloud onto the cloud itself, colouring it green, turning it into a city scale neon sign, which grows bigger as local residents take control and consume less electricity.