Ken De Cooman of BC architects, Belgium sees the most sustainable element of his Holcim Awards Acknowledgement prize winning project as the use of local trachyte stone material that is linked with local identity and craftsmanship – but linked to a global program of the nation’s Chamber of Commerce headquarters. “Weaving Publicness: Socially-integrated office building with sustainable façade” in Addis Ababa, Ethiopia aims to contribute to the spatial improvement of the urban environment, and to create an architectural dialog engaged in a global context with a strong local identity.