The pavilions of Expo 2015 in Milan, as a privileged observatory about the concept of sustainable construction in all languages of the world.

The organization of Expo 2015 in the city of Milan has prompted massive organizational efforts to set up a new fair district in one of the largest Italian cities. The urban layout of the metropolitan city has been redesigned in order to accommodate all participating nations event. Expo 2015 established through guidelines the necessity to adopt sustainable solutions for the temporary buildings of the exhibition. The article aims to see how the concepts of sustainability and recyclability have been interpreted in the language of 40 designers from different countries. Through data provided by information papers of the exhibition, a valuation of materials used in buildings was made. This research led to an analysis of different building typology involved and the materials most used to reach the goals of guidelines drawn up by Expo 2015. The perception of an event characterized by green constructions was achieved, but not every construction was aimed to be a nearly zero emission building.