The Sustainability Pavilion is one of the signature pavilions’ trilogy for Expo 2020. It aims to demonstrate the possibility of how architecture and built environment gives the possibility of a new way of a sustainable living. The pavilion design draws inspiration from the complex natural process of photosynthesis by capturing energy from the sunlight and freshwater from air humidity.
The design of the exterior courtyard is inspired by the vernacular region and provides a large, passively cooled space for visitors by allowing desirable cool south-westerly breezes to enter while blocking warmer winds. Seemingly floating over the courtyard is the Pavilion’s canopy which accommodates monocrystalline photovoltaic cells embedded in glass panels. With more than 6,000 m² of exhibition space, the Sustainability Pavilion will be used as a legacy project after the ending of Expo 2020 as it will be converted into a science museum.
Grankraft fabricated and installed the weathered steel screens that form the perimeter walls of the central courtyard of the pavilion which are sunken into the ground. Based on thermodynamic studies, the Corten wall is angled in such a way that it channels desirable prevailing wind directions as part of the ventilation strategy, aiding the passive cooling of the space.
The exhibition spaces are surrounding the courtyard behind the wall made of weathered steel. The overall area of the weathered steel is over 2000 m² and consists of more than 100 individual panels. Each panel features a unique linear design which, when assembled, forms a continuous pattern that extends across the entire courtyard. Each panel is 10m high and 2m wide and the pattern was laser cut into the weathered steel panels which are hooked to a mild steel support structure.
Weathered steel is not like any other corrosion resistant steels, such as austenitic stainless steel, that resist rust formation. The rust that is formed on the surface of mild steel does not possess stabilizing properties and will lead to flaking and de-bonding of the corroded layers over time, further exposing the steel that will cause the full corrosion if not treated with the adequate coating. In weathered steel the alloying elements cause to form an outer layer of rust which adhere to the surface of the steel. The corrosion does not penetrate deeper into the steel once the outer layer of rust has been formed as the surface layer acts as a barrier and actually protects the steel from further corrosion. This protective rust layer eliminates the need for corrosion protection through traditional coating systems.
The relatively narrow width of the panels allows to maintain the curved appearance of the overall design whilst using flat panels. The upper portion of is designed to form the balustrade of the elevated pedestrian passage which is connected to the wider EXPO campus.. To meet the delivery time, the panels were laser cut 24/7 with an overall machining time of 2 months, each panel took as much as 1.5 days to be cut. For the oxidated patina preparation, mild steel was procured and once the curvature and perforation process had concluded the patina was created through oxidation, hydrolysis, and carbonation. The patination process was done in-house.