Last year, we were involved in the design and development of a vertical algae facade for Expo 2015 in Milan. Based on our WaterLilly 2.0, the system was designed to wrap the Future Food District pavilion curated by Carlo Ratti Associati and MIT Senseable City Lab. It was a facade of 75 x 18 m, approximately 1,350 sqm. Probably the biggest photobioreactor ever designed! Unfortunately, due to a number of reasons, the design won’t be built. We publish here part of our unbuilt work. Sad that it didn’t went through :( but it was a good research work and it became the opportunity to make amazing new friends within the design team.
Facade system The system of architectural envelope is composed of two parts:
- an active facade [1348 sqm excluding openings]: surface of algal cultivation, with the equipment necessary for growing algae and an interactive lighting system. The active facade consists of 1174 active algae modules organized in 118 columns and distributed to cover the entire pavilion surface from ground to roof (+ 18,50m). A “technical basement” hosts the algae equipment, including pumps and other plant components behind a screen integrated with the rest of the facade.
- passive facades [2554 sqm excluding openings]: cladding system based on the same components of the active facade, to grant continuity of architectural design, but without the equipment for growing algae.
Algae active modules It’s the core of the system. The algal active modules are transparent plastic film growing chambers designed in a specific shape to optimize the fluid dynamics of the algal solution. The module is composed by a reinforced perimeter and a growing chamber in a central position with a side channel to avoid overflow spills. The primary supply of algal solution occurs through the opening positioned on the upper side of the chamber. The tail positioned in the lower side slips into the pocket underneath, and allows the continuous outflow of the solution, and enables the filling of the module below. Each module contains a volume of algal solution of 10/15 liters. A variant of this component, welded at its ends and equipped with an inflation valve, allows the realization of pneumatic cushions to be inflated with air for the passive facades. Hydraulic and mechanical systems The plants are grouped into five independent sectors in order to optimize operations. The plant systems are coordinated by a single control system (PLC) programmed to ensure the optimum operation of pumps and solenoids in every situation, able to handle even critical situations that may occur in case of extraordinary climatic events or accidental failures of parts of the system. At the bottom of the facade, five tanks collect the falling algae solution. They can be inspected for maintenance operations. The size of each of the five tanks (one per sector) are approximately 1×0,3×15 m, for a volume of 4,000 L and a total of 20,000 L for the whole facade. The algae solution is pumped from the algal tanks up to the top of the facade at +18.50 m where a manifold distributes it to the columns of active modules in which the solution falls by gravity back into tanks. From here the cycle begins again. The cycle is semi-closed and requires water supply limited to compensation of evaporation. Programming the algae fall It’s possible to program a system of animation and interaction to fill and empty the growing modules by acting on the solenoids located on top of each column through the PLC . The solenoid valves are normally open. They can be closed sequentially to draw waves on the facade or create full/empty areas. The system can be implemented with motion sensors that map people movement creating an interaction between facade and people. The reaction rates are not immediate and depend on the time necessary for emptying the growing chambers. Programming the lighting The active facade is also a media-facade. It’s equipped with a programmable LED lighting system, which makes it a gigantic bio-screen on which it is possible to “print” different types of animations, images or text. The LED can be operated sequentially to draw movements and create waves on the facade. The system can be implemented with motion sensors to enable people interaction. A slow pulse animation gives the idea of a breathing facade. Biological components The operation of the whole system, based on the algal fall, allows the solution to keep temperatures suitable for cultivation of nativemicroalgae, resistant to summer temperatures. EspeciallyChlorella, a native biological species, is particularly suitable to the range of temperatures present in EXPO area in the months between April and October (8 Microalgae have two cycles: flowing in the active facade, and resting in the tanks. They will tend to heat up during the journey in the facade and cool down in the tanks. Adjusting the speed of the algae fall in the facade is crucial to find the right balance of temperature. The project estimate a travel time in front of about 10 minutes. Two maintainers ensure a continuous supervision of the facades during the growing period and will be able to intervene for normal maintenance and to manage unlikely emergencies. Tests performed during the design phase have shown that the system has high volumetric productivity (0.8 g / L / day). The plastic materials of the growing chambers do not create significant changes in pH, which remains in the set range, and evaporation is contained (100 mL / day). The adhesion of the biomass to the walls is relatively limited. Cleaning cycles will be performed on a regular basis. Design Team Architectural design: Cesare Griffa (with Mattero Amela, Federico Borello, Marco Caprani) Mechanical design: Environment Park S.p.a. Biological support: F&M S.r.l. General Contractor: Tosoni Group Mechanical contractor: Tecno Delta S.r.l.