Microalgae bio-reactive façade: Location and weather-based systematic optimization

This article explores the design of microalgae biofaçade thanks to a numerical model describing the system’s thermal and biological behavior. Design options (single vs. double glazing, radiation-selective film, culture reservoir thickness) and operation strategies (light transmission, microalgae strain, sparged air origin, boiler fumes reuse) are screened systematically. The context for this investigation was the city of Marseille over a 10-year period (2013 to 2022) for which detailed meteorological data were available (air temperature, wind velocity and orientation, cloud cover, at a 3-hour resolution). These investigations revealed a very high level of interaction between the parameters (assessed by H2 Friedman index), making the system notoriously complicated to design and optimize. Nevertheless, some conclusions can be drawn. In France, fitting double glazing equipped with a greenhouse radiation-selective film is essential to harness as much heat as possible (＋16.7 % and ＋6.5 % of operation duration over year 2018, respectively). Similarly, a thermophilic strain is not relevant because overheating events are inexistent in well-designed systems. Further refinements, such as the origin of the air blown into the culture reservoir and the reuse of combustion fumes from the boiler (＋2.1 % performance), were evaluated from a technical point of view. However, their implementation would also be subjected to other considerations, such as the financial costs and environmental benefits. Finally, the model was applied to design the most efficient possible microalgae biofaçade system in the case of a hypothetical official building renovation.