As part of a research project, Arup developed a glass facade system with integrated photobioreactors; the so-called bioenergy facade.  

This is a further development of Arup’s SolarLeaf façade, the world's first algae bioreactor façade, first presented in 2013. Microalgae are cultivated in glass facade elements that generate heat for the building operation and biomass for the food and pharmaceutical industries.

With the new bioenergy facade, Arup is further developing the SolarLeaf façade both aesthetically and technologically. Three different facade elements open new possibilities for architectural design: A translucent version, which allows the green of the algae to be experienced in the interior; an opaque solution, in which the algae serve as design elements on the outer façade; and a transparent frame, for undisturbed viewing.

Not only does the bioenergy façade offer aesthetic flexibility, with this new project SolarLeaf’s technology is optimised for sustainability. Each square-meter of bioenergy façade will yield 5.5kg of biomass (which can be used in the food and pharmaceutical industries) and absorb 10kg of CO­2 per year, while converting 38% of the solar energy coming into the building into heat.

Optimisation of the photobioreactors

The glass elements of the bioenergy façade are part of a solar thermal system with which, additionally, microalgae are cultivated to build up biomass and absorb CO₂. With a thermal efficiency of 38% and a biomass conversion efficiency of 8%, the bioenergy façade is comparable to conventional solar systems. The function and cost-effectiveness of the system is to be ensured by an operator concept. The harvested algae are used in the food and pharmaceutical industries.

Computational Fluid Dynamics (CFD) simulations are used to create optimal conditions for the growth of microalgae. The computer-aided 3D models represent the flow and mixing processes within the bioreactors.

Arup is undertaking the research project in cooperation with Technische Universität Dresden and the project partners SSC GmbH, Pazdera AG and ADCO Technik GmbH. It is funded by the German Federal Ministry of Economics and Energy and is expected to be completed in April 2019 with the construction of a prototype.