Optimization models for photosynthetic bioenergy generation in building façades

Façade design optimization has a significant impact on promoting resilient solar harvesting methods in urban areas. This study introduces a new framework toward the optimal inclusion of microalgae photobioreactors in different façade geometries by developing a detailed chemical kinetics model aided by optimization techniques. Although algal bioreactive façades in recent literature are restricted to flat façades, the present study reveals that bioenergy generation can be enhanced by up to 29.6 % through optimized folded façades. Hooke-Jeeves algorithm demonstrates remarkable computational efficiency in optimizing such façades, achieving the optimal outcome with only 88 function evaluations. However, the Hooke-Jeeves algorithm has limitations when applied to free-form façades by displaying noticeable instability and reporting an optimal value approximately 40 % lower than Genetic Algorithms. Hooke-Jeeves algorithm has the possibility to conclude misleading outcomes as optimal points. This is mitigated by applying multiple initial points and verifying the outcomes with graphical optimization. In terms of energy performance, free-form façades have higher irradiation of up to 210 W/m2 compared to 180 W/m2 for flat façades. Optimal distribution of renewable modules on free-form façades increases energy generation by 14.3 %. South-facing façades produce the highest bioenergy at 2.4 W/m2, while west and east orientations generate the lowest at 0.8 W/m2.