A Review of biophilic microalgal building envelopes and an assessment of their potential performances and their limitations

Accelerating climate change and rising urban carbon emissions necessitate the development of regenerative architectural solutions that transform buildings from passive energy consumers into active ecological infrastructures. The dense morphology of contemporary cities limits the availability of land for conventional green spaces, thereby positioning building envelopes as strategic surfaces for nature-based carbon mitigation. Compared to traditional vegetated systems, microalgae-based biophilic building envelopes offer an innovative pathway; Under similar conditions, they enable active photosynthetic carbon sequestration and oxygen generation, with potentially reduced maintenance requirements and lifecycle costs. This study presents a structured explorative review of microalgal building envelopes as an emerging negative-emissions biotechnological strategy that integrates high-performance environmental engineering with living biological processes. Accordingly, the paper investigates state-of-the-art microalgal envelope systems applied to façades and onto roofs. The study evaluates microalgal cultivation techniques integrated into architectural envelopes, examining their carbon sequestration capabilities, ecological benefits, and potential contributions to bioeconomy models. Limitations related to weather variability, lifetime, and operational requirements are addressed.