Integration of self-cooling photobioreactors into the building envelope

Amin Mirabbasi

doi:10.60867/00000112

This thesis examines the architectural, environmental, and technical integration of selfcooling microalgae photobioreactors (PBRs) into building envelopes, grounded in the climatic context of Perth, Western Australia. It begins by situating PBRs within contemporary theories of sustainable architecture, biophilic design, and biomimicry, arguing that microalgal systems extend ecological design principles by coupling photosynthesis, thermal modulation, and material expressiveness within the façade. The literature review clarifies where PBRs align with or challenge core sustainability criteria, including energy reduction, carbon sequestration, shading, daylight modulation, and occupant sensory experience. Building on this conceptual framing, the thesis investigates heat-flow and thermal performance through laboratory tests, Design Builder simulations, and field experiments. Laboratory studies isolate the effects of aeration, pigmentation, and water depth on thermal behaviour, demonstrating that aeration suppresses stratification and lowers culture temperature by 2–4 °C, while microalgae modify spectral absorption and heat storage. These empirical datasets underpin simulation studies comparing PBR façades with conventional glazing, revealing lower heat flux, reduced solar gain, and delayed heat transfer. U-value analysis confirms the influence of the 80 mm water layer, with the water-filled PBR achieving significantly lower conductive heat transmission than an empty reactor or 6 mm glass façade. The technical and constructability chapter applies these findings into building practice, detailing requirements for material selection, panel fabrication, expansion joints, structural framing, aeration lines, harvesting circuits, water management, and compliance with Australian Standards. This component represents the first construction-level detailing of a flat-panel PBR system for an Australian context. A full-scale experiment in a prefabricated donga further grounds the research in real conditions. Replacing an east-facing glass window with the PBR resulted in midday indoor temperatures 1.5–2.8 °C lower and evening temperatures up to 1 °C higher, with peak negative heat flux values, confirming both cooling potential and thermal inertia. The creative component synthesises the scientific findings into architectural design. Through a curated gallery of prototypes and posters ranging from low-rise residences to mid-rise façades, tubular systems, modular hexagonal units, and an algae “tree”, the thesis explores typological adaptability and demonstrates how PBRs can become both performative and expressive elements of future buildings. Collectively, this thesis is a multidisciplinary framework, spanning theory, engineering, constructability, and design, establishing the feasibility and architectural relevance of PBR façades in hot-climate Australian conditions.

Integration of self-cooling photobioreactors into the building envelope

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