Impact of microalgae-integrated windows on building performance: Energy, daylight, and carbon analysis using an innovative simulation method

Buildings in hot semi-arid (BSk) climates face significant challenges in managing cooling loads while optimizing daylight and decarbonizing operations. This study evaluates the performance of microalgae-integrated glazing as an adaptive façade technology. A novel co-simulation framework was developed and validated (≈3 % U-factor error), coupling EnergyPlus and Radiance with a dynamic algae module that adjusts optical and thermal properties in real-time. The framework was used to assess static and dynamic configurations of two species (Chlorella vulgaris, Chlamydomonas reinhardtii) against conventional and water-filled windows across various orientations and Window-to-Wall Ratios (WWRs). Results demonstrate that orientation is critical to system selection. Dynamic microalgae systems are most effective on south and west façades, reducing cooling loads by up to 6.8 % compared to standard double-glazing. Conversely, static systems provide superior performance on east-facing façades. Both configurations outperform water-filled glazing in cooling-load reduction while enabling co-benefits. The façades actively sequester carbon at a rate of approximately 2.4 kg-CO₂/m² annually and generate electricity, though a trade-off exists between static (≈2.0 % efficiency) and dynamic (≈1.5 % efficiency) modes. This research provides orientation-specific design guidance and quantifies the multi-objective trade-offs, positioning bio-responsive façades as a viable solution for enhancing energy performance and carbon management in the built environment. • Dynamic algae windows reduce EUI by 5 % vs. double glazing, cutting cooling loads. • Static algae systems show superior carbon sequestration and energy performance. • EnergyPlus-Radiance framework enables real-time evaluation of dynamic algae façades. • Algae façades enhance daylighting and thermal comfort; east suits static, south/west suits dynamic.