Design, fabrication, and long-term performance of modular bio-based building coatings embedded with Chlorella vulgaris and Synechococcus elongatus for enhanced carbon dioxide capture

This study develops modular bio-based building coatings embedding phototrophic microorganisms for atmospheric CO 2 capture, and evaluates performance through accelerated laboratory simulations and 24-month field trials. A porous bioactive matrix (PLA–alginate with mineral fillers) supports immobilized Chlorella vulgaris and Synechococcus elongatus , protected by a polyurethane–silica semi-permeable layer. Detailed formulations and processing protocols were optimized for porosity, microbial viability, and durability. CO 2 uptake averaged 1.85 ± 0.12 g·m −2 ·day −1 initially and 1.49 ± 0.10 g·m −2 ·day −1 after aging equivalent to 8 years, representing 80.5 % retention ( n = 18; 95 % CI reported). Field trials (south-facing, temperate climate) showed seasonal variation (1.32–2.05 g·m −2 ·day −1 ). Viability (Fv/Fm, CFU) was maintained with quantified limits of detection and uncertainties. Mechanical properties and adhesion decreased by 6.8 % and 4.3 % (not statistically significant; p > 0.05). LCA (ISO 14040/44; SimaPro) indicated a 14–18 % reduction in life cycle carbon footprint vs. conventional façade systems, subject to sensitivity bounds. Accelerated aging findings are framed as equivalent exposure; generalization across climates is discussed with constraints. • Modular bio-based coating embeds Chlorella vulgaris and Synechococcus elongatus . • Sustains >80 % CO 2 capture efficiency after 8 years equivalent accelerated aging. • Maintains microbial viability under fluctuating temperature, humidity, and UV. • Reduces façade surface temperature by ~3.2 °C during peak summer conditions. • Lowers building carbon footprint by 14–18 % compared to conventional façades.