Optimizing building energy efficiency through microalgae façades: impact of cell density, biomass, and panel thickness on solar heat gain and light transmittance

Microalgae façades offer a promising strategy for enhancing building energy efficiency and advancing carbon neutrality in the built environment. This study examines the relationships between key microalgae characteristics, such as cell concentration, optical density at 600 nm (OD600), biomass, turbidity, visible light transmittance (VLT), solar heat gain coefficient (SHGC), and their effects on dynamic shading and building energy performance. A combined experimental and simulation-based methodology was adopted to assess the potential energy savings provided by microalgae façades. Façade samples were prepared with varying microalgae cell densities (10%-100%) and panel thicknesses (0.5–2 in.) to assess the influence of these variables on SHGC and VLT. Comparative simulations were conducted between a conventional reference building (in accordance with ASHRAE 90.1 standards) and a building featuring microalgae façades in Charlotte, North Carolina (climate zone 3A). Results demonstrated that both microalgae density and panel thickness significantly affect SHGC and VLT. Higher densities yielded SHGC reductions of up to 40% compared to lower-density panels. Thicker panels provided improved solar control and light modulation, underscoring their potential as adaptive façade systems. Simulation results indicate that optimizing these variables can reduce annual energy consumption by up to 6.3% when dynamically adjusted on an hourly basis.