Carbon-Negative Bio-Brick: A Mycelium–Calcium Carbonate Composite for CO₂ Sequestration, Structural Performance, and Natural Daylighting Enhancement

This study presents the development of a carbon-negative bio-brick composed of mycelium and calcium carbonate (CaCO₃), designed to reduce embodied carbon while improving mechanical, thermal, and optical performance [1]. The material leverages the CO₂-binding capability of CaCO₃ together with the lightweight fibrous network of fungal mycelium, resulting in a sustainable composite with a significantly lower carbon footprint [2]. An optimized fabrication process produced a porous microstructure that enhances compressive strength, thermal insulation, and durability relative to traditional mycelium-based materials [3]. A key contribution of this research is the introduction of a novel optical function: the ability of the bio-brick to soften, scatter, and diffusely transmit natural daylight through its internal pores, creating a passive daylighting effect not present in conventional masonry units [4]. Experimental assessments—covering mechanical testing, thermal conductivity, water absorption, and optical evaluation including light diffusion, spectral transmission, reflectance, and illumination uniformity—demonstrate clear performance improvements linked to CaCO₃ integration [5]. The results show enhanced strength, reduced thermal conductivity, and significantly improved daylight scattering that produces soft, uniform, low-glare illumination suitable for architectural environments [6]. Overall, the mycelium–CaCO₃ bio-brick operates both as a carbon-negative structural component and as a passive light-modulating element, offering a dualfunction solution capable of reducing energy demand for artificial lighting while supporting sustainable building practices [7].