<p>Meeting the growing demand for urban housing is a global sustainability challenge. Numerous studies have concluded that bio-based materials are lower carbon options compared to concrete while disregarding resource availability and harvesting emissions. This study evaluates low-carbon concrete in comparison to engineered bio-based materials and stabilized earth blocks for three issues: embodied carbon, material supply limitations and production scalability. Bio-based materials could only supply &lt;14% of global demand due to limited forest area within assumed conditions of sustainable harvesting yields. In contrast, adoption of low-carbon concrete is not resource-limited, with potential savings of 14.3 Gt.CO_2(eq.) achievable versus benchmark concrete housing from 2025-2050. Furthermore, engineered biomaterial production would need to scale up faster than low-carbon concrete, while also overcoming greater logistical and social barriers. To meet urban housing needs, low-carbon concrete is not perfect but is the lowest-carbon option that can be scaled-up to meet global demand by 2050.</p>