Exploring established and alternative building materials' lifecycles to promote circular city development in remote, arid environments

Abstract

The building and construction industry contributes 37% of global carbon emissions and 30% of global energy consumption, significantly worsening environmental issues amid the global climate crisis. Rapid urbanization, particularly in arid regions, is expected to increase these impacts as construction expands to support city development. Meanwhile, as countries aim to reduce greenhouse gas emissions, there is a shift toward circular settlements and cities, demanding substantial material and energy resources. With previous research aiming to achieve circularity in the developed world, this paper analyses the effectiveness of alternative building materials in enhancing circular dwelling construction in the Gamagara Mining Corridor, Northern Cape, South Africa, over its entire cradle-to-cradle life-cycle. A desktop Material Survey Study was conducted to identify the established material palette of the region and brick-and-mortar was identified as the predominant materials in residential buildings. A Comparative Life-Cycle Assessment was then performed on a prototypical brickand-mortar building and three alternative material scenarios: timber-framed with timberpanelling construction; 3-Dimensional Concrete Printed (3DCP) construction; and timber framing with 3-Dimensional Adobe Printed (3DAP) infill. This assessed the environmental impacts over the building's cradle-to-grave life-cycle. Additionally, a Design-for-Deconstruction Assessment was conducted on the same prototypical building and three alternative scenarios, to determine the potential for impact reduction through disassembly in the Afterlife of the building’s life-cycle. The results indicated minor variances between scenarios. Timber-framed construction with 3DAP infill was optimal for the cradle-to-grave life-cycle, while the 3DCP scenario was best for disassembly in the Afterlife. However, all scenarios performed poorly against the Global One Dwelling Building Benchmark from One Click LCA, indicating that all scenarios in this context are highly impactful buildings. No scenario emerged as superior due to necessary trade-offs between impact categories and disassembly potential. In the arid and remote Gamagara Mining Corridor of South Africa, using alternative materials in construction does not straightforwardly lead to more circular cities. The findings emphasize that focusing solely on material emissions in construction is detrimental to achieving circularity. Designers should aim to adopt a more holistic view, considering other factors equally or more important than material emissions impacts.