“Cradle to Gate” assessment of material related embodied carbon: A design stage stratagem for mid-rise housing in Sri Lanka

Abstract

Achieving low carbon buildings is seen as a key concept in order to reduce carbon emission and mitigate climate change. In contrast to operational emission, material related embodied carbon (EC) in the built environment plays a pivotal role, with the continuous consumption of high carbon emitting materials. This research relates to the ‘Cradle-to-Gate’ system boundary, while limiting its focus on building design stage decisions. A hybrid analysis approach was adopted - a bottom-up process with steps encompassing mass analysis, EC calculation, highlighting carbon hotspots, and ultimately the identification of critical building components. As a case study, multi-storey housing was selected as a critical building typology, in Sri Lanka. The results reveal ‘walls’ as a carbon hotspot that needs to be explored in strategies for mitigation. Substantial EC savings were seen in the selection of fly ash blocks as an alternate material to clay brick or cement block. Changes to the configuration of walls, specifically, bonding patterns and non-inclusion of a plaster layer, also showed savings. This paper, contributes to the understanding of material selection implications - in the cradle-to-gate stage - for the reduction of carbon emissions in mid-rise housing, in the context of Sri Lanka.