The carbon footprint and embodied energy of construction material: A comparative analysis of South African BRT stations

Abstract

This article describes strategic design decisions that architects can make during the initial stages of a project to minimise the use of construction materials, reduce carbon emissions and increase energy efficiency. A proposed prototypical Bus Rapid Transit (BRT) station Switch is used as a case study. The investigation focuses on minimising the use of construction materials through an iterative design and assessment process. This article extends an earlier study which analysed existing BRT stations in South Africa by conducting comparative life-cycle analyses (LCA). The earlier study by Hugo, Stoffberg & Barker (2012) identified a series of guidelines to inform the design of low-carbon and embodied energy BRT stations and determined a specific station, the MyCiti station, as the most efficient in terms of its carbon footprint and embodied energy intensity. As a result, the MyCiti station was identified as benchmark for future LCAs of station designs. The Switch prototypical BRT station is purpose designed for the Tshwane1 context and uses the identified guidelines (Hugo, Stoffberg & Barker, 2012) as well as carbon footprint (CF) and embodied energy (EE) of construction systems and materials as design informants generated from a study conducted by Jones (2011b). These informed material choices, use of low-carbon structural systems and integration of multifunctional station components. A cradle-to-gate2 life-cycle assessment compares the CF and EE of the Switch station and an existing South African precedent, the MyCiti station in Cape Town. The Switch station is 35% and 34% (4.08 GJ/m² & 378.6kgCO2/m² vs 6.28 GJ/m² & 574.7kgCO2/m²) more efficient than the existing MyCiti station, in terms of respective embodied energy intensity and carbon-footprint intensity. This prototype is proposed as a benchmark for prospective life-cycle analyses to inform the material choice and design of future BRT stations in South Africa.

Keywords: Bus Rapid Transit stations, carbon footprint, climate change, embodied energy, life-cycle assessment, construction materials