Mitigating climate change by minimising the carbon footprint and embodied energy of construction materials: a comparative analysis of three South African Bus Rapid Transit (BRT) stations

Abstract

English: This article investigates the role that architecture can play in mitigating climate change by comparing the environmental impact of construction material use in two existing South African Bus Rapid Transit (BRT) stations in Johannesburg and Cape Town and a proposed BRT station for Tshwane. The article will generate guidelines to improve the resource efficiency of future BRT trunk-route stations. The climate change mitigation potential of BRT stations has been determined by analysing their carbon footprint and embodied energy over the cradle to gate1 period. The quantity of construction material used in each station was calculated, while the carbon footprint intensity and embodied energy intensity were determined by means of the Inventory of Carbon & Energy (ICE) carbon and embodied energy calculator. Calculations of embodied energy of structural systems and material use reveal that the Cape Town station is 36.5% more efficient in terms of carbon footprint intensity and embodied energy intensity than the Johannesburg station and 23.2% more efficient than the Tshwane station. The station base is the most energy-intensive component, contributing an average of 38% to the total embodied energy. It was concluded that steel contributes more than 50% to the total carbon footprint and embodied energy of each station. The analysis determines that lower scaled, spatially economical structures using low embodied energy materials will positively contribute to reduced carbon footprints and thus climate change mitigation strategies. The outcomes of the article also set a benchmark for prospective life-cycle assessments (LCA) and establish design guidelines for the design of future BRT stations.

Afrikaans: Hierdie artikel spreek die rol van argitektuur in die mitigasie van klimaatsverandering aan. Deur te fokus op die konstruksiemateriaalverbruik van twee bestaande Suid-Afrikaanse ‘Bus Rapid Transit’(BRT)-stasies in Johannesburg en Kaapstad en ‘n voorgestelde BRT-stasie vir Tshwane, vergelyk die artikel die omgewingsimpak van elke stasie. Die artikel fokus daarop om riglyne vir energie- en hulpbronverbruik doeltreffende BRT stasies te identifiseer. Die klimaatsverandering mitigasie potensiaal van argitektuur is gekwantifiseer deur die stasies se koolstofinhoud en ingeslote energie vanaf die ‘cradle to gate’ periode te analiseer. Deur die hoeveelhede konstruksiematerial verbruik in elke stasie te bereken en gebruik te maak van die ‘Inventory of Carbon & Energy’ (ICE) is die koolstofinhoud en ingeslote energie-intensiteite van die elke stasie blootgelê. Die navorsing op die ingeslote energie van die struktuur en materialgebruik dui daarop dat die Kaapstad-stasie die beste vaar in terme van energie-intensiteit deur 36.5% meer hulpbronverbruikdoeltreffend te wees as die Johannesburgstasie en 23.2 % as die Tshwane-stasie. Terwyl die stasie basis as mees energieintensiewe komponent gemiddeld 38% bydra tot die totale ingeslote energie, is staal as die mees energie-ondoeltreffende materiaal geïdentifiseer. Staal dra meer as 50% by tot die totale koolstofinhoud en ingeslote energie. Hierdie artikel kom tot die gevolgtrekking dat kleiner skaal, ruimtelikdoeltreffende strukture wat lae ingeslote energiematerial gebruik, lei tot strukture met laer koolstofinhoud wat kan bydra tot klimaatsverandering mitigasiestrategieë. Die gevolgtrekkings in hierdie artikel poog om ‘n vergelykbare basislyn te stel vir toekomstige lewenssiklusanalises en terselfdertyd ontwerpbeginsels vir die ontwerp van voornemende BRT-stasies te bied.