Carbon neutral mine site accommodation village: Developing the model

Abstract

The imperative to reduce atmospheric carbon is well documented and one significant area of production is from the built form which is responsible for up to 40% of global energy consumption and 30% of the world's carbon emissions (UNEP, 2009). Over the full life cycle of buildings, which includes construction and demolition, 80-90% of this energy is used during the operational phase to heat, cool, ventilate, light and run appliances (ibid). The balance of 10-20% represents the embodied energy and is consumed during the building process of construction and production of the raw materials themselves (ibid). The embodied energy proportion varies considerably according to the life expectancy of the building. This proportion of the overall emissions will increase as the life span decreases and in the context of mine site village development is certainly on the higher side as most sites have a life span of less than 20 years. The need for the transport of goods and services, delivery of water and waste services to and from buildings adds further to account of emissions that the built form is responsible for and the total can be described as the carbon footprint. Measuring this and reducing it to a point of carbon neutrality is the overall aim of our research. The term 'carbon neutral' has been defined largely by popular usage in the past (Murray and Dey, 2007). Even within scientific literature the academic definitions are few and varied, despite a raft of papers on life cycle analysis, input and output methods and tools for carbon accounting, especially when considering which emissions of the built form life cycle are actually to be included (Wiedmann and Minx, 2008). Murray and Dev (2007) discuss the terms 'carbon neutral' and 'carbon footprint' with several references on the subject. One such, Wiedmann and Minx (2008) concludes that a carbon footprint should only include CO 2 and no other greenhouse gases (GHG) from indirect, upstream emissions, as well as direct onsite emissions. In contrast, and in the context of this paper, the calculation of the carbon footprint is regarded as comprising of all the carbon emissions from the complete life cycle of the mine site village that can reasonably be calculated, from a clear site for development through to the remediation of the site following removal or demolition. Determining which emissions can 'reasonably' be included and how they are calculated will determine the potential applicability of the model to mine site village development generally. A specific case study has been secured of a recently constructed mine site village in the heart of the Western Australia's Pilbara region built to accommodate 142 staff with an anticipated occupancy rate of 80%. This paper details the methodology employed to calculate the total carbon emissions, the carbon footprint of this purpose built village and how to reduce it effectively to a point where carbon neutrality can be claimed. A conceptual model has been developed for calculating the emissions and is represented schematically in the paper with explanation of its parts. Once the carbon account, the overall footprint, is known then the task of building a strategy for reduction can commence. This will include: reduction of the embodied energy of construction; implementation of operational energy efficiency measures; renewable energy system offsets; and accredited biomass and carbon offset of the remaining emissions. In respect of operational energy measurement data has been provided from a similar sized village which highlighted the major energy consuming circuits and systems. Consequently, the Pilbara village has been designed by electrical engineers according to this data and once in full operation needs to be verified. To achieve this a metering and remote sensing system has been designed and installed on site to measure these circuits and systems, some detail of which follows in the methodology section of this paper. The system is expected to provide substantial information which, once analysed, will provide a basis upon which to redesign the power generation and distribution systems throughout the village and make a definite contribution to the overall operational energy reduction strategy.