Post-occupancy Energy Consumption of BASIX Affected Dwellings in the Sydney Metropolitan Area

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Australian residential sector contributes approximately 13 per cent of the total greenhouse gas (GHG) emissions. The New South Wales (NSW) government in Australia has introduced mandatory energy efficiency/ GHG emissions reduction target through the Building Sustainability Index (BASIX) assessment tool, which estimates the operational energy consumption and GHG emissions from new residential developments based on information available at the building design stage. However, post-occupancy energy consumption can be different from the estimated figures at the design stage. This research aims to disentangle the relationships between various attributes that influence energy consumption at the dwelling scale through a post-occupancy residential energy performance analysis model. The model combines multidimensional attributes which include building design features, construction quality, possession of household appliances and their usage, demographic and homeowners’ energy use behaviour. The model allows comparing the estimated energy consumption/ GHG emissions from BASIX assessment with actual energy consumption/ GHG emissions in the real household environment. Data for this study has been collected from a sample of 48 BASIX affected dwellings located in the greater Sydney area which includes energy bill data, real-time monitoring of electricity consumption and indoor environment (temperature and humidity) data. This paper reports findings based on the data collected from late 2015 to mid-2016 from 16 dwellings. The initial results demonstrate discrepancies in energy consumption (therefore GHG emissions), household occupancy and breakdown of energy consumption for various services between BASIX estimates and the collected data. Given that BASIX assessment is based on information available at the design stage, the reported discrepancies are expected. More importantly, the initial results show that BASIX assessments under-estimated energy consumption for active cooling and over-estimated consumption for lighting and ventilation and other household plug loads.