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Jack Alexander Wardale

Prospects of a Shift to Passive Ventilation Solutions to Decarbonise Commercial Buildings in Australia

Background: Recent extreme climate events in Australia have enhanced pressure on the federal government to achieve ‘Net Zero’ by 2050. Buildings contribute 23-25% of total carbon emissions annually, or around 133 metric tons of carbon dioxide equivalent (MtCO2-e). The specification of active air systems, which artificially condition most buildings, is proving a barrier to reducing energy consumption.  

Aim: Explore the potential of a sustainable alternative, Passive / Natural Ventilation (NV), and how it may assist in decarbonising Australian non-domestic buildings.  

Methods: Potential annual NV operating hours were estimated based on defining an environmental acceptability threshold range. Furthermore, using Building Energy Simulation (BES) analysis techniques, cooling energy savings were identified for mixed mode (MM) buildings in Sydney, Melbourne and Brisbane (SMB). Notably, future weather files were embedded in the simulations to evaluate 2030 and 2050 climate scenarios. Finally, through integrating historic air quality statistics into the data sets, the impact of deteriorating ambient conditions, caused by severe bush fires and pollution, was assessed and discussed. 

Results: Mixed mode ventilated buildings in SMB climate zones offer different cooling energy consumption savings. Sydney has the highest energy saving potential, 41.3%-45.1%, with the savings increasing from the 2030 scenario to the 2050 scenario. Melbourne’s climate is predicted to warm, causing more heat waves and reducing NV operating potential from the present day to the 2050 projection, although NV still results in anticipated energy savings of 30.8%-37.8% per annum. Likewise, Brisbane’s cooling energy savings increased in 2030, with a slight drop by 2050 caused by forecasted variances in ambient relative humidity, resulting in a savings potential of 36.5%-42.8%. With respect to the operating implications of urban air quality, there were correlations in the results between Sydney and Melbourne, suggesting a light reduction in NV operating hours, due to air quality dropping below a ‘fair’ threshold, of between 3.6%-5.6% and 4.0%-6.7%. Moreover, Brisbane’s air pollution minimally impacted NV operation, between 1 and 3 hrs per annum.  

Conclusion: This research provides a contribution to the literature as the first study to assess the energy- and carbon-saving potential of adopting NV  under future climate scenarios for the SMB buildings sector. The study also examines the impacts of urban air pollution on NV operation.