Can commercial buildings cope with Australian bushfires? An IAQ analysis

Arianna Brambilla,Ozgur Gocer,Kenan Gocer,Christhina Candido,Marco Filippo Sangiorgio

doi:10.5334/bc.87

Abstract

The Australian 2019/20 summer witnessed an extraordinary bushfire season characterised by unprecedented duration, geographical reach and impact. The aftermath of the bushfires includes increased health-related implications on people due to short and long exposure to poor air quality. The current advice from the Australian authorities in such events is to remain indoors, as it was assumed indoor air quality (IAQ) is healthy. This paper examined that assumption and presents the case study of an office building in Canberra subjected to the 2019/20 bushfires, responding to the need of understanding the ability of air-conditioning buildings to cope with such unprecedented and extreme weather events. Measured data for indoor concentration of CO2, PM10 and PM2.5 recorded a prolonged period of concerning levels, as well as extreme concentration peaks. This poses a significant risk to the occupants’ health. The values showed peaks up to 12 times higher for PM10 and 24 times higher for PM2.5 than the recommended critical thresholds. The infiltration factor and protection performance analysis suggest that old filtering systems and low airtightness levels are not optimal in protecting the indoor environment from outdoor air pollutants. Practice relevance Results show that the concentration of the outdoor pollutant significantly exceeded thresholds for a prolonged time, posing a health risk to the population. The case study presented has been partially able to protect its occupants thanks to the heating, ventilation and air-conditioning (HVAC) response, but this brings up the concern about all those spaces where mechanical ventilation may not be installed or have the same filtering system. Evidence provided here calls for an urgent update of the protection agenda to account for extreme weather events with regard to the diverse indoor built environments, because relying on the mechanical ventilation system is no more sufficient to provide healthy and safe environments.

Highlights

IntroductionThe Australian 2019–20 bushfire season is known as the ‘black summer’
The Australian Capital Territory (ACT) Emergency Service Agency (ESA) officially declared the end of the bushfire season on 31 March 2020, but the emergency was under control by February
The severity and duration of the bushfire season have placed extreme pressure on buildings and their heating, ventilation and air-conditioning (HVAC) systems to cope with such environmental stress and protect against the smoke for a prolonged period of time

Summary

Introduction

The Australian 2019–20 bushfire season is known as the ‘black summer’ This refers to a series of extreme bushfire events that started in June 2019 and declared contained only in March 2020. A combination of an unprecedented extended period of high temperatures and drought contributed to the increase of magnitude and duration of bushfires and their subsequent impacts (Yu et al 2020). It is estimated that the fire burnt around 18.6 million ha, with catastrophic consequences to fauna and flora along with significant environmental and economic losses to affected areas. The fires destroyed 5900 buildings, threatened the wildlife population due to habitat loss and caused at least 34 fatalities, exceeding any prior bushfire event (Jolly et al 2015; Ladds et al 2017)

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Results

Conclusion