ResearchAustralian scientists say ‘simple changes’ to ventilation systems can significantly decrease transmission of COVID-19

A pilot research project led by the City of Melbourne in partnership with the University of Melbourne and Cbus Property has evaluated ventilation systems in offices as part of a new study.
Content Team2 years ago7 min

Simple changes to ventilation systems can significantly decrease the transmission of COVID-19 and reduce energy consumption in office buildings, a pilot research project led by the City of Melbourne in partnership with the University of Melbourne and Cbus Property has found.

The BREATH project tested and evaluated three different ventilation systems in a vacant CBD building over three months: Displacement ventilation air conditioning, in-ceiling air filters and natural airflow through open windows.

The BREATH project found:

  • All three ventilation systems reduced the potential transmission of airborne viruses when compared to mixed ventilation, improving safety for office workers.
  • Displacement ventilation air conditioning – which supplies air from floor level – was the most effective and energy efficient system tested, reducing COVID-19 transmission by 83 per cent, while also reducing energy consumption by 20 per cent.
  • Displacement ventilation is the most expensive to install, but there are no additional ongoing maintenance costs.
  • In-ceiling air filters reduced virus transmission by 49 per cent but resulted in a minor increase in energy consumption.
  • Opening windows reduced virus transmission by 53 per cent, but increased energy use by up to 20 per cent with seasonal temperature variations.
  • Opening windows is not available to all office buildings and is not a viable solution due to Melbourne’s climate.

The University of Melbourne’s Head of Mechanical Engineering Professor Jason Monty said the collaboration between local government, industry and academics is a world-first.

“BREATH has given us the knowledge to predict the best type of retrofit to simultaneously reduce carbon footprint and infectious disease transmission. Since the majority of city energy cost goes to ventilation of our buildings, the outcomes from BREATH will improve our ability to reach net zero carbon faster,” Professor Monty said.

Lord Mayor Sally Capp believes this industry-leading research has identified “simple but effective changes” that can be implemented in office buildings to help workers feel safe, comfortable and protected.

“The research findings are publicly available online and free for any organisation to access”, she says. “We encourage building owners, tenants and partners to take them on board, and to help us create more healthy and sustainable workspaces in the CBD.”

The BREATH project was delivered with industry partners Cbus Property, AG Coombs, SEED Engineering and Westaflex, with peer review by AURECON.

BREATH project key outcomes

​System Impact on transmission​ Installation cost per m2 ​Energy use – cost per m2  ​Changes to energy use and NABERS
​Opening windows, standarding heating, ventilation and air conditioning operations ​Approximately 53% less infections ​Nil ​Costs $6/m2 per year ​10-20% increase in energy use, loss of up to ½ NABERS star
​In-ceiling air cleaner, HEPA filtration units ​Approximately 49% less infections ​$28mwith maintenance costs of $1.5 – $3m2 per year ​Saves $4.21/m2 per year ​2% increase in energy use, no impact on NABERS
​Displacement ventilation air conditioning ​Approximately 83% less infections ​$170m2 with no additional ongoing maintenance costs ​Saves $10.67/m2 per year ​10-20% reduction in energy use, addition of up to ½ NABERS star


*NABERS is a simple, reliable sustainability rating for the built environment, which measures buildings’ efficiency across energy, water, waste and the indoor environment. NABERS provides a rating from one (making a start) to six (market leading) stars.

For more information about the BREATH project and findings, visit the City of Melbourne website.

Content Team

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