The study, knowns as the BREATH project, saw City of Melbourne BREATH pilot test and evaluate three different ventilation systems in a vacant CBD building over three months using three ventilation systems: displacement ventilation air conditioning, in-ceiling air filters and natural airflow through open windows.

Designed to support the accelerated return of up to 400,000 CBD office workers in Melbourne, the project found:

All three ventilation systems reduced the potential transmission of airborne viruses when compared to standard ceiling-based air conditioning, 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 percent, while also reducing energy consumption by 20 percent.
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 percent but resulted in a minor increase in energy consumption.
Opening windows reduced virus transmission by 53 percent, 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 BREATH project was led by City of Melbourne and delivered in partnership with Cbus Property, University of Melbourne, AG Coombs, SEED Engineering and Westaflex, with peer review by AURECON.

According to Acting Lord Mayor Nicholas Reece: “Bringing people back to the city safely remains a key priority for the City of Melbourne, and that’s why we have undertaken this pilot study.

“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.”

Image: Empty office space in Melbourne / Twitter.

Branko Miletic

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