Research results a relief for office workers

Illuminate vapor particles with green light in an office building
The BREATH project tested and evaluated three different ventilation systems in a vacant CBD building over three months. Image: Andrew Bott.

Simple changes to ventilation systems can significantly reduce transmission of COVID-19 and reduce energy consumption in office buildings, according to a pilot study led by the City of Melbourne in collaboration with the University of Melbourne and Cbus Property.

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

The project found:

  • All three ventilation systems reduced the potential transmission of airborne viruses 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 transmission of COVID-19 by 83 percent, while also reducing energy use by 20 percent.
  • Displacement ventilation is the most expensive to install, but there are no additional ongoing maintenance costs.
  • Air filters in the ceiling reduced virus transmission by 49 percent, but resulted in a small increase in energy consumption.
  • Opening windows reduced virus transmission by 53 percent, but increased energy consumption by as much as 20 percent due to seasonal temperature changes.
  • Opening windows is not possible for all office buildings and is not a viable solution due to Melbourne’s climate.

Jason Monty, head of mechanical engineering at the University of Melbourne, 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 the carbon footprint and the transmission of infectious diseases. As the majority of the city’s energy costs go to the ventilation of our buildings, BREATH’s results will give us ability to reach net zero improve carbon faster,” said Professor Monty.

University of Melbourne Vice President (Strategy and Culture) Dr. Julie Wells said the project shows how the university is addressing issues of local and global concern with its partners.

“This joint pilot demonstrates the positive impact University of Melbourne research can have on human health and energy consumption,” said Dr. wells.

“The findings provide an excellent foundation for building owners to move forward with an informed approach to ventilation options. We look forward to more great results arising from collaborative projects developed with the City of Melbourne and industry partners.”

Mayor Sally Capp said: “Getting people back to the city safely remains a top priority for the City of Melbourne, which is why we conducted this pilot study.”

“This leading research has identified simple yet effective changes that can be made in office buildings to help employees feel safe, comfortable and protected.”

“The survey results are publicly available online and freely accessible to any organization. We encourage building owners, tenants and partners to take them on board and help us create more healthy and sustainable workspaces in the CBD.”

University of Melbourne research engineer and project technical leader Dr. Grant Skidmore thanked the City of Melbourne and industry partner Cbus Property.

“We are extremely grateful for the opportunity to conduct this research. We thank both the City of Melbourne and Cbus for arranging and accommodating the work. We would also like to thank Aurecon for their peer review during the experimental design and report writing process,” said Dr. Skidmore.

City of Melbourne Sustainable Building portfolio lead councilor Elizabeth Doidge said: “We are proud to lead the way with this research, which will not only help protect Melburnians from the transmission of airborne viruses, but also help businesses by their environmental footprint and operating costs.”

“We are committed to working closely with our partners and will continue to support the creation of buildings that are more sustainable for our environment and for the future of our city, its businesses and its people.”

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

Table: main results of the BREATH project

System Impact on transmission Installation costs per m2 Energy consumption – costs per m2/yr Changes in energy consumption and NABERS
Open windows, standard heating, ventilation and air conditioning About 53% fewer infections zero Cost $6/m2 per year 10-20% increase in energy consumption, loss to ½NABERS star
In-ceiling air filter, HEPA filter units About 49% fewer infections $28m2 with maintenance costs of $1.5 – $3 million2 per year Saves $4.21/m2 per year 2% increase in energy consumption, no impact on NABERS
Displacement ventilation air conditioning About 83% fewer infections $170m2 without additional ongoing maintenance costs Saves $10.67/m2 per year 10-20% reduction in energy consumption, addition of up to ½NABERS star

NABERS is a simple, reliable sustainability rating for the built environment, which measures the efficiency of buildings in terms of energy, water, waste and the indoor environment. NABERS gives a rating of one (start) to six (market-leading) stars.

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

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