The experiment tackles ventilation, COVID-19 and energy prices

As the temperature drops in single digits, cool mornings invite you to huff and puff from those magical clouds of condensation known as dragon’s breath.

Much less charming, however, is COVID-19 which can also be breathed in, coughed and sneezed on similar clouds. This has led health authorities to advise that indoor environments should be well ventilated to reduce the spread of infections.

But such measures come at a cost.

As infections rise due to new variants, energy prices in Australia have also soared. And it turns out, shivering all day in an apartment building with all the windows open while the heaters are running isn’t just uncomfortable, it’s expensive.

A 1970s brown concrete office building on Bourke Street, Melbourne recently hosted a world-renowned experiment aimed at improving ventilation without increasing energy consumption.

The project – called Building Retrofit for Efficiency, Air Quality, Thermal Comfort and Health – bears the appropriate acronym of BREATH.

It is a collaborative effort between the City of Melbourne, the University of Melbourne’s Department of Engineering, building services specialist AG Coombs, engineering consultant Seed Engineering and air conditioning company Westaflex.

Melbourne recently hosted a world-class experiment aimed at improving ventilation without increasing energy consumption.

Its results have been peer reviewed by Aurecon consulting engineers.

Melbourne’s acting Lord Mayor, Nicholas Reece, said “state-of-the-art research has identified simple but effective changes that can be implemented in office buildings to help workers feel safe, comfortable and protected”.

Jason Monty, an engineering professor at the University of Melbourne, says the climate crisis, along with COVID-19, kick-started the project.

During the pandemic, Monty had worked on ventilation for all kinds of places, such as hospitals, government, schools, and transportation.

“But all of our recommendations during the pandemic were basically going to lead to increased energy consumption. And that was a major problem.

Read more: Climate Change Bill Hits House of Representatives: So What?

Initially, rising energy consumption was a problem no one wanted to hear about, he says.

Then late last year, Monty says, Dr Dominique Hess, the city of Melbourne’s zero-carbon building manager, called him.

“[She] basically says, ‘you’re making my job a lot harder’. Because its role is to help bring the city’s net carbon emissions to zero by 2040.”

“And she said, ‘is there anything we can do? Can we do better? »

With the help of the council, researchers gained access to an empty office building at 423 Bourke Street, which was still functioning but was due for demolition.

423 Bourke Street – the site of the experience. Photo: Petra Stock.

Monty says the ability to conduct a real-world experiment was critical to the success of the project.

“We were able to do whatever we wanted in this building, but it still worked. So we could still measure the energy consumption of the ventilation system. »

The team tested three different ventilation systems (open windows, in-ceiling air filters, and displacement ventilation conditions) against the baseline of standard building operation.

Ceiling air purifiers involved installing a HEPA (high-efficiency particulate air) filter in the ceiling, Monty says.

“A lot of people are probably familiar with home air purifiers by now, those portable devices that you can buy at an appliance store and put in your office. All schools have them, for example, all hospitals have them. But they are self contained units that require a plug and someone to turn them on etc. “It’s not really a commercial solution. What we’re talking about here is basically this portable air purifier, but ceiling mounted and also integrated with the building management system.

Displacement ventilation – a method known to be more efficient – ​​required retrofitting the existing air conditioning duct system by delivering air to the floor.

“So you literally just have to find where the ducts are in the ceiling, remove the panels, and run a pipe down to the floor. It is more or less that […] It’s definitely easier and cheaper than removing the whole ventilation system or making big changes to the fans or something like that.

Besides opening the windows, the three different ventilation systems were installed in different parts of the building, with the team conducting experiments for three months.

The ventilation performance of the different options was measured using a particle counter, an expensive device that accurately measures the concentration of particles in a room.

Monty says the team used a nebulizer with salt water to generate aerosols, to simulate the way people cough. They then used the particle counter to time how long it took for the aerosols to be cleared from the room.

“We came out of this finding that you could actually significantly reduce both energy costs and the risk of infection.”

From this information, it was then possible to calculate the risk of contracting COVID.

Measuring power consumption was much simpler, he says, using a wireless ammeter.

And what did they find?

“We set out hoping to prove that there was [ventilation] solutions that at least wouldn’t cost too much, if anything, or could save energy, but also have infection control benefits,” says Monty.

“We came out of this finding that you could actually significantly reduce both energy costs and the risk of infection.”

Research has shown that all three options – open windows, ceiling air filters, and displacement ventilation – reduce potential transmission of airborne viruses compared to normal building operation and improve office worker safety.

This is an important finding considering that not all office buildings have operable windows. And even for those who do, it can be an unwelcome step in the middle of a freezing winter or a sweltering summer.

Overall, displacement ventilation was found to be the most efficient and energy efficient system tested. Although it has higher upfront costs, this option reduced COVID-19 transmission by 83% and energy consumption by up to 20%.


Clare Walter studies the health effects of air pollution and is the director of AirFlow Workspace Solutions, a company that evaluates ventilation in the workplace.

She says the BREATH study is brilliant preliminary research that provides useful information on different ventilation options and also incorporates the associated carbon budget with each important aspect.

She says HEPA filters also remove air pollution particles from traffic, wood-burning appliances, bushfires, dust and pollens, which is good news for allergy sufferers. .

Although not in the original framework, Monty says the team also calculated the payback period for each of the options.

“We realized that [building] operators are going to need to know. There’s no point in telling them you have to pay $50,000 for a modernized system without letting them know how long it will take to pay it back.

“The more solid evidence we have to base our decisions on, the better.”

“Depending on the solution, it’s something like 10 to 15 years of return on investment, which may seem like a lot, but in terms of lifespan, it’s not a lot. But while it pays off, you also reduce your energy consumption. So you’re reducing your carbon footprint all the while. So that’s double the benefit,” says Monty.

“I think that’s what’s really exciting about these results is that they’re so clear that building owners, building managers can do something about infection control, without increasing the energy costs. In fact, they can do it while reducing energy costs.

Reece says: “The research results are publicly available online and freely available to any organization. We encourage building owners, tenants and partners to consider them and help us create healthier and more sustainable workspaces in the CBD.

“COVID is not going away, nor is climate change and with that extreme temperatures and bushfires. These are serious challenges for the construction of healthy and energy-efficient buildings in the Australian context,” says Walter.

“The more solid evidence we have to base our decisions on, the better.”

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