10/06/2021 - 08:00

Rethinking office ventilation

10/06/2021 - 08:00


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The pandemic has prompted office owners and tenants to pay more attention to how air is circulated through buildings.

Rethinking office ventilation
QED Environmental Services partner Joe Scholz. Photo: David Henry

Placing ventilation systems on the floor rather than the ceiling may seem like an odd approach to boosting the quality of indoor air.

But that’s exactly what one property group is implementing in its latest project in West Perth.

Construction is under way at DFD Rhodes’ office building on Ord Street, which plans to feature a displacement air system that delivers air via a void underneath the floor, introducing new air into the space upwards, rather than from the ceiling.

Designed by Cameron Chisholm Nicol (CCN), the 3,000-square-metre, five-storey property will be the first office building in Perth to house the displacement ventilation system.

The DFD Rhodes Office. Image: CCN

It’s a method of indoor air circulation implemented across Europe since the 1970s. Since moving from Europe to Australia in 1997, CCN managing director Dominic Snellgrove said he’d been pushing for the installation of displacement air systems in projects, but with little success.

“Change is always challenging where there is an established industry and a standard way of doing things,” Mr Snellgrove told Business News.

“Untried and [un]tested systems, at least in the Australian context, present some risk in relation to design, operation and commissioning.

“And the benefits in relation to indoor environment quality and reduced energy consumption are not well understood.”

Mr Snellgrove said studies showed a displacement air system offered significantly greater levels of clean air than traditional ceiling methods.

“Traditional systems supply air through the ceiling … they throw it down into the space like a hair dryer blowing air down into the space,” he said.

“They rely on the mixing of old air with new air to maintain temperatures.

“So that’s why, in a commercial office space, you are always sitting in your old air, because the new air delivered is essentially swirling and mixing with the old air.”

By contrast, Mr Snellgrove said displacement air systems constantly pumped new air through the building, effectively displacing the old indoor air upwards until it was extracted from the ceiling space or the ceiling void.

“The system is uni-directional,” he said.

“By supplying air at floor level, the conditioned, filtered supply air does not actively mix air within the space. It is supplied at low level and is returned at high level with minimal mixing.

“Air contamination produced in an office environment by occupants, printers, photocopiers and equipment rises upwards by convection.

“By supplying air at floor level, the conditioned and filtered supply air is not passing through contaminated areas to reach the occupied zone.

“For seated occupants, studies have shown that the ventilation effectiveness is greater by forty-four to 106 per cent, and by thirty-six to seventy-two per cent for standing persons when compared to the ventilation effectiveness for air distribution from ceiling swirl diffusers.”

Mr Snellgrove said that, as DFD Rhodes was an occupier of the building as well as an owner, it was more open to innovation and considering a displacement system – despite the price tag – given the benefits it offered over the long-term operation of the building.

A displacement ventilation system typically had a higher capital cost investment, he said, due to factors such as requiring a raised access floor system, which influenced floor to ceiling height, needing to be at least three metres, greater than the standard 2.7 metres.

However, Mr Snellgrove said the benefits, including reduced energy consumption over the life span of the building, outweighed the costs.

“Free cooling is the use of increased proportions of outside air when ambient conditions are favourable to provide space cooling,” he said.

“Typical under-floor distribution supplies air temperatures are between sixteen and eighteen degrees celcius, compared to ten to thirteen degrees for a ceiling distribution system.

“As a result, the number of hours where ‘free cooling’ can be used is substantially increased. This not only greatly improves the indoor environment quality with increased outside air, but also reduces the energy consumption of the air condition system.”

Mr Snellgrove said while CCN had convinced DFD Rhodes to explore a displacement ventilation system before the pandemic, the project had since generated a lot of interest among other clients.

“As clean air and indoor environment quality become a priority for landlords and tenants in a post-COVID workplace, there will inevitably be interest in the capacity for HVAC [heating, ventilation, and air-conditioning] systems that deliver healthier buildings and utilise less energy and provide greater occupant comfort,” he said.

“We expect there will be a lot of interest once there is something to see and feel.”

Air quality boost

There has been an uptake in building accreditations for office buildings in recent years, with particular attention given to more environmentally friendly practices, the installation of solar panels to achieve sustainability ratings, and improving wellbeing, with many projects boasting increased natural light for tenants.

Less noise, however, has been publicly made about enhancing the air inside a building.

The lack of comprehensive studies concerning air quality in Australia’s dwellings may be one reason for this.

The government agency responsible for this field (the Department of Agriculture, Water and the Environment) cites research dating back to the 1990s, pointing to one study undertaken by the CSIRO estimating the cost of poor air quality in Austrlaia may be as high as $12 billion per year.

While that figure broadly encompasses potential air pollutants such as gas heaters, little emphasis has been placed on indoor air, which is surprising considering Australians are estimated to spend about 90 per cent of their time indoors, mostly occupied in the office.

But the pandemic has sparked a renewed debate over office ventilation, according to Joe Scholz, an environmental engineer and partner at QED Environmental Services.

“Historically, air quality management has been unseen and unnoticed by the occupants unless there is a problem,” Mr Scholz told Business News.

“Now there is real interest by tenants to know what is going on behind the scenes, and most landlords have responded.”

Headquartered in West Leederville, QED provides testing, auditing and certification of the indoor environment, predominantly for offices, but also retail spaces, hospitals, health care, educational and industrial sites across Australia.

QED conducts air quality testing, ventilation assessments, mould surveys, water quality testing, asbestos tests, and also provides hazardous materials and chemicals management.

In his discussions with landlords during the pandemic, Mr Scholz said concerns over office air were initially given as reasons to not return to the office.

“I think people did have a fear of the unknown, and the unseen work of the landlord and manager with ventilation not visible,” he said.

Building performance ratings had helped dispel most tenant concerns.

While it pre-dated the pandemic, Mr Scholz said NABERS (National Australian Built Environment Rating System) and WELL Building Ratings, both of which assessed the management of the indoor environment, had become more important as tangible tools in demonstrating the management of air quality to tenants.

Mr Scholz said QED had also received an uptick in enquiries over the effectiveness of new air treatment technologies.

That included Ultraviolet Germicidal Irradiation (UVGI), which uses ultraviolet light to kill viral and bacterial organisms, as well as Photocatalytic Oxidation (PCO), an air purification technology that uses light energy to zap air pollutants.

“Quite simply, in my opinion, additional air treatment should only be considered for high-risk sites and situations: quarantine facilities, COVID treatment sites, COVID sampling clinics if indoors,” Mr Scholz said.

“The most important factor by far is the ventilation rate; that is, the amount of outside air being brought into the building to constantly flush the building.”


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