IAQ and energy – getting the balance right

The THRIVE research centre held a Future Buildings Forum in Sydney this week, focusing on the nexus between energy and indoor air quality (IAQ).

The event united experts from across a wide range of disciplines, with around 25 in person and over 50 online attendees. A strong line-up of Australian and international speakers explored how to balance our expectations for IAQ and thermal comfort with building sustainability and energy use.

Energy in the room

Sohail Hasnie, a former energy specialist with the Asian Development Bank, spoke about the potential for renewable energy and battery storage to transform the built environment – and the opportunities this might offer for using energy to improve IAQ.

Brock Manville, Energy Manager at the National Arts Gallery in Washington DC, shared the IAQ and energy journey of his facility through the COVID-19 pandemic and beyond. Of particular interest were the gallery’s air washers that not only reduced the spread of airborne viruses, but were also highly effective in eliminating odours and smoke during the wildfires of 2023.

When the COVID-19 pandemic began, the gallery doubled the rate of external air intake, and has maintained this since. According to Manville, staff have responded positively to the air quality being well serviced by the air washer and the higher levels of ventilation. The challenge the gallery now faces is maintaining staff confidence while addressing obligations to climate change.  

Professor Jason Monty from the University of Melbourne and Professor Geoff Hanmer from the University of Technology Sydney explained some of the key ventilation problems in public buildings, and the underlying issues in the national construction code (NCC).

Structural issues

VA Engineering Director Simon Witts, M.AIRAH, gave a stark explanation of what he called the biggest determinant of building design: price. As he pointed out, by the time a project reaches an engineer, there is limited scope for developing an innovative design – mostly, the requirement is the minimum standard set by the NCC. He also pointed to the lack of building commissioning, especially where the property is being constructed for developers rather than the building owner. Time allocated for commissioning in a project plan frequently gets squeezed out to compensate for earlier delays elsewhere.

John Penny, M.AIRAH, agreed, noting that commissioning remains an underused tool in providing buildings that meet their design objectives. The opportunity for commissioning during construction remains a strong contender for better construction outcomes.  

Associate Director of AIRAH’s IAQ STG Dr Claire Bird, Affil.AIRAH, attended the event and says one of the big takeaways was that some of the most serious barriers to improving IAQ are not just technical or behavioural, but systemic.

“There is a tendency for developers to focus on lowest cost, meeting minimum required standards and to push tenders in favour of the fastest timeline,” Bird says. “And when buildings are completed, a lack of oversight can lead to underperformance.

“It became very evident that we need strengthening of the NCC. And there remain several issues that members of AIRAH’s IAQ Special Technical Group have separately raised. These include the how, what and when for cheap air quality sensors, and how we gather other metrics of safe air, such as the composition of airborne particulate matter. Other factors that must be considered include dampness and volatile or semi-volatile organic compounds, which will deteriorate the quality of air in the building. Members have also expressed the desire to focus efforts on currently established energy-saving and moisture-mitigating interventions.”

Making IAQ visible

Participants discussed the “dream” of having visible sensor outputs in all public buildings, allowing people to see whether the air is safe, potentially based on the recently published blueprint for mandating indoor air quality.

But Bird warns that these parameters will not tell the whole IAQ story. She gives the example of the recommendations of ASHRAE Standard 241, which provides for the addition of air filtration devices to reduce aerosol loads at times of high infection risk. These systems improve indoor air by removing inhalable particles, but they do not remove CO₂, which can lead to elevated CO₂ levels even though the risk of airborne infection transmission has been mitigated.

“This is where it remains important to consider effective air infiltration rates, as set out under ASHRAE 241, rather than expect all HVAC systems to be able to achieve a given number of litres/second/person immediately. According to Prof. Hammer, over 90 per cent of our schools have split, recirculating HVAC systems and are likely fitted with inadequate natural ventilation to achieve either the blueprint thresholds for CO₂ or ventilation rate, or the ASHRAE 241 ventilation thresholds in a packed classroom.”

As Witts underlined during the discussion, Standard 241 also provides an option to achieve a given ventilation rate on a per person basis by controlling occupant numbers at time of increased infection risk – and explains the decision to set ventilation standards around a per person rate.

Many kinds of vulnerability

Bird also highlights the range of IAQ issues people face.

“The metrics you use to show how good your air quality is also depend on which health risks you are trying to manage,” she says. “According to the Safer Air Project, around 30 per cent or so of Australian occupants are vulnerable to serious disease from respiratory infectious diseases like COVID-19. While they might be reassured by public sensors that show low particulate and CO₂ levels, someone entering a building with chemical sensitivities will be more assured by seeing a green light for volatile organic compounds.”

Bird notes that high humidity also notably reduces occupant satisfaction with air quality.

“High humidity reportedly increases rates of emissions of VOCs from surfaces and increases the potential for dampness-associated contaminants if high levels are not curtailed,” she says. “These include aerosols from mould, unwanted bacteria, dust mites and even rodents. The survival time of many pathogens is increased under specific humidity conditions. And the people who are vulnerable are often surprising. For instance, research out of the University of Melbourne showed that the main population of people with non-allergic asthma when exposed to dampness-related changes in buildings are middle-aged men.”

Bird says, however, that despite the challenges around establishing IAQ thresholds, they offer a path forward.  

“I remain supportive of the need for IAQ thresholds as a starting point, providing that it is made clear to building users that there are limitations around dashboards that claim a safe environment based only on carbon monoxide, CO₂, respirable particulate matter (PM_2.5), and ventilation rate,” she says.

IAQ accessibility

As participants spoke about different mechanisms for improving indoor air quality – including updating building codes, regulations and standards – one suggestion that received strong support was treating IAQ as an accessibility and inclusion issue. Just as public buildings these days must be accessible for people with impaired mobility, they should be accessible to people with impaired immunity or other conditions that predispose them to medical issues such as infections, allergies or asthma.

And QUT’s Professor Lidia Morawska, leading the event, argued that this kind of accessibility should be a given, without the need for publicly visible indicators.

“We don’t go into a building and look for sensors showing that the water is suitable for drinking,” she said. “We don’t go into a restaurant and ask for a certificate to show that the food is fit for consumption. We assume these things are true.

“Equally, we should be able to enter a building and know that the air is safe to breathe.”

More information about THRIVE, including coming events, is available at the research centre website.