Australian schools need better ventilation to improve student health and productivity, according to new research from the University of New South Wales (UNSW).
A team from the UNSW Sydney’s School of Built Environment found concentrations of CO₂ in classrooms peaked significantly higher than the 850ppm threshold prescribed by the National Construction Code due to a lack of proper ventilation.
The study also showed that low ventilation rates raise the concentration of other contaminants in a classroom environment, such as emissions from the building materials and furniture and particulate matter from indoor/outdoor sources.
A critical problem
The lead author of the study, Associate Lecturer Dr Shamila Haddad, says children are particularly vulnerable to the impacts of poor air quality.
“It is a critical problem given that students spend a substantial amount of their daytime in the classroom,” Dr Haddad says. “Pollutant exposure during developmental stages may produce lifelong issues such as respiratory infections and upper and lower airways disorders.”
Dr Haddad adds that poor air quality doesn’t just affect student health and wellbeing but also learning capacity through concentration loss, tiredness and fatigue.
“Elevated CO₂ concentrations can cause headache, sleepiness, and tiredness,” she says. “Improving indoor thermal and environmental quality is as important as improving the teaching material in the classroom.”
Although each state in Australia has guidelines for indoor air quality in schools, school classroom ventilation typically relies upon natural and manual airing, which is not always possible. Often, windows are closed to avoid discomfort caused by external noise, and hot and cold weather.
“Adequate ventilation and indoor air quality in classrooms cannot be achieved by split-type air conditioners without the supply of fresh air leading to an accumulation of contaminants,” says Dr Haddad.
“A good ventilation system inside classrooms, on the other hand, can ensure good air quality and thermal comfort, which can enhance learning capacity and also protect students against the transmission of airborne diseases, like COVID-19.”
During the study, the research team installed a demand-controlled ventilation system inside a classroom to monitor air quality and pollutants.
“It utilises both natural and mechanical ventilation systems and provides an effective opportunity for controlling indoor air quality in school buildings by adjusting airflow rates based on indoor air quality measures such as CO₂, total volatile organic compound (TVOC) and thermal comfort parameters,” says Dr Shaddad.
Maintenance is key
Director and founder of Viscon systems, John Penny, M.AIRAH, has more than 30 years’ experience in building controls and helped AIRAH produce its COVID-19 guidance for Australian schools. He says that the UNSW research reflects his findings in the field.
“It’s a real concern about air quality and ventilation systems” he says.
He also warns that although CO2 based demand control systems can provide a solution, they are only as good as the underlying ventilation system, and care must be taken to maintain the sensors.
“Sensor values will drift and eventually waste energy if the readings are not checked – DA19 suggests six-monthly,” he says. “CO2 sensors also have a lag in their reading, so when a classroom goes from empty to full, it can take an hour or so for CO2 to reach a steady state. This will result in under-ventilating the room during this time. This needs to be considered in the engineering of controls.”
Barriers to healthy breathing
Both Penny and Dr Haddad acknowledge that the issue cannot be solved by technology alone. As mentioned above, occupant behaviour is one issue, as is the cost of an effective ventilation system.
“It (associated cost) is often considered high by school authorities,” says Dr Haddad, “while the long-term cost on students’ performance and wellbeing is ignored.”
She also points to a lack of solid regulations for design and retrofit of school buildings. Although guidance and standards exist, they are often ignored because they are not compulsory. And policies such as the Cooler Classrooms Program in New South Wales concentrate on split systems while largely ignoring ventilation and air quality.
“There is a real need to enforce and implement the national standards,” Dr Haddad says.
“The school boards and state governments should have requirements for air quality and ventilation in their design briefs, and requirements for architects and engineers to base designs on,” says Penny.
“School principals and facility managers should also do surveys of existing classrooms and start to address the worst rooms with air quality. There is enough evidence in many international reports that supports this approach. Portable CO2 sensors and data logging are readily available.”
To read the UNSW research report, click here.