There is concern that the coronavirus can be spread via air-conditioning systems

Words Edward Hector, SFI Group


Some suggestions include increasing ventilation rates, upgrading filtration to HEPA filters and creating a purge cycle to introduce fresh air. Also, a redesigned chilled water air handling unit system to avoid the return of air that is in the current system, essentially creating what is called a full fresh air system. The goal is to minimise design change, while considering that most current systems are compliant designs in terms of National Building Regulations.

The World Health Organisation (WHO) focuses on the particle size and amount you breathe in which is called Particulate Matter (PM). The larger the PM, the less risk is present as your body protects itself through mechanisms, such as coughing and sneezing. The smaller the size of the PM, the greater the risk because the body is unable to prevent the particle from entering, and a pathogen ends up in your bloodstream it can spread airborne viruses and diseases.

To combat the danger of small airborne pathogens, you need to know which PMs are present and we have sensors that can measure IAQ by measuring CO2 levels, PM and Volatile Organic Compounds (VOC). CO2 is caused through exhalation and the HVAC system design may have to be reviewed, based on occupancy levels while the source of VOCs may be internal and also have to be addressed at source. Other external factors contributing to poor IAQ may be CO produced by vehicles or SO2 produced by factories.

Research shows improved ventilation rates can improve cognitive ability. We need to manage ventilation more dynamically to have optimum results under varying ambient conditions and occupancy levels. This is crucial as we minimise fresh air intake to lower energy consumption since bringing hot air into a building requires additional cooling, and vice versa. We may be compliant with ventilation and fresh air, but we could still have poor IAQ.

The importance of ventilation systems

As vaccinations roll out and we return to life in the “new normal”, IAQ and ventilation will be a key determining factor in convincing people to return to public spaces. Outdoor air pollution is intrinsically linked to indoor air quality. A study showed that pollution from power plants and vehicles caused close to 9-million deaths globally in 2018 while the total number of Covid deaths is approximately 4.5-million.

Our respiratory systems are affected by PM due to pollution and is a global issue we need to pay attention to. This is particularly relevant in South Africa, where coal-fired power stations are prevalent without scrubbing technology.
Industry needs to lead towards healthier IAQ. We need to increase ventilation rates above regulated minimum standards. Approximately 65% of exposure to outdoor air pollution occurs indoors. It is clearly important to consider both indoor and outdoor air quality.

The impact of poor IAQ

Particulate matter: a complex mixture of small, solid particles and liquid droplets causes poor IAQ. Inhaling elevated levels of PM can lead to a multitude of health problems. Exposure to high levels of PM is the leading source of mortality among all outdoor air pollutants.

How to improve IAQ

Poor system design of the air-conditioning system can accumulate mould which leads to high levels of PM filtering through indoor air over the years. Ducting systems designed with the correct quantity of air arriving at the designated destination, by minimising leakages, drops in pressure and ensuring optimal distribution routes can filter out PM and keep air ducts clean which contributes to improved IAQ. Improved filtration and the use of UVC Germicidal Irradiation as well as Bipolar Ionisation are technologies gaining ground for air purification in large air-conditioning systems.

Facilities management interventions along with increased government regulation will make HVAC systems and IAQ the priority for building operators, achieving a healthier working environment, improved cognitive ability and productivity due to the reduction in the spread of pathogens within the workplace.