Edited by Eamonn Ryan from the transcript
SAIRAC Cape Town Centre hosted a technical talk on air quality and filtration last year, featuring Kritika Lalloo, a mechanical engineer and Theo van Der Linde, head of department: projects from LEEP Solution. Her speciality is energy efficiency and sustainability within the built environment.
Kritika Lalloo, a mechanical engineer andTheo Van Der Linde, head of department: projects from LEEP Solution, making their presentation. All images supplied by SAIRAC Cape Town Centre.
The talk centred around the importance of monitoring and managing air quality in various settings, including offices, hospitals, and casinos. LEEP discussed the need to reduce particulate matter and incorporate advanced technologies like IoT devices, electrostatic filter screens, UV lamps, and activated carbon infused filters to improve air quality and remove viruses. They also highlighted the importance of proper installation and maintenance of these technologies for effective disinfection and air quality enhancement.
In the presentation explored advanced air purification solutions such as filtration systems, electrostatic filters, ultraviolet germicidal irradiation, and photocatalytic oxidation. Additionally, they touched on odour control technologies used in restrooms and other spaces.
A significant portion of the talk was dedicated to understanding the Air Quality Index (AQI), which measures particulate matter, ozone, nitrogen dioxide, and carbon monoxide levels. For instance, Cape Town’s AQI was rated at 26 on July 16, indicating good air quality. They compared this with Johannesburg, which often experiences higher pollution levels.
The presentation also covered the importance of monitoring and measuring air quality using modern technologies, including Internet of Things (IoT) sensors placed around the room. Attendees had the opportunity to interact with these sensors and observe their readings during the event.
The session delved into the impact of particulate matter on health, referencing World Health Organization guidelines that suggest reducing particulate matter (PM) can significantly lower mortality rates. The speakers emphasised the role of HVAC systems in managing indoor air quality by addressing factors like temperature, humidity, and carbon dioxide levels.
For those interested in further reading, the SAIRAC Cape Town Centre is offering the book Heat and Energy by Jeff Albert, available for purchase.
The session continued with an interactive poll, aimed at assessing the audience’s understanding of particulate matter.
Participants were asked which category of PM is most harmful when it enters the lungs’ alveoli. The results highlighted a majority opinion favouring PM10, but the correct answer, as revealed by LEEP, was PM1. This finer particulate matter poses the greatest health risks as it can penetrate deeper into the lungs and even enter the bloodstream, potentially leading to severe health issues such as cardiovascular diseases and dementia.
They emphasised the importance of understanding particulate sizes. PM10, being the largest of the particles discussed, can reach the respiratory ducts and cause decreased lung function. PM2.5, smaller than PM10, can lead to skin and eye problems, while PM1, the smallest, can enter the bloodstream and cause more severe health consequences.
The presentation also highlighted historical trends in influenza cases from 1959 to 2017, noting a peak in 2017 before the introduction of the coronavirus pandemic. This data underscores the importance of monitoring and improving indoor air quality to mitigate health risks.
Focusing on indoor air quality, the talk covered the ASHRAE guidelines on Indoor Environmental Quality (IEQ), which link productivity, learning, and overall health to factors such as air quality, thermal comfort, lighting, and acoustics. Poor air quality and insufficient ventilation can lead to conditions like sick building syndrome, while inadequate thermal comfort and lighting can affect worker performance and well-being.
The discussion then shifted to various air purification and filtration technologies. LEEP explained that while air purification systems, including advanced filters and activated carbon filters, play a crucial role in improving indoor air quality, they also come with limitations. For instance, activated carbon filters have a limited lifespan and their efficiency can diminish quickly without continuous airflow. Regarding ventilation standards, the current SANS regulation requires 7.5 litres of air per second per person. However, forthcoming updates are expected to increase this requirement to 10 litres per second per person. This change aims to enhance indoor air quality but will also demand more from HVAC systems, potentially increasing energy consumption and operational costs.
One significant topic was the use of HEPA (high efficiency particulate air) filters, known for their high efficiency but also for their substantial pressure drop, which can increase system energy consumption. In contrast, the session introduced electrostatic filters as a promising alternative. Electrostatic filters, which charge particles to capture them more effectively, face efficiency issues once they become loaded with particulates. Despite this, they offer the advantage of reduced pressure drop compared to HEPA filters, making them a viable option for managing air quality with lower operational costs.
The presentation also highlighted advancements in UV-C technology. UV-C lamps, integrated into air handling units, are particularly effective at eliminating microbes, viruses, and bacteria. LEEP illustrated how UV-C light can be applied to heat exchanger coils and cooling coils to prevent the buildup of biofilms and maintain system efficiency. By breaking down biofilms, UV-C light helps improve airflow and overall performance of HVAC systems.
The discussion included a detailed explanation of ultraviolet (UV) light bands: UVA, UVB, and UVC. The UVC band, specifically around 254 nanometers, is noted for its germicidal properties, effectively disrupting the DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) of microorganisms. This spectrum is critical for effective UV-C applications in air filtration systems.
Moreover, LEEP introduced electrostatic filter screens as a modern solution that combines the benefits of traditional filters with reduced pressure drop. These screens are designed to efficiently capture charged particles, including bacteria and viruses, while allowing for improved airflow. This technology can be integrated into existing air handling units to enhance air quality without significantly increasing energy consumption.
A well-attended in person Tech Talk at Cape Town.
\They overviewed the importance of integrating new technologies with conventional systems to ensure optimal indoor air quality. The advancements discussed, including electrostatic filters and UV-C lamps, represent significant steps forward in air purification, offering more efficient and effective solutions for maintaining healthy indoor environments.
A key point made was the importance of using quartz glass to protect UV-C lamps. The quartz glass acts as a shield against dust and other particles, ensuring that the UV-C lamp remains effective over time. They stressed that the choice of quartz glass is critical, as the wrong type can diminish the lamp’s irradiance, reducing its efficiency in killing pathogens.
The effectiveness of UV-C light in killing viruses and bacteria is determined by the dosage, which is a product of UV irradiance and exposure time. The dosage required to inactivate various pathogens was discussed, referencing pre-coronavirus studies. For instance, while the dosage required to neutralise Legionella was the highest, at 0.01 minutes, the dosage for the coronavirus was 0.33 minutes.
A notable aspect of the talk was the emphasis on proper installation techniques for UV-C lamps. They advised against installing UV lamps exposed directly to the air stream. Instead, they should be enclosed in quartz glass to protect against damage and ensure consistent performance. The optimal placement of UV-C lamps is crucial for effective disinfection; they should be installed where air speed is lower to increase the contact time with the UV light.
They highlighted the benefits of precise UV-C lamp selection.
For environments requiring stringent cleanliness, such as hospitals or clean rooms, careful selection and placement of UV lamps are necessary to ensure adequate coverage and effectiveness. This involves calculating the distance between lamps and their placement relative to the coils to ensure that all areas are sufficiently exposed to UV-C light.
Typically, UV-C lamps have a lifespan of between 8 000 to 9 000 hours, depending on factors such as the cleanliness of the quartz glass and moisture levels in the environment. The installation of a control box, similar to those used for LEDs, is recommended to manage and monitor the UV lamps effectively.
- Photocatalytic Oxidation (PCO) is a technology that combines UV light with a catalyst to purify the air. The process involves a reaction between UV light and a catalyst, producing hydrogen peroxide (H₂O₂) as a byproduct. Hydrogen peroxide, a natural element found in Earth’s atmosphere, is known for its disinfectant properties. It breaks down into water and oxygen, effectively neutralising air pollutants such as bacteria, viruses, mold, volatile organic compounds (VOCs), and odours. PCO technology has been around for some time but is only now gaining traction in many regions. It involves placing a PCO unit in the air handling unit or main air duct system. As air flows through the system, the UV light reacts with the catalyst, creating hydrogen peroxide that cleans the air. This method is particularly effective in environments where pathogens or pollutants are prevalent, as it helps purify the air before it circulates through the space.
- Photo-hydro ionisation (PHI) is an advanced air purification technology developed in America that has met the strictest air quality guidelines in California. This technology involves a reaction between UV light and a specialized catalyst to produce hydrogen peroxide. Similar to PCO, PHI mimics natural processes to purify the air. The hydrogen peroxide generated helps break down pollutants, including viruses and bacteria, into harmless molecules. PHI units are compact and easy to install, making them a versatile option for various applications.
- Odour control solutions: Addressing persistent odours in commercial spaces, particularly in restrooms, is a common challenge for building managers and contractors. To combat this, portable odour control units are now available. These units, which can be installed near problem areas like restroom doors, use UV lamps and airflow to eliminate unpleasant smells. The design of these units includes a small fan that draws air through the UV lamp, where odours are neutralised. These systems are plug-and-play, making them easy to deploy without extensive modifications to existing infrastructure. They have been successfully implemented in high-traffic areas, such as shopping malls, where they have significantly reduced odour complaints. In one case, installation led to a noticeable decrease in odours within the first hour of operation, improving the overall environment for customers and staff.
These advancements underscore a broader trend towards smarter, more responsive air purification technologies that improve both system performance and occupant well-being. As the industry continues to evolve, the adoption of these cutting- edge solutions will play a crucial role in creating healthier, more efficient built environments.
