Filtration and UV Technology in HVAC systems improve air quality

Smart sensing, IoT-based solutions, and innovative filtration technologies impact indoor air quality management. Saravana Selvan, Factory Manager, Ayan Holding Group, highlights that integrating UV technology and advanced filters ensures cleaner air, targeting specific pollutants while optimising energy consumption in various indoor environments.

What features distinguish indoor air pollutants from outdoor pollution sources?  

Indoor air pollution is a significant concern in confined, air-conditioned spaces. Major pollutant contributions include volatile organic compounds (VOCs) emitted from various interior elements, such as paints and laminates, and microbial organisms recirculated in the stale air of air conditioning systems.

Though outdoor air contains various pollutants, atmospheric influences make this pollution less dangerous than indoor pollution for humans. In recirculating air systems, indoor environments are continuously exposed to these contaminants, posing disease risks to human health if these pollutants are not properly mitigated in indoor recirculating air.

How does IoT technology influence monitoring and managing IAQ in commercial spaces?  

 Due to developments in smart sensing, control, and IoT-based solutions, precise measurement of pollutants, including their categories and impact levels, is now possible to analyse, enabling the development of mitigation actions. Air-handling units (AHUs) are commonly used in large commercial spaces for comfort cooling. Still, if not properly treated, they can contribute to the recirculation of pollutants in the air stream. Conventionally, each air handler operated with minimal control through a Building Management System (BMS), and air filtration was limited to particles up to 10 microns.

However, post-COVID, there has been an increased awareness of indoor air quality. New filtration technologies target specific pollutants based on their applications. IoT plays a good role in this revolution by enabling effective monitoring, 24/7 control, data acquisition, and analysis, facilitating instant changes and solutions to improve air quality.

How do filtration systems optimise indoor air quality while minimising energy consumption?

In commercial and large air-conditioned spaces, synthetic media-based air filtering systems are commonly used to remove particles as small as 0.3 microns. These systems are designed to eliminate dust, dirt, and other particulates associated with human presence. However, higher levels of filtration result in increased power consumption by air handlers due to the pressure drop caused by these filters.

Technology advancements in filter media materials have led to technologies that reduce the pressure drop in air handling systems. Chemical and UV-based filtration methods target microorganisms and gaseous contaminants while offering a lower pressure drop in contrast to synthetic media filters. This reduction in pressure drop helps in minimising energy consumption.

How does integrating UV technology impact disinfection into HVAC systems?  

UV technology mitigates microorganism-based contamination in air streams, targeting fungal and bacterial contaminants. In air handlers, particularly in tropical regions, cooling coils often experience heavy condensation, creating ideal conditions for microbial growth on coil surfaces and in condensate drain areas. Initially, UV-C lamps were employed to eliminate microbial growth by targeting the surface area of cooling coils.

Nowadays, UV-C technology is playing multiple roles in HVAC systems. It is used for disinfecting ducts and air filtration systems coupled with catalyst-based chemical reactions. They mitigate microbial, viral, and chemically bonded contaminants in the air stream.

How do IAQ solutions address pollutants found in different indoor environments, such as offices, factories or healthcare facilities?  

Indoor air quality is a requirement in any enclosed space, irrespective of the environment, as everyone has the right to breathe clean air. Filtration systems differ based on the application environment and are categorised into two segments.

The first segment involves comfort cooling applications, which include offices, commercial spaces, industrial factories, hospitality venues, educational institutions, and entertainment zones. In these settings, maintaining air quality and comfort for occupants is better. Large media filtration systems that eliminate particulates up to PM 2.5 levels combined with UV-C emitters across cooling coils and ducts to control microbial growth help maintain the comfort and clean air in the environment.

The second segment involves precise and extreme environments where the highest level of air filtration is expected. It includes pharmaceutical manufacturing, chemical and petrochemical applications, healthcare facilities, hospitals, and speciality centres. These environments demand a precise level of air cleaning to prevent the risk of contamination spread, which could lead to disastrous outcomes. In addition to particulate filters, different combinations of chemical filtration systems are necessary.

Each application requires a different combination of filtration systems to break down the chemical bonds of contaminants and neutralise by-products harmlessly. Due to extensive research, chemical filtration systems coupled with UV-C emitters for catalytic reactions are used in these applications.

What are the benefits of using Dedicated Outdoor Air Systems (DOAS) in HVAC systems?

Outdoor air should be filtered in the recirculating air handling system of indoor air conditioning. Therefore, it is equally essential to condition the outdoor air before it mixes with indoor air to maintain indoor air quality. The dedicated outdoor air systems (DOAS) are used in HVAC setups to achieve this. These units, which include filtration and cooling/heating options, work 100 percent to condition outdoor air and deliver it into indoor air recirculating systems. Designed to serve multiple areas with a single unit, they operate on the principle that approximately 10 percent of the air in a recirculating system should be re-conditioned by outdoor air. It helps control contamination, mitigate unwanted odours, and ensure human comfort in general cooling applications.

The highest levels of filtration are necessary for precision air cleaning management applications, such as operating theatres, chemical storage rooms, and laboratory systems. In these cases, DOAS units are the best and optimal solution. These units are customised and deployed based on specific requirements to fulfil their intended purpose.

How effective are filtration technologies in mitigating infectious diseases within indoor environments?  

We experienced this issue firsthand during COVID-19. Infectious diseases can spread through indoor air conditioning systems, highlighting the urgent need for effective filtration solutions. Technological advancements have excellent solutions for this problem. Since air handlers often serve multiple areas within a single HVAC circuit, preventing cross-contamination is vital. Hence, spot purification and central purification are necessary for every application to ensure that there is no cross-contamination and that the terminals of the air streams are free from contaminants. Let us take an example of hospitals that understand this need.  

The hospital wards house patients with various diseases, creating a high risk of cross-contamination. Advanced air filtration technologies offer excellent solutions by equipping air handlers with particulate and microbial filtration systems. HEPA filters, which can filter particles as small as 0.1 microns, are installed at the air terminals of ward rooms. Deploying UV beams on the ceilings of wards acts as a disinfectant, reducing microorganisms. Hence, the return air is free of such contaminants. Modern facilities are adopting these technologies to ensure that recirculating air is clean and safe.

What measures can bring improvement in IAQ inside homes or workplaces?  

Firstly, it is essential to create a chance in any environment to access outdoor air, which is purer than indoor recirculated air. Therefore, it is necessary to design provisions for bringing in outdoor air and treating it to prevent any contamination from outdoor air affecting indoor air quality. This is where treated fresh air handlers play a vital role.

We have already discussed central air handling systems, where integrating air cleaning equipment across air streams has been effective. However, for smaller workplaces and homes, windows with filtration capabilities allow infiltration of outdoor air.

 Using a grille with particulate filters and integrating a UV-C lamp can ensure clean outdoor air intake for such settings. While dedicated room air conditioners are installed in smaller spaces, they may only sometimes include filtration systems capable of mitigating microorganisms, VOCs, and other gaseous contaminants. Therefore, standalone room air purification systems are recommended. These systems recirculate indoor air while mitigating the contaminant.

The market offers a variety of off-the-shelf options with multiple stages of filtration, providing solutions for indoor air quality management. These can serve the purpose.