Implementation Strategies for UV-C Disinfection in Commercial HVAC Systems: COVID-19 and Beyond



The current pandemic has led to an increased demand for germicidal ultraviolet disinfection technology to help control the spread of the SARS-CoV-2 virus in buildings. The World Health Organization has warned that Covid-19 “will not be the last pandemic.”1 There is now sufficient evidence pointing towards the airborne mode of transmission of the SARS-CoV-2 in addition to the droplet transmission, similar to the SARS outbreak of 2003 and the MERS outbreak in 2012.2 A recently published study has presented data demonstrating the presence of SARS-CoV2 at several locations along mechanical ventilation air return and supply pathways, including multiple locations in air handling units (AHU).3 As we move towards a post-pandemic world, we should not overlook other serious airborne infections such as seasonal flu and tuberculosis, which continue to cause widespread illness and deaths annually. In addition, the quality of building ventilation directly affects the relationship between airborne transmission of respiratory infections and the health and productivity of workers. According to the World Health Organization, approximately 30% of all commercial buildings have significant IAQ problems; in particular, ventilation systems have been implicated in the spread of infections and pollutants. The moist conditions found inside the typical AHU are breeding grounds for several types of microorganisms to thrive, including fungi and yeasts. High bacterial and fungal concentrations have been documented within HVAC systems, specifically on cooling coil surfaces and drain pans4 which leads to fouling of the coil, resulting in an increase in energy consumption. High concentrations of these microorganisms on heat exchangers have the potential to be resuspended into the airstream, possibly introducing allergens or toxins into the indoor environment. Recent outbreaks of Legionnaires’ disease have been associated with the airborne transmission of Legionella found in the building cooling towers.5 Historically, UV-C technology has been primarily used for cooling coil disinfection inside AHU with only limited applications for airstream disinfection primarily in healthcare settings. The value proposition of installing UV-C systems has primarily been to lower energy consumption due to coil cleaning, rather than improvement in indoor air quality. The current pandemic has changed this perspective with an increased interest in deploying UV-C technology for airstream disinfection and improving the indoor air quality. Various government and industry organizations, such as CDC, GSA, ASHRAE and IUVA, include UV-C as a recommended mitigation step to reduce airborne transmission and to improve the indoor air quality in commercial buildings. However, the lack of proper understanding of UV-C technology has also led to multiple challenges regarding product efficacy, safety and implementation for existing and new HVAC systems. This whitepaper will discuss key considerations to successfully implement UV-C solutions for enhanced protection and value during this pandemic and beyond.



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