How Does Ultraviolet Irradiation Work in HVAC Systems?

Without necessary safety measures, HVAC systems can distribute airborne pathogens. Ultraviolet irradiation can be a method for limiting this potential while improving the quality of indoor air.¹

Let’s take a closer look at how ultraviolet irradiation can work in an HVAC system, so HVAC technicians and those in vocational training can stay up to date with this industry trend.

What Is Ultraviolet Light?

Ultraviolet light is one of several types of light that exist within the entire light spectrum.² When measured in nanometers—one billionth of a meter—ultraviolet light waves comprise the 0-400 nm range.²

Within this subsection of the light spectrum, there are even smaller divisions.

1. UV-A Light: As the most common light waves in sunlight, this light range causes your skin to tan.²
2. UV-B Light: Similar to the previous, these waves can redden your skin and even cause skin cancer.²
3. UV-C Light: With the power to kill some nasty contaminants, these wavelengths are the sweet spot for the HVAC industry.²

How Does Ultraviolet Work in HVAC Equipment?

There’s a rich history of UV lamps being used to handle airborne contaminants.³ Early on, this technology was used to control infectious microorganisms in high risk areas like medical facilities.³ UV-C light, also known as short wave, is often considered to be the most effective for germicidal irradiation.³

UV-C fluorescent lamps are typically used to generate this wavelength.³ A lamp produces an electrical discharge via mercury vapor that’s encapsulated within a protective glass tube.³ This UV-C light is then transmitted through the tube and distributed.³

When used appropriately, UV-C light can inactivate mold, bacteria, mycoplasma and viruses.³

What Types of Ultraviolet Irradiation Are There for HVAC Systems?

Ultraviolet HVAC installations can come in one of two main categories: air sterilization and coil sterilization.²

The air-sterilization method, which is also referred to as an in-duct system because of its location, is designed to disinfect air as it’s pulled through an HVAC system via ductwork.² To increase the efficiency of this ultraviolet light for HVAC, an in-duct system is often accompanied by reflective surfaces.²

In contrast to the air-sterilization technique, coil sterilization focuses on specific high-risk components for a targeted approach to zapping air pollutants.² For example, these ultraviolet HVAC devices can be placed next to air filters, condensation pans and cooling coils to keep damp, hard-to-reach areas clean.²

How Does Ultraviolet Irradiation Work with Air Filters?

UV-C irradiation equipment is designed to handle what passes through even the highest quality air filters. The short-wavelength ultraviolet light that the equipment uses attacks the bacteria or virus and eventually causes cell death. They’ve been proven effective in eliminating bacteria, viruses, and molds that can sneak by even the best air filters.⁴

How Has COVID-19 Impacted the Use of Ultraviolet Irradiation?

The recent COVID-19 pandemic has led to a renewed interest in UV-C light, and the UV radiation has already seen a surge in demand.⁵ While more research needs to be conducted, UV-C irradiation might be able to inactivate the SARS-CoV-2 virus—the virus responsible for causing COVID-19—according to the Food and Drug Administration (FDA).⁶ Some industry professionals are predicting that the use of UV-C equipment in HVAC systems will become more commonplace as a result of the renewed interest.⁵

HVAC’s Essential Role in Healthy Indoor Air Quality

The focus on ultraviolet irradiation and ventilation to minimize the risk of spreading the virus responsible for COVID-19 underscores the importance of indoor air quality to the health of building occupants.⁶

These technologies, and the HVAC technicians who install and maintain them, are proving essential during the pandemic. The U.S. Department of Homeland Security’s Cybersecurity and Infrastructure Security Agency even deemed HVAC technicians as essential workers. That means the country needs HVAC techs to keep working during the health crisis crisis.⁷

Additional Sources
¹https://www.npr.org/sections/health-shots/2020/07/13/890387205/coronavirus-sparks-new-interest-in-using-ultraviolet-light-to-disinfect-indoor-a
²https://www.lincolntech.edu/news/skilled-trades/hvac/separating-fact-from-myth-on-hvac-uv-light-benefits
³https://cfpub.epa.gov/si/si_public_file_download.cfm?p_download_id=459522
⁴https://reviewsofairpurifiers.com/best-uv-air-purifiers/
⁵https://www.hvacinformed.com/insights/ultraviolet-irradiation-covid19-co-1571469098-ga-co-1573564123-ga.1587486872.html
⁶https://www.fda.gov/medical-devices/coronavirus-covid-19-and-medical-devices/uv-lights-and-lamps-ultraviolet-c-radiation-disinfection-and-coronavirus
⁷https://www.cisa.gov/sites/default/files/publications/Version_4.0_CISA_Guidance_on_Essential_Critical_Infrastructure_Workers_FINAL%20AUG%2018v3.pdf