UVGI vs. BPI: Which Air-Cleaning Technology Is Best for Your Building?
By Mehdi Jalayerian, PE, LEED AP and Tyler Jensen, PE, LEED AP
By Mehdi Jalayerian, PE, LEED AP and Tyler Jensen, PE, LEED AP
Two of those air-cleaning technologies that can mitigate risk include Ultraviolet Germicidal Irradiation (UVGI) and Bipolar Ionization (BPI). These can help reduce airborne exposure and may reduce disease transmission, though neither should be considered a silver bullet that can protect tenants perfectly.
What are the pros and cons of each? Let’s take a look at both.
Ultraviolet light has been used for disinfection for more than a century, with the first HVAC system application taking place in 1940. It is a thoroughly vetted technology that has a proven track record. Typical commercial products use the UV-C band wavelength of 253.7 nm, which is a near optimal wavelength for degrading organic material and inactivating microorganisms and pathogens. Use of the UV-C band energy to inactivate microorganisms is often referred to as UV Germicidal Irradiation.
UV exposure is hazardous to humans, so it is typically used in one of four configurations:
Bipolar ionization or non-thermal plasma technology (BPI) is a relatively newer technology used in HVAC systems. Different products use different technologies, but they all generally work by using electric voltage to generate ions and supply them to the occupied space. The ions work in two main ways in the space:
Bipolar ionization systems are typically installed in AHUs to distribute the ions through the ductwork system and into the occupied space. There are also packaged self-contained systems that can be mounted within critical high traffic spaces for local filtration. If installing BPI systems, further review on a case-by-case basis can help determine the appropriate BPI technology and approach for the specific building and application.
UVGI is a proven technology that can be effective at mitigating airborne infectious disease transmission. It is specifically recommended by ASHRAE in its COVID-19 response guidance.
BPI can provide many of the same benefits as UVGI, with the added benefits of odor control and VOC reduction. BPI may also kill pathogens in the air and on surfaces in the space, not just at the AHU.
However, some BPI products generate harmful ozone and there is a lack of scientific data and testing protocols with which to evaluate and compare technologies. These risks must be evaluated but can be mitigated to some extent. If BPI is used, proper specification with ozone free UL listings is critical. Field performance testing and validation is recommended to confirm the efficacy of the installed product.
Both UVGI and BPI may be appropriate for new construction and retrofit applications to improve indoor air quality and mitigate airborne infectious diseases. Careful consideration can help determine which technology is best for the application, evaluated on a case-by-case basis.
Want to learn more? Please contact Mehdi Jalayerian or Tyler Jensen.
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