A 2022 white paper by the Pacific Northwest National Laboratory (PNNL) analyzed upper-room germicidal ultraviolet (GUV) compared to other measures used in buildings for minimizing transmission of the virus that causes COVID-19. The authors found substantial evidence that upper-­room GUV is effective. They also found that GUV can accomplish this at a much lower energy consumption than increasing outdoor air ventilation.

Benefits beyond COVID

Why is COVID mitigation still a priority given the World Health Organization downgraded the pandemic from a global emergency? There are three significant reasons, according to Gabe Arnold, senior engineer at PNNL and one of the paper’s authors. First is the potential for future pandemics. Second, the pandemic awakened significant awareness and interest in indoor air quality. And third, while COVID mortality has fallen, absenteeism continues to exceed prepandemic levels, with airborne diseases in general costing businesses more than $200 billion each year due to lost productivity.

“The benefits of this technology are massive for improved public health, reducing absenteeism and increasing energy and carbon savings,” Arnold said. “I believe we are just getting started.”

GUV devices emit ultraviolet radiation to neutralize pathogens. While the UV range constitutes wavelengths from 100–400 nm, the UV-C segment (200–280 nm) is considered most effective. A challenge is that UV-C radiation can be harmful to humans. A solution is upper-room GUV disinfection, where GUV devices irradiate the air at heights of 7 or more feet, ideally paired with ventilation that constantly mixes the room air.

The value proposition for GUV is still developing, but there is evidence that it is effective against airborne pathogens. An alternative is to address ventilation options including increasing the fraction of outside air entering the building, increasing the air change rate, and adding/upgrading filtration (e.g., minimum efficiency reporting value, or MERV, 13–14) at air handlers. PNNL wanted to compare the effectiveness and energy consumption of these strategies.

The resulting paper, “Energy Implications of Using Upper Room Germicidal Ultraviolet Radiation and HVAC Strategies to Combat SARS-CoV-2,” is a meta-study evaluating existing research. The authors found that upper-room GUV is the most effective at reducing infection risk and imposes an energy cost comparable to MERV 13–14 filtration but far lower than increasing the outdoor air fraction or HVAC air change rate.

“The biggest advantage of upper-room GUV is that it is highly effective relative to other strategies such as increased air ventilation and offers an equivalent level of disinfection at a small fraction of the energy use,” Arnold said. “The biggest disadvantage is that GUV has safety implications if it is not designed and installed such that people are not exposed to UV above safety limits. The proper design and installation of GUV to ensure it is safe and effective is an essential issue that must be addressed.”

Who’s responsible?

While GUV products may be offered by lighting manufacturers, they are not lighting products. The term “germicidal lighting” is a misnomer because the technology should only be used for disinfection, not illumination. It remains open who is responsible for design and installation. Arnold said that, regardless of who “owns” it, they are electrical products and as such, ECs may find themselves installing them.

“Currently, most GUV installations are proposed, designed and installed by companies that specialize in indoor air quality and/or GUV solutions,” he said. “The question is, will the lighting, electrical or HVAC industries take on the GUV opportunity, or will it remain more of a specialized industry solution? Regardless, GUV products are effectively ‘light fixtures,’ and electrical contractors will be needed to install the products where they are permanently mounted.”

Arnold encouraged ECs engaging with the technology to receive appropriate training and work with knowledgeable personnel to design and commission installations. He pointed out that the interNational Association of Lighting Management Companies is developing a training and certification program for GUV design, installation and commissioning. Additionally, contractors might familiarize themselves with ASHRAE 241P, a code-enforceable standard in development that sets higher targets for air quality than found in the ASHRAE 62.1 indoor air quality standard. The standard is expected to be technology-neutral, allowing multiple approaches, including GUV.

Based on the results of this paper, PNNL launched a new study to explore the full range of applications, system types and climate conditions needed to characterize upper-room GUV effectiveness and energy use. Arnold said he expects the study to be published late in 2023.

“I encourage the industry to get or stay invested in this technology and become educated,” he said. “There was a lot of hype during the pandemic about GUV, but the reality is we did not have the information needed to support deployment. Some became disillusioned at the early lack of success, but there is much more to come, and we are still at the early stages.”

Check out the PNNL white paper at https://tinyurl.com/4fy658dd.