Despite recent interest, only a few lighting designers are specifying UV for projects. I spoke to several lighting designers about the impediments of UV systems to fight microbial pathogens.
Cost and Scope
C. Brooke Silber of Borealis Lighting Studio, BR+A Consulting Engineers shared her perspective. For their large health care and lab-type projects, Silber said, “UV is an obvious choice, but the barrier is cost. The cost is way too high for our clients.” Matt Caraway of Renfro Design Group pointed out that budgets are challenging for just the visible lighting needs. Caraway explained, “Typically, we handle just the visible light side of things, and even then it can be a stretch as far as getting everything done within budget.” Lisa Wong of Lam Partners agrees that UV is not typically in their scope, saying, “We are happy to work with our clients to understand pros and cons of UV disinfection, but we do not currently recommend them in our designs; UV disinfection technology is related, but separate, from architectural lighting, at this stage.”
Complexity and Controls
Caitlin Toczko of Lightcraft explained, “Many clients are curious, but then once they understand that it’s not a simple, quick cure for the current COVID-19 virus, they aren’t as excited.” Angie Ohman of Renfro Design Group pointed out “UV has issues with shadows, dosing, controls, and safety that are not easily designed around.” Brooke Silber explained when considering UV-C in hospital patient bathrooms, design of controls can be complicated, saying, “You have to make sure you have a seamless occupancy sensor that immediately turns off without delay. If you put the sensor on the outside (of the bathroom), the door has to stay shut. We’ve considered 405 nm technologies, but if the patient or the family gets up in the middle of the night, we’re concerned that the blue light will conflict with circadian stimulus.” [For more information on visible disinfection strategies offered by 405 nm products, see our 2020 publication.]
Safety Concerns
Lisa Wong pointed out, “As lighting designers, we can schedule light fixtures to be used in the space and can recommend control schedules for the facilities and maintenance staff, but we cannot oversee its proper use on a day-to-day basis.” Issues can arrive when new staff members are not properly trained on how and when to use UV disinfection technology. Maggie Golden, also of Lam Partners, avoids shining UV-C directly into occupied space. She stated, “Disinfecting surfaces is not as critical for an airborne disease and thus we would not recommend direct UV lighting currently unless we could always ensure there would be no crossover between an occupant and the UV light.”
Finishes: Damage and Appearance
David Cyr of Lilker Lighting Group, Lilker Associates Consulting Engineers, commented about damage, “Our clients in the education sector have expressed concerns about material finish degradation with UV.”
In hospital lighting design, Silber has considered visible disinfection technologies (e.g., 405 nm) that are safe for occupancy. However, she explained, “While surgeons are working in the operating room, they don’t want colored lighting impacting the appearance of patient skin tone or the visibility of screens.” Silber says she has been impressed by the sophisticated questions from collaborators, stating, “Interior designers ask how UV affects finishes. It would be nice to be able to provide them information about yellowing of lenses, and color rendering of materials.”
Matt Caraway added, for their museum and gallery projects, “UV is one of the last things the curators want in their space.”
Time Duration
Brooke Silber pointed out that in some health care spaces, it is critical that exposure time be minimized. “There’s not a lot of pushing for 405 nm in hospital operating rooms because turnaround time must be so fast,” she said. Longer wavelengths such as 405 nm take much longer to disinfect compared to UV-C. Silber also pointed out, “In the OR, our clients prefer UV disinfection robots because they can clean fast.” [For a comparison of disinfection technologies, see our 2020 publication.]
UV vs. Air Filtration
While UV technologies offer several approaches for disinfection, many clients are instead opting for improvements in their air filtration systems. David Cyr explained, “For New York City public schools, my colleagues collaborated to inspect over 100 schools. The improvements they recommended were mechanical HVAC solutions, with 2-3 air changes per hour (ACH) and Minimum Efficiency Reporting Value, MERV 13 filters.”
Figure 1: Upper-room UVGI (image created by CDC)
Good application: Upper-room UVGI
One application that has a well-established track record is upper-room ultraviolet germicidal irradiation (UVGI). The U.S. CDC has a well-illustrated factsheet explaining how upper-room UVGI works (Figure 1).
Silber explained, “The few times we’ve used UV was in upper-room applications. These are known technologies with long term field studies I can point to, not merely manufacturer claims.”
When considering UV systems in HVAC systems and upper-room UVGI, Maggie Golden agrees, “There’s potential now for these units to be used more frequently in public spaces like restaurants and large meeting spaces for disinfecting air.” Angie Ohman added, “It seems most productive to do upper-room UV rather than surface UV, both from a safety perspective and the complexity of controls.”
Aesthetics of UV Products
David Cyr is concerned with aesthetics, stating, “The really effective UV-C products, they don’t look good. They look like a big ugly bug zapper box on the wall.” Lisa Wong added, “The UV disinfection technologies that Lam Partners has seen through virtual table-tops have not particularly caught our aesthetic attention.”
Figure 2: Hybrid UV-C and visible light pendants; even with conventional low pressure discharge mercury sources, attractive pendants are available on the North American market. Image courtesy of The Lighting Quotient/elliptipar)
This has led some lighting manufacturers to develop UV products featuring a more refined architectural appearance and scale. Several hang as pendants, which can incorporate white light as well. Figure 2 shows some products recently introduced to the North American market that deliver direct/indirect illumination, while conventional 254 nm low pressure mercury lamps create upper-room UVGI.
The availability and quantum efficiency of UV LEDs are increasing; LED products that emit 275 nm UV-C wavelengths are minimal in size and could be more easily hidden in architectural features, such as with upper-room UVGI (Figure 3). [For a comparison of sources that generate UV-C, see our 2020 publication.]
Figure 3: Newer 275 nm LED technologies offer options for smaller housings that easily integrate with the architecture, as viewed in this recent example of upper-room UVGI. Photo courtesy of Purifii by Luminii
Figure 4: In addition to white downlight, conventional low pressure discharge mercury UV-C sources can be hidden in attractive pendants; this example uses a fan to actively circulate room air. Image courtesy of Air-Lume, UK
There are some products that are designed to actively move air through a hidden UV disinfection chamber. On the UK market, either conventional low pressure mercury discharge sources (Figure 4) or UV-C LED sources (Figure 5) are used in pendants that use fans to actively move air through a disinfection zone; some also incorporate white light sources.
Figure 5: For upper-room UVGI, more aesthetic form factors are becoming available with products using LEDs that emit 275 nm UV-C. This example uses a fan to actively circulate room air into the upper room disinfection zone. Image courtesy of Air-Lume, UK
What’s the Prognosis for UV Disinfection Technologies?
As new UV technologies mature, lighting designers need to continuously address these kinds of concerns. The COVID pandemic is not the last one we will face; even now, antibiotic-resistant strains of pathogenic bacteria and fungi cause illness and mortality, as well as billions of dollars of annual loss. All sectors in the lighting industry–lighting designers, engineers, manufacturers, installers, and maintenance personnel– will increasingly contribute to fighting microbial pathogens with UV disinfection technologies.
This article was originally featured in the October issue of designing lighting (dl).