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Ultraviolet Lights to the Rescue |
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Recently several clients have asked us about one of the latest developments in indoor air quality (IAQ) involving a product known as UV-C. UV-C, or ultraviolet light in the "C" band, is designed to destroy biological growths in indoor air by placing the UV-C bulbs near the chilled water coils, inside of an air handler unit. The theory is not new, but recent changes in bulb chemistry have breathed new life into bulb marketing efforts.
The C-band emissions of ultraviolet light can affect living organisms. How much has yet to be determined. Manufacturers claims that the newest models of UV-C bulbs can destroy the cell wall of biological growths, rendering them sterile. A sterile organism cannot grow or reproduce. While it sounds good in theory, there is no research yet to support the statements.
Some research, however, that has recently been completed and presented at an ASHRAE indoor air quality conference shows that while the new style UV-C bulbs are considerably more effective than previous versions, their usefulness remains limited.
This research showed that placing the bulbs above condensate pans in an air handler unit worked well at prohibiting the growth of bacteria in the drain pan. At the same time, however, the bulbs were less effective at destroying fungi which resided on the fiber insulation.
The researcher, Dr. Richard Shaughnessay of the University of Tulsa's Center for Environmental Research and Technology, found that some areas exposed within the "line of site" showed a reduction in the presence of biological organisms. Other areas which did not receive as much light (such as fiber insulation lining and downstream ductwork) showed little or no improvement.
Many factors are required to make this technology work effectively. The installation of high efficiency air filtration, reflective surfaces on the inside of air handler units, relative humidity levels consistently kept below 60%, and even regular maintenance checks to ensure that dust does not build up on the UV-C bulbs can all help to improve the technology's results.
In our opinion though, until this process is refined and new research shows proven results, building management would do better to change filters, control humidity, and perform regular maintenance in an effort to control biological organisms. |
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