The advantages of UV-C
UV-C systems provide several benefits when applied to HVAC/R systems, including:
- occupant comfort/IAQ;
- environmental responsibility; and
- economic savings.
HVAC/R system efficiency
UV-C eliminates and/or prevents the buildup of organic material on the surfaces of coiling, drain pans, and interior AHU surfaces. This improves airflow and maintains heat-transfer levels of cooling coils at as-built capacity. As a result, the HVAC/R system does not use more energy to provide the desired amount of cooling and ventilation, which maintains system energy efficiency. On average, UV-C coil installations on existing systems reduce energy use by 10 to 25 percent. (This information comes from ASHRAE RP-1738, “Field Measurement and Modeling of UV-C Cooling Coil Irradiation for HVAC Energy Use Reduction,” which can be accessed here.)
Comfort and IAQ
Clean coils and drain pans do not contribute foul odors, allergens, or pathogens to airstreams; they help the HVAC/R system sustain design temperatures and airflow rates. All these factors translate into meeting the functional and performance conditions communicated by codes, standards, and the owner’s project requirements. In so doing, it can be said UV-C systems help HVAC/R systems deliver quality, comfort, and IAQ. By extension, this means they support occupant productivity, lower incidences of sick days, and reduce hot/cold calls and other service requests. (This is derived from D. Menzies, J. Popa, J. Hanley, T. Rand, and D. Milton’s “Effect of Ultraviolet Germicidal Lights Installed in Office Ventilation Systems on Workers’ Health and Well-being,” published in The Lancet in 2003.)
UV-C systems have several characteristics consistent with green/clean technologies. For instance, they eliminate the need for chemical and mechanical (i.e. water) cleaning, which also reduces waste disposal issues. With a more efficient AHU, a UV-C system also saves energy and reduces carbon footprints. Further, since UV-C lamps are, characteristically, very similar to fluorescents (i.e. both contain mercury), they can be recycled along with, and in the same manner as, fluorescent lamps. As mentioned, they can also be integrated with a facility’s annual relamping program.
Reducing energy costs, sick calls, service calls, and system downtime for maintenance translates into significant cost savings from applying UV-C in commercial HVAC/R systems. A double-blind study was published by McGill University, Montréal, entitled “Effect of ultraviolet germicidal lights installed in office ventilation systems on workers’ health and well-being: Double-blind multiple crossover trial.” It concluded there were benefits gained by having UV-C in the HVAC/R systems. It can also be inferred buildings with highly functioning HVAC/R systems increase the value of building tenant leases because they have lower HVAC/R-related overhead and occupant turnover.