UV Cooling Coil Disinfection

UVGI for Cooling Coil Disinfection, Air Treatment, and Hospital Infection Control
Updated January, 2011

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/1MB PDF - Updated Jan 2011/

Dr. Kowalski, PE, Ph.D. developed a strong report which proves UVC can be cost justified as a capital expenditure by the savings it provides. The UVC installations provide savings in energy and maintenance costs as well as enormous benefits of a healthier indoor environment.

The report reviews the history and current literature on ultraviolet germicidal irradiation (UVGI) systems used for air and surface disinfection applications. Three of the most promising applications are addressed:

1) Cooling Coil Disinfection
2) Hospital Air & Surface Disinfection
3) Hotel and Residential Air & Surface Disinfection
4) Electric Utilities and UV Air Disinfection

The report provides an independent study proving that irradiating cooling coils with UVC will virtually prolong the life of the HVAC unit. The study includes a literature search of journals and trade magazines, including results from existing laboratory or field tests on UV equipment used in HVAC systems. The study includes analysis of UV effectiveness for cooling coils disinfection and cleaning. It provides formulas for calculating return on investment (ROI) and the savings in energy and dollars from improving or maintaining the efficiency and extending the life of existing coils. It can reasonably be expected that typical UV installations will produce payback periods of 2-4 years. The report shows an example where the payback period is achieved in only 8 months.

Applications in hospital or other health care facilities include cooling coil cleaning, medical equipment, surface disinfection in unoccupied areas, direct surgical site disinfection during procedures, and air disinfection in operating rooms, procedure rooms, delivery rooms, isolation rooms, patient wards, and general areas. UVGI may be able to reduce many types of nosocomial infections, especially those that have an airborne route of transmission. The paper explores some of the various applications for air and surface disinfection that may assist hospitals in reducing nosocomial infection rates.

Hotels may obtain significant economic benefits both from the use of UVGI to keep cooling coils clean and from improvements in air quality, which will provide a better environment for both guests and employees. The kinds of problems encountered in large hotels that are amenable to UVGI solutions are addressed in this report, and data is summarized from some previous applications.

The elimination of microbiological fouling of the cooling coils can be demonstrated through surface sampling before and after installation of the UV system. An alternative indicator of the effectiveness of UV germicidal irradiation could be coil performance, since the elimination of surface contamination should theoretically restore cooling coil performance to original design values.

It is our opinion that the UV report is very conservative in nature and will prove to be more valuable over time. The UV report was last updated January 2011 and will be updated regularly as more field data becomes available. The most recent update includes a summary of the ASHRAE Position Statement on the Application of Ultraviolet Germicidal Irradiation to Control Transmission of Airborne Disease. See the complete ASHRAE document.

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