Consulting-Specifying Engineer - September 2007 - (Page 34)

UV Germicidal Irradiation for Buildings: Formal Engineering Guidance on the way By Forrest Fencl, president, UV Resources, Huntington Beach, Calif. rooms. Contagions transfer from occupant to occupant and to the return, to be circulated (spread) to other patient areas where immunedeficient individuals may be confined for potentially unrelated care. Here, upper air UVGI systems are the most effective at inactivating the greater number of these particles. Patient-sourced and drug-resistant superbugs are returned in various concentrations to the AHU, which carries them throughout the air conveyance system to all other spaces occupied by other patients and hospital personnel. AHU air filters can play a significant role in reducing concentrations of nosocomial pathogens. However, properly located UVGI in the AHU can kill or inactivate both airborne and surface microbes as well as those caught and exposed on filter media, thus drastically reducing their concentrations, and especially their viability when and if dispersed to any space. Historically, engineers needing to apply UVGI lacked specific guidance for systems design, sizing and specification. ASHRAE recently undertook the process of approving UVGI as a required technology through the establishment of a standing technical committee. TC 2.9 was formed and the new committee is at work, among other things, writing a chapter for the 2008 Systems and Equipment handbook to address these very things. UV-C technology at large UV-C’s rising popularity beyond ASHRAE spawned research analogous to the technical committee’s goals by lesser publicized organizations such as the Air Purification Consortium (APC), the Air Cleaning Industry Expert Advisory Panel (ACIEAP) and The National Center for Energy Management and Building Technologies (NCEMBT). NCEMBT improves the efficiency, productivity and security of the U.S. building stock (no small challenge!). UVC energy is crucial to achieving each of their goals, whether to save energy, reduce maintenance or to reduce absenteeism. Also, group members are involved in high-stakes projects such as Homeland Security where application methodologies of UVGI are crucial to preclude large scale destruction resulting from terrorist activities. The worldwide UV organization is the International Ultraviolet Association (IUVA), whose key U.S. members are the same highly qualified participants noted before, each with their unique area of expertise. Prior to the creation of ASHRAE’s TC 2.9, IUVA started an aggressive program of producing draft Standards and Guidelines for UVGI that included Air and Surface Disinfection, Testing and Commissioning of In-Duct Air Treatment Systems, Installation of Air Disinfection Systems (New Building Construction) and In-Duct Air Disinfection Systems. With ASHRAE covering these same areas, IUVA has stopped its efforts for now. In either case, Standards, Guidelines and under-written independent testing and verification is moving faster than other HVAC technologies of recent history. Not covered here are other known microbial pathways such as lobbies, elevators, elevator shafts, stairwells, laundry chutes, and emergency entrances and corridors. However, they too can be effectively and affordably treated with UVGI. As the efforts of ASHRAE, IUVA and other organizations promulgate their standards and guidelines, UVGI application will increase, which does not bode well for superbugs anywhere. H ospitals are good examples of where dilution ventilation has limitations in reducing microbial contaminants; instead it’s become an energy concern. As infectious agents are “viable particles”, lessons learned from prescriptive spaces such as submarines, space stations and cleanrooms may provide researchers and practitioners with a focus on proven remediation of contaminated space air. One such treatment, ultraviolet germicidal irradiation (UVGI), has existed commercially since the 1930s, for lesser-known product and surface treatment. Does UVGI kill all microbes? Of interest, science has not uncovered a microorganism that’s resistant to the damaging effects of mechanically generated 254 nm germicidal UV energy, including the superbugs mentioned here. Another building type suffering from similar drug-resistant pathogens are the nation’s jails and prisons. Here, ventilation strategies that include air filtration, UVGI (both in-duct and upper air) and space pressure differential relationships have proved significant in the reduction of cross-infection rates. What’s the best approach for hospitals? Three methods of applying UV-C significantly reduce troublesome microbes and their resulting nosocomial effects in healthcare venues. All can be applied in any or all space applications. A reservoir and therefore source of fungi occurs in any air handling unit where various species proliferate on damp coils and in drain pans and then disperse throughout the air conveyance system infecting immunocompromised persons. UV-C lamps placed downstream of the coil bathe it, the drain pans and plenum surfaces to drastically reduce their numbers. Fungi sources that remain are found in return and makeup air where air filtration and coils arrest nearly 99% of them. However, the reservoir is gone. Other airborne pathogens result from transient, un-typed persons occupying waiting 34 Consulting-Specifying Engineer • SEPTEMBER, 2007

Table of Contents Feed for the Digital Edition of Consulting-Specifying Engineer - September 2007

Contents M/E Roundtable Cover Story: Airborne Superbugs Third-Party Liability Back to School Product Spotlight Codes & Standards Professional Practices How To New Products Jobs/Cliassifieds Specifier’s Notebook Pure Power Supplement New Technologies, Same Old Transmission Problems Wireless Battery Recharging Solar Concentration Renewables Tracking System A Mighty Wind The Importance of Load Bank Testing Quality Power for Security Systems

Consulting-Specifying Engineer - September 2007

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