Florida Hospital's experience with UV-C began in 1998 after seeing a presentation on the technology at an ASHRAE conference. A new generation of UV-C devices promised to offer an improvement over the UV lights that were long ago popular for upper air disinfection in hospitals and other heath care environments . Unlike the upper air devices, the newer UV-C lights were engineered specifically to provide peak output under HVAC conditions. Output of these devices was reportedly so much higher than conventional UV tubes in cold and moving air that they could be installed just downstream of a cooling coil to eradicate bacteria viruses, and mould.
Florida Hospital is an acute-care health system with more than 2,800 beds throughout Florida. With a network of 17 hospitals and 12 walk-in urgent care centres, Florida Hospital treats more than a million patient visits per year and is the second business system in the country.
To test the efficacy of the UV-C devices, it was decided to install the lights in Air Handling Unit (AHU) #107, a 27 year old unit located at the main Orlando campus. AHU 3107 was selected because the coil and train pan areas had a very visible build up of mould, and the coil was clogged to approximately 50%.
Within weeks after the UV-C installation, static pressure over the coil decreased from 1.8 inch of water to just 0.7 inch of water. Air velocity over the coil more than doubled, from 230 fpm to 520 fpm. Both the coil and drain pan areas looked absolutely clean, with no more visible evidence of mould or organic buildup.
The calculated decrease in energy costs for this single unit was $4,900 per year, and the total cost of installation was less than $2,000. Given the number of our facilities and the number of AHUs in these facilities, we estimate yearly energy savings well into the six figures. This estimate does not include additional savings for reduced maintenance. This works out to be a projected savings of 15% in HVAC energy system costs, conservatively speaking.
Conclusion:
Cleaning costs: UV-C devices have preformed beyond expectations for their originally intended maintenance function. E.g., to reduce or eliminate coil cleaning. Given that the AHUs red to require two coil cleanings per year on average, and we have equiped more than 100 AHUs with UV-C, we have succeeded in eliminating more than 200 coil cleaning producers annually. Cost per coil cleaning can range from $500 to $6,000. Anticipated long-term savings in dust cleaning costs should also be significant.
Reduced downtime: A reduction in the downtime associated with coil cleaning carrier s another important benefit. Whenever you shut down an AHU in a hospital, relative humidity can increase dramatically, especially in the tropical Florida climate. In turn, when timidity and temperature control are compromised, patient comfort is at stake and [roper IAQ control becomes more Challenging. UV-C helps to keep systems up and running, minimising the potential for these problems to occur.
Energy savings: By keeping coils in a constantly clean state, UV-C improves heat transfer efficiency, improves airflow through the system and allows air handlers to operate at peak profrmace. The resulting saving in HVAC sytem enerfy, estimated to be in the six figures annually, would be enough to pay back the cost of the UV-C installation very quickly.
