Case Studies


  • The Queen's Medical Center – Honolulu, HI – Coil Irradiation & On-the-Fly Kill – noticeably improved indoor air quality, return to design HVAC system performance after degradation of over 30%.
  • St. Michaels Hospital – Texarkana, TX – Coil Irradiation – 7 month payback, eliminated indoor air quality complaints.  
  • Florida Hospital System – Orlando, FL – Coil Irradiation – 6 month payback, improved IAQ (mold completely eliminated from downstream HEPA filtration).
  • Children's Hospital SUNY – Buffalo, NY – On-the-Fly Kill – Reduction in microbial counts for infants in the neonatal ward (6 Log reduction).
  • Henry Mayo Hospital – Newhall, CA – Coil Irradiation – Returned system to original operating characteristics yielding a payback of less than 5 months, improvement in IAQ despite HEPA filtration already being in place.



  • Public Service Company of Oklahoma– Tulsa, OK – Coil Irradiation – Eliminated serious indoor air quality complaints, allowed for shutdown of additional chillers (300 tons of cooling reduction).
  • Harris County Municipal Offices – Houston, TX – Coil Irradiation – Eliminated indoor air quality complaints, total maintenance and energy savings in excess of $20k per year.
  • Louisiana State University – Baton Rouge, LA – Coil Irradiation – 30 days of UV treatment brought significant pressure drop reduction across air handler, savings of $15k due to elimination of need to buy new coil modules.


Sampling of articles and studies regarding the efficacy of UV systems:


January 2007 HPAC Engineering Magazine article details the opportunity to use UVC for controlling nosocomial (hospital acquired infections) through air system improvements.


Effect of Ultraviolet Germicidal Lights Installed in Office Ventilation Systems on Workers' Health and Well-being: double-blind multiple crossover trial
- McGill Study – November 2003 The Lancet


Assessment of UVGI used on drip pans and cooling coils within ventilation systems of office buildings would reduce microbial contamination, and thus occupants' work-related symptoms (double blind, multiple crossover trial of 771 participants in office buildings in Montreal, Canada over a 12 week period). Operation of UVGI resulted in 99% reduction of microbial and endotoxin concentrations on irradiated surfaces within the ventilation systems. On the basis of within-person estimates, use of UVGI was associated with significantly fewer work-related symptoms overall, as well as respiratory and mucosal symptoms than was non-use. Reduction of work-related symptoms was greatest among atopic workers and never-smokers. The technique reduced overall worker sickness by 20%, including a 40% drop in breathing problems. "Installation of UVGI in most North American offices could resolve work-related symptoms in about 4 million employees caused by microbial contamination of heating, ventilation and air-conditioning systems."


The Characterization of Upper-Room Ultraviolet Germicidal Irradiation in Inactivating Airborne Microorganisms
- January 2002 Environmental Health Perspectives


Assessment of efficacy of upper-room UVGI in reducing the concentration of Serratia marcescens and Mycobacterium bovis bacille Guerin (BCG) aerosols in an enclosed space. Results indicated that UVGI that occurs in the upper portion of air in a room economically reduces exposure to Mycobacterium Tuberculosis (MTB) droplet nuclei.


Environmental Health Article
UV Irradiation in the Home Improves Kid's Asthma

- May 2006 Journal of Asthma    


In a 28 week 'crossover' trial, researchers assesses respiratory symptoms in 19 children with asthma first while UVGI units were running in the home and then when dummy units were installed, or vice versa. Compared with the placebo situation, the use of UVGI was associated with a significant improvement in the children's peak expiratory flow rate. In addition, it was reported that asthma medication usage was reduced 51%, compared to 13% with the placebo.


Efficacy of Ultraviolet Irradiation in Controlling the Spread of Tuberculosis
- October 2002 University of Colorado and National Jewish Medical and Research Center for the Disease Control and Prevention (CDC) / National Institute for Occupational Safety and Health (NIOSH)          


Study quantified the impact of environmental factors on the response of airborne bacteria to UVGI in a full-scale room application. Overall, UVGI was shown to be very effective at inactivating airborne bacteria in the room environment. Achieved an inactivation rate of 16 ACH (air changes per hour) for M. tb surrogates and a reduction of airborne concentrations by 90%.


Effects of Ceiling-Mounted HEPA-UV Air Filters on Airborne Bacteria Concentrations in an Indoor Therapy Pool Building
- February 2005 Journal of the Air & Waste Management Association


Study assessed effectiveness of HEPA with internal UV lamps for their ability to remove or inactivate bacterial aerosol. The combined technologies were found to reduce concentrations of culturable bacteria by 69% (year one) and 80% (year two) and total bacteria by 12% and 76% over the same monitoring period. Study states that ceiling mounted HEPA with UV are a potential control to prevent the spread of bioaerosol contaminants through indoor environments.


Ultraviolet Light for Coil Cleaning in Schools
- March 2006 Engineered Systems


Summary of paper from May 2006 California Energy Commission (CEC) Study (see Advanced HVAC Systems for Improving Indoor Environmental Quality and Energy Performance of California K-12 Schools). Finds that UVGI can be used effectively for the purposes of improving Indoor Air Quality and saving time and money through improved operational efficiency and reduced maintenance on HVAC systems.


Advanced HVAC Systems for Improving Indoor Environmental Quality and Energy Performance of California K-12 Schools
- May 2006 California Energy Commission (CEC)


The CEC installed UVGI in 36 packaged air conditioning units in three school districts across California and compared their performance to 18 control units in those school districts over a six week period starting in August 2005. Results showed that the UVGI notably reduced the levels of microbial counts in the evaporator coils in the air conditioning units (reductions of 65 to 100% of colony forming units were found). Airflow and efficiency measurements were also made showing positive trends in reducing pressure drop and improving air flow.