The use of ultraviolet germicidal irradiation (UVGI) within an air handling unit (AHU) is growing rapidly. Typically UV lamps are installed for one of two reasons. In one application, high levels of UV energy are installed in the AHU ducting for disinfection of microbes in moving air streams. In another very popular application and the application of subject for this research, UVC energy is applied to the air conditioning coil and drain pan to prohibit microbial growth (bacteria and mold) from fouling the coil and drain pan. This application is reported to reduce maintenance costs, reduce pressure drop across the evaporator coils, and improved heat transfer of evaporator coils, therefore resulting in overall energy savings. The energy savings are also a result of improved air flow and reduction in required air handler (fan) energy. In additions to these changes the use of UVGI on air conditioning coils has been demonstrated to improve the indoor air quality and result in indirect savings such as improved employee or student attendance, reduction of complaints and reduction of respiratory illness. The goal of the research is to demonstrate, in existing field installations that UV technology can contribute to energy savings and improve indoor air quality in buildings.