Providing an efficient and effective means for disinfecting surfaces and air are crucial as we continue to open more businesses and schools during the Covid-19 pandemic. Although there is no one solution that will ensure complete elimination of the virus, UV lighting has been proven to help mitigate the spread of pathogens. UV products have been used for decades to disinfect surfaces but have primarily been used within healthcare applications.
UV lighting is classified in three wavelengths including UV-A, UV, B, and UV-C but of the three UV light wavelengths, UV-C lighting is the most effective means of germicidal disinfection. UV-C has the ability to kill bacteria, mold, and fungus, as well as the ability to deactivate viruses (including Covid-19) with the proper dosage on surfaces. UV-C lighting is used in several different ways to provide disinfection within a space including upper-room disinfection, direct whole room disinfection, mobile units to disinfect high touch surfaces, and installing UV-C lamps in air handling units. Each building should be evaluated individually to determine which method will be most effective for the application.
This blog will focus mostly on direct (whole room) exposure and upper-room disinfection methods for UV disinfection lighting. Interest in UV-C in non-healthcare applications has grown during the Covid-19 pandemic due to it’s potential to deactivate the Covid-19 virus when it is directly applied to surfaces or in the air.
Upper-Room Disinfection
Upper room germicidal UV utilizes UV-C lamps aimed at the ceiling with no direct contact with the skin or eyes of the occupants in the building, which permits the system to operate constantly. This approach is considered safer than providing the UV-C lights directly to the surfaces in the room. Additionally, the Illuminating Engineering Society (IES) recommends upper-room UV as the most effective method for disinfecting air within a space.
The upper-room method works best with taller ceilings and requires a minimum of 7’ ceiling in order to be effective and safe. When using this application, the UV-C light fixtures are wall mounted around the perimeter of the room and the lights are aimed toward the ceiling at an angle. This method is most effective with proper air mixing within the room by the HVAC system but can also be effective without as well.
Whole Room Disinfection
Although the upper-room UV-C fixtures are effective in disinfecting the air, they do not disinfect surfaces. UV-C lighting is also very effective at disinfecting surfaces and can be achieved by installing UV-C lighting fixtures within the space or utilizing portable UV-C lighting. When installing as a permanent solution, the lights are ceiling mounted within the room or wall mounted on the perimeter of the room and angled toward the floor. However, it should be noted that although UV-C are effective in disinfecting surfaces, the UV light can be harmful to the skin and eyes. Precautions should be taken when utilizing UV-C lights for direct (whole room) disinfection. This includes only activating the UV-C lights when a room is not occupied, which requires controls such as occupancy sensors and door switches that will turn off the lighting prior to anyone entering the room.
The UV-C lights can be used when the room is occupied but they will need to be provided with the proper PPE to protect their skin and eyes. Due to the potential hazard, this is not a common design approach and is not recommended by IES except during a pandemic scenario on a temporary basis when other options won’t be effective.
Understand there is no one solution that will work universally for each facility and careful consideration should be taken before moving forward with a means of UV disinfection for your facility. This includes evaluating the ceiling heights, room dimensions, initial cost, how quickly it can be implemented etc. Answering these questions early on will help determine the means by which disinfection will be achieved within a space.
Written by: Cameron Bellao, PE, LEED AP
Electrical Engineering Manager