UV Light Disinfection: HVAC vs Upper-Room UV Fixtures

As more businesses begin to open and we understand more about the spread of COVID-19, interest in disinfection methods has grown. As experts in lighting, we often field questions regarding germicidal fixtures. Below, we explain how UV light can be used to disinfect a space, as well as the two most commonly used fixtures used to disinfect the air.

UV Light Disinfection

Before we explain the differences between upper-room and HVAC fixtures, it is important that you understand how UV light can help disinfect a space.

Ultraviolet (UV) light is measured by wavelength. Based on the length of the wavelength, UV light is classified as either UV-A, UV-B, or UV-C. While there are different applications for all types of UV light, only UV-C is germicidal. This is because, UV-C wavelengths damage, or destroy, the DNA and RNA of microorganisms, which prevent them from spreading.


We are asked if All UV lighting acts as a disinfectant on a regular basis. The simple answer is no. But then how do you know which product you need for your facility? In, Does All UV Light Act as a Disinfectant? we walk you through the different forms of UV lighting, and in UV-C Light Fixtures Explained we show examples of the different types of lamps and fixtures to consider.


When paired with manual cleaning, UV-C light disinfection is an excellent way to prevent the spread of illnesses. Because UV-C light works on microorganisms that exist in the air, underwater, and on surfaces, various fixtures have been developed to support all types of applications.

UV-C light has been known to cause mild skin and eye irritation. Because of this, protective measures must be taken when surface applications are in process. However, upper-room and HVAC applications can run regardless of occupancy. With that said, keep reading to learn more about the differences between upper-room and HVAC UV applications and which may be the right type for you.

Upper-Room UV Disinfection

Upper-room, also known as upper-air, UV fixtures can only be installed in rooms where ceiling heights are 7 feet or more. Installed on walls above people’s heads, upper-room UV fixtures can be used even when rooms are occupied. This is because the fixtures emit UV-C upwards, above, and away from skin and eyes.

But how does this help to disinfect air? Air is constantly circulated throughout a room. This means it rises in and out of the emission zone, being disinfected as it circulates through. While fans or HVAC systems help facilitate a more rapid circulation of the air, these things are not required as air will circulate regardless.

Pros of Upper-Room UV Light Disinfection

  • 24/7 Application: Because these fixtures work above occupants’ heads, upper-room UV devices can be used 24 hours a day, 7 days a week. Unlike overhead fixtures, which can be turned on only when proper personal equipment is equipped or rooms are unoccupied, these can run constantly. This means high-use areas, such as grocery stores and restaurants, can run these fixtures whether customers are in the store or not.
  • Highly Effective: Hospitals have been proponents of upper-room UV fixtures for decades. This is because studies have proven an 80% reduction in the transmission of illnesses, particularly tuberculosis when upper-room fixtures are used.
  • Safe: When these fixtures are installed correctly, the risk of human eye or skin exposure is almost non-existent. In fact, the only real concern comes during the maintenance of the devices themselves. However, as with all electrical fixtures, these devices should be turned off when maintenance personnel are working on them, which significantly reduces the risk of exposure.

Cons of Upper-Room UV Light Disinfection

  • No Surface Disinfection: Unlike ceiling-mounted UV-C fixtures, which point directly down, upper-room devices do not disinfect surfaces. This means that surfaces like countertops, chairs, and floors, are not being disinfected. Often, this means that portable UV-C devices or ceiling fixtures should be purchased or used in addition to upper-room models if surface disinfection is a concern.
  • Requires Specific Installation Configurations: Because a ceiling height of at least 7 feet is required, upper-room UV fixture will not work in every space. In addition to this, extremely large rooms, with more open spaces, will require specialized configurations to ensure the area is entirely disinfected.

UV Light in HVAC

When it comes to HVAC use, there are two main applications for UV light. Coil-mounted UV fixtures are installed near or on the coils and drain pans within an HVAC system. Coil-mounted fixtures are typically used on larger systems, where there is more room for them to be installed.  Duct-mounted fixtures, however, are more often used in smaller systems. These fixtures help to disinfect air as it passes through an HVAC system.

Regardless of whether you opt for coil- or duct-mounted fixtures, UV light in HVAC systems has multiple benefits. First, it helps to disinfect air that enters and circulates throughout the entire building, meaning clean air is re-introduced into the area. Second, UV-C light kills potential mold and fungus that is known to grow within HVAC systems themselves.

Pros of HVAC UV Light Disinfection

  • 24/7 Application: As with upper-room UV fixtures, the HVAC version can also be run all day, every day. Because they are installed within the HVAC system itself, there is no risk of human eye or skin contact with the UV-C light.
  • Easily Configured: Certain models of HVAC UV light fixtures are highly configurable. That means there is a way to install UV light in almost any HVAC system, regardless of its size or design.
  • Reduced Maintenance: HVAC equipment requires regular maintenance due to build-up. Because UV light kills off unwanted pathogens and microorganisms, it helps to reduce build-up and, therefore, maintenance.

Cons of HVAC UV Light Disinfection

  • Energy Expenses: Installing new fixtures may mean your energy expenses increases. Some users, however, have found this to be a temporary increase. This is because it takes time for the UV fixtures to thoroughly disinfect an entire HVAC system and reduce, or eliminate, build up. However, once this does occur, many HVAC systems run more efficiently, meaning costs often come back down.
  • Lower Transmission Reduction: While the air circulating throughout your HVAC system is disinfected before being re-introduced to the room below, these fixtures do little to help prevent the transmission of person-to-person microorganisms. As with the upper-room fixtures, this often means portable or ceiling-mounted UV lights are also required if surface disinfection is

Upper-Room vs HVAC UV Fixtures

Both upper-room and HVAC UV disinfection help to foster a healthier indoor environment. Both are proven methods of disinfecting air and both can be run constantly, regardless of occupancy. However, only upper-room fixtures are known to reduce airborne, person-to-person transmission of illnesses.

That being said, most experts recommend the installation of both fixtures. This provides the most thorough disinfection of airborne pathogens.

Since both fail to disinfect surfaces below, however, portable devices, tabletop units, and handheld fixtures are also available. This ensures all surfaces within a space are disinfected and thoroughly cleaned.


We are sure you have additional questions. Have you checked out our Ultraviolet Lighting FAQ page? We provide the answers to the most common UV lighting questions as well as links for more learning opportunities.


Upper-Room and HVAC UV Light Disinfection with Action Services Group

Now that you know more about how upper-room and HVAC UV light fixtures work, you may have additional questions. If you would like to learn more about these applications or would like to schedule a consultation, please contact Action Services Group today, by calling 800-223-0982 or email info@actionservicesgroup.com!

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