HVAC Maintenance, Defects, and Disclosures in the Coronavirus Era

By Ritchie Lipson, Esq., Brittany Grunau, Esq., and J. Scott Friesen, P.E.

This article first appeared in The Communicator, Winter 2021. To read more, click here

As COVID-19 continues to spread throughout the population and the scientific community is still researching the many unknowns of the virus, it is vital that managers and boards of directors are diligent in their maintenance of buildings so as to keep occupants safe as well as to avoid potential liability. An open letter supported by 239 scientists, dated July 6, 2020, stated that there is a "real risk" that the coronavirus can be airborne. (Morawaska L, Milton, D. It is Time to Address Airborne Transmission of COVID-19, July 6, 2020). While there is little information known on ventilation and filtration requirements and the impact on the spread of COVID-19, it can be reasonably inferred that knowledge of how your system works and reacting accordingly could be an important mitigation factor. Maintenance of HVAC systems and air quality, making claims for any defects, and disclosures regarding air systems are essential practices related to COVID-19.


Every building’s HVAC system has minimum maintenance requirements for equipment and filters. Not only should managers and facilities personnel review these requirements, but they should also make sure that these requirements are fulfilled so that the systems continue to function effectively. Adequate-strength filters should be installed in buildings and changed at reasonable intervals.

The most common filter rating system is called the Minimum Efficiency Reporting Value ("MERV rating"). MERV ratings range from 1 -20. Pursuant to LEED v4.1, ventilation systems should have a minimum MERV rating of 13. Indeed, data has shown that MERV 13-16 will filter 80 percent of microorganisms smaller than 0.3 micrometers, which includes a majority of viruses and small bacteria. (Kowalski W, Bahnfleth, W. MERV Filter Models for Aerobiological Applications. January 2002). As the coronavirus particle is 0.125 micrometers, which is significantly smaller than 0.3 micrometers, a manager should also not advise occupants that its filters are filtering the coronavirus.

Prior to buying the highest MERV rated filter, however, managers or facilities personnel should seek advice from their HVAC service professional as to what filter the system can handle; some HVAC systems are not equipped to handle certain rated filters because they could restrict air flow, freeze the coil and/or damage other HVAC equipment.

If the HVAC system is compatible with a High Energy Particulate Filter (HEPA filter), the property manager should strongly consider installing a HEPA filter. In a NASA study that evaluated the efficacy of HEPA filters, it was found that they remove "virtually all" particulates in the range of 0.01-2.5 micrometers. (Perry J.L., Agui, J.H, Vijayakumar. Submicron and Nanoparticulate Matter Removal by HEPA-Rated Media Filters and Packed Beds of Granular Materials. January 5, 2016: 7, 13.) Notably, some states are considering making the use of HEPA filters mandatory within high-traffic buildings such as malls. If a HEPA filter cannot be installed due to system limitations, an adequate MERV rated filter as recommended by an HVAC professional should be used.

Once an appropriate HEPA or MERV rated filter is attained, managers should ensure that the filters are changed at a reasonable frequency. The frequency at which the filter needs to be changed varies by filter type, location, and environmental factors, and therefore should be assessed by an HVAC service professional.

Failure to properly maintain a building can potentially expose homeowners to the coronavirus, and potentially expose the HOA to claims due to negligent maintenance of the building. The standard of care for air handling systems and the coronavirus for managers will be guided by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE). As of July 1, 2020, ASHRAE has approved the following two statements regarding HVAC systems as they relate to the coronavirus:

  • "Transmission of SARS-CoV-2 [COVID-19] through the air is sufficiently likely that airborne exposure to the virus should be controlled. Changes to building operations, including the operation of heating, ventilating, and air-conditioning systems, can reduce airborne exposures.
  • Ventilation and filtration provided by heating, ventilating, and air-conditioning systems can reduce the airborne concentration of SARS-CoV-2 and thus the risk of transmission through the air. Unconditioned spaces can cause thermal stress to people that may be directly life threatening and that may also lower resistance to infection. In general, disabling of heating, ventilating, and air-conditioning systems is not a recommended measure to reduce the transmission of the virus."

Thus, while specific maintenance methods have not been recommended by ASHRAE at this time, it is apparent that failure to reasonably maintain the building’s HVAC exposes the manager to liability for any outbreak. ASHRAE guidance on HVAC maintenance should be continuously monitored and can be found at: https://www.ashrae.org/technical-resources/resources.


Managers and boards should be cognizant of deficiencies in both the design and construction of the building that could have an impact on the health and safety of its occupants. Here, a primary focus should be on the HVAC system, both its integrity as well as the transmission of air between units.

The transmission of air between spaces may occur in several different ways. The following are a few common possibilities:

  • The mixing of return air in a common air handling unit

Common areas found in larger buildings typically have a central air handling unit which takes return air back from the spaces, mixes it together, filters it, heats or cools it, and then supplies it back to the various locations. This is a common scenario where air from one space mixes with all rooms within the zone. It is important to ensure there is the required amount of outside air being introduced at the air handling unit as well as adequate and maintained filtration, both of which work to reduce or eliminate exposure to any contaminants in the air from transferring to a space other than where it originated.

Typically, units are separated by fire-rated assemblies, usually one or two-hour rated. If pipe or duct penetrations are not properly sealed, not only could fire or hot gases pass from unit to unit, but contaminated air could as well. If an occupant of unit "201" is quarantined at home due to an active COVID-19 infection and there are breaches, the virus-laden air could pass through to the adjacent unit "202," exposing a high-risk occupant to the disease.

Of particular importance, and often found in high-rise construction, is a failure of the contractor to properly install the return air ducting component of the HVAC system. It is common for the architect to locate the air handler in the ceiling plenum and to duct both conditioned air and return air through the plenum. According to the National Electric Code, a plenum is a "compartment or chamber to which one or more air cuts are connected and forms part of the air distribution system." Good industry practice is to duct the return air vents directly to the air handler, rather than have an open plenum become the "duct;" most air handlers are specifically designed to be ducted. However, if due to cost-cutting or sloppy construction the return air is not ducted, potential fire related code violations could occur, as well as the unit drawing return air from the entirety of the unit or even adjacent units if the ceiling area separating the walls is not properly sealed.

  • Direct openings in the walls between spaces

Openings in walls between spaces can occur between units as well, especially in multi-story buildings. In this case it is common to find openings in the walls and floor/ceilings, which are not properly sealed, allowing for an open "free area" for air to migrate. Air migration primarily occurs from a difference in the air pressure between the two sides. Inadequate or omitted fire stopping is one way to promote and allow a pathway for the air to migrate along with a differential pressure. The pressure differential can be in the form of an exhaust fan enabled on one side of the wall drawing air across to make up the air removed.


Open plenums over multiple units is not uncommon in high rise apartments, hotels, and condominiums. These same open plenums could provide an outlet for viruses and bacteria to transfer from room to room or unit to unit.

Many homeowners may not be familiar with the air handling system within the building they live. It would be prudent for the board or manager to inform occupants of the type of air handling system in place so that the occupants can make informed health decisions. Disclosed information to occupants should include the air handling maintenance protocols, the type of filters installed within the building, as well as whether the air handling system distributes air within one room in each unit, within multiple rooms within a unit, and/or between multiple units. For example, if a resident is quarantining a family member with COVID-19 in a room in their unit, the resident within the unit and other residents within the building might make different decisions on whether they remain in the building depending on how the air is distributed and what level air filter is installed. Again, managers should not advise occupants that filters are removing the coronavirus from the air.

Moreover, candid disclosure of this information provides another layer of protection for the board and manager from lawsuits for negligence and misrepresentation. A legal professional can help draft such a disclosure so that it maximizes liability protection.

The key to protecting associations from liability related to COVID-19 outbreaks via air handling systems is maintaining air handling systems and their components, addressing any design or installation defects via the assertion of claims against responsible parties, and also disclosing the type of air handling system installed within the buildings.

Ritchie Lipson, Esq. is director of client relations and leads business development efforts for Kasdan LippSmith Turner LLP in Arizona, California, New Mexico, and Hawaii. For more than 20 years, Lipson has limited his practice to representation of homeowners associations, residential property owners, school districts, municipalities, and commercial investors to assist in the fair resolution of their claims for defective construction.

Brittany Grunau is a partner with Kasdan LippSmith Turner LLP in the firm’s Irvine, California office. Her practice is focused on construction defect litigation. She brings her experience in professional liability, insurance defense, personal injury, and environmental regulation to the firm.

J. Scott Friesen, P.E. is a licensed professional engineer with more than 23 years of experience in design, construction administration, and forensic analysis of mechanical HVAC, plumbing, fire protection, and energy management systems for commercial, institutional, and residential projects. He is licensed in several states, including California, Hawaii, and Arizona. Friesen has worked for a major HVAC equipment manufacturer and also served on the IPC Code Development Committee in 2015 and 2018.

("COVID-19 (Coronavirus) Preparedness Resources." ASHRAE. https://www.ashrae.org/technical-resources/resources, July 1, 2020.)



Sign up for our monthly newsletter for the latest industry news and events.