Workers Still Fear a Return to Buildings - How HVAC Can Help Ease Trepidation

Social Distancing
Figure 1 - Social Distancing

According to Korn Ferry (a global HR consulting firm) 50% of worldwide workers are afraid to return to their offices despite social distancing practices that have been implemented, such as limiting occupancy, employee temperature scanning, face masks, special workspace accommodations and additional cleaning measures. David Schurk looks at the issues.

Within cities, more people are starting or continuing to work from home which has resulted in office vacancies skyrocketing and rents plummeting. Information from Colliers International (a leading global commercial real estate service and investment management firm) reports that vacancies soared by 10.2% in the first quarter of 2020 and have continued to rise. The commercial real estate market is experiencing negative impact to their financial bottom line as never seen in more recent times. What can be done to ease trepidation and help reengage our workforce population back into an eager economy awaiting their return to buildings and structures of all types?  

 One important piece to this puzzle may be something recently dubbed “HVAC Social Distancing”, but what does that really mean? In Figure-1 you will notice the slight difference between the left-and right-hand pictures. By implementing specific Heating, Ventilating, and Air-Conditioning (HVAC) system measures such as effective ventilation and filtration, along with the addition of Advanced Air Cleaning Technologies, professionals in the facility management and HVAC fields are striving to drive a wedge between building occupants and the very small “droplet nuclei” aerosols (in red circle) transporting airborne virus, that when inhaled may result in the transmission of COVID-19 along with other diseases.

Recent Guidance

Unfortunately, little is yet is really known with regard to the novel SARS-CoV-2 virus which causes the disease COVID-19. Preliminary research indicates this virus (like many others) can be transported within the air as fine or ultra-fine submicron particles, further classified as droplet nuclei. These are the result of respiratory fluids which are aerosolized when expelled to the indoor environment by an infected individual who may be coughing, sneezing, talking, or breathing. These aerosol droplets include mucosal and saliva fluids containing an assortment of liquids, salts, viruses, bacteria, volatile compounds, etc.

A scientific study published in the American Journal of Infection Control titled Particle Control Reduces Fine and Ultrafine Particles Greater than HEPA Filtration in Live Operating Rooms and Kills Biological Warfare Surrogate, has concluded that many very small particles and pathogens may be of insufficient mass to be controlled by bulk airflow and can remain suspended in the indoor air for days or even weeks. It’s reported that significant fractions of the fine and ultra-fine particles in the air may not be effectively transported to or removed by conventional air filters, which of course can only be effective at removing those particles and pathogens that reach them, not those that remain suspended in the space.

In November of 2020 the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) stated in a journal Industry News article titled ETF Chair: Limited Virus Knowledge is Key Challenge, that research has not provided evidence of the transmission of (SARS-CoV-2) virus through HVAC systems, although within a space air motion caused by HVAC system components as well as fans can be a factor. On March 23, 2021, Centres for Disease Control Preventions (CDC) updated their COVID-19 Ventilation FAQ’s titled: Can COVID-19 be Transmitted Through HVAC Ventilation Systems? They stated that the risk of spreading SARS-CoV-2 through ventilation systems is not currently clear, and that while airflows within a particular space may help spread disease among people in that space, there is no definitive evidence to date that viable virus has been transmitted through an HVAC system to result in disease transmission to people in other spaces served by the same system. In a January 2021 peer-reviewed ASHRAE Journal article titled Preparing HVAC Systems Before Reoccupying a Building, authors stated that the growing science around far-field aerosol transmission may essentially negate the need for in-duct or air system control technologies such as UV lights.


Actionable Solutions

Based on current guidance it appears evident that we may want to consider addressing occupant transmission of SARS-CoV-2 in the space itself, where it originates and may remain. While traditional ventilation and filtration are the cornerstone of any buildings HVAC system, Advanced Air Cleaning Technologies are available which can complement both by helping to enhance the quality of air provided to the occupied space. Ensuring traditional system-installed methodologies are effective at actually “reaching-into” the occupied environment would be a major accomplishment for all building air cleaning systems, therefore something different than what we are now doing may warrant consideration

Easily understood is a simple concept that if the pollutants in the space are removed, they are no longer a concern to its inhabitants. Comprehending this, along with all the dynamics discussed above is key in helping us to properly design buildings that can better contribute to the well-being and productivity of occupants breathing the indoor air.

Needlepoint Bipolar Ionization (NPBI) is a patented air cleaning technology that can be mounted in the HVAC system yet works on the contaminants and pollutants in the space, where we are being told the issues of concern originate and may remain. While not a filter itself, NPBI can supplement traditional ventilation and filtration by influencing the removal of small airborne particulate (viruses, pathogens, and other contaminants) from the environment based on the principle of electrostatic attraction and agglomeration. Ions, like those already abundant in cleaner outdoor air, are generated from within the HVAC system so that when released and distributed throughout the building can mix with room air and attach (electrostatically) to airborne particles. As these charged particles are increasingly attracted and joined to one another, their size and weight is increased to the point where they (now being larger) can be more easily influenced by HVAC system air movement. Particles may now be effectively removed from the space and exhausted, filtered, or treated. Air filters become more effective at removing these larger particles from the air, while any other internally mounted HVAC system air purification device (including filters) can encounter the pollutants they have been tasked with cleaning, those which before may have remained in the space untouched.

Applied upstream of wet cooling coils, NPBI can help eliminate issues with biofilm and microbial growth (mold) in HVAC systems which in the past could be transferred through HVAC ductwork and into the occupied space, becoming another issue of concern

Recent air ionization testing and analysis by the Built Environment Research Group, Department of Civil, Architectural, and Environmental Engineering at the Illinois Institute of Technology has presented some compelling results. The Clean Air Delivery Rate (CADR) of a tested air cleaner was improved by 44% for 0.9-1.0 µm size particles (smoke), 19% for 0.5-3.0 µm size particles (dust), and 53% for 5.0 to 10.0 µm size particled (pollen). Based on these results, scientists estimated that between 20-50% of the measured CADR during normal operation may be attributable to the ionization process. With the basic understanding that everything in the air we breathe is a particle, and that their removal is fundamental in improving IAQ, this important research provides additional insight into how the air may be more effectively cleaned.


Ventilation and filtration are two key components in creating truly productive environments for individuals occupying buildings of all types. The more efficient each is the better the results will be, individually or in combination. The field of indoor air quality is ripe for advancements that can make improved indoor air quality more effective and affordable. Add to this an assurance that the HVAC system is being properly serviced and maintained over its operational lifetime and you will have taken major steps toward making sure we are truly cleaning the air we breathe.

David Schurk DES., CEM. LEED-AP., CDSM., CWEP., SFP., CIAQM., HCCC., serves as Director of Healthcare and Applied Engineering Markets for Global Plasma Solutions, headquartered in Charlotte NC (USA). David is a Licensed Designer of Engineering Systems with over 38-years of experience in the design and analysis of heating, ventilating, and air-conditioning systems for a variety of market sectors, with a special focus on hospital and healthcare environmental control and indoor air quality. He is also an ASHRAE Distinguished Lecturer.

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