By following these ASHRAE approaches for HVAC systems, facilities can best fight the continuing pandemic.
To minimize the spread of the COVID-19 virus and its variants, building owners and facility managers are turning to trusted sources for advice on protocols and ways to improve the operation and efficacy of their heating, ventilation, and air-conditioning (HVAC) systems.
The virus may live in the ambient air, suspended in aerosols inhaled by infected persons, as we learned collectively during the pandemic. Understanding this mode of transmission has influenced suggestions made to building operators by informed entities.
The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), the world’s premier technical society for HVAC concerns, has provided thorough recommendations to help detect and manage any difficulties with HVAC systems connected to a viral transmission. For all major building types, ASHRAE developed recommendations that provide concrete guidance and direction for managing air quality and improving ventilation in offices, schools, places of worship or assembly, and other venues where large numbers may gather. Other significant organizations that impact the built environment, such as the Centers for Disease Control and Prevention, the United States Green Building Council, and the United States Environmental Protection Agency, have accepted these suggestions.
COVID changes
Things have altered for those who have not been physically present at work since the outbreak began. Before entering the facility, individuals may be required to complete a self-assessment by filling out a form or submitting their status via a smartphone app.
Occupants may be required to pass through a checkpoint where their temperature is measured, and their contact information is obtained in the event of unintentional virus exposure. People may notice hand sanitizing stations throughout the workplace, as well as possible floor marks, to maintain social separation. Transparent barriers can be used to conceal reception desks, coffee stations, photocopying facilities, and even workstations. Cleaning crews may go over premises daily to ensure that surfaces are sanitized. The building operators can address the risk of COVID-19 infection with the occupants by making certain physical adjustments to the workplace.
But what about the additional health measures that are being taken? Building HVAC systems work behind the scenes to purify the air we breathe every day.
Ensuring cleaner air
Large electric fan machines called air handlers are commonly used in buildings to distribute air through the spaces. Depending on the location and time of year, air handlers in most buildings pull a percentage of fresh air from the outside, mix it with ambient air from within the building, and then heat or cool it, as well as dehumidify or add humidity.
Passing the air through filters, which remove dust, soot, and other airborne contaminants is a part of the air handling process. After that, the treated air is transferred to the occupied areas where we work. The related air distribution infrastructure (ductwork) and air handling equipment are both expensive and somewhat fixed. In most buildings, they are difficult to change. This complicates our efforts to improve the air quality in a building to reduce the risk of COVID-19 transmission.
Air handlers are efficient at moving air throughout a facility, including virus-containing airborne particles. As a result, the focus is on how to adapt or operate this equipment in such a way that transmission is minimized. The American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) proposes four approaches:
- Dilution. Diluting the air is one approach to reduce the amount of COVID aerosols in a space. A “cloud” of COVID-19 aerosols can be thinned out in the same way that a smoke-filled room can be thinned out by bringing fresh air into the room. As a result, building operators are being directed to maximize the amount of fresh air brought into their structures. This method is not without its drawbacks. In areas where summers are hot and humid, or winters are frigid and dry, HVAC equipment may not have the heating or cooling capacity to handle these higher volumes of untreated air. As a result, we must consider additional approaches for improving air quality.
- Filtration. The filtration in air handlers should also be checked, according to facility managers. Typical filtration is ineffective and designed to reduce the spread of relatively big pollutants such as dust or dander. COVID-19 virus aerosols are so tiny that they will pass through most building air filters. Filter types designed to collect extremely small particles are recommended by ASHRAE. COVID-19 presents a unique filtration issue because there are few efficient choices for protecting against the virus’s size and the aerosols it travels in. This means that the recommended filtration is both expensive and scarce. Furthermore, these filters make air handlers work harder, which may interfere with optimum air circulation within the facility.
- Occupant-based solutions. Because HVAC systems have such tight constraints, operators are seeking ways to change people’s behavior in the workplace. Rather than increasing the amount of fresh air brought into the building, they ask that people utilize a given room for a maximum amount of time and then take breaks between uses to allow the HVAC systems to purge and clean the space for the next gathering. While this limits the amount of time a room can be used during the day, it provides a cost-effective alternative to dilution.
- Portable filtration units. The use of portable filtration systems in occupied spaces is another useful alternative. These devices cleanse the air of any contaminants in high volume, far more than air handlers are capable of processing, by rapidly passing ambient air through hospital-grade air filters known as HEPA filters. They can be compact, relatively inexpensive, mobile, and adaptable to most office designs because they merely filter and do not treat the air. These machines continually flow air through filters, scrubbing out anything undesirable in the air within a given room, and can even be positioned at a workplace to provide individualized protection. Some machines feature ultraviolet lamps or ionization units to give the air flowing through an extra anti-bacterial treatment.
Learn more about filtration/disinfection for Clean Air for your facility – ASHRAE
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