The most recent information released by the Centers for Disease Control (CDC) indicates that COVID-19 spreads via:
- Person-to-person by direct contact
- Person-to-person through airborne respiratory droplets if the infected person should sneeze or cough
- Surface-to-person if the person touches a surface or object where the virus currently “lives” and then touches their own eyes, nose, or mouth
Most doctors and researchers believe that people are at their most contagious — and most likely to infect someone else — when they show symptoms; however, it’s also possible to spread the virus even if someone is asymptomatic.
Preventative steps to reduce transmission
The continued, virulent spread of COVID-19 shows a definite connection between our health and the environment. Super-spreader events have taken place in over 28 countries including the United States: at a choir rehearsal in Washington state, a Chicago funeral, a birthday party, and more. In fact, some scientists think super-spreader events may be responsible for up to 80% of coronavirus infections.
Studies have determined that the highly contagious coronavirus can be transmitted by air and that the tiny virus particles — about 0.1 microns — can remain active up to three hours after release. Therefore, building managers, operations managers, and other safety experts should take steps to optimize outside air ventilation and take steps in airflow disinfection to limit any viral spread.
Update heating, ventilation, and air conditioning (HVAC) systems
Mechanical engineer and licensed Professional Engineer Edward Alonso, a CREA United member, says that while it’s possible to update HVAC systems to help reduce the airborne spread of COVID-19, many of the solutions can generate significant costs. “There are different options available to update HVAC systems to improve their ability to stop the virus. However,” he cautions, “you’ll likely spend a lot of money in those modifications — and unless your system’s returns are lower to the floor, they most likely won’t catch all of the virus particles.”
Buildings with older or less flexible systems might require an upgrade of HVAC hardware such as:
- Using variable-speed fan motors to replace fixed-speed fan motors, which will increase airflow control
- Upgrading to more sophisticated, pressure sensitive airflow control systems that facilitate a smoother airflow adjustment
- Installing high performance air purification systems
With their potential to spread a virus across rooms, making control-setting changes and upgrades may mitigate the spread. Reduce recirculation by reconfiguring ducted HVAC systems to increase rate of exchange with fresh outside air. Run HVAC systems throughout the weekend to continue air replacement and maximize dilution ventilation.
Investigate technologies for better air purification
The most common, effective method for air purification includes filtration; however, irradiation and thermal sterilization also work. HVAC systems can also use ionic purifiers and ozone generators to render coronavirus inactive via a sterilization process. ASHRAE has released a variety of resources to guide operators on optimal HVAC system use.
Commercial or residential HVAC systems could have filters installed at the air inlet, outlet, or within the central air handling unit. Where possible, consider installing a pre-filter for incoming air, too. Air filters receive their ratings based on how efficiently they filter certain particle sizes. A MERV 16 filter is equivalent to an N-95 respirator and can stop 95% of particles that are between 0.3 and 1.0 microns (like smoke and exhaled droplets) and requires moderate to heavy air pressure.
A HEPA filter, the P-100 respirator equivalent, captures over 99% of particles — like bacteria and viruses — that are 0.3 microns small. However, modifying existing HVAC systems with HEPA filters can cost between thousands and millions of dollars (depending on the current system). HEPA filters are more restrictive and require more fan power, additional ductwork, and more energy to support. A typical retail, school, or commercial building system isn’t able to manage the requirements of a HEPA filter.
Needlepoint Bipolar Ionization
Alonso recommends a more cost-effective solution: installing a needlepoint bipolar ionization system. This system can be inserted into an existing HVAC system — in most cases by attaching it to the entering side of a cooling coil or. Main supply duct— to magnetize particles traveling iinto the occupied space. The particles stick together and, as the groups of particles grow larger, drop out of the airstream and onto the floor where regular cleaning sweeps them up.
A recent study conducted by Innovative Bioanalysis labs indicated that needlepoint bipolar ionization inactivates:
- 84.2% of the virus in 10 minutes
- 92.6% of the virus in 15 minutes
- 99.4% of the virus in 30 minutes
While not currently recognized by AHSRAE, this specific type of bipolar ionization does not create harmful levels of ozone. It has been tested in accordance with UL 2998 which limits ozone to 0.005 parts per million by volume. It’s installable in existing or new HVAC equipment and does not require increasing system pressure, adding fans, upsizing filters, or significantly changing air handlers or duct work.
Airflow management
Studies indicate that changing indoor airflow patterns may help reduce transmission, especially when the following principles are applied:
- Ensuring a steady, slow air speed
- Encouraging a vertical laminar airflow in lieu of a turbulent airflow
- Directing potentially contaminated air away from people and out of the rooms
Managing inter room airflow
It’s possible to take steps that prevent contamination between rooms, which is a possibility since coronavirus can spread via airborne transmission. In addition to installing or upgrading HVAC systems (which can run into substantial costs), building managers can also:
- Install air curtains at doorways
- Install gates at doors
- Add overpressure above suspended ceilings to prevent air from flowing through suspended ceilings from one room to another
- Upgrade suspended ceilings, perhaps retrofitting with gasketing in areas that need a negative-pressure environment which will trap and prevent airborne contaminants from escaping the negative-pressure space
Engineering Controls
Some of the recommended steps require a significant investment of time and capital. Immediate steps that building managers can take include:
- Increasing ventilation by bringing in more outdoor air through HVAC systems or even opening windows, where possible
- Strengthening cleaning protocols by increasing cleaning frequency, replenishing cleaning supplies regularly, keeping restrooms stocked with paper towels, soap, and hand sanitizer, and disabling automatic hand dryers
- Maintaining humidity levels between 40 to 60% via HVAC systems or by installing portable humidifiers throughout the building
- Ensuring full function of exhaust fans in restrooms
- Considering the use of ultraviolet germicidal irradiation (UVGI) as an additional method for inactivating the virus; however, UV light (which UVGI uses) requires line of sight to work most effectively. When it’s used to target filters within the HVAC system, it’s most effective — but only if the filters have also caught and trapped the virus
- Modifying demand-control ventilation controls that reduce air supply based on occupancy levels or temperature; make sure that any changes still maintain building code ventilation requirements
A caveat to some of these approaches: Most HVAC systems bring in 18% to 20% outside air. The mid-Atlantic states have a limited time to take advantage of “free cooling” days: days when the HVAC system detects an ideal outside air temperature and humidity conditions that require minimal — if any — heat and cooling. Most existing HVAC systems aren’t equipped to handle a significant increase in the intake of fresh outside air. Without the capacity to warm or cool air efficiently and effectively, inside spaces become very uncomfortable. To accommodate this approach can require a large amount of capital to make the necessary modifications.
The CDC has also published a COVID-19 workplace health and safety plan development guide. It offers a checklist of steps to take before resuming business operations — and recommends policies, procedures, and other steps to mitigate the exposure of people to COVID-19 once they’ve returned to work.
As the world continues to navigate through these uncharted times, the members of CREA United are here to help. From building retrofits to design upgrades and legal services to commercial real estate guidance, our members are ready to provide collaborative expert advice in a wide range of areas, including those services you may need to ensure the safety your tenants.
