HVAC Methods to Gradual Coronavirus Unfold
Adequate ventilation and air filtration are crucial strategies in buildings to slow down COVID-19.
The main cause of the transmission of COVID-19 is direct exposure to airborne respiratory particles of the virus. The likelihood of contracting the virus in this way is greatly reduced if people follow social distancing guidelines and wear personal protective equipment (PPE) properly. However, if a facility has an inadequate ventilation system, the same air will continue to circulate and could potentially re-suspend COVID-19 particles.
Poorly recycled air allows virus particles to live longer on surfaces and get into the air if they are disturbed. To ensure that clean air is circulating in a facility, managers must ensure that technicians regularly monitor and update the HVAC system accordingly. The air filters commonly used in most facilities are typically of a Minimum Efficiency Rating (MERV). These filters are unable to capture smaller particles, including resuspended droplets of virus. HEPA filters can trap the smallest particles and are primarily used in healthcare facilities where the need for this level of filtration is greater.
Retrofitting an HVAC system to accommodate HEPA filters would be a large investment for non-healthcare facilities. Fortunately, managers have alternatives to maximize indoor air quality. The easiest way to increase ventilation is to open windows. However, this is not a viable option for certain facilities in areas with high levels of outdoor air pollution or in buildings with permanently sealed windows.
The ventilation rates improve when the demand-controlled ventilation is deactivated and when the minimum outside air dampers are fully open. As the ventilation of a facility increases, it is important to increase the airflow at the same time to ensure the constant reintroduction of clean air. Facilities that lack the equipment needed to improve airflow can install variable speed fans.
Managers in many facilities struggle with varying levels of occupancy as operations expand and contract due to local restrictions. As the occupancy of a building increases, so does the chance that COVID-19 particles will accumulate. The most effective strategy for preventing virus transmission is to limit the number of occupants. For buildings where the capacity of the occupants cannot be restricted, technicians can place portable air purifiers in the desired areas.
While managers planning upgrades of key areas of facilities must consider the expectations and needs of all parties including executives, inmates, and visitors, perhaps the most important goal of all is to ensure both public health and safety.
Scott Lance, LEED AP O + M, is a project engineer at Horizon Engineering Associates, who specialize in building commissioning and energy analysis.