Post-Covid Systems Adapt to Maximize Air Quality


Advances and adaptations in mechanical systems that regulate air flow and quality continue to evolve since the outbreak of the coronavirus.

As professionals continue returning to the office – at least for some of their work week – those responsible for ensuring optimal air quality in these environments are increasingly choosing to upgrade their air filtration systems to trap as many troublesome particles as possible before they reach the workspace.

“At the start of the pandemic in Spring 2020, some cities and states such as New York (state) mandated the use of higher-grade air filters,” says Chris Currie, vice president at Charles E. Jarrell Contracting Company Inc. “New York’s governor required shopping malls to upgrade to MERV-13 (Minimum Efficiency Reporting Value) filters as a condition of reopening. As guidance rather than a mandate, the Centers for Disease Control and Prevention recommended that all businesses improve their central air filtration systems with MERV-13 filters.”

Over the past two years in particular, mechanical contractors nationwide have been busy engineering modifications to air handling systems that allow for a higher-rated MERV filter, according to Currie, although obtaining the necessary materials remains a challenge.

“The higher the MERV rating, the higher the pressure drop,” he says. “Fan motors must have enough surplus capacity to handle this pressure drop. Thus, we’re continuing to see clients updating their commercial HVAC (heating, ventilating and air conditioning) systems, but oversized systems, their parts and pieces are hard to come by.”

Bipolar ionization is another technology that aids building owners in maintaining healthy levels of air quality. Currie says the concept behind BPI involves introducing electrical probes into the supply and/or return airstream so that any microparticles floating past these charged electrodes will adopt the probe’s positive or negative charges. Then as the particles become charged, they stick to each other. The larger collective particle, comprised of individual particles that glom together, either drops out of the air or is filtered by a lower-grade MERV filter.

“Bipolar ionization has been around for 20 years,” he says, “but now it has broader application.”

Specialized Engineering Solutions Associate Principal Scott Winfrey says making sure a facility is designed with enough fan-handling units to support the usage of upgraded HEPA (high-efficiency particulate absorbing) filters is critical.

“Another option is to install HEPA racks that you do not intend to use in air handlers under normal operations, and only use the HEPA filters in a pandemic situation,” says Winfrey. “Consider engineering your air handling units to handle dual conditions for heating and cooling coils … minimum outside air intake for normal conditions, and 100 percent outside air for pandemic and emergency conditions.”

The use of high-intensity ultraviolet (UV) lights or other similar air treatment systems at the cooling coils, Winfrey adds, can help keep coils clean but are also effective in killing a high percentage of virus particles passing through the air handling unit.

“The pandemic has taught us the impact of HVAC systems in keeping occupants safe and designing flexibility into spaces,” he says.

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