What is the impact of Coronavirus on the HVAC industry?

Introduction

This blog delves into the challenges this pandemic is levying on the HVAC industry now and in the future. Coronavirus (COVID-19) is believed to be transmitted through close person to person contact, as well as air particles created from a cough or sneeze. While washing your hands and actively sanitizing surfaces that encounter outside pathogens are the proper precautions to take, what about the safety measures for homes and buildings with an HVAC system distributing air? Just as an unsuspecting person could inhale such transmittable particles and become infected, HVAC systems return (inhale) air and distribute it throughout a building.

What options are available to possibly mitigate the spreading of coronavirus particles through HVAC systems?

  • Neutralization
  • Filtration
  • Dilution

Neutralization:

Testing is ongoing to find ways to neutralize the coronavirus within the body as well as the air. This involves the process of verifying ionizers that have a measurable kill rate for coronavirus (COVID-19). Ionizers, which create positive and negative particles that can be mixed into an air stream, are already proven to kill pathogens such as norovirus, tuberculosis, MRSA and others. The ions created put pathogens under oxidative stress that damage the pathogens’ components and ultimately lead to death.

Filtration:

Many individuals will have heard of HEPA filters, perhaps not what it stands for, (High-Efficiency Particulate Air), and consider these systems to be the cream of the crop. The standard for HEPA filters is for the removal of 99.97% of particles that are 0.3 micrometers in size. The capture efficiency actually increases with particles smaller or larger than 0.3 micrometers, making the filters able to catch viruses on the nanometer scale. However, not every HVAC system currently has or could handle the pressure drop from a HEPA filter, so steps to clump viruses and particles together (agglomeration) to a larger size is extremely beneficial. The ionizers that kill certain viruses/bacteria also promote agglomeration since positive and negative ions attract molecules, thus increasing the size of the particle which gives filters with less efficiency a way to capture “smaller” particles.

Dilution:

Dilution of the air by means of bringing in fresh outside air helps improve indoor air quality (IAQ). As the system runs and mixes returned air from the space with fresh air from outside the building, eventually the space will have completed an air change. The higher air changes an HVAC system can provide to the space means for less time that the recirculated, possibly infectious air has to pass through filters and be distributed back to the space.

Why the HVAC industry cares?

Not only do HVAC systems provide occupants with comfort from the hot summers and the chilling winters, but it handles a vital aspect of life for occupants, air, and what is in that air matters! Hospital HVAC systems, by code, are the best equipped at utilizing the above options to clean the air and thankfully so. However, residential and various other commercial HVAC systems are most likely unable to use any of these options, at least not to their full extent. Building codes have been slowly trending towards higher indoor air quality (IAQ) throughout the years with an uptick in ventilation rates (cfm/sf and cfm/person) along with new calculations methods for determining fresh outside air requirements. ASHRAE 170, Ventilation for Healthcare Facilities, lays out the guidelines for HVAC system design yet only requires systems in place for filtration and dilution. If not adopted into codes for residential and commercial buildings, surely there will be a growing push for capabilities of neutralizing harmful pathogens in our air for healthcare facilities. The aftereffects that arise from this pandemic will surely result in reconsiderations for what inhabits the air and different design choices we should take to offset its negative outcomes.

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