TAB Journal Fall 2020 - 14

Dealing with the Impact of COVID-19
on Current HVAC Systems and Equipment
Lawrence S. Poos, PE, TBE
Test and Balance Corporation


As we collect and assess empirical data
on the impact of the COVID-19 pandemic
on our everyday lives here in the United
States, all of our resources are focused on
how we might minimize - and possibly
prevent - the considerable damage caused
by COVID-19 or another super-contagious
virus in the future. There are no easily
identifiable catch-all solutions. However, if
we approach this task from a preventative,
proactive vantage point, separately deal
with each mechanism of virus spread and
how to combat them, we stand a far better
chance of containing the spread of the
virus and limiting the collateral damage it
can cause.
Some of the facts gleaned from watching
the White House's daily briefings during
the first two months of the COVID-19
pandemic in the U.S. are that crucial
to slowing the forward progress of any
pandemic is identifying and understanding
how the virus spreads. Per information
shared by the Coronavirus Task Force, the
primary assumptions given concerning
the spread of the virus are that the main
transmission routes are:
1.	Water vapor droplets from sneezing,
coughing or talking individuals infected
with the virus.
2.	Touching individuals infected with the
3.	Touching surfaces carrying the infection
such as clothes, utensils, furniture, etc.,
and then touching one's face.
The following information was published
by the Centers for Disease Control and
Prevention concerning the spread of


*	 The virus is thought to spread mainly
from person-to-person.
*	 Between people who are in close contact
with one another (within about 6 ft.).
*	 Through respiratory droplets produced
when an infected person coughs,
sneezes, or talks.
*	 These droplets can land in the mouths
or noses of people who are nearby or
possibly be inhaled.
*	 COVID-19 may be spread by people
who are not showing symptoms.


It could be concluded from the above
discussion that the heating ventilation
& air conditioning (HVAC) systems in
commercial buildings for employment,
socializing, and even in individual
homes and residences, could be possible
pandemic transmission routes and promote
the ongoing spread of the virus. This is
somewhat intuitive because it is generally
understood that airborne respiratory
droplets from virus-infected individuals
can be carried by a facility's HVAC/air
handling system. Such conclusions have
been reached by reputable organizations
like the National Institutes of Health,
which recently stated: " Scientists found
that Severe Acute Respiratory Syndrome
Coronavirus 2 was detectable in aerosols
for up to three hours. "
Other research and studies, undertaken in
the U.S. and abroad, have concluded that
aerosol transmission of a virus is possible
since a virus can remain active in
aerosols for several hours. If the airborne
virus happens to be present in a location
that has poor, or minimal ventilation,

then secondary infections from the virus
are certainly possible.
In addition, there have been reports and
recommendations that return air (i.e. air
recirculated by a facility's HVAC system)
should not be utilized in any building's
mechanical ventilation system, that virus
particles present in an HVAC system's
return air ducts can re-enter and be
re-introduced into the building's supply
air distribution system, and that all return
air and/or recirculation air dampers
should therefore be manually closed at
the central HVAC equipment so that
this equipment operates on 100 percent
outdoor air (OA).
While utilizing increased amounts of OA
does help dilute the concentration of any
airborne contaminants, increasing the
percentage of OA can also result in major
HVAC system problems if the HVAC
equipment is not designed to handle the
increased percentage of OA. It is critical,
then, that building/facility owners and
individuals in the HVAC industry must
apply common sense, logic and reasoning
to some of the recommendations to

TAB Journal Fall 2020


TAB Journal Fall 2020

Table of Contents for the Digital Edition of TAB Journal Fall 2020

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