ASHRAE Journal - September 2021 - 8

LETTERS
Return
Ductwork
Requirement
For Airborne
Pathogens
I disagree with the conclusion
of June's ASHRAE Journal column,
" ASHRAE TC 5.2 White Paper:
Return Ductwork Requirement for
Airborne Pathogens Through the
Airstream, " by John Constantinide,
P.E., Member ASHRAE, and
Christopher Ruch, Member
ASHRAE.
I do not believe a ducted return
system will in general benefit occupants.
Non-ducted return systems
have great advantage over ducted
return systems in terms of cost,
simplicity and energy efficiency.
Ducted return systems should
only be used in hospitals and labs
where room pressure control and
return air static pressure control are
important. Maintenance workers
can wear respirators if they believe
they are in danger entering a return
air plenum.
Robin J. Rader, P.E., Member ASHRAE, Fairbanks, Alaska
The Author Responds
Thank you for your response. The
column was an introduction to the
associated white paper with the
same title available on the ASHRAE
Technical Committee 5.2 website
(https://tinyurl.com/cmhwksh3).
The benefits of open ceiling plenum
return systems are presented
in the white paper. They are compared
to multiple energy and health
concerns with open ceiling plenum
returns and the benefits of ducted
8
ASHRAE JOURNAL ashrae.o rg
return systems. Concerns include
reduced exposure control, infiltration,
reduced source control and
cleaning and disinfecting.
The pandemic shined a light on
the importance of all design considerations.
Health and safety benefits
along with energy concerns should
be considered for every project.
After an evaluation of concerns and
benefits, the Technical Committee
recommends ducted return systems
in all buildings as prioritized by
occupancy classification and use.
Priority 1: Medical Facilities-
Institutional (Group I), Medical
Office Buildings, buildings used for
medical purposes, or any building
that has high chance to be commandeered
during a pandemic to act as
a medical facility.
Priority 2: Educational Facilities
(Group E).
Priority 3: Assembly Areas (Group
A), Business (Group B), Factory
(Group F), Mercantile (Group M),
Residential (Group R).
This recommendation would
include new construction and shell
and core renovations and additions.
Return duct retrofits should be considered
for Priority 1 buildings.
Regarding hazard to maintenance
workers in air plenums, the use
of respirators does limit airborne
particulates and contaminants from
being directly breathed in by maintenance
workers. As noted in the
white paper, maintenance activities
can agitate particles and fungal
spores. Along with potential introduction
to the airstream, this agitation
can contaminate maintenance
workers' clothing and equipment,
causing potential contaminant
exposure to workers once respirators
are removed, and occupants
S E PTEM B E R 2021
outside of the plenum area. Ducted
returns would reduce the presence
of these particulates.
Thank you for the opportunity
to share our thoughts on this
recommendation.
John Constantinide, P.E., Member ASHRAE,
Merritt Island, Fla.; Christopher Ruch, Member ASHRAE,
Falls Church, Va.
School Pushes
IAQ, Efficiency
Boundaries
In the the fine article " School
Pushes IAQ, Energy-Efficiency
Boundaries " by Lee Harrelson, P.E.,
Associate Member ASHRAE; Ray
Beaufait, Member ASHRAE; Brice
Watson, P.E., Associate Member
ASHRAE; Brian Turner, P.E.,
Member ASHRAE in May's ASHRAE
Journal, the use of CO2 scrubbers
seems to be particularly helpful for
improving the IAQ in schools.
The authors also mention that
the innovative CO2 scrubbers in
the ventilation system reduce the
outdoor air supply to reach ASHRAE
Standard 62.1-2010 by reducing the
ambient VOC elements and CO2.
This method reduces energy consumption.
However, harmful compounds
and CO2 are flushed back to
the ambient air when the scrubber
elements reach their maximum
capacity. Therefore, the environmental
footprint of the building is
not reduced, and this flush-back
method does not contribute to the
global warming issue, while the
same amount of CO2 and VOC elements
are still kept in the ambient
air.
It would be much better to use
CCS methods (carbon capture and
https://www.tinyurl.com/cmhwksh3 http://www.ashrae.org/

ASHRAE Journal - September 2021

Table of Contents for the Digital Edition of ASHRAE Journal - September 2021

Contents
ASHRAE Journal - September 2021 - Intro
ASHRAE Journal - September 2021 - Cover1
ASHRAE Journal - September 2021 - Cover2
ASHRAE Journal - September 2021 - 1
ASHRAE Journal - September 2021 - Contents
ASHRAE Journal - September 2021 - 3
ASHRAE Journal - September 2021 - 4
ASHRAE Journal - September 2021 - 5
ASHRAE Journal - September 2021 - 6
ASHRAE Journal - September 2021 - 7
ASHRAE Journal - September 2021 - 8
ASHRAE Journal - September 2021 - 9
ASHRAE Journal - September 2021 - 10
ASHRAE Journal - September 2021 - 11
ASHRAE Journal - September 2021 - 12
ASHRAE Journal - September 2021 - 13
ASHRAE Journal - September 2021 - 14
ASHRAE Journal - September 2021 - 15
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ASHRAE Journal - September 2021 - 18
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ASHRAE Journal - September 2021 - 20
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ASHRAE Journal - September 2021 - Cover3
ASHRAE Journal - September 2021 - Cover4
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