ASHRAE Journal - July 2021 - 23

COLUMN IEQ APPLICATIONS
infl uence on contaminant removal effectiveness than air
changes.7
Air distribution is also included in the ASHRAE
Epidemic Task Force's Core Recommendations, which
state that, " [w]here directional airfl ow is not specifi -
cally required, or recommended as the result of a risk
assessment, promote mixing of space air without causing
strong air currents that increase direct transmission
from person-to-person. " 8
An effective method of limiting occupants' exposure
to contaminants is source capture. Designers apply
this principle when using kitchen hoods, as described
in ASHRAE Standard 154-2016.9 Other common
applications of source capture include manufacturing
tool exhaust systems, decontamination and sterilization
areas and benchtop snorkels in science and
research laboratories. The American Conference of
Governmental Industrial Hygienists publishes a design
manual10 covering many topics related to source capture
systems.
Source capture works best when there is a known and
stationary, or at the very least limited in motion, source
of contaminants, and effective velocities can be achieved
to capture the contaminants. In cases where the contaminants
are widespread or would only be considered
nuisances outside of the space in which they are generated,
containment may be an effective strategy. Two
examples of containment devices include air curtains
and fume hoods. Both devices maintain velocity at a
boundary to inhibit the passage of contaminants.
An alternative to maintaining velocity is to maintain
pressure between spaces, because a fi xed pressure
difference induces air movement in a prescribed
direction to either exclude or contain contaminants.
ASHRAE/ASHE Standard 170-2021 includes exclusionary
pressure relationships, such as the +0.01 in. w.g. (2.5 Pa)
pressure requirement for protective environment
rooms and operating rooms and containment pressure
relationships, as with the -0.01 in. w.g. (-2.5 Pa) pressure
requirements for AII rooms.7ASHRAE Standard
62.1-2019 includes exclusionary pressure relationships
with its positive pressure requirements for occupied
spaces relative to environmental tobacco smoke areas,
attached parking garages and the outdoors, and includes
containment pressure relationships with requirements
for negative pressure of Class 4 exhaust air ducts and all
spaces requiring exhaust air.11
The broad inclusion of containment and source control
requirements within ASHRAE standards is not new
and should not be surprising, but it is not as frequently
discussed as other requirements of the standards that
relate directly to the well-mixed assumption. The wellmixed
model as applied to ventilation leads to the conclusion
that the solution to pollution is dilution. This is
only logical since in an ideally mixed environment the
only way to remove a contaminant is to dilute it. This
way of thinking leads to an emphasis on increasing air
change rates, removing contaminants from the supply
airstream with fi lters or air cleaners or removing
contaminants directly from the space. This emphasis
has been refl ected in government guidance12 and
the media13 on strategies to deal with the COVID-19
pandemic.
Although dilution and fi ltration can often be effective
in improving indoor air quality, they do not refl ect
the entirety of the recommendations of ASHRAE. It is
incumbent upon our community to not only be knowledgeable
of, but conversant in, all the design strategies
for a built environment that is other than ideal.
References
1. 2019 ASHRAE Handbook-HVAC Applications.
2. Straub, H.E., S.F. Gilman, S. Konzo. 1956. " Distribution of Air
Within a Room for Year-Round Air Conditioning-Part I. " University
of Illinois Engineering Experiment Station, Bulletin No. 435.
3. Straub, H.E. M.M. Chen. 1957. " Distribution of Air Within
a Room for Year-Round Air Conditioning-Part II. " University of
Illinois Engineering Experiment Station, Bulletin No. 442.
4. Burkett, J. 2021. " Virus transmission modes and mitigation
strategies, part 2: Airborne transmission and distribution. " ASHRAE
Journal 63(4):10 - 16.
5. ANSI/ASHRAE Standard 55-2020, Thermal Environmental
Conditions for Human Occupancy.
6. ANSI/ASHRAE/ASHE Standard 170-2021, Ventilation of Health
Care Facilities.
7. Memarzadeh, F., W. Xu. 2012. " Role of air changes per hour
(ACH) in possible transmission of airborne infections. " Build Simul
5(1):15 - 28. https://doi.org/10.1007/s12273-011-0053-4
8. ASHRAE Epidemic Task Force. 2021. " Core Recommendations
for Reducing Airborne Infectious Aerosol Exposure. " ASHRAE.
https://tinyurl.com/2m9bmtd7
9. ANSI/ASHRAE Standard 154-2016, Ventilation for Commercial
Cooking Operations.
10. ACGIH. 2019. Industrial Ventilation: A Manual of Recommended
Practice for Design, 30th Edition. Cincinnati: ACGIH.
11. ANSI/ASHRAE Standard 62.1-2019, Ventilation for Acceptable
Indoor Air Quality.
12. CDC. 2021. " Ventilation in Buildings. " Centers for Disease
Control and Prevention. https://tinyurl.com/j3fpertv
13. Mandivilli, A. 2020. " How to Keep the Coronavirus at Bay
Indoors. " NYTimes.com. https://tinyurl.com/57y3yjvv
J U LY 2 0 2 1 ashrae.org ASHRAE JOURNAL
23
https://www.doi.org/10.1007/s12273-011-0053-4 https://www.tinyurl.com/2m9bmtd7 https://www.tinyurl.com/j3fpertv http://www.NYTimes.com https://www.tinyurl.com/57y3yjvv http://www.ashrae.org

ASHRAE Journal - July 2021

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

Contents
ASHRAE Journal - July 2021 - Intro
ASHRAE Journal - July 2021 - Cover1
ASHRAE Journal - July 2021 - Cover2
ASHRAE Journal - July 2021 - 1
ASHRAE Journal - July 2021 - Contents
ASHRAE Journal - July 2021 - 3
ASHRAE Journal - July 2021 - 4
ASHRAE Journal - July 2021 - 5
ASHRAE Journal - July 2021 - 6
ASHRAE Journal - July 2021 - 7
ASHRAE Journal - July 2021 - 8
ASHRAE Journal - July 2021 - 9
ASHRAE Journal - July 2021 - 10
ASHRAE Journal - July 2021 - 11
ASHRAE Journal - July 2021 - 12
ASHRAE Journal - July 2021 - 13
ASHRAE Journal - July 2021 - 14
ASHRAE Journal - July 2021 - 15
ASHRAE Journal - July 2021 - 16
ASHRAE Journal - July 2021 - 17
ASHRAE Journal - July 2021 - 18
ASHRAE Journal - July 2021 - 19
ASHRAE Journal - July 2021 - 20
ASHRAE Journal - July 2021 - 21
ASHRAE Journal - July 2021 - 22
ASHRAE Journal - July 2021 - 23
ASHRAE Journal - July 2021 - 24
ASHRAE Journal - July 2021 - 25
ASHRAE Journal - July 2021 - 26
ASHRAE Journal - July 2021 - 27
ASHRAE Journal - July 2021 - 28
ASHRAE Journal - July 2021 - 29
ASHRAE Journal - July 2021 - 30
ASHRAE Journal - July 2021 - 31
ASHRAE Journal - July 2021 - 32
ASHRAE Journal - July 2021 - 33
ASHRAE Journal - July 2021 - 34
ASHRAE Journal - July 2021 - 35
ASHRAE Journal - July 2021 - 36
ASHRAE Journal - July 2021 - 37
ASHRAE Journal - July 2021 - 38
ASHRAE Journal - July 2021 - 39
ASHRAE Journal - July 2021 - 40
ASHRAE Journal - July 2021 - 41
ASHRAE Journal - July 2021 - 42
ASHRAE Journal - July 2021 - 43
ASHRAE Journal - July 2021 - 44
ASHRAE Journal - July 2021 - 45
ASHRAE Journal - July 2021 - 46
ASHRAE Journal - July 2021 - 47
ASHRAE Journal - July 2021 - 48
ASHRAE Journal - July 2021 - 49
ASHRAE Journal - July 2021 - 50
ASHRAE Journal - July 2021 - 51
ASHRAE Journal - July 2021 - 52
ASHRAE Journal - July 2021 - 53
ASHRAE Journal - July 2021 - 54
ASHRAE Journal - July 2021 - 55
ASHRAE Journal - July 2021 - 56
ASHRAE Journal - July 2021 - 57
ASHRAE Journal - July 2021 - 58
ASHRAE Journal - July 2021 - 59
ASHRAE Journal - July 2021 - 60
ASHRAE Journal - July 2021 - 61
ASHRAE Journal - July 2021 - 62
ASHRAE Journal - July 2021 - 63
ASHRAE Journal - July 2021 - 64
ASHRAE Journal - July 2021 - 65
ASHRAE Journal - July 2021 - 66
ASHRAE Journal - July 2021 - 67
ASHRAE Journal - July 2021 - 68
ASHRAE Journal - July 2021 - 69
ASHRAE Journal - July 2021 - 70
ASHRAE Journal - July 2021 - 71
ASHRAE Journal - July 2021 - 72
ASHRAE Journal - July 2021 - 73
ASHRAE Journal - July 2021 - 74
ASHRAE Journal - July 2021 - 75
ASHRAE Journal - July 2021 - 76
ASHRAE Journal - July 2021 - 77
ASHRAE Journal - July 2021 - 78
ASHRAE Journal - July 2021 - 79
ASHRAE Journal - July 2021 - 80
ASHRAE Journal - July 2021 - 81
ASHRAE Journal - July 2021 - 82
ASHRAE Journal - July 2021 - 83
ASHRAE Journal - July 2021 - 84
ASHRAE Journal - July 2021 - 85
ASHRAE Journal - July 2021 - 86
ASHRAE Journal - July 2021 - 87
ASHRAE Journal - July 2021 - 88
ASHRAE Journal - July 2021 - 89
ASHRAE Journal - July 2021 - 90
ASHRAE Journal - July 2021 - 91
ASHRAE Journal - July 2021 - 92
ASHRAE Journal - July 2021 - 93
ASHRAE Journal - July 2021 - 94
ASHRAE Journal - July 2021 - 95
ASHRAE Journal - July 2021 - 96
ASHRAE Journal - July 2021 - 97
ASHRAE Journal - July 2021 - 98
ASHRAE Journal - July 2021 - 99
ASHRAE Journal - July 2021 - 100
ASHRAE Journal - July 2021 - 101
ASHRAE Journal - July 2021 - 102
ASHRAE Journal - July 2021 - 103
ASHRAE Journal - July 2021 - 104
ASHRAE Journal - July 2021 - 105
ASHRAE Journal - July 2021 - 106
ASHRAE Journal - July 2021 - 107
ASHRAE Journal - July 2021 - 108
ASHRAE Journal - July 2021 - 109
ASHRAE Journal - July 2021 - 110
ASHRAE Journal - July 2021 - 111
ASHRAE Journal - July 2021 - 112
ASHRAE Journal - July 2021 - Cover3
ASHRAE Journal - July 2021 - Cover4
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2021november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2021november_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_XCODFR
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QSLFGO
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ILKVNM
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2021
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OPDJKD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_VJKSRY
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SDHUTC
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JPPKRR
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SDLTTH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_CKLLES
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_SLDOX
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_HJETUK
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_OLUHGE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2020october
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2020october_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ZERDGH
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_QVMNEO
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_RTPOKE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_BBATRE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_STUBMW
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TPEMPE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_JNMKDS
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_FBTTPA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_WQMMNE
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_TVBRYN
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_showguide2020
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_KTUZMA
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_ABEDGD
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201910
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201909
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2019septmeber_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2019september
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201908
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201907
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201906
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201905
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201904
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2019april
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201903
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2019march
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201902
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201901
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_showguide2019
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018december
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018november
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2018fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2018fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_2018october
https://www.nxtbook.com/nxtbooks/ashrae/ashraemexico_2018
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201810
https://www.nxtbook.com/nxtbooks/ashrae/ashraeinsights_201806
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201805
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201804
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201803
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201712
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201711
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201710
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2017fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2017fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201709
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201705
https://www.nxtbook.com/nxtbooks/ashrae/ashrae_meetinginsert_201610
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2016fall_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2016fall
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acrexindia
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2015summer_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_amca_2015summer
https://www.nxtbook.com/nxtbooks/amca/2014summer2
https://www.nxtbook.com/nxtbooks/amca/2014summer
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acma_2014summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201311
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201309
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_acmasupp_2013fall
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201305
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201303
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2013winter
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201211
https://www.nxtbook.com/nxtbooks/ashrae/achr_expo_mexico2012
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201209
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201208_v3
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201208_v2
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2012summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201205
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201203
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2012winter
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201111_v2
https://www.nxtbook.com/nxtbooks/ashrae/ashraejournal_201109_v2
https://www.nxtbook.com/nxtbooks/ashrae/pubcatalog_2011summer
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201105
https://www.nxtbook.com/nxtbooks/ashrae/meetingplanner_201103
https://www.nxtbookmedia.com