ASHRAE Journal - June 2024 - 46

TECHNICAL FEATURE
CFD Analysis of DCV
For Laboratory Facilities
BY KISHOR KHANKARI, PH.D., FELLOW ASHRAE
The primary objective of laboratory ventilation systems is to provide a safe and
comfortable environment to personnel. Therefore, often a high air change rate per
hour (ach) of up to 12 for laboratory spaces and up to 20 for vivariums is specified
to meet these goals.1 However, demand-control ventilation (DCV) systems can help
reduce the high energy demands and operating costs of HVAC systems for laboratories
by selectively increasing the supply airflow rate only when required under critical
events such as an accidental spill or leakage of chemicals, rather than operating labs
constantly under high air change rates. This study, with the help of computational
fluid dynamics (CFD) simulations, evaluates the impact of DCV on the environmental
conditions in a laboratory under an accidental spill scenario.
Introduction
The high ach numbers specified in the literature
are mostly consensus based on simplistic approaches
involving idealistic conditions of perfect mixing of
contaminants with the supply air. However, such
instantaneously well-mixed conditions are rarely
achievable even with the most simple lab layouts.
To compensate for a variety of uncertainties, including
imperfect mixing, traditionally safety factors were used
in the specification of supply airflow rates, which often
resulted in specifying higher ach. Once facilities are
designed for high ach, they often continue to operate
under high ach, which incurs high energy consumption,
high carbon emissions and high operating costs.2
According to ANSI/ASSP Z9.5-2002, Laboratory
Kishor Khankari, Ph.D., is the president at AnSight LLC in Ann Arbor, Mich.
46
ASHRAE JOURNAL ashrae.org J U N E 2024
Ventilation, the minimum ventilation rate is
recommended to be based on the demand for
ventilation required to meet the needs of the occupants
and is determined through a hazard evaluation and risk
assessment. This standard further states that " both the
magnitude of the flow and the resulting airflow patterns
in the room shall be considered when evaluating the
effectiveness of dilution and contaminant removal. " 3
Although high supply airflow rates can reduce the
overall concentration of contaminants, it may not be
necessary to operate the labs under high ach all the
time. Studies of several labs showed that the number
of events for which the contaminant concentration
exceeded the minimum threshold values and required
more than the minimum dilution airflow was about 1%
to 2%.4 Under critical situations, such as in the case of
an accidental spill, it is important to control the spread

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ASHRAE Journal - June 2024

Table of Contents for the Digital Edition of ASHRAE Journal - June 2024

Contents
ASHRAE Journal - June 2024 - Intro
ASHRAE Journal - June 2024 - CT1
ASHRAE Journal - June 2024 - CT2
ASHRAE Journal - June 2024 - Cover1
ASHRAE Journal - June 2024 - Cover2
ASHRAE Journal - June 2024 - 1
ASHRAE Journal - June 2024 - Contents
ASHRAE Journal - June 2024 - 3
ASHRAE Journal - June 2024 - 4
ASHRAE Journal - June 2024 - 5
ASHRAE Journal - June 2024 - 6
ASHRAE Journal - June 2024 - 7
ASHRAE Journal - June 2024 - 8
ASHRAE Journal - June 2024 - 9
ASHRAE Journal - June 2024 - 10
ASHRAE Journal - June 2024 - 11
ASHRAE Journal - June 2024 - 12
ASHRAE Journal - June 2024 - 13
ASHRAE Journal - June 2024 - 14
ASHRAE Journal - June 2024 - 15
ASHRAE Journal - June 2024 - 16
ASHRAE Journal - June 2024 - 17
ASHRAE Journal - June 2024 - 18
ASHRAE Journal - June 2024 - 19
ASHRAE Journal - June 2024 - 20
ASHRAE Journal - June 2024 - 21
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ASHRAE Journal - June 2024 - 23
ASHRAE Journal - June 2024 - 24
ASHRAE Journal - June 2024 - 25
ASHRAE Journal - June 2024 - 26
ASHRAE Journal - June 2024 - 27
ASHRAE Journal - June 2024 - 28
ASHRAE Journal - June 2024 - 29
ASHRAE Journal - June 2024 - 30
ASHRAE Journal - June 2024 - 31
ASHRAE Journal - June 2024 - 32
ASHRAE Journal - June 2024 - 33
ASHRAE Journal - June 2024 - 34
ASHRAE Journal - June 2024 - 35
ASHRAE Journal - June 2024 - 36
ASHRAE Journal - June 2024 - 37
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ASHRAE Journal - June 2024 - 43
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ASHRAE Journal - June 2024 - 45
ASHRAE Journal - June 2024 - 46
ASHRAE Journal - June 2024 - 47
ASHRAE Journal - June 2024 - 48
ASHRAE Journal - June 2024 - 49
ASHRAE Journal - June 2024 - 50
ASHRAE Journal - June 2024 - 51
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ASHRAE Journal - June 2024 - 53
ASHRAE Journal - June 2024 - 54
ASHRAE Journal - June 2024 - 55
ASHRAE Journal - June 2024 - 56
ASHRAE Journal - June 2024 - 57
ASHRAE Journal - June 2024 - 58
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ASHRAE Journal - June 2024 - 60
ASHRAE Journal - June 2024 - 61
ASHRAE Journal - June 2024 - 62
ASHRAE Journal - June 2024 - 63
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ASHRAE Journal - June 2024 - 65
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ASHRAE Journal - June 2024 - 67
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ASHRAE Journal - June 2024 - 70
ASHRAE Journal - June 2024 - 71
ASHRAE Journal - June 2024 - 72
ASHRAE Journal - June 2024 - Cover3
ASHRAE Journal - June 2024 - Cover4
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