ASHRAE Journal - May 2022 - 50

IEQ APPLICATIONS
Column
ASHRAE Position
Document on Indoor CO2
ANDREW PERSILY, PH.D., FELLOW/LIFE MEMBER ASHRAE; WILLIAM P. BAHNFLETH, PH.D., P.E., PRESIDENTIAL MEMBER/FELLOW ASHRAE; HOWARD KIPEN, M.D.; JOSEPHINE LAU, PH.D.,
MEMBER ASHRAE; CORINNE MANDIN, PH.D.; CHANDRA SEKHAR, PH.D, FELLOW ASHRAE; PAWEL WARGOCKI, PH.D., MEMBER ASHRAE; LAN CHI NGUYEN WEEKES, P.E., MEMBER ASHRAE
Indoor CO2 concentrations are often discussed in the context of ventilation and
indoor air quality (IAQ), including indoor CO2 as an IAQ metric, ventilation rate
estimation using CO2 as a tracer gas, control of outdoor air ventilation and impacts
of CO2 on building occupants. More recently CO2 has been discussed in the context
of airborne infectious disease transmission. However, many applications of indoor
CO2 do not reflect a sound technical understanding of the relationship between
indoor CO2 concentrations, ventilation and IAQ, and some applications have actually
been technically flawed. In response to these concerns, ASHRAE has recently issued
a Position Document (https://tinyurl.com/2p97a7zw) on the role of indoor CO2 in
the context of building ventilation and IAQ. This column presents the positions and
recommendations in the document, which also contains a thorough discussion of the
supporting background and extensive references for the interested reader.
The full ASHRAE Position Document on Indoor Carbon
Dioxide addresses the use of CO2 as a metric of IAQ
and ventilation, impacts of CO2 on building occupants,
indoor CO2 concentration measurement, use of CO2 to
control outdoor air intake rates, and the relationship of
indoor CO2 to airborne infectious disease transmission.
It also includes the motivations for developing the document
and contains a background section that discusses
the history of indoor CO2 concentrations in the context
of ventilation and IAQ, health and cognitive impacts of
exposure to CO2, existing standards and regulations for
indoor CO2 concentrations, CO2 as an indicator of IAQ
and ventilation, use of CO2 as a tracer gas for estimating
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ASHRAE JOURNAL ashrae.o rg M AY 2022
ventilation rates, increases in outdoor CO2 concentrations,
air cleaning directed at CO2 removal alone
and CO2 as an indicator of the risk of airborne disease
transmission.
Andrew Persily, Ph.D., is a mechanical engineer at National Institute of Standards and
Technology in Gaithersburg, Md. William P. Bahnfleth, Ph.D., P.E., is a professor at The
Pennsylvania State University, in University Park, Pa. Howard Kipen, M.D., is a professor
at Rutgers University-School of Public Health, in Piscataway, N.J. Josephine Lau, Ph.D.,
is an associate professor at the University of Nebraska-Lincoln in Lincoln, Neb. Corinne
Mandin, Ph.D., is head of the Indoor Air Quality Observatory, Scientific and Technical
Centre for Building (CSTB) in Paris. Chandra Sekhar, Ph.D., is a professor at National
University of Singapore in Singapore. Pawel Wargocki, Ph.D., is an associate professor
at Technical University of Denmark in Copenhagen, Denmark. Lan Chi Nguyen Weekes,
P.E., is director of physical resources at La Cité College, in Ottawa, Ontario, Canada.

https://www.tinyurl.com/2p97a7zw http://ashrae.org

ASHRAE Journal - May 2022

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