ASHRAE Journal - February 2021 - 4

180 Technology Parkway
Peachtree Corners, GA 30092
Phone: 404-636-8400
Fax: 404-321-5478 | www.ashrae.org
DIRECTOR OF ASHRAE PUBLICATIONS & EDUCATION
Mark S. Owen
EDITORIAL
Editor
Sarah Foster
sfoster@ashrae.org
Managing Editor
Mary Kate McGowan
mmcgowan@ashrae.org
Assistant Managing Editor
Jeri Alger
jalger@ashrae.org
Associate Editor
Rebecca Matyasovski
rmatyasovski@ashrae.org
Associate Editor
Tani Palefski
tpalefski@ashrae.org
PUBLISHING SERVICES
Publishing Services Manager
David Soltis
Production
Jayne Jackson
ADVERTISING
Associate Publisher,
ASHRAE Media Advertising
Greg Martin
gmartin@ashrae.org
Senior Coordinator-Advertising
Production and Operations
Vanessa Johnson
vjohnson@ashrae.org
Coordinator-Circulation Development
Austin Brafford
abrafford@ashrae.org
ASHRAE OFFICERS
President
Charles E. Gulledge III, P.E.
President-Elect
Michael Schwedler, P.E.
Treasurer
Farooq Mehboob, P.E.
Vice Presidents
Donald L. Brandt
K. William Dean, P.Eng.
William F. McQuade, P.E.
Tim McGinn, P.E.
Secretary & Executive Vice President
Jeff H. Littleton
POLICY GROUP
2020 - 21 Chair
Publications Committee
Hugh D. McMillan III, P.E.
Washington Ofﬁce
washdc@ashrae.org

COMMENTARY
COMMENTARY

Debunking UVGI Myths
During the COVID-19 pandemic, interest has grown in
technologies that help to mitigate transmission of the
disease. Ultraviolet germicidal irradiation (UVGI) is one
such technology, so ASHRAE Journal talked to William
P. Bahnﬂeth, Ph.D., P.E., Presidential Member/Fellow
ASHRAE, and chair of the Epidemic Task Force, to understand the misconceptions that people may be having about UVGI.
For example, one common misconception revolves around the perceived newness of the technology. It's actually been around since the
1930s and is approved by the U.S. Centers for Disease Control and
Prevention for use in control of tuberculosis.
Bahnﬂeth also discusses ways to achieve the best outcome. He recommends to " deﬁne the performance goals for a UVGI system, i.e., what
dose needs to be delivered over what period of time for the design level
of microbial susceptibility and under what ambient conditions-temperature and air speed. " These goals can help with lamp selection and
ensure that the required amount of UV-C is delivered.
More information is available in Chapter 62 of the 2019 ASHRAE
Handbook-HVAC Applications and in Chapter 17 of the 2020 ASHRAE
Handbook-HVAC Systems and Equipment. The interview with Bahnﬂeth
starts on page 22.
Applying a new technology or theory begins with understanding the
basics. Cascade control theory has the same goal as closed-loop control
theory: to keep the controlled variable at setpoint. However, it also offers
beneﬁts such as the ability to limit the manipulated variable and to more
quickly identify any disturbances to the system. The article starting on
page 14 is meant to give readers a foundational understanding of cascade
control theory to help them better articulate sequences and to understand the best situations for using cascade control.
The tremendous amount of data associated with operating a district heating system can make it difﬁcult to manage it. On page 36, the
authors suggest using an algorithm to help eliminate data that can be
considered abnormal.
Other topics in this issue include:
* A column on page 46 discusses resolving high humidity in spaces
using chilled water fan coil units using two case studies.
* Understanding where vapor barriers should go in parking garages
is explored on page 30.
* The history of indoor carbon dioxide concentrations in Standard
62.1 is discussed on page 74.
Enjoy the issue.
Sarah Foster, ASHRAE Journal Editor
Mission Statement: ASHRAE Journal reviews current HVAC&R technology of broad interest through publication of application-oriented articles. ASHRAE
Journal's editorial content ranges from back-to-basics features to reviews of emerging technologies, covering the entire spectrum of professional interest
from design and construction practices to commissioning and the service life of HVAC&R environmental systems.

ASHRAE JOURNAL

ashrae.org

FEBRUARY 2021

http://www.ashrae.org http://ashrae.org

ASHRAE Journal - February 2021

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