ASHRAE Journal - February 2023 - 7

LETTERS
will grow in the next decade. It
seems to me the most important
thing ASHRAE could do, immediately,
is to add the obvious step:
measure the air.
Like the tools, your column also
breezed past the topic of measurement.
So, I'm interested in your
opinion on the matter.
Travis R. English,
Member ASHRAE, Fountain
The Author Responds
Thank you for taking the time
to read the column and for your
thoughtful comments. When I fi rst
started writing the column I was
focused on specifi cally addressing
the criticisms of ASHRAE Standards
and pointing out that all of the topics
discussed at the White House
Summit were already addressed by
ASHRAE in some form and many
were in the process of being developed
into the standards.
You do make a good point that
unless you follow the Indoor Air
Quality Procedure, you are not
compelled to measure air quality.
From my perspective this is because
the ventilation rates are based on
achieving a vote of not unacceptable
from 80% of the occupants; they are
not intended to control specifi c contaminants
to specifi c thresholds.
In terms of measurement, I think
you are also breezing past some of
the very real questions about how
we should use indoor air quality
measurements.
Let's start with the most basic
design based on achieving a certain
maximum level based on a design
background condition. This is
certainly achievable, but it requires
several things. First, we have to
identify the contaminants we are
seeking to control. Second, we must
gather data of background levels
of those contaminants. Third, we
must understand the sources of
those contaminants. Finally, we
must adopt limits from recognized
regulating bodies that we can
control to.
Let's look at your list of contaminants:
we can certainly regulate any
of the PM buckets; we could regulate
CO2, but there is signifi cant debate
on what an appropriate limit is; regulating
TVOCs is perilous because it
is an aggregate measurement, and
even low levels of certain VOCs can
be very harmful; we already have
rules for humidity and temperature
in ASHRAE Standard 55. So let's
assume we establish limits for those
air constituents we can.
Then we need to have a method
of determining the background
conditions and sources of those
contaminants, similar to the climate
database. There are weather stations
with air quality readings, but this
is not universal and we still need
to aggregate and analyze the data.
Even when we get this data we still
have the issue of internal sources;
are these understood well enough to
design engineering controls around,
and do those internal sources
require different strategies than the
external sources?
So having said all of this, I do think
that developing design standards
around obtaining limits is possible-
the IAQP already allows this-but it
is not nearly as simple as buying a
desktop IAQ monitor.
Now let's take a look at the active
control scenario. In this case you
have your IAQ monitor and it reads
an elevated level of a contaminant
in your space. What is the control
response to this information? Does
the ventilation system increase
air volumes? What if the source of
the particulates is the ventilation
air? Do we put safeties in place
to cut off ventilation when the
source is external, or do we alarm
and continue to ventilate? What
if there is an air cleaner? Should
we mandate its priority relative to
changes in ventilation rates?
It is not my intention to be dismissive,
but rather to point out that
these are all questions that need to
be answered and agreed upon by the
committee before we can change the
standard. In fact some of these questions
have been asked recently with
respect to controls for hazardous
outdoor air conditions.
I know you have been working on
indoor air quality in health-care
spaces for many years now and
are familiar with the CMP process.
There are currently two proposals
under consideration by SSPC 62.1,
one to restore the requirements of
active measurement of outdoor airfl
ow rates, and another to publicly
display ventilation information. I
can easily envision a third proposal
that requires the inclusion of indoor
air quality metrics in either or both
of these requirements. I cannot predict
if any of these will be accepted,
but you are not alone in your position,
and we are always interested in
constructive proposals to improve
the standard. Even if air quality
control does not enter the standard
in an analogous manner to thermostatic
control, there are a multitude
of conceivable uses for measured
data that could be used to improve
design practices.
Brendon J. Burley, Ph.D., P.E.,
Member ASHRAE, Baltimore
F E B R U A RY 2 0 2 3 ashrae.o rg ASHRAE JOURNAL
7
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ASHRAE Journal - February 2023

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