ASHRAE Journal - July 2023 - 90

Raise IAQ, Not Building Energy Profi le
The CDC recently updated its key
recommendations for raising indoor air
quality (IAQ) in buildings via improved
ventilation. This update comes in the
wake of new research underlining the
importance of clean of air in occupied
spaces.
A study (Air Pollution and Mortality at
the Intersection of Race and Social
Class | NEJM) published in the New
England Journal of Medicine projects that
bolstering air pollution standards from 12
to 8 ug/m3 (micrograms per cubic meter)
would reduce premature deaths.
New analysis of research by public health
scientists at Harvard (Ambient air pollution
and clinical dementia: systematic review
and meta-analysis | The BMJ) provides
evidence of a connection between
dementia and the inhalation of PM 2.5
(airborne particles less than 2.5 microns in
width).
Multiple sources, including Harvard
Healthy Buildings, EPA Clean Air in Building
Challenge, ASHRAE, and the Lancet
Commission recommend increased
ventilation and MERV 13 or greater fi ltration.
The CDC now suggests providing 5 ACH,
which may include a combination of
ventilation, fi ltration and air treatment in
order to meet the target.
Unfortunately, increasing fresh air carries
an energy burden. Outdoor air must
be conditioned to maintain building
temperatures. As such, the goals of
increasing fresh air and maintaining a low
carbon footprint are at odds.
In any scenario where increasing fresh air
may be prohibitive, in-room air fi ltration can
be used to dramatically improve IAQ.
Portable air fi lter systems can be used,
and permanent air fi ltration fi xtures can
be installed. How effectively each option
reduces airborne contaminants depends
largely on the design of the system and
where it's located.
Cleaning Air Effi ciently and Quietly
Armstrong World Industries developed
the StrataClean IQ™
Air Filtration System
in response to the real threats posed by
unhealthy indoor environments.
Designed for commercial buildings, the
StrataClean IQ is suspended within the
ceiling, providing MERV 13 fi ltration and
operating independently of the facility's
HVAC equipment. The system uses a quiet
fan to draw air through a MERV 13 fi lter
before being discharged back into the
occupied space.
With the fan continuously running, air in the
occupied space is constantly fi ltered to
provide purifi ed air. The system operates
as quietly as 29 dBA, and consumes only
15 watts per hour. Designed for a 1,000
square-foot space, the StrataClean IQ
provides 1.5 ACH on its highest of three
fan speed settings. The CDC and ASHRAE
suggest 5 ACH, which is a 3 ACH increase
from pre-COVID minimum ventilation
guidance of 2 ACH. Installation of two
StrataClean units in a 1,000 square-foot
space add 3 ACH, helping to meet the
guidance.
nineteen students and one teacher. One
student posed as infected by dispersing
contaminated respiratory aerosols into
the room.
A simulation was conducted with 3 ACH
of base ventilation, and alternately with
those ACH plus supplemental in-room air
cleaners. For supplemental air cleaners,
two cases were modeled: one case with
the StrataClean IQ installed in the ceiling
and operating on its highest setting (230
CFM), and one case with a portable air
cleaner of equivalent CFM on the fl oor.
Room occupancy sensors can be used
to control the unit to save energy and
maximize clean air while the space
is occupied. The system's 24 " x 24 "
design allows for simple installation in
any suspended ceiling system. It's also
compatible with drywall ceilings.
Armstrong World Industries developed the
StrataClean IQ with the belief that ceilingmounted
air fi ltration systems are more
effective than portable fi ltration systems.
Proof of Concept: StrataClean IQ™
Reduces Exposure in Classrooms
Jaros, Baum & Bolles Consulting
Engineers, LLP (JB&B) performed a study
on airborne particle transfer and exposure
in a typical classroom. The computational
fl uid dynamics (CFD) simulation study
modeled a 625 square-foot classroom
with three 3 ACH provided by the building's
ventilation system. The classroom had
Summary
Ceiling placement proved to be up to
35% more effective than fl oor placement;
while also being a quiet, less-invasive
solution. Floor mounted systems create
trip hazards, taking up fl oor space, and
create opportunity for the fi ltration system
to come unplugged or damaged.
" A poorly positioned in-room portable
air cleaner risks furniture or people
obstructing the airfl ow through the air
cleaner, compromising its effi ciency, and
as a result, supports the use of in-ceiling
air cleaners instead of a portable system
wherever possible, " said Gregory A.
James, Head of Building Physics and
CFD at JB&B.
The study indicates that placement of an
air purifi cation device is more critical than
the capacity. The StrataClean IQ installation
delivered up to 30% lower exposure than
the portable unit with equivalent CFM. One
StrataClean IQ reduced airborne particulate
by up to 75%.
Armstrong World Industries
2500 Columbia Ave
Lancaster, PA
1-877-276-7876 | techline@armstrongceilings.com | armstrongceilings.com/stratacleaniq
http://www.armstrongceilings.com/stratacleaniq
ASHRAE Journal - July 2023

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