ASHRAE Journal - May 2023 - 52

TECHNICAL FEATURE
TABLE 2a Air quality thresholds and action levels: continous monitoring.
PARAMETER
RECOMMENDED
METHOD
PM2.5
(mg/m3)
Carbon
dioxide
(ppm)
Temperature
(°F)
Humidity (%)
TVOCs (ppb)
Real-time light
scattering or
gravimetric
Non-dispersive
infrared
radiation (NDIR)
Thermistor
R = thin film
capacitative
Photoionization
detector
32
5
1 ppb
140
95
10,000
ppm
RANGE
(MIN)
RANGE
(MAX)
ACCURACY RESOLUTION
0.001 150 ±5% flow ±1%
1
5,000
3%,
50 ppm
±1
±3%
±3% at
calibration
point
Ozone
Electrochemical 1 ppb
500
ppb
* 68°F to 75°F for winter and 73°F to 79°F for summer
TABLE 2b Air quality thresholds and action levels: lab testing-intgrated sampling.
PARAMETER
Formaldehyde
Acetaldehyde
Volatile organic compounds
Fungi
(Aspergillus fumigatus)
Hydrogen Peroxide
RECOMMENDED METHOD
ASTM D5197
ASTM D4710
EPA TO-17
ASTM D7391
Galson Labs LC SOP-57
DETECTION LEVEL
1 µg
50 µg
1-3 µg
13 s/m3
2 µg
for VAV zone and system calculations, which was developed
for this project, was published through ASHRAE in
2021.5
Phase 1: Sensor Installation and Baseline Data Collection
The project team installed airborne contaminant sensors
in 76 locations in the hospital and one location on
the roof. Sensors were installed in administration and
staff offices, workstation suites, conference rooms, engineering
office, physician dining room, waiting rooms,
nurses' stations and patient rooms. Sensors measured
temperature, humidity (RH), carbon dioxide (CO2), particulates
(PN1+). Twenty-six sensors also measured total
volatile organic compounds (TVOC). Two indoor sensors
and the roof sensor measured ozone (O3).
The indoor air quality data was collected in 15-minute
52
ASHRAE JOURNAL ashrae.o rg M AY 2023
intervals continuously throughout the project. A twomonth
period of data was collected prior to any changes
to the ventilation system. In addition to air quality
data, building automation data was collected including
ventilation rates; duct static pressure; supply, return,
and zone temperatures; fan speed; and chilled water
and boiler energy data for all affected air handlers in
the building.
Phase 2: Variable Air Volume (VAV) Conversions
The project team reprogrammed existing constantair
volume (CAV) terminal units to VAV operation. The
VAV conversion affected most zones in the tower, except
those designated as critical areas. Critical areas were
the emergency department and any space with a coderequired
pressurization.
At the time of this project, the California mechanical
code allowed a minimum of 2 ach in patient rooms
with 100% outdoor air. Readers should note that
ASHRAE/ASHE Standard 170-2017 requires a minimum
of 4 ach of total air; as such, the minimums implemented
in this project would not meet some codes.
Phase 3: Airborne Contaminant-Based Ventilation
The final phase of the project involved further
1 ppm
0.1
0.1
ACTION
LEVEL
0.012
mg/m3
500 ppm
over
OSA
LIMIT
0.015
mg/m3
700 ppm
over OSA
ASHRAE
55*
30% to
50%
1 ppb 300 ppb 650 ppb
REFERENCED
STANDARDS
EPA NAAQS,
CARB
ANSI/ASHRAE
62.1-2016
Appendix D
ANSI/ASHRAE
55-2013
ANSI/ASHRAE
55-2013
LEED v4,
EQc 3.2;
Molhave,
et al.
5%
1 ppb
60 ppb 75 ppb
LEED v4,
EQc 3.2;
Molhave,
et al.
Housekeeping
cleaners, antiseptics,
equipment,
building
materials
Ground level
ozone (nonattainment
areas),
office
equipment
PROBABLE
SOURCES
Outdoor air,
construction/
renovation,
maintenance
Human activity
PROCEDURE AFTER EXCEEDING
ACTION LEVEL
Identify source, check HVAC
and building pressures
Check ventilation, occupant
density
Assess HVAC system
Assess HVAC system
Identify, control sources
HVAC, filtration
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ASHRAE Journal - May 2023

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