Wireless indoor air quality (iaq) monitoring in classrooms and laboratorie…
-
Upload
jennifer-maclachlan -
Category
Technology
-
view
1.910 -
download
1
description
Transcript of Wireless indoor air quality (iaq) monitoring in classrooms and laboratorie…
PID Analyzers, LLC
1
Wireless indoor air quality (IAQ) monitoring in classrooms and
laboratories (VOC's, CO, CO2, and T)
PID Analyzers, LLC
2
Introduction
High levels of CO2 (>1,000 ppm) can result in students feeling drowsy or sick
Poor air quality in school classrooms is a serious problem now a “typical 700-square-foot classroom with 20 to 30 occupants ventilated by a standard HVAC system”. (Aiken, Tom, Cleanfax Online: http://www.cleanfax.com/disaster-restoration/article/maintaining-healthy-classrooms-with-air-quality-monitors)
We initially used a Model 114 IR Analyzer but we also designed a low cost single channel IR logger for CO2 to monitor labs, offices & class rooms
A positive benefit to improving IAQ in classrooms is that a number of studies have shown that improved air quality can lead to higher test scores. (Aiken, Tom, Cleanfax Online: http://www.cleanfax.com/disaster-restoration/article/maintaining-healthy-classrooms-with-air-quality-monitors)
PID Analyzers, LLC
3
ASHRAE’S POSITION ON CARBON DIOXIDE (CO2) LEVELS
American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) has a guideline of 1,000 ppm CO2 for indoor spaces
CO2 has been used as a basis for ventilationCO2 levels are good predictors or surrogates for human
emitted bioeffluents (i.e., odors)If the ventilation rate is set so that 1000 ppm CO2 is not
exceeded and if CO2 is controlled by any method other than dilution, the effects of possible elevation of other contaminants must be considered.”
CO2 levels should be measured during the time of occupancy which is defined for the classroom as the time between initial occupancy in the morning and dismissal time for the students.
PID Analyzers, LLC
4
CO2 Levels & Health Effects
325 - 350 ppm – background (normal) outdoor air level 750- 1,000 ppm - typical level found in occupied
spaces with reasonable air exchange. 1,000 – 2,000 ppm - level associated with complaints
of drowsiness and poor air. 2,000 – 5,000 ppm – level associated with headaches,
sleepiness, and stagnant, stale, stuffy air. Poor concentration, loss of attention, increased heart rate and slight nausea may also be present.
>5,000 ppm – Exposure may lead to serious oxygen deprivation resulting in permanent brain damage, coma and even death.
PID Analyzers, LLC
5
IR Sensor Schematic-CO2
PID Schematic-VOC’s
IR Sensor & VOC sensor Schematic
PID Analyzers, LLC
6
IR spectrum of CO2 Dual Beam IR Meas. & Ref. Wavelengths
IR Spectrum for CO2
PID Analyzers, LLC
7
2/1/2011 8:52 2/1/2011 9:07 2/1/2011 9:21 2/1/2011 9:36 2/1/2011 9:50 2/1/2011 10:04
-50
0
50
100
150
200
250
300
350
400
450
325326.3327.6
416416
370.5369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2369.2367.9367.9367.9369.2367.9367.9367.9367.9367.9367.9
314.6
367.9367.9367.9367.9367.9367.9367.9367.9367.9
314.6314.6314.6314.6314.6
367.9367.9367.9367.9367.9
-6-8-11
154233439
192161274
27118126107
15678101181491199915991617
520
739131081318
VOC's and CO2 Variation in Laboratory
Series1Moving average (Series1)Series3Moving average (Series3)
ppb V
OC
(R
ed)
/
ppm
CO
2 (
Yell
ow
)
Laboratory 200 sq ft/person
PID Analyzers, LLC
8
CO2 in Office (75 sq ft/person)
PID Analyzers, LLC
Components of Single Channel Logger
45 hours for CO2150 Hours for EC
rechargeable
Enclosure
Battery
9
PID Analyzers, LLC
10
Model 114 IR CO2 Photo of Classroom
CO2 in Classroom
PID Analyzers, LLC
11
CO2 Variation in Different Locations Location & Description
123456789
101112131415
0 200 400 600 800 1000 1200 1400
Variation of CO2
ppm CO2
Roo
m #
1 lab 4 people 2 office 3 people 3 home 2 people 4 classroom 15 students 4 teachers 5 outside air near office 6 class room 20 students 2 teachers 7 outside air on cc 8 Hotel room 9 Hotel corridor 10 classroom 25 people 11 classroom larger 40 people 12 classroom 10 people 13 classroom 3 people 14 classroom no people 15 classroom 13 people
CO2 Measurements
PID Analyzers, LLC
12
Conclusions
CO2 is a good indicator of room air quality and problems can be found quickly and efficiently
Initial measurements were made with a CO2 Model 114 IR but a single channel CO2 dosimeter has been designed and will be available in the Fall 2012
Many rooms were found to be close to 1,000 ppm in homes, offices and classrooms in the winter. With adequate ventilation, warmer temperatures, average classrooms could be 750 ppm or lower
The Bluetooth slave module is capable of sending data 100-200’ to a master module in a PC