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INDOOR AIR

QUALITYCO2 SENSORS

& DEMAND CONTROLLED

VENTILATION

This material is based upon work supported by the National Science Foundation under Grant No. 1132585 and by the IEEE Control Systems Society (CSS). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation or IEEE CSS.

We also gratefully acknowledge RET (Research Experiences for Teachers), on Sensor Networks, Electrical Engineering Department, and Institute of Applied Sciences, UNT, Denton, Texas.

Project Goals

Build experimental IAQ CO2 monitoring system with “On Demand” ventilation capabilities

Compare performance of the prototype CO2 sensor with the professional grade GrayWolf IAQ measurement system

Test IAQ CO2 sensor in simulated classroom environment to collect building material effects on CO2 levels

Analyze IAQ data Develop a lesson plan and prepare hardware and

software for inclusion in a high school classroom

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Government and PolicyASHRAE- American Society of Heating, Refrigerating and

Air-Conditioning Engineers A building technology society with more than 50,000

members worldwide. The Society and its members focus on building systems, energy efficiency, indoor air quality and sustainability within the industry.

EPA- United States Environmental Protection Agency The Indoor Environments Division has created partnerships

with public and private sector entities to help encourage the public to take action to minimize their risk and mitigate indoor air quality problems.

Government and Policy

OSHA- Occupational Health and Safety Administration

A part of the United States Department of Labor.

Created by Congress with the Occupational Safety and Health Act of 1970

Purpose is to assure safe and healthful working conditions for working men and women by setting and enforcing standards and by providing training, outreach, education, and assistance.

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Current CO2 Standards

ASHRAE (American Society of Heating, Refrigerating, & Air-Conditioning Engineers)

Standard 62.1-2010 Allowable CO2 levels for occupied spaces

CO2 not to exceed 1,000 ppm, but levels less than 800 ppm indicates that sufficient ventilation is being applied to the building

CO2 levels > 5000ppm can cause health risks

Professional Grade Monitoring Systems

PPM Technology Wireless IAQ Profile Monitor

GrayWolf Direct Sense IAQ monitor

Not adaptable to “On Demand” ventilation needs

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Professional Grade Monitoring Systems

GrayWolf Direct Sense IAQ monitor with IQ610 probeWPIAQ-PLUS WolfPack IAQ Plus Survey & Monitoring Kit $7449IQ-610 Probe measures ppb VOCs, CO2, CO, %RH and temperature Multi-function

Simultaneous measurement of up to six (6) key IAQ indicators with one probe; VOCs, CO2 (dilution ventilation), CO, %RH, °C/°F plus an additional toxic gas sensor (from a broad choice of specific gases)

Optional particle concentration or particle count module Up to 4 GrayWolf probes (20+ sensors), plus a particulate sensor may be connected

simultaneously to any platform Data Logging

Manual "snapshot" or automatic "trend" data logging Store enhanced survey information on-site; data plus text, audio notes, photos, videos, drawings

and more... Back-lit color display

Clearly displays numerous readings simultaneously; auto-scrolls for >8 parameters Automatically updates as probes are plugged in View data in tabular or graphic formats

Reporting Download logged data and notes to WolfSense® PC software (included) for analysis and efficient,

detailed reporting Optional "Advanced Report Generator: IAQ Edition" software automates comprehensive IAQ

report generation Optional GrayWolfLive™ allows remote access to data and notes via WiFi

Not adaptable to “On Demand” ventilation needshttp://www.wolfsense.com/pdf/GrayWolf-Indoor-Air-Quality-IAQ-Meter-Brochure-lo.pdf

Professional Grade Monitoring Systems

PPM Technologies Wireless IAQ Profile MonitorEach unit can monitor 3-7 parameters

ParametersFormaldehyde, Glutaraldehyde, Temperature, Humidity, Nitrogen Dioxide (NO2), Carbon Monoxide (CO), Carbon Dioxide (CO2), Sulphur Dioxide (SO2), Total Volatile Organic Compounds (TVOC's), Methane (CH4), Ammonia (NH3), Ozone (O3), Water (H20) single zone sensing cable, Smoke Sensor

The Manager PC connects to the mesh network via a special node which is capable of receiving and transmitting information to the IAQ Profile Monitor. The Manager PC can view, run and control the real time monitoring and data logging of air quality in a building at the click of a button.

The PPMonitor software enables the data to be viewed graphically, produce reports and statistical data, run schedules as well as alarm functions and notifications for more effective and economical building management.

Not adaptable to “On Demand” ventilation needs

http://www.ppm-technology.com/IAQ%20Profile%20Monitor.htm

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Professional Grade Monitoring SystemsVAISALA

GMD/W20 Carbon Dioxide Transmitters

Developed Specifically for

Demand Controlled Ventilation

Applications

Professional Grade Monitoring Systems

Designed for use in ventilation-related applications

Transmitters can be used independently, or incorporated into building energy management systems

Duct or Wall mount

1 transmitter per HVAC Zone

Measurement Capabilities 0-20,000 ppm

Accuracy +/- 2%

Response Time 1 minute

Power Consumption < 2.5 W

Several configuration options available (ie: Display types and output options)

Data logging options available

Cost: Approximately $410 per room/HVAC Zone

VAISALAGMD/W20

Carbon Dioxide Transmitters

http://www.vaisala.com/en/products/carbondioxide/Pages/GM20.aspx

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RET PrototypeMG-811 Gas Sensor Module (1) – Carbon Dioxide $52.95

Arduino One Board (2 @ 26.96ea.) $53.92

Xbee Proto-shield Kit (2@ 14.95ea.) $29.90

Xbee Pro S1 (2@ 32.00ea) $64.00

12 V adapter (2@ 8.95ea.) $17.90

9 V adapter (2@ 6.26ea.) $12.52

12 V DC Fan (1) $5.95

N-Channel MOSFET 60V,30A (1) $0.86

Diode Rectifier 50V, 1A (1) $0.14

Miscellaneous Parts $10.00

Total Cost of Prototype Unit $248.14

Applications of IAQ monitoring Systems

Research proved that the majority of the monitoring systems in use were developed to check for air quality issues after building occupants exhibit symptoms. CO2 poisoning symptoms include such as issues with fatigue, headaches, dizziness, nausea, vomiting, shortness of breath, confusion, loss of concentration, blurred vision, and loss of consciousness.

While these systems are useful, our goal was to establish a cost effective wireless IAQ unit that will continuously monitor CO2 levels and turn on ventilation fans before the building’s population begins to show adverse effects.

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SourcesASHRAE Position Document on Indoor Air Quality Discusses the relationship between energy efficient buildings while still

maintaining proper IAQ Investigates sick building syndrome, which is the collection of several

symptoms related to poor IAQ, including nausea, fatigue, itchy eyes and skin, headaches, and upper respiratory symptoms

Gives guidelines for acceptable IAQ, including CO2 levels ASHRAE Standard 62: Optimizing Energy Use and Ventilation

National Institute of Standards and Technology- Emmerich, Persily State-of-the-Art Review of CO2 Demand Controlled Ventilation (DCV) Oxygen depletion cited as cause of poor IAQ Emission rate of occupant generated CO2 is relevant to IAQ DCV Sensors located close to doors/windows give inaccurate CO2 readings Building features influence CO2 DCV effectiveness

Existence of unpredictable occupant variations Building/climate requiring year round heating/air conditioning Low pollutant emissions from non-occupant sources

SourcesEPA Has established the

“IAQ tools for schools program” which provides products and materials to schools to help them implement an IAQ management program http://www.epa.gov/iaq/schools/actionkit.html

Posted several sources linking poor IAQ to poor student performance, mainly due to absences related to asthma

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SourcesDoes Pollution Increase School Absences-Currie, Hanushek, Kahn, Neidell, and Rivkin Discusses outdoor carbon monoxide (CO2) levels and their relationship

to student absences Discuss outdoor CO2 level relationship to indoor CO2 level Discuss outdoor ozone with student absences Discuss particulate matter and it relationship to student absences

Demand Controlled Ventilation (DCV) using CO2- Schell and Inthout Developing control systems based upon readings from CO2 sensors Based on ASHRAE ventilation rates Increasing ventilation rates will decrease CO2 levels Discuss the change from a fixed system to a DCV system

SourcesDemand Control Ventilation (DCV) Using CO2- Schell, Inhout CO2 based DCV based on occupancy increasingly used Indoor CO2 measurements correlate to occupancy CO2 can be used to control any per-person ventilation rate CO2 filtration/removal methods must be by dilution 1916 reference to CO2 and ventilation- Mechanical

Engineer’s handbook by McGraw-Hill

The Research of Carbon Dioxide Gas Monitoring Platform based on the Wireless Sensor Networks (WSN)- Zhou, Chen Developed a WSN suitable for unattended environment

monitoring. System design could be adapted for use in CO2 DCV

application

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WSN Benefits Wireless sensor network technology promises a wide

range of applications such as monitoring moisture levels in soil to applying Demand Controlled Ventilation (DCV) technology to alleviate CO2 levels in a structure. The benefits include reduced installation & system costs, increased flexibility, and simplification of deployment.

With the addition of an Ethernet Access Point a wireless network can then be accessed from any location in the world via the internet.

Open source programming (such as used with Arduino) reduces costs incurred by proprietary software.

IAQ CO2 Sensor and Filter Amplifier Board

Compact Carbon Dioxide Sensor MG811

High Sensitivity

Detection Range: 0-10,000 ppm

Detects through electrode reaction

Increased CO2 produces less V Need for V amplifier board

Need for calibration with Grey Wolf

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Wireless Prototype

CO2 Sensor Assembly Demand Controlled Ventilation Assembly

Transmitter Receiver

You know what would be neat? A spec sheet with factual information. Spec sheet misdemeanor- computer fan

Speed check one- photogate method

Frequency check- matched with frequency generator

Strobe light- Arduino style

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Air flow measurements

Fancy way- Bernoulli’s Principle

http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

The Return of Air flow measurements

The “parsons trashbag method”

Airflow created by our fan-.34CFM

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Spec Sheet Felony- the CO2 sensor

Where does CO2 go?

Low chamber test

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Where does CO2 go? mid chamber test

High chamber test

Where does CO2 go?

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Test Simulations

Simulation 1: Dry Wall, unpainted (2 pcs. 5” x 26”) Simulation 2: Linoleum Floor Tile (1 sq. ft.) Simulation 3: Ceiling Tile (2 ea. - 1 sq. ft. each) Simulation 4: Bricks (3 ea. 7.5” x 3.5” x 2”) Simulation 5: Plants (1 Fern & 1 Caladium) Simulation 6: Cinder Block, unpainted (16”x 7.5” x

3.5”)

o Each simulation was monitored using our IAQ prototype, the Grey Wolf, and a Dell computer.

o Each simulation was tested to see if the building materials had any effect on the CO2 level

o We then analyzed the data to identify certain trends based upon each simulation

Dry wall

Floor tile

Ceiling tile

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Brick test

plants

Cinder block

Cinder block eats CO2- film at 11

CO2 dropped from 28500ppm to 174ppm in 4 hours and 34 minutes. The room was 800ppm.

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Possible Mechanism Cinder block is largely composed of di-

and tri- calcium silicate, or2CaOSiO2 and 3CaOSiO2

CaCO3 (s) → CaO(s) + CO2 (g) Typically accomplished between 500 and

600 Celcius. The reaction is reversible

DCV vs. gravity

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Further Work

Larger scale tests with a room and a fan that will vent to the outside.

Chemical tests to definitively determine the mechanism for CO2 absorption.

A more controllable environment (humidity, temperature) because the CO2 sensor is sensitive to both.

Conclusion Potential hazardous gases in the work place are a critical issue. Too often,

these gases are undetected until the employee becomes ill or a foul odor is reported by building occupants. By the time this occurs, occupants will have suffered exposure to poor air quality. The next step is to test the building with an expensive sensor unit to determine the source of the problem. With an on-demand venting system in place, IAQ issues could be dealt with immediately.

While running the Grey Wolf and the prototype board, there seemed to be a lag in the data acquisition for the prototype. As far as room ventilation is concerned, a few seconds shouldn’t matter at all, so this doesn’t seem to be a concern. The prototype reading seemed more stable while the Grey Wolf readings were “noisier.” This could be due to the fact that the prototype simply doesn’t have the resolution capability of the Grey Wolf. This is potentially a benefit, as a noisy signal near the fan activation criterion could cause the fan to stop and start at small intervals. This could be mitigated with proper coding.

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Tech FestCO2 Monitoring Game

1. Students blow into straws which they have inserted into boxes containing CO2 sensors.

2. Arduino sends signal to turn on lights as CO2 level increases.

3. 1st person to get the top light to turn on is winner.

Prizes TBD by Rudi.