CO2 Meter - A do-it-yourself carbon dioxide measuring

FHAACHEN

UNIVERSITYOFAPPLIEDSCIENCES

CO2 Meter

A do-it-yourself carbon dioxidemeasuring device for the classroom

T. Dey, I. Elsen, A. Ferrein, T. Frauenrath, M. Reke, S. SchifferMakerspace of Faculty 5 (Electrical Engineering and Information Technology)& Mobile Autonomous Systems and Cognitive Robotics Institute (MASCOR)FH Aachen University of Applied Sciences

Int’l Workshop on AI and Digital Technologies in Coronavirus Pandemic and Beyond (COVID-19)at the PErvasive Technologies Related to Assistive Environments Conference (PETRA) 2021

© FH AACHEN UNIVERSITY OF APPLIED SCIENCES | CO2 Meter Team

FHAACHEN


Motivation

Life with Corona

◮ Social distancing, lockdown measures, mutations

◮ Pupils have to undergo distance learning

Challenges & Deficiencies

◮ Especially younger kids cannot stay at home forever

◮ One-should-fit-all recommendations on ventilation

◮ Little information on risk in particular situation

Our Contribution

◮ Cheap but precise device for reliably measuring CO2 levels in classrooms

◮ Accessible self-assembly kit, also used as a vehicle for STEM education

◮ Connected device to collect more information and for analysis

© FH AACHEN UNIVERSITY OF APPLIED SCIENCES | CO2 Meter Team PETRA 2021 - COVID-19 WS | 2

FHAACHEN


Background & Related Work

Background

◮ Corona precaution measures work (hygiene, distance, masks, ventilation)

◮ Transmission via aerosols → risk of infection particularly high indoors[Lednicky et al., 2020, Peng and Jimenez, 2020]

◮ Effects of distance learning [OECD, 2021], [Ravens-Sieberer et al., 2021]

◮ Current recommendations not flexible, not fitted for individual setting

Related Work

◮ CO2 as a proxy for aerosol level / air quality, e.g. [Johnson et al., 2018]

◮ Models for transmission of respiratory diseases[Riley et al., 1978, Rudnick and Milton, 2003, Dai and Zhao, 2020]

◮ CO2-based ventilation [Batterman, 2017, Pang et al., 2021]

◮ Our hardware approach is not unique, instead use common practices[Clements et al., 2017, Spinelle et al., 2017, Pino et al., 2019, Martin et al., 2017]


FHAACHEN


CO2 Meter

Overview

◮ Measure current CO2 level via an NDIR sensor

◮ Display ventilation recommendation via Green-Yellow-Red LEDs

◮ Further information via LCD display (temp., rel. humidity, history, ...)

◮ Different modes of operation and connected via WiFi network

Features

◮ Designed as a do-it-yourself (DIY) kit

◮ Setup and config via web interface

◮ Display values via web GUI + display

◮ WiFi as an Access Point or as a client

◮ Data can be send to an MQTT server


FHAACHEN


Sensor Selection & Kit Components

Sensor Selection

◮ VOC -vs- NDIR

◮ different vendors

◮ comparative evaluation 600

650

700

750

800

850

000000

010000

020000

030000

040000

050000

060000

070000

080000

0

5

10

15

20

25

30

35

Mea

suredC

O2Lev

el[ppm]

Temperature[°C]

Date-Time

SCD30SensorIDsd8bfc014ac9cMHZSensorIDs483fda00180a

Kit Components

CO2 Sensor Sensirion SCD30

Microcontroller NodeMCU ESP8266-12F

Display 1,3 inch OLED I2C 128 x 64 pixels

Traffic Light LED Traffic Light Module

Real-time Clock DS3231 real-time clock

Power Supply USB Wall plug + Micro-USB cable

Clamps + Wiring Wago Connectors + Jumper Wires


FHAACHEN


User Interface

User Interface Browser

User Interface Display


FHAACHEN


Software System Architecture

WiFi

MQTT Broker

User Mobile

LocalDatabase

Sensor

Display

RTCNodeMCU

I²C

DIO

CO2 Meter

RemoteDatabase

CO2 Meter

AccessPoint

Internet


FHAACHEN


OpModes & Connects

NoFi �þStandalone, no network, data only on device

LocalAP T Æ/§/B

Local Access Point, data via web UI

WiFi Client O T Æ§B

Client in existing WLAN, data via web UI in LAN

WiFi Client + MQTT Client B§Æ T O T , / T � / A

Client in network, additionally data tx to MQTT serverData reporting and analysis possible (_ / ` / ^ / ÿ)


FHAACHEN


Target Group and Training Material

Kit to interactively learn about technology

◮ Bonding with device through DIY kit

◮ No soldering, ok even for young learners

◮ Make technology tangible, HW -vs- SW

◮ Workshops by academic staff

◮ Parent projects, school clubs

Workshops & Videos as Training Material

Unboxing - Components

https://youtu.be/aAsCkTMjA_8

Assembly - Electronics

https://youtu.be/_UIu_xenOVU

Assembly - Chassis Box

https://youtu.be/eZ1lCGSWcG0


FHAACHEN


Data Processing

MQTT Messages

1 {CO2Meter: {

2 "id": deadbeef_12345,

3 "temperature": 23.42,

4 "relhumidity": 42.00,

5 "co2levelppm": 815.0,

6 }

7 }

Data Portal

Data Analytics

◮ Collecting sensor values via MQTT

◮ Other data acquired seperately

◮ Backend works in real-time


FHAACHEN


Conclusion

Summary

◮ A do-it-yourself carbon dioxide measuring device for the classroom

◮ Accessible, low-priced, extensible, easy to set up, connected system

◮ Immediate support for safe(r) in-person education in the pandemic

Work in Progress

◮ nearly 300 devices deployed in schools at different levels

◮ Currently preparing release of firmware source code

Outlook

◮ Pilot installations deployed, constantly increasing number of devices

◮ Device is beneficial beyond the pandemic (air quality + STEM edu)


FHAACHEN


Team & Contact

Prof. Thomas Dey Prof. Ingo Elsen Prof. Alexander Ferrein

Prof. Tobias Frauenrath Prof. Michael Reke Dr. Stefan Schiffer

[email protected]

maskor.fh-aachen.de/co2meter

MASCOR Institute & FB 5 MakerspaceFH Aachen Univ of Applied SciencesEupener Str. 7052066 Aachen


FHAACHEN


Bibliography I

Batterman, S. (2017).Review and extension of CO2-based methods to determine ventilation rates with application to schoolclassrooms.International Journal of Environmental Research and Public Health, 14(2).

Clements, A. L., Griswold, W. G., RS, A., Johnston, J. E., Herting, M. M., Thorson, J., Collier-Oxandale, A., andHannigan, M. (2017).Low-cost air quality monitoring tools: From research to practice (a workshop summary).Sensors, 17(11).

Dai, H. and Zhao, B. (2020).Association of infected probability of COVID-19 with ventilation rates in confined spaces: a Wells-Rileyequation based investigation.medRxiv.

Johnson, D. L., Lynch, R. A., Floyd, E. L., Wang, J., and Bartels, J. N. (2018).Indoor air quality in classrooms: Environmental measures and effective ventilation rate modeling in urbanelementary schools.Building and Environment, 136:185–197.

Lednicky, J. A., Lauzardo, M., Fan, Z. H., Jutla, A., Tilly, T. B., Gangwar, M., Usmani, M., Shankar, S. N.,Mohamed, K., Eiguren-Fernandez, A., Stephenson, C. J., Alam, M. M., Elbadry, M. A., Loeb, J. C.,Subramaniam, K., Waltzek, T. B., Cherabuddi, K., Morris, J. G., and Wu, C.-Y. (2020).Viable SARS-CoV-2 in the air of a hospital room with COVID-19 patients.medRxiv.


FHAACHEN


Bibliography II

Martin, C. R., Zeng, N., Karion, A., Dickerson, R. R., Ren, X., Turpie, B. N., and Weber, K. J. (2017).Evaluation and environmental correction of ambient CO2 measurements from a low-cost NDIR sensor.Atmospheric measurement techniques, 10(7):2383–2395.

OECD (2021).The State of School Education.

Pang, Z., Hu, P., lu, X., Wang, Q., and O’Neill, Z. (2021).A smart CO2-based ventilation control framework to minimize the infection risk of COVID-19 in publicbuildings.preprint available athttps://www.researchgate.net/publication/349121056_A_Smart_CO2-Based_Ventilation_Control_

Framework_to_Minimize_the_Infection_Risk_of_COVID-19_In_Public_Buildings.

Peng, Z. and Jimenez, J. L. (2020).Exhaled CO2 as COVID-19 infection risk proxy for different indoor environments and activities.medRxiv.

Pino, H., Pastor, V., Grimalt-Álvaro, C., and López, V. (2019).Measuring CO2 with an arduino: creating a low-cost, pocket-sized device with flexible applications thatyields benefits for students and schools.Journal of Chemical Education, 96(2):377–381.


FHAACHEN


Bibliography III

Ravens-Sieberer, U., Kaman, A., Erhart, M., Devine, J., Hölling, H., Schlack, R., Löffler, C., Hurrelmann, K.,and Otto, C. (2021).Quality of life and mental health in children and adolescents during the first year of the covid-19 pandemicin germany: Results of a two-wave nationally representative study.

Riley, E., Murphy, G., and Riley, R. (1978).Airborne spread of measles in a suburban elementary school.American journal of epidemiology, 107(5):421–432.

Rudnick, S. and Milton, D. (2003).Risk of indoor airborne infection transmission estimated from carbon dioxide concentration.Indoor Air, 13(3):237–245.

Spinelle, L., Gerboles, M., Villani, M. G., Aleixandre, M., and Bonavitacola, F. (2017).Field calibration of a cluster of low-cost commercially available sensors for air quality monitoring. Part B:NO, CO and CO2.Sensors and Actuators B: Chemical, 238:706–715.


Documents

CO2 Meter - A do-it-yourself carbon dioxide measuring