Last modified January 17, 2021
- 1 ❔ Is it possible to reduce the possibility of contracting Covid with a CO₂ meter of less than 20 Euros?
- 2 ❓ What does CO₂ (Carbon Dioxide) have to do with Covid?
- 3 ⚠️ The air we breathe and the Covid
- 4 💹 The CO meter figures
- 5 👁️🗨️ Homemade CO₂ meter structure
- 6 ✔️ Build the homemade CO₂ meter
- 7 📺 Video with the complete CO2 Meter tutorial
- 8 🔵 Using the CO₂ meter
- 9 Benefits of this CO₂ meter project
- 10 🌀 Home CO₂ Meter Options and Extensions
- 11 🛒 What if I want to buy a ready-made CO2 meter?
- 12 📢 Do you have problems? CO2 meter faq
- 13 📜 History of the eMariete CO2 meter
- 13.1 Power from NodeMCU, Wemos Mini D1 and Arduino
- 13.2 MH-Z19B FALSE CO2 Sensors
- 13.3 3D printed box for CO2 meter
- 13.4 Using a buzzer with ESPEasy
- 13.5 The MH-Z19B CO2 Sensor Bible
- 13.6 Connect an SSD1306 OLED screen to ESPEasy
- 13.7 Comparison of CO2 sensors MH-Z19B vs Senseair S8
- 13.8 A homemade CO2 meter with Wifi against the coronavirus
- 13.9 How do I go about creating a new circuit?
- 13.10 Wifi Home CO2 Meter (Knowing We Breathe)
- 13.11 60
❔ Is it possible to reduce the possibility of contracting Covid with a CO₂ meter of less than 20 Euros?
Well, the answer is a resounding YES!, Y In this article I am going to tell you why this is so, and how you can build your own homemade CO₂ meter.
What I propose is a CO₂ (carbon dioxide) meter with home wifi, what you can build for less than 20 Euros, and that I guarantee that the result is a more precise instrument with more functionalities than commercial CO₂ meters costing several hundred euros..
This meter uses a CO2 sensor with NDIR technology And it has nothing to do with the € 40 or € 50 meters sold online in terms of reliability and accuracy. It has an internal temperature sensor, so that measurements are automatically recalculated based on variations in ambient temperature.
Don't be scared by the length of this article. Yes, it is long, but it has nothing to do with the difficulty. This article is long because I have decided to explain everything step by step, in great detail and with captures, photographs and even videos of each step. I really could have written a much shorter article explaining how to build this CO2 meter, but it wouldn't have been that comprehensive.
The idea is that anyone can build this CO2 meter, no need for prior knowledge or special equipment (Except for the welder, which, as we will see later, we can even do without).
However, if you don't want to build your own CO meter, because you do not have time, you do not like the gadget, or any other reason, You can access a buying guide with the best offers in commercial CO₂ meters by clicking here, you can buy it at a good price and have it at home quickly.
❓ What does CO₂ (Carbon Dioxide) have to do with Covid?
Absolutely nothing. However, these two words together are on the lips of many experts in the health and scientific community. Why? Keep reading…
CO₂ is a dangerous gas for humans. In high concentrations it can cause ailments such as vertigo, headaches, increased blood pressure, accelerated heart rate, and in the most severe cases it can lead to suffocation and loss of consciousness.
The Covid, it is not the name of the virus, is the name of the disease caused by Coronavirus SARS-CoV-2.
We have been talking and hearing about the Coronavirus for months at all times, maybe too much for our good mental health, so I'm not going to comment on anything about him. Everything I can say about the Coronavirus, surely, you already know.
Just remember that, today, the only way to prevent Covid is to protect yourself against the SARS-CoV-2 coronavirus and this is achieved through fairly basic, almost hygienic practices. And at the bottom of all this is that who avoids the occasion avoids the danger.
⚠️ The air we breathe and the Covid
Even though CO₂ has no direct relationship with Covid, If that there is a very important indirect relationship and, this is, the quality of the air we breathe and the viral load that air may have.
When there are several people in a room and one of them is a carrier of the virus, this remains suspended in the air for a variable time, at the expense of other people sharing the room they can be infected. These are the famous aerosol sprays, of which we have heard so much lately.
The more time passes, the more the viral load present in the air increases, with which more it goes increasing the danger from other people catching it.
For this reason, adequate air renewal in the room is essential, and this is achieved by ventilating.
In work environments it is more or less common to have a forced air system that facilitates ventilation and air exchange (and even filtering through HEPA filters) but this it is very rare in private homes, where the only option is usually to ventilate by opening the windows.
The problem is that the virus is invisible, we cannot look at the air and see the viral load it has to decide to ventilate when we see that it is necessary. This is where the CO₂ meter comes into play.
As the Superior Council of Scientific Investigations (CSIC), in its guide to reduce the risk of contagion, CO₂ measurements are one of the best ways to control that we are maintaining adequate ventilation:
CO₂ (carbon dioxide) it is a gas that we expel naturally when we breathe, so that knowing the concentration of this gas in the environment we can have an idea of what «loaded»What is the air in that room, what allows us to decide when to ventilate and for when to do it.
This is especially important in winter, since, due to the low temperatures, we tend to ventilate much less, delaying the time to open the windows.
💹 The CO meter figures
CO₂ is naturally present in the air in an approximate proportion of 420 ppm (420 parts per million, or what is the same 420 parts of CO2 per million parts of air).
The trick is in control how many parts per million CO₂ we have at all times and ventilate when that number reaches a certain figure, which we consider too high, and continue to ventilate until that value drops again around 420 ppm.
And what is that magic number, or from how many parts per million of CO₂ do we have to ventilate?
There is no magic number, but we can use some standards to help us understand when the number is too high. The maximum CO₂ concentration recommended by the WHO for healthy environments is 1000 ppm. As a general rule, a concentration of CO₂ less than 800 ppm is considered adequate, although the ideal is that it should be closer to 500 ppm.
RITE regulations in educational centers
To have an idea of what the standards on air quality indicate, we can take as an example the regulations for educational centers.
In Spain the main regulatory framework on indoor air quality is the Regulation of Thermal Installations in Buildings (RITE), which classifies air quality into 4 categories: IDA 1, IDA 2, IDA 3 and IDA 4 (for its acronym of English “indoor air”).
- EDUCATIONAL CLASSROOMS, IDA category 2 (good quality air) is required to which the RITE assigns a limit value of +500 ppm on the CO₂ concentration of the outside.
- NURSERIES the requirement is increased to IDA 1 (optimum quality air) to which the RITE assigns a limit value of +350 ppm on the CO₂ concentration of the outside.
Examples and actual figures of CO₂ concentrations in a home
To better understand where these CO₂ values move, I am going to put you as an example my own house.
This graph corresponds to the concentration of CO₂ in the living room of my house on a Saturday in November (all closed tight due to the cold).
What can we see in this graph?
Basically that CO₂ levels are very high, and that they remain above the values recommended by the WHO almost all day.
- Despite the fact that, when the room is ventilated, around 2:00 p.m. and for half an hour, the CO₂ values fall close to 450 ppm, the zero air renewal causes the values to rise again quickly, reaching dangerous levels 2300 ppm.
- This day, the five members of the family (and the dog) have seen a movie on the projector in the living room, which explains this notable increase in CO₂ in the afternoon.
- It is clearly appreciated how the CO₂ has risen rapidly from 3:00 p.m. (when we have all gathered to eat).
Of course, the air quality in this room leaves a lot to be desired and is something I am going to work on. I'm going to have the home automation system (which has voice prompts in almost every room) announce alerts when the numbers get too high and do reminders that you have to ventilate at the best hours.
The data in the living room is taken with a Netatmo weather station, which has an indoor CO₂ sensor.
In the following graph you can see the CO2 data from my cave (my room of tinker):
This data is updated in real time, if you stay a while looking at it, you will see how each minute, approximately, a new measure appears.
Below I explain how you can create a graph like this, free and easily.
👁️🗨️ Homemade CO₂ meter structure
The CO₂ meter that I am going to describe it has nothing to envy to commercial units of several hundred euros, being superior in many cases, both for precision and functionalities.
It has the following characteristics, advantages and functionalities:
Economic. Less than 20 Euros
- High accuracy (50 ppm + 3% of reading)
- Connection Wifi
- Smart (can perform many tasks based on the data)
- Web server internal
- Integration with home automation system
- Publication of data on the internet
- Support of MQTT
- LCD display optional
The CO₂ meter with WiFi is composed of only two components, Low cost:
- NodeMCU module, with ESP8266 microcontroller with integrated WiFi
- CO₂ sensor MH-Z19B
Its construction, commissioning and use is very easy, I estimate that you can do this project in one or two hours. We just have to follow these steps to build our CO₂ meter with WiFi:
- Download the firmware from this website
- Record ESP8266 Microcontroller Module
- Connect CO₂ sensor MH-Z19B using only four wires
I have chosen low cost components to build the carbon dioxide meter, in order to keep the price very low.
Buying the components in the links that I propose in AliExpress, with shipping from China, the costs would be:
|MH-Z19B|| Some 18 Euros for the CO₂ sensor MH-Z19B in this AliExpress link. It is a store with many positive reviews and shipping is by AliExpress Standard Shipping, so you should have it at home in about two weeks. |
I recommend that you order the one with a range of 5000 ppm.
* I temporarily withdraw it until I find a better provider. See below for other options.
Be careful not to buy the MH-Z19C version for the moment because it might not be compatible. I'm working in it.
|NodeMCU|| Some 2 Euros from the plate NodeMCU with ESP8266 microcontroller in this AliExpress link. It also has many positive reviews and if you choose AliExpress Standard Shipping, which costs less than € 2, you should receive it in a couple of weeks. |
You will see that there are several models. I recommend that you ask for the one that says «CP2102«
There is a real avalanche of fake MH-Z19B sensors, both on AliExpress and Amazon. These sensors give measures very far from reality, in the best case.
I spend a lot of time checking purchase links that I put and trying to make sure, as much as possible, that they are original, but sometimes there are surprises.
If you want to play it safe, and you don't mind spending a little more, I suggest you use the sensor instead of the MH-Z19B Senseair S8 LP. In addition to being less likely to receive a fake one, it is a better quality than MH-Z19B.
I leave you here the link to which I bought. It seems original and it came to me very quickly (one week):
If you don't mind spending a little more, I recommend the sensor Senseair S8 LP.
Costs about 24 Euros in this AliExpress link.
It is a store with many positive reviews and shipping is by AliExpress Standard Shipping, so you should have it at home in about two weeks.
I bought it here. I arrive very fast (one week) and it seems original.
The maximum allowable voltage for this sensor, according to the manufacturer's data sheet, is 5.25 volts. In some cases (due to tolerances of the USB port used and the components) the voltage at the Vin pin of the NodeMCU could reach up to 5.55 volts, so I recommend that you have a measuring instrument to check it before connecting the sensor.
If you don't want to wait that long, you have the option of buying these components on Amazon, with fast shipping. It is more expensive, but if you want it quickly, you will have it at home in 24 hours.
- This MH - Z19 C02 gas sensor has high sensitivity, high resolution.
- Provides a variety of forms output modes, such as UART and PWM wave.
- Anti water vapor interference, no poisoning.
- Temperature compensated, excellent linear output.
- ⭐ Powerful Microcontroller: The AZ-Delivery Module is a powerful ESP8266 (ESP-12F) microcontroller with 802.11 b / g / n WLAN and integrated antenna.
- ⭐ Rapid Prototyping: It is simple to use, allowing you to easily create prototypes through simple programming through Lua code or Arduino code. Plus, with a motherboard-compatible design (28mm pin spacing).
- ⭐ Dimensions (L x W x H): 58mm x 31mm x 13mm.
- ⭐ Large storage and processing space: AZ-Delivery ESP8266 with Wi-Fi has large storage and processing space on board that allows it to integrate with application-specific sensors and devices and support minimal load during runtime. Boost your development in the fastest way combining with NodeMcu Firmware!
- ⭐️ Welcome to the AZDelivery family! Here you will find high-quality products for your Arduino and Raspberry Pi projects. We are pleased to offer you a series of application examples, comprehensive installation guides, E-Books, libraries, and personalized assistance. AZDelivery: Your Microelectronics Expert!
- ESP8266 CP2102 NodeMCU LUA ESP-12E WIFI serial wireless module.
- Efficient Microcontroller ESP8266 (ESP-12E) with WLAN 802.11 b / g / n and integrated 25dBm antenna.
- Built-in micro-USB, with flash and reset switches, easy to program.
- Convenient prototyping through simple programming by Lua-Script or Ar duino-Code and compatible Breadboard construction.
- Full I / O port and Wireless 802.11 compatible download, no reboot required.
Other purchase options:
Right now, when there are so many fake MH-Z19B sensors, the most advisable thing would be to buy it in the official store of the sensor manufacturer (Winsen), in this way you will have the security of receiving the original sensor.
The problem is that the manufacturer does not sell the MH-Z19B one by one, but it has to be two by two. So if you want to build two, or have someone who wants another, this may be a good option:
|MH-Z19B||2 CO₂ sensors MH-Z19B for about 36 Euros in which it says it is the official manufacturer store on AliExpress. |
Here you will have the sure to receive the original sensor, and not a copy.
I recommend that you order the one with a range of 5000 ppm.
Just missing a box.
As a box I propose four options:
- Leave it «in the air«. If it is going to be hidden, it is an inaccessible place, there should be no major problem.
- Put it somewhere ornamental element, any adornment or accessory that is in the room and that allows to hide and protect it.
- Buy one plastic box. I use one that I buy from 10 to 10 in several similar assemblies. Simple and cheap. You can find it here, although there are many similar ones. You can also use one of the gray boxes that are usually used in outdoor electrical installations, drilling it properly.
- A 3d printed box. It is the solution that I used. You can find the design and tutorial on this blog.
You have to consider two important things: You have to try keep the MH-Z19B as hot as possible because its measurements are sensitive to temperature and you have to install it so that it receives the air from the room without problems (Do not put it in a closed box or with little ventilation).
CO₂ sensor MH-Z19B
The MH-Z19B carbon dioxide gas sensor is a general-purpose, small-size smart sensor that uses the principle of non-scattered infrared (NDIR) to detect the presence of CO₂ in the air. It has good selectivity, long service life, and other characteristics, such as built-in temperature compensation.
It has simultaneous serial, analog and PWM output and is easy to use. It is a high-performance sensor that combines reliable infrared absorption gas detection technology with good design and an attractive price.
MH-Z19B sensor parameters
|Gas detected||Carbon dioxide|
|Operating voltage||4.5 ~ 5.5 V DC|
|Average current||<60m A (@ 5V supply)|
|Peak current||150 mA (supply @ 5V)|
|Interface level||3.3 V (compatible with 5V)|
|Measuring range||0 ～ 2000 ppm
0 ～ 5000 ppm
|exit sign||Serial (UART) - TTL level 3.3 V - PWM analog output|
|Preheating time||3 minutes|
|Operating temperature||0 ~ 50 ° C|
|Operating humidity||0 to 90% RH (non-condensing)|
|Dimensions||33mm × 20mm × 9mm (Length * Width * Height)|
|Lifetime||> 5 years|
|Gold-plated gas chamber, waterproof and corrosion resistant|
|High sensitivity, low power consumption|
|Temperature compensation, excellent linear output|
MH-Z19B Sensor Applications
|HVAC Refrigeration Equipment|
|Surveillance and air quality equipment|
|Fresh air systems|
|Air purification equipment|
|Schools and educational centers|
You can see here his datasheet.
The ESP8266 module
The ESP8266 module is a complete microcontroller on a small chip that includes Wifi and TCP / IP stack and is also very cheap.
|ESP8266 usually used mounted on a moduleas it does not include flash memory or USB and needs some external components to work.|
For this montage I have chosen the NodeMCU module why:
I could have chosen any other module, such as the very large and small ESP12E, but it would have complicated the assembly a lot, due to the additional components that would have been necessary and also its programming, as it does not have a USB port.
With the NodeMCU everything is much easier.
That said, there are other versions of the NodeMCU module, like the little Wemos D1 Mini, which you can choose. The assembly will be very similar, although you will not be able to use the instructions and photos on this page directly.
I have a Wemon D1 Mini around here, so if there are many requests, I will consider making a prototype with it to document it on the blog and take pictures.
✔️ Build the homemade CO₂ meter
Enough of introduction, explanations, data and verbiage and Let's go to the mess! To construction!
You have, below, a video with the entire detailed process, to make it easier for you.
The construction of the CO₂ meter, commissioning and use is very easy, I estimate that you can do this project in one or two hours. We just have to follow these steps to build our CO₂ meter with Wifi:
- Download the firmware from this website
- Record ESP8266 Microcontroller Module
- Connect CO₂ sensor MH-Z19B using only four wires
I find it a useful and quick project for the experienced hobbyist and a excellent first project for the newcomer to electronic gadgets. (Only four welds! Who gives more for less?)
Download the CO meter firmware
The first thing you have to do is download the program to your computer what then we will load in the NodeMCU and that it will control the operation of our CO₂ meter.
This program is based on the fantastic project ESPEasy, that I have been using for several years with very good results.
To simplify the task as much as possible, and that you do not have to search and download the different necessary programs and files (and find which are the correct ones to use, because there are many), you can download it from here with one click Y in one package that I have prepared and that it contains just what is necessary.
Below you can find the video with detailed instructions for the ESPEasy recording in the NodeMCU.
IF you have a board other than NodeMCU (4MB memory) you may have to download the complete package from the ESPEasy releases page on GitHub. This is necessary, for example, with the Wemos D1 Mini Lite board.
Connect CO₂ sensor MH-Z19B
Connecting the MH-Z19B sensor to the NodeMCU is very easy, it only requires four connections.
You will need to a soldering iron, tin and a pay a little attention, but it shouldn't take you more than 5 or 10 minutes, even if you have little experience in these matters, or be your first electronics project.
For connection of the MH-Z19B sensor to the NodeMCU, we will use the cable that comes with the MH-Z19B, cutting the connector on the end.
If your sensor is not the version that comes with a connector, nothing happens, you will need some cables to connect it.
Once we have cut the connector, we strip the cables and make the following connections (please note that this pin number does not match the manufacturer's):
|Pin MH-Z19B||Colour||Function||NodeMCU connection|
|1||Brown||Analog output||Without connection|
|3||Black||Negative power supply (GND)||Pin GND|
|4||Red||Positive feeding (Vin)||Pin Vin|
|5||blue||Data input (RXD)||Pin TX|
|6||Green||Data output (TXD)||RX pin|
Check that your sensor matches the connections and uses the same colors.
The user Joaquin tells us in the comments below (thanks Joaquin!), That the sensor he has received has the cables of other colors.
The manufacturer recommends that, when welding with a soldering iron, it be done at a temperature of (350 ± 5) ° C, and that the soldering time is 3 seconds maximum.
In the following images you can see the assembly process, including its connections, in detail:
Cut the CO2 sensor connector
In my case, I ordered the MH-Z19B sensor version with connector.
The first thing I do is, since the cable has a connector on both sides, cut the connector on one side.
Remove unnecessary cables
The connector comes with all seven wires attached.
Since we only have to connect four (Black, Red, Blue and Green), I remove the other three cables so they are out of the way.
Stripping the wires
We strip the end of the four cables.
It is enough to peel one or two millimeters. The shorter the "cleaner" will be when soldered.
We carefully solder the supply of the MH-Z19B sensor to the NodeMCU
- Red wire (positive) to terminal marked Vin
- Black wire (negative) to terminal marked GND
Solder the data cables
We solder the data input and output cables from the MH-Z19B to the NodeMCU
- Blue wire (RXD, data input) to terminal marked TX (data output)
- Green wire (TXD, data out) to terminal marked RX (data in)
This is how the wiring will be, once we have soldered the four cables.
The finished CO2 meter
Now it only remains to connect the sensor to the NodeMCU, being careful not to put the connector backwards.
This will be how our CO2 meter will look, once the four cables are soldered and the sensor connected.
We only need to place it in the box or in a place where it is protected (even if it is on air).
📺 Video with the complete CO2 Meter tutorial
🔵 Using the CO₂ meter
At this point, the CO₂ meter with Wi-Fi is finished. We only have to configure it, place it in the room we want to control and read the CO₂ data from time to time.
CO₂ meter setup with Wifi
The meter needs a basic configuration to function, which basically consists of: Setting up the Wi-Fi to connect it to our home network and tell ESP Easy which sensors it has connected (in this case only the MH-Z19B) and what to do with them.
ESP8266 Wifi Configuration
As soon as you record the ESP8266, and to facilitate the configuration of the Wifi, you will see that it creates an access point called ESP-Easy.
All we have to do is connect from our computer, tablet or telephone to that access point and configure the meter, in a very simple way, through a web page, thanks to the fact that the program that we have recorded in the ESP8266 includes a web server with the necessary pages for easy setup.
Configuration of the ESP8266 inputs and outputs
Through the same web page that we have used to configure the Wifi connection, we can now configure the inputs and outputs of the ESP8266 to tell you what's connected.
In our case, the only thing our ESP8266 has connected is the MH-Z19B sensor and we are going to configure it so that it knows how to read the values that this generates and what to do with them.
As you will discover, it is very easy to expand the project to include other sensors and actuators as temperature and humidity sensors, LCD screens, etc. We can even make our circuit control the air conditioner of the room.
Reading the CO₂ data from our meter
Our CO₂ meter with Wifi is already working, reading the CO₂ data from the air in the room where we have placed it and processing that data.
To read and process this data we have many possibilities that will allow us to read the CO₂ value directly and do many other things, such as store them, create graphics, create alarms of various types when certain values are reached, integrate them with our home automation system and much more.
The most basic use is see the CO₂ present in the room in real time. For that we only have to connect to a meter web page, with the web browser of our computer, tablet or mobile phone and access the "Devices" tab, where we can see the existing value at that very moment. The most recommended is save this page to our favorites, for access it easily and directly whenever we want.
Benefits of this CO₂ meter project
There are several projects similar to this on the internet. From small basic prototypes with the basic functionalities to obtain local CO2 measurements to complete systems that include all kinds of functionalities, proprietary software platform for capture and visualization, mobile app, etc.
I am going to present here what I think are the main advantages and benefits and the advantages From this project of CO2 meter.
Reliability of measurements
What a CO₂ meter has to do, as obvious as it may seem, is to measure and CO₂, and do it with a certain precision (that you know how much CO₂, there is with enough precision), reliability (that the meter works correctly at all times) and repeatability (always measure the same thing under the same conditions).
There are many projects that promise to measure CO2 but actually use electrochemical sensors of general use for the detection of organic volatiles that do not measure only CO2, but all those gases together, so you really don't know what you are measuring.
There are, for example, many "CO2 meters" using sensors like the MQ-135 or the CCS811, but these sensors they are not used to measure CO2. These sensors measure all organic gases together (Ammonia, Nitrogen Dioxide, Alcohol, Benzene, Carbon Dioxide and Monoxide, smoke, etc.), so if there is someone who is throwing hydroalcoholic gel or someone smoking or there is a source of combustion, such as a fireplace, the measurements will trigger without the possibility of knowing what is causing them to shoot.
The project that I present here uses an NDIR sensor that only measures CO₂. The same sensor used in commercial meters for hundreds of euros. When we obtain a measure we will know that that measure it is from CO₂ and not from other gases, which may not interest us.
Ease of construction
In many projects that are online, we see that they are relatively complex to build, with many components and welds. Sometimes it is necessary to have measuring instruments to make adjustments.
This project has been designed to be exceptionally easy to build and is within reach of anyone with no knowledge of electronics. You only have to make four connections and it does not require measuring instruments or adjustments of any kind.
Ease of programming
Many of the projects that we find on the internet are complicated to program. It is even necessary to have programming tools, such as compilers, IDEs, or specific editors.
Also in many projects we have to edit configuration files by hand, which makes it difficult for the non-expert user.
In this project, no need to program anything. Everything is pre-programmed and all you have to do is record the supplied program, which you can download from this page, in NodeMCU with a very simple process, following the video that I have prepared.
Easy to set up
Many projects have very complicated configuration processes, for non-experts, in which it is necessary to modify multiple parameters, in many cases modifying parameter files by hand or even the source code of the program before loading it into the meter.
In this project, all the configuration is done very easily, through a web page. No need to edit files by hand or modify code.
Easy to calibrate
Many projects, especially those based on sensors like the MQ-135 and the like, need tedious and very complicated calibration processes, which sometimes have to be repeated daily.
This project does not require any type of calibration. The sensor comes already factory calibrated and then I know autocalibrate him alone periodically.
Expandable modular design
Most existing designs on the internet have certain functionalities and these are what they are. It is not possible to reduce or expand the design without making changes to the electronics and, above all, programming.
This project is completely modular and expandable no need for programming changes nor in the basic circuit. We can start with a basic CO₂ meter and later expand it, in a very simple way, with different types of screens, LEDs, additional sensors (such as temperature and humidity), etc.
Communications and integration
That the CO2 meter can communicate with the outside and send its data (and even receive it) is very useful on many occasions. In most projects available on the internet, either the meter you have no possibility of communication, or your possibilities are very limited.
This project, on the contrary, has some huge communication possibilities that allows you to send data to virtually any device or system, without making any changes to your programming, supporting most possibilities like MQTT, HTTP, Telnet, UDP, P2P, etc.
In most projects the possibilities to consult the data are very limited. Being necessary to do major changes in your design or programming to be able to add new display options.
In this project, we can visualize the data, both in real time and historical, very easily in multiple ways: integrated web page, screens of various types, multi-color LEDs, mobile app, historical graphics on cloud platforms such as Thinkspeak, etc..
On many occasions it is interesting to know the CO2 concentration or historical remotely.
With most devices that we find on the internet this would be impossible or would require important changes in your programming.
With this project this is very simple, being able to consult from the mobile, at any time and from anywhere in the world, current and historical measurements.
Most projects offer real-time measurements, but do not have any data persistence system, to be able to store measurements for later analysis or integration into other systems.
This project allows, in addition to the easy use of cloud services (such as Thingspeak, IFTTT and similar), the storage of measurements in your 4Mb SPIFFS internal memory, databases like InfluxDB (both local and remote) and even the recording data to SD card for long-term non-connectivity operation.
Portability and mobility
Sometimes it is interesting to be able use the CO2 meter portable or on the move. Most of the existing projects on the internet do not contemplate this possibility.
This project contemplates the permanent configuration of two wifi networks, so that if the first is not available, the meter connects to the second automatically.
Not only that, but if we turn on the meter in a place where there is no Wi-Fi network that it has configured, It will automatically enable us a web page to which we can connect from the mobile to configure any other Wi-Fi network in a few seconds.
We can also configure the second wifi network so that use the internet connection that our mobile provides automatically.
In addition, being fed by a standard micro USB port, we can use a normal powerbank to run the meter on battery (based on my tests we can expect a autonomy of up to 48 hours depending on the powerbank we use).
I will also shortly publish a extension to equip our meter with internal lithium-ion battery (also called Li-Ion) with built-in charger.
🌀 Home CO₂ Meter Options and Extensions
The ESP8266 controller and the firmware it is based on are very powerful and we allows you to add endless possibilities.
Next, we are going to see some of the simpler possibilities that this carbon dioxide meter allows us.
These extensions are those that are explained in this blog and in my YouTube videos (some have been contributions that users like you have made to the blog), but you can easily make many more extensions yourself.
Add an OLED screen
In the following article you can see the step-by-step tutorial to add an OLED screen to the meter, in case you prefer to see the values easily, without the need for a mobile or computer.
Add a custom box
A custom box is the perfect complement to our meter. It will give a more professional finish and will protect the assembly from bumps and snags.
Add notices and audible alarms
You can easily add a buzzer and set alarms and warnings when certain CO2 levels are reached.
In this article you have a complete explanation with everything you have to do prepared to copy and paste.
Creation of CO₂ evolution graph
As a second example, we are going to create, in a very easy way, a graph with the evolution of CO₂ of the room, using the free cloud service from ThingSpeak like this:
ThingSpeak, from the Mathworks company, allows us to store the data from our sensors in the cloud for free and consult them from our mobile, tablet or computer.
Thanks to user ManeKoYou can see quick instructions in the comments below for sending data to ThingSpeak.
Prepare yourself a console
I have it ready to see the graphics of all the sensors on the mobile, and the truth is that it looks great.
- 65W SuperDart load
- Snapdragon 720G processor
- Sony 64MP Quad Camera
- 6.4 '' Super AMOLED Fullscreen screen
- Screen size: 6.4 inches
🛒 What if I want to buy a ready-made CO2 meter?
If, for whatever reason, you don't want to build your own homemade CO2 meter, you have the option of buying a commercial one. Plug and play.
There are many models on the market, but, I must warn you that many of them are worth absolutely nothing, in order to measure the concentration of CO2, because they have a type of sensor that is affected by all types of gases and the meter is not capable of distinguishing CO2 from any other gas (and there are many gases in the air that go and they come, so you'll never know if it's measuring CO2 or something else).
Whichever meter you buy, I recommend that you buy one that has an NDIR sensor (And keep in mind that, if it doesn't wear it, it probably won't wear it).
If you want a commercial meter that is not very expensive and that works well, I would propose one of these two options:
- Date, time, CO2, humidity, temperature (℃ / ℉ switchable) full color, 3.2-inch screen, and other data clearly.
- The application field of the carbon dioxide detector is public site, agriculture, animal husbandry, industry and more. With professional-grade detection technology, this CO2 meter has stable performance and high precision.
- You can store up to 999 groups of data and have a historical data trend table for you to review.
- Real-time CO2 monitoring by the high precision sensor, and it will alarm you once the CO2 exceeds the setting value.
- Compact size with portable storage, easy to operate and carry. The rechargeable lithium battery is included or can be powered via a 5V USB cable.
- Level of air quality, humidity, temperature and noise
- Tips on creating a healthier environment
- 3 profiles in the app: baby, person with asthma, general
- Real-time notifications (ios 9 or higher for iphone, ipad, ipod, android 4.2 or higher)
- Connect multiple healthy home coaches to your smartphone to control multiple rooms
I have this one down here that is very similar, but with some additional things that make it a weather station:
- Control your indoor and outdoor environment in real time: indoor and outdoor temperature, humidity and air quality, indoor noise level, barometric pressure
- Receive alerts in real time: with our weather station, configure indoor and outdoor alerts and receive notifications on your smartphone; you will know when to ventilate with the ventilation alert
- Access your data remotely and with your voice: access your weather measurements with ease and at any time from your smartphone, tablet or computer, or by using your voice to interact with alexa on amazon echo or with siri thanks to the compatibility with apple homekit
- Analyze the past: access the history of your data to observe what happens when you are not there or analyze the graphs to understand the weather trends
- Foresee the future: check the 7-day weather forecast to adapt your clothing and your outdoor activities
You also have the option to visit this CO2 meter buying guide.
📢 Do you have problems? CO2 meter faq
Although the project is really simple, there is always the possibility that you may have a question or that some kind of problem will appear.
Here are the most frequent questions asked by users who have been encouraged to build the CO2 meter.
📜 History of the eMariete CO2 meter
Here you can consult the articles that I have published over the years (since 2017 when I published the first prototype) related to the CO₂ meter.
In these articles you can find a lot of information to expand the meter, learn more, troubleshoot, etc.