CO2 on a giant screen for bars, restaurants, classrooms and the like

Last modified March 19, 2021

There are many people who are looking for a CO2 meter with a large display that can be seen at a distance for installation in hospitality, schools, gyms and the like.

The truth is that the system is so flexible which, as you will see later, not only allows the creation of huge display panels (from 5 ″ mobiles to 7 ″ tablets, 12.9 ″ iPads to 100 ″ Smart TVs), but it is possible to create extremely small screens, like the floating window for teachers I teach below.

During this time I have realized various prototypes and experiments with different types of displays. I have used large seven segment LED displays, matrix panels, addressable panels, etc.

The problem I encountered was, on the one hand, the rigidity of the system (each person has different tastes and needs and it would have been necessary to adapt the system to many different types of hardware) on the other hand the construction difficulty and the cost.

Finally, I said to myselfWhy not take advantage of the fact that the CO2 meter has a complete integrated web server and take advantage of it to display it on all types of screens?

Said and done, I rolled up my sleeves, got to work and today I bring you the result ...

It is not finished yet, but I want you to open your mouth about what is coming.

My knowledge of CSS (I defend myself, but I have not mastered it) makes it go slower than I would like, and it gives me much more work than necessary.

If you have CSS knowledge and want to collaborate, write to me through the Telegram group, please. With a little help we can achieve something very, very attractive and interesting from which many people who need it can benefit.

CO₂ meter on monitor or TV

CO₂ benefits on the big screen

To be based on HTML, CSS, and JavaScript (web technologies)There are many benefits to be gained from this large screen display system.

Aside from the obvious benefit, which is possible view information remotely, we would have the following:

  • Great flexibility content and design
  • No investment. Needless nothing else than the home CO₂ meter of this blog (and the device where you want to view it, of course).
  • Adaptable to all types of devices (Phones, tablets, computers, Smart TV, etc.).
  • Design possibility responsive (self-adaptation to the display device).
  • Multiple simultaneous clients.
  • possibility of integrate other sources of information.
  • Complete freedom to choose colors, sizes, fonts, etc.
  • System completely autonomous (does not need internet connection to work)
  • No library dependencies like jQuery or others.
  • Customizable logo (I take everything) easily.
  • Possibility of defining multiple pages with different layouts.

Large screen CO₂ meter capabilities

Although, at the moment, it is only a prototype (soon I will publish instructions and the necessary files, on this same page, so you can do it too), the display system already has the following functionalities:

  • Display of any parameter CO₂ meter (such as temperature and humidity, in these examples).
  • Real-time display without reloading the page.
  • Display of historical charts (from Thingspeak or others).
  • Color change, according to the CO₂ level (traffic light effect) with user adjustable levels.
  • Possibility of viewing external data.

Of all of them, which will be good for one or other people, I think that the most interesting and useful for everyone is that the display always shows the current CO₂ value. You do not need to reload the page or press any button to have the data of that moment.

Display devices

There are many devices in which the visualization of CO2 is possible. Whether you need a small autonomous system, with a tablet, for example, for medium-sized spaces such as a Large format TV, for large venues, you always have a choice.


The tablet is the quintessential display device.

There are really cheap Android tablets, even older tablets, that you may no longer use, and that you can use for this by giving them a new youth.

They are ideal to put them fixed on the wall with some kind of support, like this:

Dockem Koala Mount Tablet Wall Mount: No-Damage Universal Wall Station for iPads, iPad Airs, Pro, 9.7, Galaxy Tab / Note and Other Tablets (Black version)
  • DAMAGE FREE INSTALLATION AND REMOVAL: Installs in less than 2 minutes using 3M Damage Free Command Strips (included) that are rated to hold up to 2.25kg each; no need for screws or holes; designed for use on flat, smooth surfaces (screw-in versions, Koala Mount with screws and Koala Mount 2.0 sold separately)
  • UNIVERSAL: Uses 2 separate brackets that can be set to any distance required by your device, allowing full width compatibility. This includes iPads 1, 2, 3, 4 and the New iPad 9.7, Pro, Air, Air 2, most Samsung tablets, and many more. The brackets will fit any device 11mm thick or less. It can be used with protective covers as long as its thickness is less than 11mm.
  • SIMPLE: Super easy donning and doffing, can be set to portrait or landscape mode. No need for extra accessories; no special covers or add-ons are required on your tablet. Full access to ports / buttons on devices larger than 7-8 '' may work better with our Koala Mount 2.0. Pre-installed cable clips to help keep your cable tidy.
  • MOUNTING: Comes with 3M Regular Command Strips that are not designed to function in areas exposed to high temperatures or humidity (such as the bathroom). For this, 3M manufactures special water and heat resistant strips. Also, Command Strips tend not to work well on textured surfaces and some papers. We highly recommend taking our Endurance Test. Command Strips are not reusable after being removed.
  • NOTE ON COMPATIBILITY: While it fits most popular tablets, the mounts can lock ports / buttons on both sides between 3.8cm and 9.5cm from the bottom (7-8 '' tablets like the iPad Mini may have ports blocked in landscape mode - if this is your case you can see our Koala Mount 2.0).

Smart tv

Most of the Smart TV of recent years support HTML, CSS and JavaScript (internet technologies) so it will be very easy to use them as a CO₂ display device.

This is a perfect solution for really big rooms in which we need the information to be seen from all points.

We can put a SmartTV of 4K and 58 ″, for relatively little money that it will be seen from far away.

Normal TVs (with the help of, for example, an Amazon Fire TV Stick)

If you have a slightly old television, or any monitor with HDMI input, you can use it to display CO₂ levels using, for example, a Fire TV Stick:

Fire TV Stick Lite with Alexa voice control | Lite (without TV controls), HD streaming
  • Our most affordable Fire TV Stick: fast streaming and Full HD quality. Comes with the Alexa voice control | Lite.
  • Press the button and ask Alexa: use your voice to search for content and start playback in multiple apps.
  • Thousands of apps, Alexa skills, and channels, including Netflix, YouTube, Prime Video, Disney +, DAZN, Atresplayer, Mitele, and more. Subscription charges may apply.
  • Amazon Prime members have unlimited access to thousands of movies and series episodes.
  • Live TV: Watch live TV shows, news and sports with subscriptions to DAZN, Atresplayer, Movistar + and more.

Teams of teacher, monitor, supervisor, etc.

Not everything is giant screens. Sometimes the essence comes in a small bottle.

Sometimes it is important that the teacher, monitor, supervisor, etc. have a chance to see permanently the CO₂ level in the environment.

In this picture (Bottom right) you can see as a small window "fleet" on the teacher's computer above what he is doing, allowing you to view the CO₂ level at all times. The teacher can drag the window to move it around, resize it and of course, hide it.


As with everything, this system also has its limitations.

These are the ones I know so far (if you discover another, let me know to include it).

  • Low security: Not valid if you want to show "sensitive" data. It is intended for public data, so you do not care if someone, in any way, connects and gets it.
  • Concurrent users: The microcontroller used in the CO₂ meter (ESP8266) is not a real web server, so it will not support many connections at the same time. I have tried it with four simultaneous connections and it works, but I don't know how many it would last. This is intended to connect a few display devices, not a lot of people to connect to the CO₂ meter directly.

Display examples

I will leave you here some examples of what I'm doing, to give you the idea:

Recommended tablets

Almost any tablet should do as a display device. Logically there are so many models that it is difficult to know a priori if any of them will not work for some reason.

Most importantly, when used as a display device is that the tablet is able to be turned on and charge simultaneously. Almost all do, but not all, I, for example, I have one that, even though it's plugged in, consumes more than it charges, so after a few hours it turns off.

I recommend that you buy your tablet on Amazon, where you can return it and exchange it for another if it does not work, without any problem.

Here are some of the best-selling tablets from Amazon:

SaleBestseller No. 1
Lenovo M10 FHD Plus- 10.3" Full HD/IPS tablet (MediaTek Helio P22T, 4 GB RAM, 64 GB expandable up to 256 GB, Android 9, Wifi + Bluetooth 5.0), Gray
  • 10.3" FullHD (1920x1200) TDDI 330nits touchscreen display
  • MediaTek Helio P22T processor (8C, 8x A53 @ 2.3GHz)
  • 4GB Soldered LPDDR4x RAM memory
  • 64GB storage expandable up to 256GB
  • Integrated graphics card Qualcomm Adreno 505 GPU
SaleBestseller No. 2
Tablet 10.4 Inch Android 11, 8GB RAM 128GB ROM Tablet PC TECLAST T40Pro with Octa-Core 2.0 GHz,8MP+13MP,FHD Screen Resolution 1200x2000(4G LTE Dual SIM and TF 512GB,Bluetooth 5.0,Battery 7000mAh).
  • 10.4 inch tablet and metal body:Tablet 10.4 inch with 2000 x 1200 resolution combines TDDI and T-color technology to enhance the color and detail of images. Metal body combined with sandblasting process makes it look more elegant and feel more comfortable. Using 12nm process, it can effectively reduce heat generation while maintaining high performance.
  • Android 11 and octa-core processor :Tablet comes with Android 11 pre-installed, giving you more control over your privacy and data. You can control the permissions you want to share with apps on your phone, preventing information leakage and also facilitating daily operations. Tablet is equipped with UNISOC T618 processor,the highest frequency of the tablet is 2.0GHz, providing great performance for video, work or games.
  • 8GB RAM 128GB ROM:TECLAST T40 Pro Tablet comes with 8GB RAM to offer you an outstanding multitasking experience. High-speed storage of 128GB your large-scale games and audio-visual works can be stored at will.Listening to music and watching videos can bring you more An experience like being on the spot.In addition, the tablet supports 512GB TF cards to expand the storage capacity.
  • 8MP+13MP HD Camera:T40 Pro Tablet has HD Camera an 8MP front camera and a 13MP rear camera to capture your precious moments and share them with your friends in video chats.Tablet features four speakers with a sweet unobstructed sound chamber and a separate smart amplifier chip for even better sound quality.
  • Fast Charging and Stable Connectivity: Tablet In addition to the large 7000 mAh battery, the tablet also adds 18W USB-PD fast charging protocol, which makes the tablet last longer and charge faster. High-speed dual-band Wi-Fi and Bluetooth 5.0 low energy for fast fun.
Bestseller No. 4
Samsung Galaxy Tab A8 - Tablet de 10.5”, 64GB, Wifi, Android, Color Gray (Versión Española)
  • From epic movies to tutorial content to pass the time in style, the Galaxy Tab A8 invites you into a wider world with its larger and improved field of view.
  • Built to deliver an immersive experience, the Galaxy Tab A8 opens up an immersive universe of content, games and activities for even the youngest users.
  • Con el procesador de ocho núcleos emparejado con hasta 4 GB de RAM y hasta 64 GB de almacenamiento interno, la Galaxy Tab A8 viene siempre lista para asumir cualquier desafío sin ralentizar la velocidad o agotar la batería.
  • With Samsung TV Plus, you get free, instant TV anytime, anywhere. Enjoy thousands of hours of news, sports, movies, and a wide variety of content.
  • Enjoy immersive sound thanks to its quad speakers with Dolby Atmos technology
Bestseller No. 5
Tablet 10.1 Inch Android 10.0 - RAM 4GB | 64GB ROM - WiFi - Octa Core (Google GMS Certified) - JUSYEA Tablet - 6000mAh Battery - Cover (Black)
  • ULTRA STRONG PARAMETERS: Thank you for purchasing the JUSYEA tablet: Android 10.0 built-in original J6 ecosystem, 10-inch large glass screen G + G process and support 1280 * 800 pixels, with eMMC technology support 4GB RAM + 64GB ROM ( 4-128GB Micro SD card support) 5.0 + 8.0MP dual camera, 6000mAh built-in battery, only support wifi
  • THE MOST PRACTICAL APP: tablet supports 30 days standby, 6-8 hours continuous video playback, the latest Android10.0 tablet supports all GOOGLE Play Store applications to download (supports weather, video, games, beauty, education, etc.). You can use the tablet more conveniently and quickly anywhere, while also being your best companion for office, Internet browsing, home rest, travel - Netflix Support
  • YOU HAVE MORE - JUSYEA 10-inch tablet is your best choice. More for you: J6 tablet, 5V 2A European standard charger, 100mm Type-C data cable, capacitor pen, instruction manual, high-end protective case, corded earphone, Plastic protective film (non-tempered film) and the most important warranty service
  • PRODUCT UPDATE: The J6 tablet uses a Type-C interface to maximize charge protection and service life. To prevent the screen from being scratched and damaged during transportation, the tablet has two layers of Plastic Protective Film (non-tempered film) on the screen. When you receive the tablet, you can tear off the first layer. And use gift box packaging, the tablet is very suitable to send your loved ones, teachers, children and lovers as gifts
  • THE BEAT SERVICE: JUSYEA has been processing and designing for more than 10 years. For products sold online in Europe, we have the best customer service staff and the best support from software and hardware engineers. At the same time, you will enjoy 1 + 1 year of VIP service. If you have any questions, please contact our staff without hesitation. We will serve you until you are satisfied. JUSYEA is worth your purchase

If you use any tablet that is sold on Amazon (whether it is included in this list or not) tell me, with the results obtained, to be able to advise users.

6 thoughts on “El CO2 en pantalla gigante para bares, restaurantes, aulas y similares”

  1. Hello, how is this project going? I would like to be able to test it for my place.
    It seems to me that they are going to make it mandatory.
    I have asked the pieces to go assembling it. I'll give you the ember with my problems 🙂

    A greeting.

  2. Hello! Please can you publish at least the basics to be able to view the data on a tablet? Even if it's just the real-time value! Thank you very much for the work !! All the best

    • Hi Jordi.

      We are just picking it up, with the help of comrade Sey. Let's see if we can give it a good push and can publish it shortly.

      A greeting.

  3. Hello,

    Lately I follow your blog day by day. I am a teacher and I am about to start the CO2 meter project, with students. From what you see in an image, it seems that you use Thingspeak to publish the sensor readings, I have tried but I have not been able to achieve it, I just discovered ESPeasy and I still do not understand the platform, nor MQTT. However, with Arduinoblocks I have had no problems. Could you tell me a tutorial to connect to Thingspeak? I don't think I have a problem if it's in English.
    I have also observed in the video about MH-Z19B that there doesn't seem to be much difference between the results of the original MH-Z19B and the reference Senseair, right?
    Greetings, and thank you very much for all the work you do and show us.
    Thank you


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