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.
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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.

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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.

TD Systems K58DLX11US - 58 Inch 4K UHD Android 9.0 and HBBTV Smart TVs, 1500 PCI Hz, 3X HDMI, 2X USB. DVB-T2 / C / S2, Hotel Mode. Televisions
  • ✅ 58 Inch Led TVs. Resolution 3840 x 2160 pixels (Ultra HD 4K), and HDR10, energy efficiency A, Dolby Digital Plus sound, Smart TV.
  • ✅ Connections: 3x HDMI, 2x USB, composite video input, CI + common interface port, digital audio output, headphone output, RJ45 ethernet LAN port, Wifi, Bluetooth.
  • ✅ DVB-T2 / C / S2 digital tuner, with Hbbtv hybrid television system, suitable for all countries of the European Union. Second generation tuner. Product Notes
  • ✅ Smart TV with Android 9.0 (AOSP) operating system. CPU: Arm Corex A55 Quad Core at 1.1 GHz, GPU: Mali 470x3 at 600 Mhz. RAM: 1.5 Gb, and 8 Gb of storage.
  • ✅ Accessories: Remote control with batteries included. User manual and on-screen texts (OSD) in Spanish, English, French, German, Italian, and Portuguese.

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.

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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:

Bestseller No. 1
Tablet 10.1 Inch Android 10.0 Ultra-Portable Tablet - RAM 4GB | 64GB Expandable (Google gsm Certified) -JUSYEA - 8000mAh Battery - WiFi —Mouse | Keyboard and Others - Red
  • ULTRA STRONG PARAMETERS: Thank you for purchasing the JUSYEA tablet: Android 10.0 built-in original J5 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, built-in 8000mAh battery, only support wifi
  • THE MOST PRACTICAL APP: tablet supports 30 days of standby, 6-8 hours of continuous video playback, the latest Android 10.0 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: J5 tablet, 5V 2A European standard charger, 100mm Type-C data cable, capacitor pen, instruction manual, high-end protective case, Bluetooth keyboard, wireless mouse, Type-C adapter, protective film and service most important warranty
  • PRODUCT UPDATE: The J5 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 protective 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
SaleBestseller No. 2
Lenovo Tab P11 Pro - 11.5 "WQXGA Tablet (Qualcomm Snapdragon 730G, 6GB RAM, 128GB Storage, Android 10, WiFi + Bluetooth), Gray
  • 11.5 "WQXGA touchscreen, 2560x1600 pixels, OLED, 350nits, Dolby Vision, 100% sRGB, Glossy
  • Qualcomm Snapdragon 730G processor (8C, 8x Kryo 470 @ 2.2GHz)
  • 6GB LPDDR4x RAM (uMCP, DRAM), expandable up to 1TB
  • 128GB storage (uMCP, UFS 2.1) expandable up to 256GB with Fat32 memory, up to 1TB with ExFat memory
  • Integrated graphics card Qualcomm Adreno 618 GPU
SaleBestseller No. 3
Huawei Mediapad T5 - Tablet (Wi-Fi, Full HD Screen, 32 GB of Internal Memory (Expandable), 2 GB of RAM, 5100 mAh battery), Color Black
  • 25.6 cm (10.1 inch) IPS FHD display with Eye-Care mode.
  • 5 megapixel main camera and 2 megapixel front camera.
  • 32 GB of internal memory, 2 GB of RAM.
  • Expandable memory up to 256 GB via microSD card.
  • Powerful battery with 5100 mAh (typical value) and 4980 mAh (nominal value).
Bestseller No. 4
10 Inch YOUXD Tablet, 4GB RAM 64GB 3G Memory Android 10 Tablet Certified by Google GMS SIM TF, GPS WiFi Support (White)
  • 【UPDATED 10.0】 The latest 10.0 tablet operating system enjoys more powerful performance, and the system operation will be more smooth and stable, 4GB RAM 64GB ROM storage is enough to download more applications, photos, large files, songs , e-books, videos on the tablet at the same time. In addition, the tablet is super responsive, provides a more pleasant experience when browsing the web or watching programs excessively.
  • 【HD SCREEN】 10 '' widescreen offers you full enjoyment of digital device compared to phones that have limited screen. 1280 * 800 HD resolution brings you vivid image display that shows you more excellent details. With 4GB of RAM and a powerful quad-core processor, just enjoy your favorite apps like Netflix, Facebook, Hulu, Instagram, TikTok, and more.
  • 【EXCELLENT BROWSING】 The Android tablet supports 3G and WiFi network connection, allowing you to browse efficiently whenever you want. When you have a video call or voice call with your family, friends, in another scenario, you are having an online conference, 10 inch Android tablets always support your communication. The metal body creates a stylish appearance and a comfortable touch feeling.
  • 【ENTERTAINMENT DEVICE】 Featured with dual 5.0MP HD cameras on the front and 8.0MP on the rear, 10-inch Android tablets could take high-quality pictures just like your mobile phone does. Thanks to the HiFi quality speaker, Android tablets produce more natural and clear sound without noise while watching videos or playing games, you can also choose the game mode without distraction.
  • 【POWERFUL BATTERY】 The 8000 mAh large capacity rechargeable battery built into the tablet ensures long playing time. It only takes 3 hours for a full charge, a full charge supports 10 hours of talk time, 3-5 hours of movie time. You do not need to charge your tablet frequently and you are free to purchase endless entertainment: movies, TV episodes, e-books, songs and games.

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.

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

  1. 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

    • Edito :: Reviewing the blog, I have seen some instructions in the entry so I'll try to see what I can do.

      Thank you.

      • Hello Alberto.

        I'm glad you found the instructions to send the data to Thingspeak.

        The differences between the measurements of the MH-Z19B and the Senseair S8 LP are not great, both sensors measure quite well. The Senseair S8 LP is faster at detecting changes.

        For any questions you have, I will be happy to give you a hand. The best is through Telegram group:

        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.


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