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

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.

Televisions Smart TV 58 Inch 4k UHD Android 9.0 and HBBTV, 1500 PCI Hz, 3X HDMI, 2X USB. DVB-T2 / C / S2, Hotel Mode - TD Systems K58DLX11US TVs
  • ✅ 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:

Introducing the Fire TV Stick Lite with Alexa Voice Remote | Lite (without TV controls), HD streaming, 2020 model
  • 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 Eurosport, ITV Hub, Sky News 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:

Bestseller No. 1
Huawei Mediapad T5 - 10.1 "FullHD Tablet (Wi-Fi, 2GB RAM, 32GB ROM, Android 8.0, EMUI 8.0), Black Color
  • 10.1 inch IPS FullHD touch screen with 1920 x 1200 pixel resolution and Eye-Care mode.
  • Metal body, elegant design, 460g, 7.8MM.
  • 2GB of RAM, 32GB of storage expandable up to 256GB via microSD card (not included), long battery life with 5100 mAh.
  • 5 megapixel main camera and 2 megapixel front camera.
  • Android 8.0+ and EMUI 8.0 Operating System
Bestseller No. 2
SAMSUNG Galaxy Tab A 7 | 10.4 "FullHD Tablet (WiFi, Octa-Core Qualcomm Snapdragon 662 Processor, 3GB RAM, 32GB Storage, Upgradable Android) - Gray Color [Spanish version]
  • 10.4 "FullHD touch screen with a resolution of 2000 x 1200 pixels
  • Qualcomm Snapdragon 662 processor, Octa-core
  • 3GB RAM, 32GB storage with microsd slot expandable up to 1TB
  • 8MP rear camera
  • 7,040mAh battery with 15W fast charge and upgradeable Android operating system
Bestseller No. 3
10 Inch YOTOPT Tablet, 4GB of RAM and 64GB of 4G LTE Memory Android 9.0 Tablet Certified by Google GMS Dual SIM and TF, GPS WiFi Support (Gold)
  • 【Advanced System】 Android 9.0 is licensed by Google GMS. It works better, faster and more secure than other systems. You can download all Android Apps, for example, outube, Netflix, Instagram and games etc ...
  • 【Powerful Networks】 4G and Wifi. It has two SIM card slots. You can call by phone or connect online wherever and whenever you want.
  • 【Large Memory】 4GB RAM + 64GB ROM, you can download many App from Google Play. Besides, you can add more 128GB Micro SD card to save the songs, videos, photos and files. 5mp front camera and 2mp rear camera.
  • 【Powerful Features】 Powerful Quad-Core processor with power saving function and then multitask super fast. This way it is used more quickly and fluidly. It can be quickly connected to the keyboard and other devices via Bluetooth. And GPS equipped for traveling.
  • 【Pleasant Shopping Experience】 : Leather cases, keyboards, charger and OTG line all included. If the tablet has problems in a year, we will help you with the repair (not artificial damage). You can buy with confidence.
Bestseller No. 4
Blackview Tab8 Tablet 10.1 Inch Android 10 4G LTE 5G WIFI, 4GB RAM + 64GB ROM (TF 128GB), Octa-Core, 6580mAh Battery, Tablet with 13MP + 5MP Camera, 1920 * 1200, Dual SIM / Face ID / GPS / OTG / Bluetooth-Gray
  • 🚀 【Newest Android 10 system and 4GB RAM + 64GB ROM】 Equipped with Android 10.0, Tab8 offers more performance, works faster, and Google GMS certified system protects your privacy security, artificial intelligence provides higher speed to calculate and less energy costs. 4GB of RAM ensures the perfect functioning of the Android 10 system, and 64GB of storage (expandable up to 128GB with TF Card) allows you to store more games and documents
  • 📡 【DUAL SIM 4G LTE + WIFI and Octa-Core Processor】 Keep connection anywhere and anytime, simply, with sim card, you are ready to travel anywhere with Tab8. At the same time, the good tablet is with wifi connection support. The strong octa-core processor, with a maximum frequency of 1.6GHz, helps you maintain the best connection of both 4G LTE and Wi-Fi with advanced algorithm. In addition, it can be connected to a keyboard using a cable or bluetooth
  • 🔊 【10.1 inch Full HD and Stereo Speaker】 The digital tablet has a 10.1 inch full HD screen (1920 * 1200) displays high quality images anywhere. Dual speaker brings you cinema experience in your own home, two speakers give higher volume, you can share interesting videos with more friends. The brightness intensity is automatically adjusted according to the medium, together with the eye protection mode, brings you a comfortable viewing experience
  • 📷 【Fantastic 13MP rear + 5MP front camera】 Tab8 tablet has a 5MP front camera, offers you an incomparable experience for selfie, at the same time, the face unlock speed has gone up quite a bit thanks to that front camera. With the 13MP rear camera, you can achieve high-quality photos, the moments captured by the easy-to-use tablet will be your most vivid and unforgettable memory, and with the large 10.1-inch screen, you can edit the photos with all the details.
  • 🔋 【6580 mAh battery and 2 year warranties】 Tab8 large tablet has a large battery of 6580mAh, provides 8 hours of video and game, more than 20 hours for music, the Type-C interface, allows faster charging, And with the OTG function, data can be transmitted between different electrical products easily. With a 2-year warranty, you don't have to worry about potential problems. In addition, the box includes a protective cover
Bestseller No. 5
Goodtel Tablet 10 Inch Android 10.0, Equipped Octa-Core Processor 1.6Ghz Cores, 4GB Ram + 64GB ROM, Microsd 4-128GB / Dual Camera / WiFi / Android Tablet with Bluetooth Keyboard and Mouse -Red
  • [LATEST ANDROID SYSTEM] Our tablet is equipped with advanced Android 10.0 system, which is faster, better and more secure than other systems. GOOGLE Play is pre-installed, which has better application compatibility. You can download many apps from Google Play
  • [WORK AND STUDY] GOODTEL 10-inch tablet, beautiful appearance and comfortable hand feeling. The screen resolution is 1200 * 800, equipped with 2 front and rear cameras (5MP + 8MP), which support remote work, learning, games, and video viewing. Use Word, Excel, OneNote, Outlook, PowerPoint, Wps Office to save ideas, organize notes, and analyze data anytime, anywhere.
  • [EXCELLENT MEMORY] 4GB RAM + 64GB ROM, Bluetooth 4.0 function, 2.4Ghz WiFi. Provides faster application launch and smoother gaming experience. Supports 4-128GB Micro SD. You can add a Micro SD card to save songs, videos, photos and files.
  • [SATISFACTORY PRICE] Our tablet has good operating speed and compatibility, and the price is reasonable. If you buy our product. You will get 1x GOODTEL G2 tablet, 1x Bluetooth keyboard, 1x Stylus, 1x Mouse, 1x the audio headphones, 1x AC adapter, 1x OTG cable, 1x user manual, 1x dust proof cloth, 1x Type-C. There is a soft and thin protective film on the screen that can be torn off and The best gift for parents, relatives, friends.
  • [PLEASANT SHOPPING EXPERIENCE] GOODTEL has 15 years of design, production and sales experience as well as a professional customer service team. At the same time, our tablets have a 24-month after-sales service period, so that customers can shop more safely. Note: If you have any suggestions about the product and the shopping experience, please contact us as soon as possible, we will solve all the problems within 24 hours.

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.

3 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.


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