Visual CO2 is a signaling device for the level of CO2 concentration in the air, using three light indicators. It also has temperature and humidity measurement that can be viewed through a mobile application. The design of the device generates a flow of air throughout the interior of the beacon through natural convection. Ambient air is captured through three holes located at the bottom, and circulates all the way through the interior until it comes out at the top.

Visual CO2 device (100-240 VAC adapter included)

Inside the base is the CO2 sensor that, using NDIR infrared absorption technology, allows the concentration in parts per million to be measured very precisely according to the amount of infrared light absorbed by the CO2 particles present in the air.

A microcontroller manages the sensor signals and controls the beacon lighting based on CO2 concentration levels.

CO2 concentration to lights relationship

These thresholds have been defined based on recent studies by various international organizations that relate the concentration of CO2 with the risk of transmission of COVID19:

  • Government of Japan: Monitoring carbon dioxide concentration in a room as an indicator of ventilation (link)
  • European Federation of Ventilation and Air Conditioning: How to operate HVAC and other building service systems to prevent the spread of the coronavirus (SARS-CoV-2) disease (COVID-19) in workplaces (link)
  • Government of the UK: Role of Ventilation in Controlling SARS-CoV-2 Transmission (link)
  • Harvard University: 5 Step guide to checking ventilation rates in classrooms (link)
  • Ministerio de Sanidad del Gobierno de España:  Evaluación del riesgo de la transmisión de SARS-CoV-2 mediante aerosoles. Medidas de prevención y recomendaciones (link)

Mobile app

Controlling the CO2 level allows, in addition to improving people’s comfort and health, optimizing energy consumption related to heating and cooling systems.

The device also measures ambient temperature and humidity, and has a wireless communication system that allows it to be connected to any mobile device that has Visual CO2 App installed, which can be downloaded for free.



The device has three modes of calibration settings:
– Manual calibration
– Auto calibration
– Permanent auto calibration

The selection of the operating mode is done by pressing a small button located inside the beacon, accessible from one of the holes in the base.

The first time the beacon is turned on, the operating mode will be auto calibration, and the device will start to function and measure normally.

Under normal circumstances, you do not need to do anything other than connect the device to the power.

Only if you want the highest precision, or if you notice any significant deviation in the measurements, you can proceed with one of the two calibration modes described.

Calibration mode selection and times