What Is a CO2 Sensor and How Does It Work?

A carbon dioxide (CO2) sensor is a device used to measure the concentration of carbon dioxide gas in the atmosphere.

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What Is a CO2 Sensor and How Does It Work?

What is a CO2 sensor?

carbon dioxide (CO2) sensor is a device used to measure the concentration of carbon dioxide gas in the atmosphere. 

It is measured using “parts per million” (ppm) and typically has a presence of around 400 ppm

Carbon Dioxide is an odorless and colorless gas, and it has long been identified as one of the key “greenhouse” gases that affect the earth’s atmosphere. The gas, alongside Methane, Nitrous Oxide, and Fluorinated Gases, creates a barrier in the upper atmosphere that causes heat to be retained. This results in increased temperatures, rising sea levels, and changes to land usage.

CO2 is created during respiration, combustion, and organic decomposition, and is also found indoors. This is a result of both external atmospheric CO2 and internal production from the presence of people. 

How do CO2 sensors work?

CO2 can be detected and measured through different technologies, including

  • nondispersive infrared (NDIR) monitors the absorption of infrared light at a specific wavelength (4.3 μm), a wavelength at which CO2 has very strong absorption. If the infrared light is absorbed, then CO2 is present, whereas non absorption indicates a lack of CO2. The more infrared light that is absorbed the higher the concentration of CO2.
  • photoacoustic spectroscopy subjects a sample to pulses of electromagnetic energy that is tuned specifically to the absorption wavelength of CO2. With each pulse of energy, the CO2 molecules within the sample will absorb and generate pressure waves via the photoacoustic effect. These pressure waves are then detected with an acoustic detector and converted to a usable CO2 reading through a computer or microprocessor.
  • Electrochemical carbon dioxide sensors measure electrical current to determine how much CO2 is present in the air. When CO2 enters the sensor, it chemically reacts within a polymer surface, resulting in an electrical charge. The type and amount of electrical charge is then used to determine how much CO2 is present.

NDIR CO2 sensors have performance advantages over other detection technologies due to long-term stability, accuracy, and low power consumption for CO2 measurement. 

Why are CO2 levels important?

High concentration levels in a confined or poorly ventilated environment can cause harmful reactions in people.

A recent study, as reported in Nature, has identified the following characteristics related to increased CO2 concentrations:

 

CO2 concentration in atmosphere (parts per million)

Duration of exposure

Adverse health outcomes associated with acute CO2 exposure

CO2 retention

1,000–5,000

<4 hrs

Inflammation

2,000–4,000

2 hrs

Cognitive effects

1,000–2,700

1–6 hrs

Adverse health outcomes associated with chronic CO2 exposure

Chronic, low-grade systemic inflammation

~3,000

13 days

Bone demineralization and kidney calcification

~2,000–3,000

60–90 days

Behavioural changes and physiological stress

700–3,000

13 – 15 days

 Additionally, other research shows the positive health and productivity benefits of controlling indoor CO2 levels in office environments. Some studies even show that working in an office with optimized CO2 levels, managed through intelligent ventilation, can increase productivity by 60%.

Finally, and more relevant recently, as a result of extensive research into the transmission of COVID-19, it has been shown that there is a correlation between the concentration of CO2 and aerosols, one of main the transmission pathways of viruses such as COVID-19 or influenza. By controlling the CO2 level indoors it is possible to manage the risk of virus transmission.

Clearly, these recent studies show that both short-term and long-term exposure to CO2 is extremely bad for health. Detection and reduction of this harmful gas are therefore critical for any healthy working environment.

The Disruptive Technologies Wireless CO2 Sensor

Disruptive Technologies Wireless CO2 Sensors make use of NDIR technology. The sensor can measure CO2 concentrations between 1 and 5000 ppm with an accuracy of ± 45 ppm.

In addition, the sensor has been combined with temperature, relative humidity, and barometric pressure sensors to offer a single form factor device that can monitor the status of typical environmental measures in an office.

The wireless CO2 sensor builds on DTs core market-leading sensor features, including

  • Long wireless range:
    • 100 m (330 ft) in a typical indoor environment
    • 2 km (6600 ft) line-of-sight
  • 10-year battery life (using two replaceable AA batteries)
  • Peel-and-stick mount for simple installation
  • Full compatibility with the Cloud Connector, which securely relays monitored data using  SecureDataShot™ technology, into the Cloud for processing

3 Benefits of Using a CO2 sensor

By collecting and analyzing the monitored data from the CO2 sensors companies can quickly and efficiently identify the potential build-up of CO2 in their offices and indoor spaces.

Combining the sensors with Demand Controlled Ventilation (DCV), a company will be able to automatically regulate airflow within the office to respond to CO2 concentrations at any given time. This both provides a better work environment but also saves energy as the ventilation systems will only be operating when needed.

The three key benefits of measuring CO2 levels with sensors and ventilating accordingly are:

1) a healthy and safe working environment with CO2 levels managed to be within the accepted and healthy range of less than 1000ppm

2) improved productivity as the proven impact on cognitive skills from elevated CO2 concentration is alleviated

3) energy-savings through optimized use of ventilation systems

Wrapping up CO2

Carbon Dioxide is a potentially harmful gas when present in elevated concentrations. Its detection and dispersal are essential to stop a number of unhealthy and productivity-reducing conditions for employees.

The early detection of rising CO2 levels, using IoT-based wireless CO2 sensors, allows an organization to respond quickly and to take preventative measures long before harmful levels affect employee health and wellbeing.

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