What is a carbon dioxide sensor?

A carbon dioxide (CO2) sensor is a device used to measure the concentration of carbon dioxide gas in the atmosphere. It is measured in "parts per million" (ppm) and typically around 400 ppm is present.

Carbon dioxide, a colorless and odorless gas, has long been considered one of the main "greenhouse" gases affecting Earth's atmosphere. This gas, along with methane, nitrous oxide and fluorinated gases, forms a barrier in the upper atmosphere, allowing heat to be retained. This leads to higher temperatures, rising sea levels and changes in land use.

Carbon dioxide is produced during respiration, combustion and decomposition of organic matter and is also present indoors. This is a result of CO2 in the outside atmosphere and carbon dioxide produced in the human body.

How does a carbon dioxide sensor work?

Carbon dioxide can be detected and measured by different techniques, including non-dispersive infrared (NDIR) monitoring the absorption of infrared light at a specific wavelength (4.3 μm), which strongly absorbs CO2. If the infrared light is absorbed, CO2 is present, and non-absorption indicates a lack of CO2. The more infrared rays absorbed, the higher the CO2 concentration.

Photoacoustic spectroscopy subjects a sample to pulses of electromagnetic energy specifically tuned to the CO2 absorption wavelength. With each pulse of energy, CO2 molecules in the sample are absorbed by the photoacoustic effect and generate pressure waves. These pressure waves are then detected by an acoustic detector and converted into a usable CO2 reading by a computer or microprocessor.

Electrochemical carbon dioxide sensors measure electrical current to determine how much carbon dioxide is present in the air. When CO2 enters the sensor, it chemically reacts on the polymer surface, creating an electrical charge. The type and amount of charge is then used to determine how much CO2 is present. NDIR CO2 sensors have performance advantages over other detection technologies due to the long-term stability, accuracy, and low power consumption of CO2 measurements.

3 benefits of using a CO2 sensor

By collecting and analyzing monitoring data from CO2 sensors, companies can quickly and efficiently identify potential buildup of CO2 in their offices and indoor spaces. Combining sensors with demand-controlled ventilation (DCV), companies will be able to automatically adjust airflow in offices in response to CO2 concentrations over time. This both provides a better working environment and saves energy since the ventilation system will only run when needed.

The three main benefits of using sensors to measure CO2 levels and ventilating accordingly are:

1) Healthy and safe working environment, carbon dioxide concentration is controlled within an acceptable health range, less than 1000ppm

2) Productivity increases as effects of elevated CO2 levels on cognitive skills are demonstrated

3) Energy savings through optimal use of the ventilation system