Reliable CO2 Measurement for Air Quality, Safety and Process Control

Carbon dioxide (CO2) is widely monitored as an indicator of indoor air quality, ventilation efficiency and process conditions. Accurate CO2 measurement supports occupant comfort, energy optimization and safety across commercial, industrial and transportation environments. Alphasense CO2 sensors use non-dispersive infrared (NDIR) technology to deliver stable, selective, and long-life CO2 measurement.


Sensor Product Overview


Fixed and Portable Instruments


  • IRC-A1 – NDIR CO2 Sensor
    • The IRC-A1 is a compact NDIR CO2 sensor designed for general air-quality and environmental monitoring. Its optical measurement principle provides excellent selectivity to CO2 with minimal cross-sensitivity to other gases. The IRC-A1 is well suited for indoor air-quality monitors, HVAC controls and fixed installations requiring long-term stability.
  • IRC-AT – Temperature-Compensated NDIR CO2 Sensor
    • The IRC-AT builds on the IRC-A1 by integrating enhanced temperature compensation, improving accuracy across wider operating conditions. This makes the IRC-AT ideal for portable instruments or environments where temperature variation could otherwise influence CO2 readings.

Choosing the Right CO2 Sensor by Application


Indoor Air Quality & HVAC Control


  • IRC-A1 provides reliable CO2 tracking for ventilation demand control.
  • IRC-AT is preferred where temperature swings require additional compensation.

Portable Air-quality Instruments


  • IRC-AT supports stable readings in handheld and mobile platforms.

Process Monitoring & Enclosed Spaces


  • IRC-A1 | IRC-AT - both sensors provide selective CO2 detection without consumable elements.

Key Benefits Across the CO2 Sensor Portfolio


  • NDIR technology for long life and stability
  • Minimal cross-sensitivity
  • Suitable for continuous monitoring
  • Low maintenance compared to chemical sensors

Why OEMs Choose Alphasense


Alphasense CO2 sensors combine optical accuracy, robust packaging, and instrument-ready interfaces, allowing OEMs to deploy reliable CO2 monitoring with minimal calibration drift.

How NDIR CO2 Sensors Work


NDIR CO2 sensors determine gas concentration by measuring how much infrared (IR) light is absorbed by CO2 at specific wavelengths. For Alphasense IRC A-Series CO2 Sensors, each sensor integrates an IR source, an optical cavity, a dual-channel detector, and a thermistor. IR light emitted from the source travels through the optical cavity, where incoming gas diffuses freely. CO2 molecules absorb IR energy at their characteristic wavelengths. The dual-channel detector measures this effect using two filtered paths:

  • Active channel – passes only the CO2 absorption wavelength. When CO2 is present, less IR reaches this detector, producing a reduced signal.
  • Reference channel – passes a non-absorbing wavelength. Its signal remains unaffected by gas concentration.
By comparing the active and reference signals, the sensor compensates for changes in source intensity, contamination, and optical aging. The internal thermistor supports temperature compensation to maintain stable performance across environmental conditions.

This differential optical approach delivers a robust, drift-resistant measurement of CO2 concentration based on the Beer–Lambert absorption principle.

Why Measure Carbon Dioxide


CO2 levels are used to assess:

  • Indoor air quality and ventilation
  • Occupancy trends
  • Process efficiency
  • Safety in confined spaces

Select CO2 Sensor

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